Add m-esr52 at 52.6.0

245 files changed, 59965 insertions, 0 deletions

diff --git a/dom/bindings/AtomList.h b/dom/bindings/AtomList.h
new file mode 100644
index 000000000..53765e101
--- /dev/null
+++ b/dom/bindings/AtomList.h
@@ -0,0 +1,27 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_AtomList_h
+#define mozilla_dom_AtomList_h
+
+#include "jsapi.h"
+#include "mozilla/dom/GeneratedAtomList.h"
+
+namespace mozilla {
+namespace dom {
+
+template<class T>
+T* GetAtomCache(JSContext* aCx)
+{
+  auto atomCache = static_cast<PerThreadAtomCache*>(JS_GetContextPrivate(aCx));
+
+  return static_cast<T*>(atomCache);
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_AtomList_h
diff --git a/dom/bindings/BindingDeclarations.h b/dom/bindings/BindingDeclarations.h
new file mode 100644
index 000000000..c712511ab
--- /dev/null
+++ b/dom/bindings/BindingDeclarations.h
@@ -0,0 +1,535 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A header for declaring various things that binding implementation headers
+ * might need.  The idea is to make binding implementation headers safe to
+ * include anywhere without running into include hell like we do with
+ * BindingUtils.h
+ */
+#ifndef mozilla_dom_BindingDeclarations_h__
+#define mozilla_dom_BindingDeclarations_h__
+
+#include "js/RootingAPI.h"
+#include "js/Value.h"
+
+#include "mozilla/Maybe.h"
+#include "mozilla/RootedOwningNonNull.h"
+#include "mozilla/RootedRefPtr.h"
+
+#include "mozilla/dom/DOMString.h"
+
+#include "nsCOMPtr.h"
+#include "nsStringGlue.h"
+#include "nsTArray.h"
+
+class nsIPrincipal;
+class nsWrapperCache;
+
+namespace mozilla {
+namespace dom {
+
+// Struct that serves as a base class for all dictionaries.  Particularly useful
+// so we can use IsBaseOf to detect dictionary template arguments.
+struct DictionaryBase
+{
+protected:
+  bool ParseJSON(JSContext* aCx, const nsAString& aJSON,
+                 JS::MutableHandle<JS::Value> aVal);
+
+  bool StringifyToJSON(JSContext* aCx,
+                       JS::Handle<JSObject*> aObj,
+                       nsAString& aJSON) const;
+
+  // Struct used as a way to force a dictionary constructor to not init the
+  // dictionary (via constructing from a pointer to this class).  We're putting
+  // it here so that all the dictionaries will have access to it, but outside
+  // code will not.
+  struct FastDictionaryInitializer {
+  };
+
+  bool mIsAnyMemberPresent = false;
+
+private:
+  // aString is expected to actually be an nsAString*.  Should only be
+  // called from StringifyToJSON.
+  static bool AppendJSONToString(const char16_t* aJSONData,
+                                 uint32_t aDataLength, void* aString);
+
+public:
+  bool IsAnyMemberPresent() const
+  {
+    return mIsAnyMemberPresent;
+  }
+};
+
+// Struct that serves as a base class for all typed arrays and array buffers and
+// array buffer views.  Particularly useful so we can use IsBaseOf to detect
+// typed array/buffer/view template arguments.
+struct AllTypedArraysBase {
+};
+
+// Struct that serves as a base class for all owning unions.
+// Particularly useful so we can use IsBaseOf to detect owning union
+// template arguments.
+struct AllOwningUnionBase {
+};
+
+
+struct EnumEntry {
+  const char* value;
+  size_t length;
+};
+
+class MOZ_STACK_CLASS GlobalObject
+{
+public:
+  GlobalObject(JSContext* aCx, JSObject* aObject);
+
+  JSObject* Get() const
+  {
+    return mGlobalJSObject;
+  }
+
+  nsISupports* GetAsSupports() const;
+
+  // The context that this returns is not guaranteed to be in the compartment of
+  // the object returned from Get(), in fact it's generally in the caller's
+  // compartment.
+  JSContext* Context() const
+  {
+    return mCx;
+  }
+
+  bool Failed() const
+  {
+    return !Get();
+  }
+
+  // It returns the subjectPrincipal if called on the main-thread, otherwise
+  // a nullptr is returned.
+  nsIPrincipal* GetSubjectPrincipal() const;
+
+protected:
+  JS::Rooted<JSObject*> mGlobalJSObject;
+  JSContext* mCx;
+  mutable nsISupports* MOZ_UNSAFE_REF("Valid because GlobalObject is a stack "
+                                      "class, and mGlobalObject points to the "
+                                      "global, so it won't be destroyed as long "
+                                      "as GlobalObject lives on the stack") mGlobalObject;
+};
+
+// Class for representing optional arguments.
+template<typename T, typename InternalType>
+class Optional_base
+{
+public:
+  Optional_base()
+  {}
+
+  explicit Optional_base(const T& aValue)
+  {
+    mImpl.emplace(aValue);
+  }
+
+  bool operator==(const Optional_base<T, InternalType>& aOther) const
+  {
+    return mImpl == aOther.mImpl;
+  }
+
+  template<typename T1, typename T2>
+  explicit Optional_base(const T1& aValue1, const T2& aValue2)
+  {
+    mImpl.emplace(aValue1, aValue2);
+  }
+
+  bool WasPassed() const
+  {
+    return mImpl.isSome();
+  }
+
+  // Return InternalType here so we can work with it usefully.
+  template<typename... Args>
+  InternalType& Construct(Args&&... aArgs)
+  {
+    mImpl.emplace(Forward<Args>(aArgs)...);
+    return *mImpl;
+  }
+
+  void Reset()
+  {
+    mImpl.reset();
+  }
+
+  const T& Value() const
+  {
+    return *mImpl;
+  }
+
+  // Return InternalType here so we can work with it usefully.
+  InternalType& Value()
+  {
+    return *mImpl;
+  }
+
+  // And an explicit way to get the InternalType even if we're const.
+  const InternalType& InternalValue() const
+  {
+    return *mImpl;
+  }
+
+  // If we ever decide to add conversion operators for optional arrays
+  // like the ones Nullable has, we'll need to ensure that Maybe<> has
+  // the boolean before the actual data.
+
+private:
+  // Forbid copy-construction and assignment
+  Optional_base(const Optional_base& other) = delete;
+  const Optional_base &operator=(const Optional_base &other) = delete;
+
+protected:
+  Maybe<InternalType> mImpl;
+};
+
+template<typename T>
+class Optional : public Optional_base<T, T>
+{
+public:
+  Optional() :
+    Optional_base<T, T>()
+  {}
+
+  explicit Optional(const T& aValue) :
+    Optional_base<T, T>(aValue)
+  {}
+};
+
+template<typename T>
+class Optional<JS::Handle<T> > :
+  public Optional_base<JS::Handle<T>, JS::Rooted<T> >
+{
+public:
+  Optional() :
+    Optional_base<JS::Handle<T>, JS::Rooted<T> >()
+  {}
+
+  explicit Optional(JSContext* cx) :
+    Optional_base<JS::Handle<T>, JS::Rooted<T> >()
+  {
+    this->Construct(cx);
+  }
+
+  Optional(JSContext* cx, const T& aValue) :
+    Optional_base<JS::Handle<T>, JS::Rooted<T> >(cx, aValue)
+  {}
+
+  // Override the const Value() to return the right thing so we're not
+  // returning references to temporaries.
+  JS::Handle<T> Value() const
+  {
+    return *this->mImpl;
+  }
+
+  // And we have to override the non-const one too, since we're
+  // shadowing the one on the superclass.
+  JS::Rooted<T>& Value()
+  {
+    return *this->mImpl;
+  }
+};
+
+// A specialization of Optional for JSObject* to make sure that when someone
+// calls Construct() on it we will pre-initialized the JSObject* to nullptr so
+// it can be traced safely.
+template<>
+class Optional<JSObject*> : public Optional_base<JSObject*, JSObject*>
+{
+public:
+  Optional() :
+    Optional_base<JSObject*, JSObject*>()
+  {}
+
+  explicit Optional(JSObject* aValue) :
+    Optional_base<JSObject*, JSObject*>(aValue)
+  {}
+
+  // Don't allow us to have an uninitialized JSObject*
+  JSObject*& Construct()
+  {
+    // The Android compiler sucks and thinks we're trying to construct
+    // a JSObject* from an int if we don't cast here.  :(
+    return Optional_base<JSObject*, JSObject*>::Construct(
+      static_cast<JSObject*>(nullptr));
+  }
+
+  template <class T1>
+  JSObject*& Construct(const T1& t1)
+  {
+    return Optional_base<JSObject*, JSObject*>::Construct(t1);
+  }
+};
+
+// A specialization of Optional for JS::Value to make sure no one ever uses it.
+template<>
+class Optional<JS::Value>
+{
+private:
+  Optional() = delete;
+
+  explicit Optional(const JS::Value& aValue) = delete;
+};
+
+// A specialization of Optional for NonNull that lets us get a T& from Value()
+template<typename U> class NonNull;
+template<typename T>
+class Optional<NonNull<T> > : public Optional_base<T, NonNull<T> >
+{
+public:
+  // We want our Value to actually return a non-const reference, even
+  // if we're const.  At least for things that are normally pointer
+  // types...
+  T& Value() const
+  {
+    return *this->mImpl->get();
+  }
+
+  // And we have to override the non-const one too, since we're
+  // shadowing the one on the superclass.
+  NonNull<T>& Value()
+  {
+    return *this->mImpl;
+  }
+};
+
+// A specialization of Optional for OwningNonNull that lets us get a
+// T& from Value()
+template<typename T>
+class Optional<OwningNonNull<T> > : public Optional_base<T, OwningNonNull<T> >
+{
+public:
+  // We want our Value to actually return a non-const reference, even
+  // if we're const.  At least for things that are normally pointer
+  // types...
+  T& Value() const
+  {
+    return *this->mImpl->get();
+  }
+
+  // And we have to override the non-const one too, since we're
+  // shadowing the one on the superclass.
+  OwningNonNull<T>& Value()
+  {
+    return *this->mImpl;
+  }
+};
+
+// Specialization for strings.
+// XXXbz we can't pull in FakeString here, because it depends on internal
+// strings.  So we just have to forward-declare it and reimplement its
+// ToAStringPtr.
+
+namespace binding_detail {
+struct FakeString;
+} // namespace binding_detail
+
+template<>
+class Optional<nsAString>
+{
+public:
+  Optional() : mPassed(false) {}
+
+  bool WasPassed() const
+  {
+    return mPassed;
+  }
+
+  void operator=(const nsAString* str)
+  {
+    MOZ_ASSERT(str);
+    mStr = str;
+    mPassed = true;
+  }
+
+  // If this code ever goes away, remove the comment pointing to it in the
+  // FakeString class in BindingUtils.h.
+  void operator=(const binding_detail::FakeString* str)
+  {
+    MOZ_ASSERT(str);
+    mStr = reinterpret_cast<const nsString*>(str);
+    mPassed = true;
+  }
+
+  const nsAString& Value() const
+  {
+    MOZ_ASSERT(WasPassed());
+    return *mStr;
+  }
+
+private:
+  // Forbid copy-construction and assignment
+  Optional(const Optional& other) = delete;
+  const Optional &operator=(const Optional &other) = delete;
+
+  bool mPassed;
+  const nsAString* mStr;
+};
+
+template<class T>
+class NonNull
+{
+public:
+  NonNull()
+#ifdef DEBUG
+    : inited(false)
+#endif
+  {}
+
+  // This is no worse than get() in terms of const handling.
+  operator T&() const {
+    MOZ_ASSERT(inited);
+    MOZ_ASSERT(ptr, "NonNull<T> was set to null");
+    return *ptr;
+  }
+
+  operator T*() const {
+    MOZ_ASSERT(inited);
+    MOZ_ASSERT(ptr, "NonNull<T> was set to null");
+    return ptr;
+  }
+
+  void operator=(T* t) {
+    ptr = t;
+    MOZ_ASSERT(ptr);
+#ifdef DEBUG
+    inited = true;
+#endif
+  }
+
+  template<typename U>
+  void operator=(U* t) {
+    ptr = t->ToAStringPtr();
+    MOZ_ASSERT(ptr);
+#ifdef DEBUG
+    inited = true;
+#endif
+  }
+
+  T** Slot() {
+#ifdef DEBUG
+    inited = true;
+#endif
+    return &ptr;
+  }
+
+  T* Ptr() {
+    MOZ_ASSERT(inited);
+    MOZ_ASSERT(ptr, "NonNull<T> was set to null");
+    return ptr;
+  }
+
+  // Make us work with smart-ptr helpers that expect a get()
+  T* get() const {
+    MOZ_ASSERT(inited);
+    MOZ_ASSERT(ptr);
+    return ptr;
+  }
+
+protected:
+  T* ptr;
+#ifdef DEBUG
+  bool inited;
+#endif
+};
+
+// Class for representing sequences in arguments.  We use a non-auto array
+// because that allows us to use sequences of sequences and the like.  This
+// needs to be fallible because web content controls the length of the array,
+// and can easily try to create very large lengths.
+template<typename T>
+class Sequence : public FallibleTArray<T>
+{
+public:
+  Sequence() : FallibleTArray<T>()
+  {}
+};
+
+inline nsWrapperCache*
+GetWrapperCache(nsWrapperCache* cache)
+{
+  return cache;
+}
+
+inline nsWrapperCache*
+GetWrapperCache(void* p)
+{
+  return nullptr;
+}
+
+// Helper template for smart pointers to resolve ambiguity between
+// GetWrappeCache(void*) and GetWrapperCache(const ParentObject&).
+template <template <typename> class SmartPtr, typename T>
+inline nsWrapperCache*
+GetWrapperCache(const SmartPtr<T>& aObject)
+{
+  return GetWrapperCache(aObject.get());
+}
+
+struct MOZ_STACK_CLASS ParentObject {
+  template<class T>
+  MOZ_IMPLICIT ParentObject(T* aObject) :
+    mObject(aObject),
+    mWrapperCache(GetWrapperCache(aObject)),
+    mUseXBLScope(false)
+  {}
+
+  template<class T, template<typename> class SmartPtr>
+  MOZ_IMPLICIT ParentObject(const SmartPtr<T>& aObject) :
+    mObject(aObject.get()),
+    mWrapperCache(GetWrapperCache(aObject.get())),
+    mUseXBLScope(false)
+  {}
+
+  ParentObject(nsISupports* aObject, nsWrapperCache* aCache) :
+    mObject(aObject),
+    mWrapperCache(aCache),
+    mUseXBLScope(false)
+  {}
+
+  // We don't want to make this an nsCOMPtr because of performance reasons, but
+  // it's safe because ParentObject is a stack class.
+  nsISupports* const MOZ_NON_OWNING_REF mObject;
+  nsWrapperCache* const mWrapperCache;
+  bool mUseXBLScope;
+};
+
+namespace binding_detail {
+
+// Class for simple sequence arguments, only used internally by codegen.
+template<typename T>
+class AutoSequence : public AutoTArray<T, 16>
+{
+public:
+  AutoSequence() : AutoTArray<T, 16>()
+  {}
+
+  // Allow converting to const sequences as needed
+  operator const Sequence<T>&() const {
+    return *reinterpret_cast<const Sequence<T>*>(this);
+  }
+};
+
+} // namespace binding_detail
+
+// Enum to represent a system or non-system caller type.
+enum class CallerType : uint32_t {
+  System,
+  NonSystem
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_BindingDeclarations_h__
diff --git a/dom/bindings/BindingUtils.cpp b/dom/bindings/BindingUtils.cpp
new file mode 100644
index 000000000..33f5f7a44
--- /dev/null
+++ b/dom/bindings/BindingUtils.cpp
@@ -0,0 +1,3549 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "BindingUtils.h"
+
+#include <algorithm>
+#include <stdarg.h>
+
+#include "mozilla/Assertions.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/Preferences.h"
+#include "mozilla/SizePrintfMacros.h"
+#include "mozilla/Unused.h"
+#include "mozilla/UseCounter.h"
+
+#include "AccessCheck.h"
+#include "jsfriendapi.h"
+#include "nsContentUtils.h"
+#include "nsGlobalWindow.h"
+#include "nsIDocShell.h"
+#include "nsIDOMGlobalPropertyInitializer.h"
+#include "nsIPermissionManager.h"
+#include "nsIPrincipal.h"
+#include "nsIXPConnect.h"
+#include "nsUTF8Utils.h"
+#include "WorkerPrivate.h"
+#include "WorkerRunnable.h"
+#include "WrapperFactory.h"
+#include "xpcprivate.h"
+#include "XrayWrapper.h"
+#include "nsPrintfCString.h"
+#include "mozilla/Sprintf.h"
+#include "nsGlobalWindow.h"
+
+#include "mozilla/dom/ScriptSettings.h"
+#include "mozilla/dom/DOMError.h"
+#include "mozilla/dom/DOMErrorBinding.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/HTMLObjectElement.h"
+#include "mozilla/dom/HTMLObjectElementBinding.h"
+#include "mozilla/dom/HTMLSharedObjectElement.h"
+#include "mozilla/dom/HTMLEmbedElementBinding.h"
+#include "mozilla/dom/HTMLAppletElementBinding.h"
+#include "mozilla/dom/Promise.h"
+#include "mozilla/dom/ResolveSystemBinding.h"
+#include "mozilla/dom/WebIDLGlobalNameHash.h"
+#include "mozilla/dom/WorkerPrivate.h"
+#include "mozilla/dom/WorkerScope.h"
+#include "mozilla/dom/XrayExpandoClass.h"
+#include "mozilla/jsipc/CrossProcessObjectWrappers.h"
+#include "nsDOMClassInfo.h"
+#include "ipc/ErrorIPCUtils.h"
+#include "mozilla/UseCounter.h"
+
+namespace mozilla {
+namespace dom {
+
+using namespace workers;
+
+const JSErrorFormatString ErrorFormatString[] = {
+#define MSG_DEF(_name, _argc, _exn, _str) \
+  { #_name, _str, _argc, _exn },
+#include "mozilla/dom/Errors.msg"
+#undef MSG_DEF
+};
+
+#define MSG_DEF(_name, _argc, _exn, _str) \
+  static_assert(_argc < JS::MaxNumErrorArguments, \
+                #_name " must only have as many error arguments as the JS engine can support");
+#include "mozilla/dom/Errors.msg"
+#undef MSG_DEF
+
+const JSErrorFormatString*
+GetErrorMessage(void* aUserRef, const unsigned aErrorNumber)
+{
+  MOZ_ASSERT(aErrorNumber < ArrayLength(ErrorFormatString));
+  return &ErrorFormatString[aErrorNumber];
+}
+
+uint16_t
+GetErrorArgCount(const ErrNum aErrorNumber)
+{
+  return GetErrorMessage(nullptr, aErrorNumber)->argCount;
+}
+
+void
+binding_detail::ThrowErrorMessage(JSContext* aCx, const unsigned aErrorNumber, ...)
+{
+  va_list ap;
+  va_start(ap, aErrorNumber);
+  JS_ReportErrorNumberUTF8VA(aCx, GetErrorMessage, nullptr, aErrorNumber, ap);
+  va_end(ap);
+}
+
+bool
+ThrowInvalidThis(JSContext* aCx, const JS::CallArgs& aArgs,
+                 bool aSecurityError, const char* aInterfaceName)
+{
+  NS_ConvertASCIItoUTF16 ifaceName(aInterfaceName);
+  // This should only be called for DOM methods/getters/setters, which
+  // are JSNative-backed functions, so we can assume that
+  // JS_ValueToFunction and JS_GetFunctionDisplayId will both return
+  // non-null and that JS_GetStringCharsZ returns non-null.
+  JS::Rooted<JSFunction*> func(aCx, JS_ValueToFunction(aCx, aArgs.calleev()));
+  MOZ_ASSERT(func);
+  JS::Rooted<JSString*> funcName(aCx, JS_GetFunctionDisplayId(func));
+  MOZ_ASSERT(funcName);
+  nsAutoJSString funcNameStr;
+  if (!funcNameStr.init(aCx, funcName)) {
+    return false;
+  }
+  const ErrNum errorNumber = aSecurityError ?
+                             MSG_METHOD_THIS_UNWRAPPING_DENIED :
+                             MSG_METHOD_THIS_DOES_NOT_IMPLEMENT_INTERFACE;
+  MOZ_RELEASE_ASSERT(GetErrorArgCount(errorNumber) <= 2);
+  JS_ReportErrorNumberUC(aCx, GetErrorMessage, nullptr,
+                         static_cast<const unsigned>(errorNumber),
+                         funcNameStr.get(), ifaceName.get());
+  return false;
+}
+
+bool
+ThrowInvalidThis(JSContext* aCx, const JS::CallArgs& aArgs,
+                 bool aSecurityError,
+                 prototypes::ID aProtoId)
+{
+  return ThrowInvalidThis(aCx, aArgs, aSecurityError,
+                          NamesOfInterfacesWithProtos(aProtoId));
+}
+
+bool
+ThrowNoSetterArg(JSContext* aCx, prototypes::ID aProtoId)
+{
+  nsPrintfCString errorMessage("%s attribute setter",
+                               NamesOfInterfacesWithProtos(aProtoId));
+  return ThrowErrorMessage(aCx, MSG_MISSING_ARGUMENTS, errorMessage.get());
+}
+
+} // namespace dom
+
+namespace binding_danger {
+
+template<typename CleanupPolicy>
+struct TErrorResult<CleanupPolicy>::Message {
+  Message() { MOZ_COUNT_CTOR(TErrorResult::Message); }
+  ~Message() { MOZ_COUNT_DTOR(TErrorResult::Message); }
+
+  nsTArray<nsString> mArgs;
+  dom::ErrNum mErrorNumber;
+
+  bool HasCorrectNumberOfArguments()
+  {
+    return GetErrorArgCount(mErrorNumber) == mArgs.Length();
+  }
+};
+
+template<typename CleanupPolicy>
+nsTArray<nsString>&
+TErrorResult<CleanupPolicy>::CreateErrorMessageHelper(const dom::ErrNum errorNumber,
+                                                      nsresult errorType)
+{
+  AssertInOwningThread();
+  mResult = errorType;
+
+  mMessage = new Message();
+  mMessage->mErrorNumber = errorNumber;
+  return mMessage->mArgs;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SerializeMessage(IPC::Message* aMsg) const
+{
+  using namespace IPC;
+  AssertInOwningThread();
+  MOZ_ASSERT(mUnionState == HasMessage);
+  MOZ_ASSERT(mMessage);
+  WriteParam(aMsg, mMessage->mArgs);
+  WriteParam(aMsg, mMessage->mErrorNumber);
+}
+
+template<typename CleanupPolicy>
+bool
+TErrorResult<CleanupPolicy>::DeserializeMessage(const IPC::Message* aMsg,
+                                                PickleIterator* aIter)
+{
+  using namespace IPC;
+  AssertInOwningThread();
+  nsAutoPtr<Message> readMessage(new Message());
+  if (!ReadParam(aMsg, aIter, &readMessage->mArgs) ||
+      !ReadParam(aMsg, aIter, &readMessage->mErrorNumber)) {
+    return false;
+  }
+  if (!readMessage->HasCorrectNumberOfArguments()) {
+    return false;
+  }
+
+  MOZ_ASSERT(mUnionState == HasNothing);
+  mMessage = readMessage.forget();
+#ifdef DEBUG
+  mUnionState = HasMessage;
+#endif // DEBUG
+  return true;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SetPendingExceptionWithMessage(JSContext* aCx)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(mMessage, "SetPendingExceptionWithMessage() can be called only once");
+  MOZ_ASSERT(mUnionState == HasMessage);
+
+  Message* message = mMessage;
+  MOZ_RELEASE_ASSERT(message->HasCorrectNumberOfArguments());
+  const uint32_t argCount = message->mArgs.Length();
+  const char16_t* args[JS::MaxNumErrorArguments + 1];
+  for (uint32_t i = 0; i < argCount; ++i) {
+    args[i] = message->mArgs.ElementAt(i).get();
+  }
+  args[argCount] = nullptr;
+
+  JS_ReportErrorNumberUCArray(aCx, dom::GetErrorMessage, nullptr,
+                              static_cast<const unsigned>(message->mErrorNumber),
+                              argCount > 0 ? args : nullptr);
+
+  ClearMessage();
+  mResult = NS_OK;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::ClearMessage()
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(IsErrorWithMessage());
+  delete mMessage;
+  mMessage = nullptr;
+#ifdef DEBUG
+  mUnionState = HasNothing;
+#endif // DEBUG
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::ThrowJSException(JSContext* cx, JS::Handle<JS::Value> exn)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(mMightHaveUnreportedJSException,
+             "Why didn't you tell us you planned to throw a JS exception?");
+
+  ClearUnionData();
+
+  // Make sure mJSException is initialized _before_ we try to root it.  But
+  // don't set it to exn yet, because we don't want to do that until after we
+  // root.
+  mJSException.setUndefined();
+  if (!js::AddRawValueRoot(cx, &mJSException, "TErrorResult::mJSException")) {
+    // Don't use NS_ERROR_DOM_JS_EXCEPTION, because that indicates we have
+    // in fact rooted mJSException.
+    mResult = NS_ERROR_OUT_OF_MEMORY;
+  } else {
+    mJSException = exn;
+    mResult = NS_ERROR_DOM_JS_EXCEPTION;
+#ifdef DEBUG
+    mUnionState = HasJSException;
+#endif // DEBUG
+  }
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SetPendingJSException(JSContext* cx)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(!mMightHaveUnreportedJSException,
+             "Why didn't you tell us you planned to handle JS exceptions?");
+  MOZ_ASSERT(mUnionState == HasJSException);
+
+  JS::Rooted<JS::Value> exception(cx, mJSException);
+  if (JS_WrapValue(cx, &exception)) {
+    JS_SetPendingException(cx, exception);
+  }
+  mJSException = exception;
+  // If JS_WrapValue failed, not much we can do about it...  No matter
+  // what, go ahead and unroot mJSException.
+  js::RemoveRawValueRoot(cx, &mJSException);
+
+  mResult = NS_OK;
+#ifdef DEBUG
+  mUnionState = HasNothing;
+#endif // DEBUG
+}
+
+template<typename CleanupPolicy>
+struct TErrorResult<CleanupPolicy>::DOMExceptionInfo {
+  DOMExceptionInfo(nsresult rv, const nsACString& message)
+    : mMessage(message)
+    , mRv(rv)
+  {}
+
+  nsCString mMessage;
+  nsresult mRv;
+};
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SerializeDOMExceptionInfo(IPC::Message* aMsg) const
+{
+  using namespace IPC;
+  AssertInOwningThread();
+  MOZ_ASSERT(mDOMExceptionInfo);
+  MOZ_ASSERT(mUnionState == HasDOMExceptionInfo);
+  WriteParam(aMsg, mDOMExceptionInfo->mMessage);
+  WriteParam(aMsg, mDOMExceptionInfo->mRv);
+}
+
+template<typename CleanupPolicy>
+bool
+TErrorResult<CleanupPolicy>::DeserializeDOMExceptionInfo(const IPC::Message* aMsg,
+                                                         PickleIterator* aIter)
+{
+  using namespace IPC;
+  AssertInOwningThread();
+  nsCString message;
+  nsresult rv;
+  if (!ReadParam(aMsg, aIter, &message) ||
+      !ReadParam(aMsg, aIter, &rv)) {
+    return false;
+  }
+
+  MOZ_ASSERT(mUnionState == HasNothing);
+  MOZ_ASSERT(IsDOMException());
+  mDOMExceptionInfo = new DOMExceptionInfo(rv, message);
+#ifdef DEBUG
+  mUnionState = HasDOMExceptionInfo;
+#endif // DEBUG
+  return true;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::ThrowDOMException(nsresult rv,
+                                               const nsACString& message)
+{
+  AssertInOwningThread();
+  ClearUnionData();
+
+  mResult = NS_ERROR_DOM_DOMEXCEPTION;
+  mDOMExceptionInfo = new DOMExceptionInfo(rv, message);
+#ifdef DEBUG
+  mUnionState = HasDOMExceptionInfo;
+#endif
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SetPendingDOMException(JSContext* cx)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(mDOMExceptionInfo,
+             "SetPendingDOMException() can be called only once");
+  MOZ_ASSERT(mUnionState == HasDOMExceptionInfo);
+
+  dom::Throw(cx, mDOMExceptionInfo->mRv, mDOMExceptionInfo->mMessage);
+
+  ClearDOMExceptionInfo();
+  mResult = NS_OK;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::ClearDOMExceptionInfo()
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(IsDOMException());
+  MOZ_ASSERT(mUnionState == HasDOMExceptionInfo || !mDOMExceptionInfo);
+  delete mDOMExceptionInfo;
+  mDOMExceptionInfo = nullptr;
+#ifdef DEBUG
+  mUnionState = HasNothing;
+#endif // DEBUG
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::ClearUnionData()
+{
+  AssertInOwningThread();
+  if (IsJSException()) {
+    JSContext* cx = dom::danger::GetJSContext();
+    MOZ_ASSERT(cx);
+    mJSException.setUndefined();
+    js::RemoveRawValueRoot(cx, &mJSException);
+#ifdef DEBUG
+    mUnionState = HasNothing;
+#endif // DEBUG
+  } else if (IsErrorWithMessage()) {
+    ClearMessage();
+  } else if (IsDOMException()) {
+    ClearDOMExceptionInfo();
+  }
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SetPendingGenericErrorException(JSContext* cx)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(!IsErrorWithMessage());
+  MOZ_ASSERT(!IsJSException());
+  MOZ_ASSERT(!IsDOMException());
+  dom::Throw(cx, ErrorCode());
+  mResult = NS_OK;
+}
+
+template<typename CleanupPolicy>
+TErrorResult<CleanupPolicy>&
+TErrorResult<CleanupPolicy>::operator=(TErrorResult<CleanupPolicy>&& aRHS)
+{
+  AssertInOwningThread();
+  aRHS.AssertInOwningThread();
+  // Clear out any union members we may have right now, before we
+  // start writing to it.
+  ClearUnionData();
+
+#ifdef DEBUG
+  mMightHaveUnreportedJSException = aRHS.mMightHaveUnreportedJSException;
+  aRHS.mMightHaveUnreportedJSException = false;
+#endif
+  if (aRHS.IsErrorWithMessage()) {
+    mMessage = aRHS.mMessage;
+    aRHS.mMessage = nullptr;
+  } else if (aRHS.IsJSException()) {
+    JSContext* cx = dom::danger::GetJSContext();
+    MOZ_ASSERT(cx);
+    mJSException.setUndefined();
+    if (!js::AddRawValueRoot(cx, &mJSException, "TErrorResult::mJSException")) {
+      MOZ_CRASH("Could not root mJSException, we're about to OOM");
+    }
+    mJSException = aRHS.mJSException;
+    aRHS.mJSException.setUndefined();
+    js::RemoveRawValueRoot(cx, &aRHS.mJSException);
+  } else if (aRHS.IsDOMException()) {
+    mDOMExceptionInfo = aRHS.mDOMExceptionInfo;
+    aRHS.mDOMExceptionInfo = nullptr;
+  } else {
+    // Null out the union on both sides for hygiene purposes.
+    mMessage = aRHS.mMessage = nullptr;
+  }
+
+#ifdef DEBUG
+  mUnionState = aRHS.mUnionState;
+  aRHS.mUnionState = HasNothing;
+#endif // DEBUG
+
+  // Note: It's important to do this last, since this affects the condition
+  // checks above!
+  mResult = aRHS.mResult;
+  aRHS.mResult = NS_OK;
+  return *this;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::CloneTo(TErrorResult& aRv) const
+{
+  AssertInOwningThread();
+  aRv.AssertInOwningThread();
+
+  aRv.ClearUnionData();
+  aRv.mResult = mResult;
+#ifdef DEBUG
+  aRv.mMightHaveUnreportedJSException = mMightHaveUnreportedJSException;
+#endif
+
+  if (IsErrorWithMessage()) {
+#ifdef DEBUG
+    aRv.mUnionState = HasMessage;
+#endif
+    aRv.mMessage = new Message();
+    aRv.mMessage->mArgs = mMessage->mArgs;
+    aRv.mMessage->mErrorNumber = mMessage->mErrorNumber;
+  } else if (IsDOMException()) {
+#ifdef DEBUG
+    aRv.mUnionState = HasDOMExceptionInfo;
+#endif
+    aRv.mDOMExceptionInfo = new DOMExceptionInfo(mDOMExceptionInfo->mRv,
+                                                 mDOMExceptionInfo->mMessage);
+  } else if (IsJSException()) {
+#ifdef DEBUG
+    aRv.mUnionState = HasJSException;
+#endif
+    JSContext* cx = dom::danger::GetJSContext();
+    JS::Rooted<JS::Value> exception(cx, mJSException);
+    aRv.ThrowJSException(cx, exception);
+  }
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SuppressException()
+{
+  AssertInOwningThread();
+  WouldReportJSException();
+  ClearUnionData();
+  // We don't use AssignErrorCode, because we want to override existing error
+  // states, which AssignErrorCode is not allowed to do.
+  mResult = NS_OK;
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::SetPendingException(JSContext* cx)
+{
+  AssertInOwningThread();
+  if (IsUncatchableException()) {
+    // Nuke any existing exception on cx, to make sure we're uncatchable.
+    JS_ClearPendingException(cx);
+    // Don't do any reporting.  Just return, to create an
+    // uncatchable exception.
+    mResult = NS_OK;
+    return;
+  }
+  if (IsJSContextException()) {
+    // Whatever we need to throw is on the JSContext already.
+    MOZ_ASSERT(JS_IsExceptionPending(cx));
+    mResult = NS_OK;
+    return;
+  }
+  if (IsErrorWithMessage()) {
+    SetPendingExceptionWithMessage(cx);
+    return;
+  }
+  if (IsJSException()) {
+    SetPendingJSException(cx);
+    return;
+  }
+  if (IsDOMException()) {
+    SetPendingDOMException(cx);
+    return;
+  }
+  SetPendingGenericErrorException(cx);
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::StealExceptionFromJSContext(JSContext* cx)
+{
+  AssertInOwningThread();
+  MOZ_ASSERT(mMightHaveUnreportedJSException,
+             "Why didn't you tell us you planned to throw a JS exception?");
+
+  JS::Rooted<JS::Value> exn(cx);
+  if (!JS_GetPendingException(cx, &exn)) {
+    ThrowUncatchableException();
+    return;
+  }
+
+  ThrowJSException(cx, exn);
+  JS_ClearPendingException(cx);
+}
+
+template<typename CleanupPolicy>
+void
+TErrorResult<CleanupPolicy>::NoteJSContextException(JSContext* aCx)
+{
+  AssertInOwningThread();
+  if (JS_IsExceptionPending(aCx)) {
+    mResult = NS_ERROR_DOM_EXCEPTION_ON_JSCONTEXT;
+  } else {
+    mResult = NS_ERROR_UNCATCHABLE_EXCEPTION;
+  }
+}
+
+template class TErrorResult<JustAssertCleanupPolicy>;
+template class TErrorResult<AssertAndSuppressCleanupPolicy>;
+template class TErrorResult<JustSuppressCleanupPolicy>;
+
+} // namespace binding_danger
+
+namespace dom {
+
+bool
+DefineConstants(JSContext* cx, JS::Handle<JSObject*> obj,
+                const ConstantSpec* cs)
+{
+  JS::Rooted<JS::Value> value(cx);
+  for (; cs->name; ++cs) {
+    value = cs->value;
+    bool ok =
+      JS_DefineProperty(cx, obj, cs->name, value,
+                        JSPROP_ENUMERATE | JSPROP_READONLY | JSPROP_PERMANENT);
+    if (!ok) {
+      return false;
+    }
+  }
+  return true;
+}
+
+static inline bool
+Define(JSContext* cx, JS::Handle<JSObject*> obj, const JSFunctionSpec* spec) {
+  return JS_DefineFunctions(cx, obj, spec);
+}
+static inline bool
+Define(JSContext* cx, JS::Handle<JSObject*> obj, const JSPropertySpec* spec) {
+  return JS_DefineProperties(cx, obj, spec);
+}
+static inline bool
+Define(JSContext* cx, JS::Handle<JSObject*> obj, const ConstantSpec* spec) {
+  return DefineConstants(cx, obj, spec);
+}
+
+template<typename T>
+bool
+DefinePrefable(JSContext* cx, JS::Handle<JSObject*> obj,
+               const Prefable<T>* props)
+{
+  MOZ_ASSERT(props);
+  MOZ_ASSERT(props->specs);
+  do {
+    // Define if enabled
+    if (props->isEnabled(cx, obj)) {
+      if (!Define(cx, obj, props->specs)) {
+        return false;
+      }
+    }
+  } while ((++props)->specs);
+  return true;
+}
+
+bool
+DefineUnforgeableMethods(JSContext* cx, JS::Handle<JSObject*> obj,
+                         const Prefable<const JSFunctionSpec>* props)
+{
+  return DefinePrefable(cx, obj, props);
+}
+
+bool
+DefineUnforgeableAttributes(JSContext* cx, JS::Handle<JSObject*> obj,
+                            const Prefable<const JSPropertySpec>* props)
+{
+  return DefinePrefable(cx, obj, props);
+}
+
+
+// We should use JSFunction objects for interface objects, but we need a custom
+// hasInstance hook because we have new interface objects on prototype chains of
+// old (XPConnect-based) bindings. We also need Xrays and arbitrary numbers of
+// reserved slots (e.g. for named constructors).  So we define a custom
+// funToString ObjectOps member for interface objects.
+JSString*
+InterfaceObjectToString(JSContext* aCx, JS::Handle<JSObject*> aObject,
+                        unsigned /* indent */)
+{
+  const js::Class* clasp = js::GetObjectClass(aObject);
+  MOZ_ASSERT(IsDOMIfaceAndProtoClass(clasp));
+
+  const DOMIfaceAndProtoJSClass* ifaceAndProtoJSClass =
+    DOMIfaceAndProtoJSClass::FromJSClass(clasp);
+  return JS_NewStringCopyZ(aCx, ifaceAndProtoJSClass->mToString);
+}
+
+bool
+Constructor(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  const JS::Value& v =
+    js::GetFunctionNativeReserved(&args.callee(),
+                                  CONSTRUCTOR_NATIVE_HOLDER_RESERVED_SLOT);
+  const JSNativeHolder* nativeHolder =
+    static_cast<const JSNativeHolder*>(v.toPrivate());
+  return (nativeHolder->mNative)(cx, argc, vp);
+}
+
+static JSObject*
+CreateConstructor(JSContext* cx, JS::Handle<JSObject*> global, const char* name,
+                  const JSNativeHolder* nativeHolder, unsigned ctorNargs)
+{
+  JSFunction* fun = js::NewFunctionWithReserved(cx, Constructor, ctorNargs,
+                                                JSFUN_CONSTRUCTOR, name);
+  if (!fun) {
+    return nullptr;
+  }
+
+  JSObject* constructor = JS_GetFunctionObject(fun);
+  js::SetFunctionNativeReserved(constructor,
+                                CONSTRUCTOR_NATIVE_HOLDER_RESERVED_SLOT,
+                                js::PrivateValue(const_cast<JSNativeHolder*>(nativeHolder)));
+  return constructor;
+}
+
+static bool
+DefineConstructor(JSContext* cx, JS::Handle<JSObject*> global, const char* name,
+                  JS::Handle<JSObject*> constructor)
+{
+  bool alreadyDefined;
+  if (!JS_AlreadyHasOwnProperty(cx, global, name, &alreadyDefined)) {
+    return false;
+  }
+
+  // This is Enumerable: False per spec.
+  return alreadyDefined ||
+         JS_DefineProperty(cx, global, name, constructor, JSPROP_RESOLVING);
+}
+
+static JSObject*
+CreateInterfaceObject(JSContext* cx, JS::Handle<JSObject*> global,
+                      JS::Handle<JSObject*> constructorProto,
+                      const js::Class* constructorClass,
+                      unsigned ctorNargs, const NamedConstructor* namedConstructors,
+                      JS::Handle<JSObject*> proto,
+                      const NativeProperties* properties,
+                      const NativeProperties* chromeOnlyProperties,
+                      const char* name, bool defineOnGlobal)
+{
+  JS::Rooted<JSObject*> constructor(cx);
+  MOZ_ASSERT(constructorProto);
+  MOZ_ASSERT(constructorClass);
+  constructor = JS_NewObjectWithGivenProto(cx, Jsvalify(constructorClass),
+                                           constructorProto);
+  if (!constructor) {
+    return nullptr;
+  }
+
+  if (!JS_DefineProperty(cx, constructor, "length", ctorNargs,
+                         JSPROP_READONLY)) {
+    return nullptr;
+  }
+
+  // Might as well intern, since we're going to need an atomized
+  // version of name anyway when we stick our constructor on the
+  // global.
+  JS::Rooted<JSString*> nameStr(cx, JS_AtomizeAndPinString(cx, name));
+  if (!nameStr) {
+    return nullptr;
+  }
+
+  if (!JS_DefineProperty(cx, constructor, "name", nameStr, JSPROP_READONLY)) {
+    return nullptr;
+  }
+
+  if (DOMIfaceAndProtoJSClass::FromJSClass(constructorClass)->wantsInterfaceHasInstance) {
+    JS::Rooted<jsid> hasInstanceId(cx,
+      SYMBOL_TO_JSID(JS::GetWellKnownSymbol(cx, JS::SymbolCode::hasInstance)));
+    if (!JS_DefineFunctionById(cx, constructor, hasInstanceId,
+                               InterfaceHasInstance, 1,
+                               // Flags match those of Function[Symbol.hasInstance]
+                               JSPROP_READONLY | JSPROP_PERMANENT)) {
+      return nullptr;
+    }
+  }
+
+  if (properties) {
+    if (properties->HasStaticMethods() &&
+        !DefinePrefable(cx, constructor, properties->StaticMethods())) {
+      return nullptr;
+    }
+
+    if (properties->HasStaticAttributes() &&
+        !DefinePrefable(cx, constructor, properties->StaticAttributes())) {
+      return nullptr;
+    }
+
+    if (properties->HasConstants() &&
+        !DefinePrefable(cx, constructor, properties->Constants())) {
+      return nullptr;
+    }
+  }
+
+  if (chromeOnlyProperties) {
+    if (chromeOnlyProperties->HasStaticMethods() &&
+        !DefinePrefable(cx, constructor,
+                        chromeOnlyProperties->StaticMethods())) {
+      return nullptr;
+    }
+
+    if (chromeOnlyProperties->HasStaticAttributes() &&
+        !DefinePrefable(cx, constructor,
+                        chromeOnlyProperties->StaticAttributes())) {
+      return nullptr;
+    }
+
+    if (chromeOnlyProperties->HasConstants() &&
+        !DefinePrefable(cx, constructor, chromeOnlyProperties->Constants())) {
+      return nullptr;
+    }
+  }
+
+  if (proto && !JS_LinkConstructorAndPrototype(cx, constructor, proto)) {
+    return nullptr;
+  }
+
+  if (defineOnGlobal && !DefineConstructor(cx, global, name, constructor)) {
+    return nullptr;
+  }
+
+  if (namedConstructors) {
+    int namedConstructorSlot = DOM_INTERFACE_SLOTS_BASE;
+    while (namedConstructors->mName) {
+      JS::Rooted<JSObject*> namedConstructor(cx,
+        CreateConstructor(cx, global, namedConstructors->mName,
+                          &namedConstructors->mHolder,
+                          namedConstructors->mNargs));
+      if (!namedConstructor ||
+          !JS_DefineProperty(cx, namedConstructor, "prototype",
+                             proto,
+                             JSPROP_PERMANENT | JSPROP_READONLY,
+                             JS_STUBGETTER, JS_STUBSETTER) ||
+          (defineOnGlobal &&
+           !DefineConstructor(cx, global, namedConstructors->mName,
+                              namedConstructor))) {
+        return nullptr;
+      }
+      js::SetReservedSlot(constructor, namedConstructorSlot++,
+                          JS::ObjectValue(*namedConstructor));
+      ++namedConstructors;
+    }
+  }
+
+  return constructor;
+}
+
+static JSObject*
+CreateInterfacePrototypeObject(JSContext* cx, JS::Handle<JSObject*> global,
+                               JS::Handle<JSObject*> parentProto,
+                               const js::Class* protoClass,
+                               const NativeProperties* properties,
+                               const NativeProperties* chromeOnlyProperties,
+                               const char* const* unscopableNames,
+                               bool isGlobal)
+{
+  JS::Rooted<JSObject*> ourProto(cx,
+    JS_NewObjectWithUniqueType(cx, Jsvalify(protoClass), parentProto));
+  if (!ourProto ||
+      // We don't try to define properties on the global's prototype; those
+      // properties go on the global itself.
+      (!isGlobal &&
+       !DefineProperties(cx, ourProto, properties, chromeOnlyProperties))) {
+    return nullptr;
+  }
+
+  if (unscopableNames) {
+    JS::Rooted<JSObject*> unscopableObj(cx, JS_NewPlainObject(cx));
+    if (!unscopableObj) {
+      return nullptr;
+    }
+
+    for (; *unscopableNames; ++unscopableNames) {
+      if (!JS_DefineProperty(cx, unscopableObj, *unscopableNames,
+                             JS::TrueHandleValue, JSPROP_ENUMERATE)) {
+        return nullptr;
+      }
+    }
+
+    JS::Rooted<jsid> unscopableId(cx,
+      SYMBOL_TO_JSID(JS::GetWellKnownSymbol(cx, JS::SymbolCode::unscopables)));
+    // Readonly and non-enumerable to match Array.prototype.
+    if (!JS_DefinePropertyById(cx, ourProto, unscopableId, unscopableObj,
+                               JSPROP_READONLY)) {
+      return nullptr;
+    }
+  }
+
+  return ourProto;
+}
+
+bool
+DefineProperties(JSContext* cx, JS::Handle<JSObject*> obj,
+                 const NativeProperties* properties,
+                 const NativeProperties* chromeOnlyProperties)
+{
+  if (properties) {
+    if (properties->HasMethods() &&
+        !DefinePrefable(cx, obj, properties->Methods())) {
+      return false;
+    }
+
+    if (properties->HasAttributes() &&
+        !DefinePrefable(cx, obj, properties->Attributes())) {
+      return false;
+    }
+
+    if (properties->HasConstants() &&
+        !DefinePrefable(cx, obj, properties->Constants())) {
+      return false;
+    }
+  }
+
+  if (chromeOnlyProperties) {
+    if (chromeOnlyProperties->HasMethods() &&
+        !DefinePrefable(cx, obj, chromeOnlyProperties->Methods())) {
+      return false;
+    }
+
+    if (chromeOnlyProperties->HasAttributes() &&
+        !DefinePrefable(cx, obj, chromeOnlyProperties->Attributes())) {
+      return false;
+    }
+
+    if (chromeOnlyProperties->HasConstants() &&
+        !DefinePrefable(cx, obj, chromeOnlyProperties->Constants())) {
+      return false;
+    }
+  }
+
+  return true;
+}
+
+void
+CreateInterfaceObjects(JSContext* cx, JS::Handle<JSObject*> global,
+                       JS::Handle<JSObject*> protoProto,
+                       const js::Class* protoClass, JS::Heap<JSObject*>* protoCache,
+                       JS::Handle<JSObject*> constructorProto,
+                       const js::Class* constructorClass,
+                       unsigned ctorNargs, const NamedConstructor* namedConstructors,
+                       JS::Heap<JSObject*>* constructorCache,
+                       const NativeProperties* properties,
+                       const NativeProperties* chromeOnlyProperties,
+                       const char* name, bool defineOnGlobal,
+                       const char* const* unscopableNames,
+                       bool isGlobal)
+{
+  MOZ_ASSERT(protoClass || constructorClass,
+             "Need at least one class!");
+  MOZ_ASSERT(!((properties &&
+                (properties->HasMethods() || properties->HasAttributes())) ||
+               (chromeOnlyProperties &&
+                (chromeOnlyProperties->HasMethods() ||
+                 chromeOnlyProperties->HasAttributes()))) || protoClass,
+             "Methods or properties but no protoClass!");
+  MOZ_ASSERT(!((properties &&
+                (properties->HasStaticMethods() ||
+                 properties->HasStaticAttributes())) ||
+               (chromeOnlyProperties &&
+                (chromeOnlyProperties->HasStaticMethods() ||
+                 chromeOnlyProperties->HasStaticAttributes()))) ||
+             constructorClass,
+             "Static methods but no constructorClass!");
+  MOZ_ASSERT(bool(name) == bool(constructorClass),
+             "Must have name precisely when we have an interface object");
+  MOZ_ASSERT(!protoClass == !protoCache,
+             "If, and only if, there is an interface prototype object we need "
+             "to cache it");
+  MOZ_ASSERT(bool(constructorClass) == bool(constructorCache),
+             "If, and only if, there is an interface object we need to cache "
+             "it");
+  MOZ_ASSERT(constructorProto || !constructorClass,
+             "Must have a constructor proto if we plan to create a constructor "
+             "object");
+
+  JS::Rooted<JSObject*> proto(cx);
+  if (protoClass) {
+    proto =
+      CreateInterfacePrototypeObject(cx, global, protoProto, protoClass,
+                                     properties, chromeOnlyProperties,
+                                     unscopableNames, isGlobal);
+    if (!proto) {
+      return;
+    }
+
+    *protoCache = proto;
+  }
+  else {
+    MOZ_ASSERT(!proto);
+  }
+
+  JSObject* interface;
+  if (constructorClass) {
+    interface = CreateInterfaceObject(cx, global, constructorProto,
+                                      constructorClass, ctorNargs,
+                                      namedConstructors, proto, properties,
+                                      chromeOnlyProperties, name,
+                                      defineOnGlobal);
+    if (!interface) {
+      if (protoCache) {
+        // If we fail we need to make sure to clear the value of protoCache we
+        // set above.
+        *protoCache = nullptr;
+      }
+      return;
+    }
+    *constructorCache = interface;
+  }
+}
+
+bool
+NativeInterface2JSObjectAndThrowIfFailed(JSContext* aCx,
+                                         JS::Handle<JSObject*> aScope,
+                                         JS::MutableHandle<JS::Value> aRetval,
+                                         xpcObjectHelper& aHelper,
+                                         const nsIID* aIID,
+                                         bool aAllowNativeWrapper)
+{
+  js::AssertSameCompartment(aCx, aScope);
+  nsresult rv;
+  // Inline some logic from XPCConvert::NativeInterfaceToJSObject that we need
+  // on all threads.
+  nsWrapperCache *cache = aHelper.GetWrapperCache();
+
+  if (cache && cache->IsDOMBinding()) {
+      JS::Rooted<JSObject*> obj(aCx, cache->GetWrapper());
+      if (!obj) {
+        obj = cache->WrapObject(aCx, nullptr);
+      }
+
+      if (obj && aAllowNativeWrapper && !JS_WrapObject(aCx, &obj)) {
+        return false;
+      }
+
+      if (obj) {
+        aRetval.setObject(*obj);
+        return true;
+      }
+  }
+
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!XPCConvert::NativeInterface2JSObject(aRetval, nullptr, aHelper, aIID,
+                                            aAllowNativeWrapper, &rv)) {
+    // I can't tell if NativeInterface2JSObject throws JS exceptions
+    // or not.  This is a sloppy stab at the right semantics; the
+    // method really ought to be fixed to behave consistently.
+    if (!JS_IsExceptionPending(aCx)) {
+      Throw(aCx, NS_FAILED(rv) ? rv : NS_ERROR_UNEXPECTED);
+    }
+    return false;
+  }
+  return true;
+}
+
+bool
+TryPreserveWrapper(JSObject* obj)
+{
+  MOZ_ASSERT(IsDOMObject(obj));
+
+  if (nsISupports* native = UnwrapDOMObjectToISupports(obj)) {
+    nsWrapperCache* cache = nullptr;
+    CallQueryInterface(native, &cache);
+    if (cache) {
+      cache->PreserveWrapper(native);
+    }
+    return true;
+  }
+
+  // If this DOMClass is not cycle collected, then it isn't wrappercached,
+  // so it does not need to be preserved. If it is cycle collected, then
+  // we can't tell if it is wrappercached or not, so we just return false.
+  const DOMJSClass* domClass = GetDOMClass(obj);
+  return domClass && !domClass->mParticipant;
+}
+
+// Can only be called with a DOM JSClass.
+bool
+InstanceClassHasProtoAtDepth(const js::Class* clasp,
+                             uint32_t protoID, uint32_t depth)
+{
+  const DOMJSClass* domClass = DOMJSClass::FromJSClass(clasp);
+  return static_cast<uint32_t>(domClass->mInterfaceChain[depth]) == protoID;
+}
+
+// Only set allowNativeWrapper to false if you really know you need it, if in
+// doubt use true. Setting it to false disables security wrappers.
+bool
+XPCOMObjectToJsval(JSContext* cx, JS::Handle<JSObject*> scope,
+                   xpcObjectHelper& helper, const nsIID* iid,
+                   bool allowNativeWrapper, JS::MutableHandle<JS::Value> rval)
+{
+  if (!NativeInterface2JSObjectAndThrowIfFailed(cx, scope, rval, helper, iid,
+                                                allowNativeWrapper)) {
+    return false;
+  }
+
+#ifdef DEBUG
+  JSObject* jsobj = rval.toObjectOrNull();
+  if (jsobj &&
+      js::GetGlobalForObjectCrossCompartment(jsobj) == jsobj) {
+    NS_ASSERTION(js::GetObjectClass(jsobj)->flags & JSCLASS_IS_GLOBAL,
+                 "Why did we recreate this wrapper?");
+  }
+#endif
+
+  return true;
+}
+
+bool
+VariantToJsval(JSContext* aCx, nsIVariant* aVariant,
+               JS::MutableHandle<JS::Value> aRetval)
+{
+  nsresult rv;
+  if (!XPCVariant::VariantDataToJS(aVariant, &rv, aRetval)) {
+    // Does it throw?  Who knows
+    if (!JS_IsExceptionPending(aCx)) {
+      Throw(aCx, NS_FAILED(rv) ? rv : NS_ERROR_UNEXPECTED);
+    }
+    return false;
+  }
+
+  return true;
+}
+
+bool
+QueryInterface(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  JS::Rooted<JS::Value> thisv(cx, JS_THIS(cx, vp));
+  if (thisv.isNull())
+    return false;
+
+  // Get the object. It might be a security wrapper, in which case we do a checked
+  // unwrap.
+  JS::Rooted<JSObject*> origObj(cx, &thisv.toObject());
+  JS::Rooted<JSObject*> obj(cx, js::CheckedUnwrap(origObj,
+                                                  /* stopAtWindowProxy = */ false));
+  if (!obj) {
+      JS_ReportErrorASCII(cx, "Permission denied to access object");
+      return false;
+  }
+
+  // Switch this to UnwrapDOMObjectToISupports once our global objects are
+  // using new bindings.
+  nsCOMPtr<nsISupports> native;
+  UnwrapArg<nsISupports>(obj, getter_AddRefs(native));
+  if (!native) {
+    return Throw(cx, NS_ERROR_FAILURE);
+  }
+
+  if (argc < 1) {
+    return Throw(cx, NS_ERROR_XPC_NOT_ENOUGH_ARGS);
+  }
+
+  if (!args[0].isObject()) {
+    return Throw(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
+  }
+
+  nsCOMPtr<nsIJSID> iid;
+  obj = &args[0].toObject();
+  if (NS_FAILED(UnwrapArg<nsIJSID>(obj, getter_AddRefs(iid)))) {
+    return Throw(cx, NS_ERROR_XPC_BAD_CONVERT_JS);
+  }
+  MOZ_ASSERT(iid);
+
+  if (iid->GetID()->Equals(NS_GET_IID(nsIClassInfo))) {
+    nsresult rv;
+    nsCOMPtr<nsIClassInfo> ci = do_QueryInterface(native, &rv);
+    if (NS_FAILED(rv)) {
+      return Throw(cx, rv);
+    }
+
+    return WrapObject(cx, ci, &NS_GET_IID(nsIClassInfo), args.rval());
+  }
+
+  nsCOMPtr<nsISupports> unused;
+  nsresult rv = native->QueryInterface(*iid->GetID(), getter_AddRefs(unused));
+  if (NS_FAILED(rv)) {
+    return Throw(cx, rv);
+  }
+
+  *vp = thisv;
+  return true;
+}
+
+void
+GetInterfaceImpl(JSContext* aCx, nsIInterfaceRequestor* aRequestor,
+                 nsWrapperCache* aCache, nsIJSID* aIID,
+                 JS::MutableHandle<JS::Value> aRetval, ErrorResult& aError)
+{
+  const nsID* iid = aIID->GetID();
+
+  RefPtr<nsISupports> result;
+  aError = aRequestor->GetInterface(*iid, getter_AddRefs(result));
+  if (aError.Failed()) {
+    return;
+  }
+
+  if (!WrapObject(aCx, result, iid, aRetval)) {
+    aError.Throw(NS_ERROR_FAILURE);
+  }
+}
+
+bool
+UnforgeableValueOf(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  args.rval().set(args.thisv());
+  return true;
+}
+
+bool
+ThrowingConstructor(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  return ThrowErrorMessage(cx, MSG_ILLEGAL_CONSTRUCTOR);
+}
+
+bool
+ThrowConstructorWithoutNew(JSContext* cx, const char* name)
+{
+  return ThrowErrorMessage(cx, MSG_CONSTRUCTOR_WITHOUT_NEW, name);
+}
+
+inline const NativePropertyHooks*
+GetNativePropertyHooksFromConstructorFunction(JS::Handle<JSObject*> obj)
+{
+  MOZ_ASSERT(JS_IsNativeFunction(obj, Constructor));
+  const JS::Value& v =
+    js::GetFunctionNativeReserved(obj,
+                                  CONSTRUCTOR_NATIVE_HOLDER_RESERVED_SLOT);
+  const JSNativeHolder* nativeHolder =
+    static_cast<const JSNativeHolder*>(v.toPrivate());
+  return nativeHolder->mPropertyHooks;
+}
+
+inline const NativePropertyHooks*
+GetNativePropertyHooks(JSContext *cx, JS::Handle<JSObject*> obj,
+                       DOMObjectType& type)
+{
+  const js::Class* clasp = js::GetObjectClass(obj);
+
+  const DOMJSClass* domClass = GetDOMClass(clasp);
+  if (domClass) {
+    bool isGlobal = (clasp->flags & JSCLASS_DOM_GLOBAL) != 0;
+    type = isGlobal ? eGlobalInstance : eInstance;
+    return domClass->mNativeHooks;
+  }
+
+  if (JS_ObjectIsFunction(cx, obj)) {
+    type = eInterface;
+    return GetNativePropertyHooksFromConstructorFunction(obj);
+  }
+
+  MOZ_ASSERT(IsDOMIfaceAndProtoClass(js::GetObjectClass(obj)));
+  const DOMIfaceAndProtoJSClass* ifaceAndProtoJSClass =
+    DOMIfaceAndProtoJSClass::FromJSClass(js::GetObjectClass(obj));
+  type = ifaceAndProtoJSClass->mType;
+  return ifaceAndProtoJSClass->mNativeHooks;
+}
+
+static JSObject*
+XrayCreateFunction(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                   JSNativeWrapper native, unsigned nargs, JS::Handle<jsid> id)
+{
+  JSFunction* fun;
+  if (JSID_IS_STRING(id)) {
+    fun = js::NewFunctionByIdWithReserved(cx, native.op, nargs, 0, id);
+  } else {
+    // Can't pass this id (probably a symbol) to NewFunctionByIdWithReserved;
+    // just use an empty name for lack of anything better.
+    fun = js::NewFunctionWithReserved(cx, native.op, nargs, 0, nullptr);
+  }
+
+  if (!fun) {
+    return nullptr;
+  }
+
+  SET_JITINFO(fun, native.info);
+  JSObject* obj = JS_GetFunctionObject(fun);
+  js::SetFunctionNativeReserved(obj, XRAY_DOM_FUNCTION_PARENT_WRAPPER_SLOT,
+                                JS::ObjectValue(*wrapper));
+#ifdef DEBUG
+  js::SetFunctionNativeReserved(obj, XRAY_DOM_FUNCTION_NATIVE_SLOT_FOR_SELF,
+                                JS::ObjectValue(*obj));
+#endif
+  return obj;
+}
+
+static bool
+XrayResolveAttribute(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                     JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                     const Prefable<const JSPropertySpec>* attributes,
+                     const jsid* attributeIds,
+                     const JSPropertySpec* attributeSpecs,
+                     JS::MutableHandle<JS::PropertyDescriptor> desc,
+                     bool& cacheOnHolder)
+{
+  for (; attributes->specs; ++attributes) {
+    if (attributes->isEnabled(cx, obj)) {
+      // Set i to be the index into our full list of ids/specs that we're
+      // looking at now.
+      size_t i = attributes->specs - attributeSpecs;
+      for ( ; attributeIds[i] != JSID_VOID; ++i) {
+        if (id == attributeIds[i]) {
+          cacheOnHolder = true;
+
+          const JSPropertySpec& attrSpec = attributeSpecs[i];
+          // Because of centralization, we need to make sure we fault in the
+          // JitInfos as well. At present, until the JSAPI changes, the easiest
+          // way to do this is wrap them up as functions ourselves.
+          desc.setAttributes(attrSpec.flags);
+          // They all have getters, so we can just make it.
+          JS::Rooted<JSObject*> funobj(cx,
+            XrayCreateFunction(cx, wrapper, attrSpec.accessors.getter.native, 0, id));
+          if (!funobj)
+            return false;
+          desc.setGetterObject(funobj);
+          desc.attributesRef() |= JSPROP_GETTER;
+          if (attrSpec.accessors.setter.native.op) {
+            // We have a setter! Make it.
+            funobj =
+              XrayCreateFunction(cx, wrapper, attrSpec.accessors.setter.native, 1, id);
+            if (!funobj)
+              return false;
+            desc.setSetterObject(funobj);
+            desc.attributesRef() |= JSPROP_SETTER;
+          } else {
+            desc.setSetter(nullptr);
+          }
+          desc.object().set(wrapper);
+          return true;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+static bool
+XrayResolveMethod(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                  JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                  const Prefable<const JSFunctionSpec>* methods,
+                  const jsid* methodIds,
+                  const JSFunctionSpec* methodSpecs,
+                  JS::MutableHandle<JS::PropertyDescriptor> desc,
+                  bool& cacheOnHolder)
+{
+  const Prefable<const JSFunctionSpec>* method;
+  for (method = methods; method->specs; ++method) {
+    if (method->isEnabled(cx, obj)) {
+      // Set i to be the index into our full list of ids/specs that we're
+      // looking at now.
+      size_t i = method->specs - methodSpecs;
+      for ( ; methodIds[i] != JSID_VOID; ++i) {
+        if (id == methodIds[i]) {
+          cacheOnHolder = true;
+
+          const JSFunctionSpec& methodSpec = methodSpecs[i];
+          JSObject *funobj;
+          if (methodSpec.selfHostedName) {
+            JSFunction* fun =
+              JS::GetSelfHostedFunction(cx, methodSpec.selfHostedName, id,
+                                        methodSpec.nargs);
+            if (!fun) {
+              return false;
+            }
+            MOZ_ASSERT(!methodSpec.call.op, "Bad FunctionSpec declaration: non-null native");
+            MOZ_ASSERT(!methodSpec.call.info, "Bad FunctionSpec declaration: non-null jitinfo");
+            funobj = JS_GetFunctionObject(fun);
+          } else {
+            funobj = XrayCreateFunction(cx, wrapper, methodSpec.call,
+                                        methodSpec.nargs, id);
+            if (!funobj) {
+              return false;
+            }
+          }
+          desc.value().setObject(*funobj);
+          desc.setAttributes(methodSpec.flags);
+          desc.object().set(wrapper);
+          desc.setSetter(nullptr);
+          desc.setGetter(nullptr);
+          return true;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+// Try to resolve a property as an unforgeable property from the given
+// NativeProperties, if it's there.  nativeProperties is allowed to be null (in
+// which case we of course won't resolve anything).
+static bool
+XrayResolveUnforgeableProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                               JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                               JS::MutableHandle<JS::PropertyDescriptor> desc,
+                               bool& cacheOnHolder,
+                               const NativeProperties* nativeProperties)
+{
+  if (!nativeProperties) {
+    return true;
+  }
+
+  if (nativeProperties->HasUnforgeableAttributes()) {
+    if (!XrayResolveAttribute(cx, wrapper, obj, id,
+                              nativeProperties->UnforgeableAttributes(),
+                              nativeProperties->UnforgeableAttributeIds(),
+                              nativeProperties->UnforgeableAttributeSpecs(),
+                              desc, cacheOnHolder)) {
+      return false;
+    }
+
+    if (desc.object()) {
+      return true;
+    }
+  }
+
+  if (nativeProperties->HasUnforgeableMethods()) {
+    if (!XrayResolveMethod(cx, wrapper, obj, id,
+                           nativeProperties->UnforgeableMethods(),
+                           nativeProperties->UnforgeableMethodIds(),
+                           nativeProperties->UnforgeableMethodSpecs(),
+                           desc, cacheOnHolder)) {
+      return false;
+    }
+
+    if (desc.object()) {
+      return true;
+    }
+  }
+
+  return true;
+}
+
+static bool
+XrayResolveProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                    JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                    JS::MutableHandle<JS::PropertyDescriptor> desc,
+                    bool& cacheOnHolder, DOMObjectType type,
+                    const NativeProperties* nativeProperties)
+{
+  bool hasMethods = false;
+  if (type == eInterface) {
+    hasMethods = nativeProperties->HasStaticMethods();
+  } else {
+    hasMethods = nativeProperties->HasMethods();
+  }
+  if (hasMethods) {
+    const Prefable<const JSFunctionSpec>* methods;
+    const jsid* methodIds;
+    const JSFunctionSpec* methodSpecs;
+    if (type == eInterface) {
+      methods = nativeProperties->StaticMethods();
+      methodIds = nativeProperties->StaticMethodIds();
+      methodSpecs = nativeProperties->StaticMethodSpecs();
+    } else {
+      methods = nativeProperties->Methods();
+      methodIds = nativeProperties->MethodIds();
+      methodSpecs = nativeProperties->MethodSpecs();
+    }
+    JS::Rooted<jsid> methodId(cx);
+    if (nativeProperties->iteratorAliasMethodIndex != -1 &&
+        id == SYMBOL_TO_JSID(
+                JS::GetWellKnownSymbol(cx, JS::SymbolCode::iterator))) {
+      methodId =
+        nativeProperties->MethodIds()[nativeProperties->iteratorAliasMethodIndex];
+    } else {
+      methodId = id;
+    }
+    if (!XrayResolveMethod(cx, wrapper, obj, methodId, methods, methodIds,
+                           methodSpecs, desc, cacheOnHolder)) {
+      return false;
+    }
+    if (desc.object()) {
+      return true;
+    }
+  }
+
+  if (type == eInterface) {
+    if (nativeProperties->HasStaticAttributes()) {
+      if (!XrayResolveAttribute(cx, wrapper, obj, id,
+                                nativeProperties->StaticAttributes(),
+                                nativeProperties->StaticAttributeIds(),
+                                nativeProperties->StaticAttributeSpecs(),
+                                desc, cacheOnHolder)) {
+        return false;
+      }
+      if (desc.object()) {
+        return true;
+      }
+    }
+  } else {
+    if (nativeProperties->HasAttributes()) {
+      if (!XrayResolveAttribute(cx, wrapper, obj, id,
+                                nativeProperties->Attributes(),
+                                nativeProperties->AttributeIds(),
+                                nativeProperties->AttributeSpecs(),
+                                desc, cacheOnHolder)) {
+        return false;
+      }
+      if (desc.object()) {
+        return true;
+      }
+    }
+  }
+
+  if (nativeProperties->HasConstants()) {
+    const Prefable<const ConstantSpec>* constant;
+    for (constant = nativeProperties->Constants(); constant->specs; ++constant) {
+      if (constant->isEnabled(cx, obj)) {
+        // Set i to be the index into our full list of ids/specs that we're
+        // looking at now.
+        size_t i = constant->specs - nativeProperties->ConstantSpecs();
+        for ( ; nativeProperties->ConstantIds()[i] != JSID_VOID; ++i) {
+          if (id == nativeProperties->ConstantIds()[i]) {
+            cacheOnHolder = true;
+
+            desc.setAttributes(JSPROP_ENUMERATE | JSPROP_READONLY | JSPROP_PERMANENT);
+            desc.object().set(wrapper);
+            desc.value().set(nativeProperties->ConstantSpecs()[i].value);
+            return true;
+          }
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+static bool
+ResolvePrototypeOrConstructor(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                              JS::Handle<JSObject*> obj,
+                              size_t protoAndIfaceCacheIndex, unsigned attrs,
+                              JS::MutableHandle<JS::PropertyDescriptor> desc,
+                              bool& cacheOnHolder)
+{
+  JS::Rooted<JSObject*> global(cx, js::GetGlobalForObjectCrossCompartment(obj));
+  {
+    JSAutoCompartment ac(cx, global);
+    ProtoAndIfaceCache& protoAndIfaceCache = *GetProtoAndIfaceCache(global);
+    JSObject* protoOrIface =
+      protoAndIfaceCache.EntrySlotIfExists(protoAndIfaceCacheIndex);
+    if (!protoOrIface) {
+      return false;
+    }
+
+    cacheOnHolder = true;
+
+    desc.object().set(wrapper);
+    desc.setAttributes(attrs);
+    desc.setGetter(nullptr);
+    desc.setSetter(nullptr);
+    desc.value().set(JS::ObjectValue(*protoOrIface));
+  }
+  return JS_WrapPropertyDescriptor(cx, desc);
+}
+
+#ifdef DEBUG
+
+static void
+DEBUG_CheckXBLCallable(JSContext *cx, JSObject *obj)
+{
+    // In general, we shouldn't have cross-compartment wrappers here, because
+    // we should be running in an XBL scope, and the content prototype should
+    // contain wrappers to functions defined in the XBL scope. But if the node
+    // has been adopted into another compartment, those prototypes will now point
+    // to a different XBL scope (which is ok).
+    MOZ_ASSERT_IF(js::IsCrossCompartmentWrapper(obj),
+                  xpc::IsContentXBLScope(js::GetObjectCompartment(js::UncheckedUnwrap(obj))));
+    MOZ_ASSERT(JS::IsCallable(obj));
+}
+
+static void
+DEBUG_CheckXBLLookup(JSContext *cx, JS::PropertyDescriptor *desc)
+{
+    if (!desc->obj)
+        return;
+    if (!desc->value.isUndefined()) {
+        MOZ_ASSERT(desc->value.isObject());
+        DEBUG_CheckXBLCallable(cx, &desc->value.toObject());
+    }
+    if (desc->getter) {
+        MOZ_ASSERT(desc->attrs & JSPROP_GETTER);
+        DEBUG_CheckXBLCallable(cx, JS_FUNC_TO_DATA_PTR(JSObject *, desc->getter));
+    }
+    if (desc->setter) {
+        MOZ_ASSERT(desc->attrs & JSPROP_SETTER);
+        DEBUG_CheckXBLCallable(cx, JS_FUNC_TO_DATA_PTR(JSObject *, desc->setter));
+    }
+}
+#else
+#define DEBUG_CheckXBLLookup(a, b) {}
+#endif
+
+/* static */ bool
+XrayResolveOwnProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                       JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                       JS::MutableHandle<JS::PropertyDescriptor> desc,
+                       bool& cacheOnHolder)
+{
+  cacheOnHolder = false;
+
+  DOMObjectType type;
+  const NativePropertyHooks *nativePropertyHooks =
+    GetNativePropertyHooks(cx, obj, type);
+  const NativePropertiesHolder& nativeProperties =
+    nativePropertyHooks->mNativeProperties;
+  ResolveOwnProperty resolveOwnProperty =
+    nativePropertyHooks->mResolveOwnProperty;
+
+  if (type == eNamedPropertiesObject) {
+    // None of these should be cached on the holder, since they're dynamic.
+    return resolveOwnProperty(cx, wrapper, obj, id, desc);
+  }
+
+  // Check for unforgeable properties first.
+  if (IsInstance(type)) {
+    const NativePropertiesHolder& nativeProperties =
+      nativePropertyHooks->mNativeProperties;
+    if (!XrayResolveUnforgeableProperty(cx, wrapper, obj, id, desc, cacheOnHolder,
+                                        nativeProperties.regular)) {
+      return false;
+    }
+
+    if (!desc.object() && xpc::AccessCheck::isChrome(wrapper) &&
+        !XrayResolveUnforgeableProperty(cx, wrapper, obj, id, desc, cacheOnHolder,
+                                        nativeProperties.chromeOnly)) {
+      return false;
+    }
+
+    if (desc.object()) {
+      return true;
+    }
+  }
+
+  if (IsInstance(type)) {
+    if (resolveOwnProperty) {
+      if (!resolveOwnProperty(cx, wrapper, obj, id, desc)) {
+        return false;
+      }
+
+      if (desc.object()) {
+        // None of these should be cached on the holder, since they're dynamic.
+        return true;
+      }
+    }
+
+    // If we're a special scope for in-content XBL, our script expects to see
+    // the bound XBL methods and attributes when accessing content. However,
+    // these members are implemented in content via custom-spliced prototypes,
+    // and thus aren't visible through Xray wrappers unless we handle them
+    // explicitly. So we check if we're running in such a scope, and if so,
+    // whether the wrappee is a bound element. If it is, we do a lookup via
+    // specialized XBL machinery.
+    //
+    // While we have to do some sketchy walking through content land, we should
+    // be protected by read-only/non-configurable properties, and any functions
+    // we end up with should _always_ be living in our own scope (the XBL scope).
+    // Make sure to assert that.
+    JS::Rooted<JSObject*> maybeElement(cx, obj);
+    Element* element;
+    if (xpc::ObjectScope(wrapper)->IsContentXBLScope() &&
+        NS_SUCCEEDED(UNWRAP_OBJECT(Element, &maybeElement, element))) {
+      if (!nsContentUtils::LookupBindingMember(cx, element, id, desc)) {
+        return false;
+      }
+
+      DEBUG_CheckXBLLookup(cx, desc.address());
+
+      if (desc.object()) {
+        // XBL properties shouldn't be cached on the holder, as they might be
+        // shadowed by own properties returned from mResolveOwnProperty.
+        desc.object().set(wrapper);
+
+        return true;
+      }
+    }
+
+    // For non-global instance Xrays there are no other properties, so return
+    // here for them.
+    if (type != eGlobalInstance) {
+      return true;
+    }
+  } else if (type == eInterface) {
+    if (IdEquals(id, "prototype")) {
+      return nativePropertyHooks->mPrototypeID == prototypes::id::_ID_Count ||
+             ResolvePrototypeOrConstructor(cx, wrapper, obj,
+                                           nativePropertyHooks->mPrototypeID,
+                                           JSPROP_PERMANENT | JSPROP_READONLY,
+                                           desc, cacheOnHolder);
+    }
+
+    if (id == SYMBOL_TO_JSID(JS::GetWellKnownSymbol(cx, JS::SymbolCode::hasInstance)) &&
+        DOMIfaceAndProtoJSClass::FromJSClass(js::GetObjectClass(obj))->
+          wantsInterfaceHasInstance) {
+      cacheOnHolder = true;
+      JSNativeWrapper interfaceHasInstanceWrapper = { InterfaceHasInstance,
+                                                      nullptr };
+      JSObject* funObj = XrayCreateFunction(cx, wrapper,
+                                            interfaceHasInstanceWrapper, 1, id);
+      if (!funObj) {
+        return false;
+      }
+
+      desc.value().setObject(*funObj);
+      desc.setAttributes(JSPROP_READONLY | JSPROP_PERMANENT);
+      desc.object().set(wrapper);
+      desc.setSetter(nullptr);
+      desc.setGetter(nullptr);
+      return true;
+    }
+  } else {
+    MOZ_ASSERT(IsInterfacePrototype(type));
+
+    if (IdEquals(id, "constructor")) {
+      return nativePropertyHooks->mConstructorID == constructors::id::_ID_Count ||
+             ResolvePrototypeOrConstructor(cx, wrapper, obj,
+                                           nativePropertyHooks->mConstructorID,
+                                           0, desc, cacheOnHolder);
+    }
+
+    // The properties for globals live on the instance, so return here as there
+    // are no properties on their interface prototype object.
+    if (type == eGlobalInterfacePrototype) {
+      return true;
+    }
+  }
+
+  if (nativeProperties.regular &&
+      !XrayResolveProperty(cx, wrapper, obj, id, desc, cacheOnHolder, type,
+                           nativeProperties.regular)) {
+    return false;
+  }
+
+  if (!desc.object() &&
+      nativeProperties.chromeOnly &&
+      xpc::AccessCheck::isChrome(js::GetObjectCompartment(wrapper)) &&
+      !XrayResolveProperty(cx, wrapper, obj, id, desc, cacheOnHolder, type,
+                           nativeProperties.chromeOnly)) {
+    return false;
+  }
+
+  return true;
+}
+
+bool
+XrayDefineProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                   JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                   JS::Handle<JS::PropertyDescriptor> desc,
+                   JS::ObjectOpResult &result, bool *defined)
+{
+  if (!js::IsProxy(obj))
+    return true;
+
+  const DOMProxyHandler* handler = GetDOMProxyHandler(obj);
+  return handler->defineProperty(cx, wrapper, id, desc, result, defined);
+}
+
+template<typename SpecType>
+bool
+XrayAttributeOrMethodKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                          JS::Handle<JSObject*> obj,
+                          const Prefable<const SpecType>* list,
+                          const jsid* ids, const SpecType* specList,
+                          unsigned flags, JS::AutoIdVector& props)
+{
+  for (; list->specs; ++list) {
+    if (list->isEnabled(cx, obj)) {
+      // Set i to be the index into our full list of ids/specs that we're
+      // looking at now.
+      size_t i = list->specs - specList;
+      for ( ; ids[i] != JSID_VOID; ++i) {
+        // Skip non-enumerable properties and symbol-keyed properties unless
+        // they are specially requested via flags.
+        if (((flags & JSITER_HIDDEN) ||
+             (specList[i].flags & JSPROP_ENUMERATE)) &&
+            ((flags & JSITER_SYMBOLS) || !JSID_IS_SYMBOL(ids[i])) &&
+            !props.append(ids[i])) {
+          return false;
+        }
+      }
+    }
+  }
+  return true;
+}
+
+#define ADD_KEYS_IF_DEFINED(FieldName) {                                      \
+  if (nativeProperties->Has##FieldName##s() &&                                \
+      !XrayAttributeOrMethodKeys(cx, wrapper, obj,                            \
+                                 nativeProperties->FieldName##s(),            \
+                                 nativeProperties->FieldName##Ids(),          \
+                                 nativeProperties->FieldName##Specs(),        \
+                                 flags, props)) {                             \
+    return false;                                                             \
+  }                                                                           \
+}
+
+
+bool
+XrayOwnPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                    JS::Handle<JSObject*> obj,
+                    unsigned flags, JS::AutoIdVector& props,
+                    DOMObjectType type,
+                    const NativeProperties* nativeProperties)
+{
+  MOZ_ASSERT(type != eNamedPropertiesObject);
+
+  if (IsInstance(type)) {
+    ADD_KEYS_IF_DEFINED(UnforgeableMethod);
+    ADD_KEYS_IF_DEFINED(UnforgeableAttribute);
+    if (type == eGlobalInstance) {
+      ADD_KEYS_IF_DEFINED(Method);
+      ADD_KEYS_IF_DEFINED(Attribute);
+    }
+  } else if (type == eInterface) {
+    ADD_KEYS_IF_DEFINED(StaticMethod);
+    ADD_KEYS_IF_DEFINED(StaticAttribute);
+  } else if (type != eGlobalInterfacePrototype) {
+    MOZ_ASSERT(IsInterfacePrototype(type));
+    ADD_KEYS_IF_DEFINED(Method);
+    ADD_KEYS_IF_DEFINED(Attribute);
+  }
+
+  if (nativeProperties->HasConstants()) {
+    const Prefable<const ConstantSpec>* constant;
+    for (constant = nativeProperties->Constants(); constant->specs; ++constant) {
+      if (constant->isEnabled(cx, obj)) {
+        // Set i to be the index into our full list of ids/specs that we're
+        // looking at now.
+        size_t i = constant->specs - nativeProperties->ConstantSpecs();
+        for ( ; nativeProperties->ConstantIds()[i] != JSID_VOID; ++i) {
+          if (!props.append(nativeProperties->ConstantIds()[i])) {
+            return false;
+          }
+        }
+      }
+    }
+  }
+
+  return true;
+}
+
+#undef ADD_KEYS_IF_DEFINED
+
+bool
+XrayOwnNativePropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                          const NativePropertyHooks* nativePropertyHooks,
+                          DOMObjectType type, JS::Handle<JSObject*> obj,
+                          unsigned flags, JS::AutoIdVector& props)
+{
+  MOZ_ASSERT(type != eNamedPropertiesObject);
+
+  if (type == eInterface &&
+      nativePropertyHooks->mPrototypeID != prototypes::id::_ID_Count &&
+      !AddStringToIDVector(cx, props, "prototype")) {
+    return false;
+  }
+
+  if (IsInterfacePrototype(type) &&
+      nativePropertyHooks->mConstructorID != constructors::id::_ID_Count &&
+      (flags & JSITER_HIDDEN) &&
+      !AddStringToIDVector(cx, props, "constructor")) {
+    return false;
+  }
+
+  const NativePropertiesHolder& nativeProperties =
+    nativePropertyHooks->mNativeProperties;
+
+  if (nativeProperties.regular &&
+      !XrayOwnPropertyKeys(cx, wrapper, obj, flags, props, type,
+                           nativeProperties.regular)) {
+    return false;
+  }
+
+  if (nativeProperties.chromeOnly &&
+      xpc::AccessCheck::isChrome(js::GetObjectCompartment(wrapper)) &&
+      !XrayOwnPropertyKeys(cx, wrapper, obj, flags, props, type,
+                           nativeProperties.chromeOnly)) {
+    return false;
+  }
+
+  return true;
+}
+
+bool
+XrayOwnPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                    JS::Handle<JSObject*> obj,
+                    unsigned flags, JS::AutoIdVector& props)
+{
+  DOMObjectType type;
+  const NativePropertyHooks* nativePropertyHooks =
+    GetNativePropertyHooks(cx, obj, type);
+  EnumerateOwnProperties enumerateOwnProperties =
+    nativePropertyHooks->mEnumerateOwnProperties;
+
+  if (type == eNamedPropertiesObject) {
+    return enumerateOwnProperties(cx, wrapper, obj, props);
+  }
+
+  if (IsInstance(type)) {
+    // FIXME https://bugzilla.mozilla.org/show_bug.cgi?id=1071189
+    //       Should do something about XBL properties too.
+    if (enumerateOwnProperties &&
+        !enumerateOwnProperties(cx, wrapper, obj, props)) {
+      return false;
+    }
+  }
+
+  return type == eGlobalInterfacePrototype ||
+         XrayOwnNativePropertyKeys(cx, wrapper, nativePropertyHooks, type,
+                                   obj, flags, props);
+}
+
+const JSClass*
+XrayGetExpandoClass(JSContext* cx, JS::Handle<JSObject*> obj)
+{
+  DOMObjectType type;
+  const NativePropertyHooks* nativePropertyHooks =
+    GetNativePropertyHooks(cx, obj, type);
+  if (!IsInstance(type)) {
+    // Non-instances don't need any special expando classes.
+    return &DefaultXrayExpandoObjectClass;
+  }
+
+  return nativePropertyHooks->mXrayExpandoClass;
+}
+
+bool
+XrayDeleteNamedProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                        JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                        JS::ObjectOpResult& opresult)
+{
+  DOMObjectType type;
+  const NativePropertyHooks* nativePropertyHooks =
+    GetNativePropertyHooks(cx, obj, type);
+  if (!IsInstance(type) || !nativePropertyHooks->mDeleteNamedProperty) {
+    return opresult.succeed();
+  }
+  return nativePropertyHooks->mDeleteNamedProperty(cx, wrapper, obj, id,
+                                                   opresult);
+}
+
+JSObject*
+GetCachedSlotStorageObjectSlow(JSContext* cx, JS::Handle<JSObject*> obj,
+                               bool* isXray)
+{
+  if (!xpc::WrapperFactory::IsXrayWrapper(obj)) {
+    JSObject* retval = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+    MOZ_ASSERT(IsDOMObject(retval));
+    *isXray = false;
+    return retval;
+  }
+
+  *isXray = true;
+  return xpc::EnsureXrayExpandoObject(cx, obj);;
+}
+
+DEFINE_XRAY_EXPANDO_CLASS(, DefaultXrayExpandoObjectClass, 0);
+
+NativePropertyHooks sEmptyNativePropertyHooks = {
+  nullptr,
+  nullptr,
+  nullptr,
+  {
+    nullptr,
+    nullptr
+  },
+  prototypes::id::_ID_Count,
+  constructors::id::_ID_Count,
+  nullptr
+};
+
+const js::ClassOps sBoringInterfaceObjectClassClassOps = {
+    nullptr,               /* addProperty */
+    nullptr,               /* delProperty */
+    nullptr,               /* getProperty */
+    nullptr,               /* setProperty */
+    nullptr,               /* enumerate */
+    nullptr,               /* resolve */
+    nullptr,               /* mayResolve */
+    nullptr,               /* finalize */
+    ThrowingConstructor,   /* call */
+    nullptr,               /* hasInstance */
+    ThrowingConstructor,   /* construct */
+    nullptr,               /* trace */
+};
+
+const js::ObjectOps sInterfaceObjectClassObjectOps = {
+  nullptr, /* lookupProperty */
+  nullptr, /* defineProperty */
+  nullptr, /* hasProperty */
+  nullptr, /* getProperty */
+  nullptr, /* setProperty */
+  nullptr, /* getOwnPropertyDescriptor */
+  nullptr, /* deleteProperty */
+  nullptr, /* watch */
+  nullptr, /* unwatch */
+  nullptr, /* getElements */
+  nullptr, /* enumerate */
+  InterfaceObjectToString, /* funToString */
+};
+
+bool
+GetPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       JS::Handle<JS::Value> receiver, JS::Handle<jsid> id,
+                       bool* found, JS::MutableHandle<JS::Value> vp)
+{
+  JS::Rooted<JSObject*> proto(cx);
+  if (!js::GetObjectProto(cx, proxy, &proto)) {
+    return false;
+  }
+  if (!proto) {
+    *found = false;
+    return true;
+  }
+
+  if (!JS_HasPropertyById(cx, proto, id, found)) {
+    return false;
+  }
+
+  if (!*found) {
+    return true;
+  }
+
+  return JS_ForwardGetPropertyTo(cx, proto, id, receiver, vp);
+}
+
+bool
+HasPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       JS::Handle<jsid> id, bool* has)
+{
+  JS::Rooted<JSObject*> proto(cx);
+  if (!js::GetObjectProto(cx, proxy, &proto)) {
+    return false;
+  }
+  if (!proto) {
+    *has = false;
+    return true;
+  }
+
+  return JS_HasPropertyById(cx, proto, id, has);
+}
+
+bool
+AppendNamedPropertyIds(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       nsTArray<nsString>& names,
+                       bool shadowPrototypeProperties,
+                       JS::AutoIdVector& props)
+{
+  for (uint32_t i = 0; i < names.Length(); ++i) {
+    JS::Rooted<JS::Value> v(cx);
+    if (!xpc::NonVoidStringToJsval(cx, names[i], &v)) {
+      return false;
+    }
+
+    JS::Rooted<jsid> id(cx);
+    if (!JS_ValueToId(cx, v, &id)) {
+      return false;
+    }
+
+    bool shouldAppend = shadowPrototypeProperties;
+    if (!shouldAppend) {
+      bool has;
+      if (!HasPropertyOnPrototype(cx, proxy, id, &has)) {
+        return false;
+      }
+      shouldAppend = !has;
+    }
+
+    if (shouldAppend) {
+      if (!props.append(id)) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+bool
+DictionaryBase::ParseJSON(JSContext* aCx,
+                          const nsAString& aJSON,
+                          JS::MutableHandle<JS::Value> aVal)
+{
+  if (aJSON.IsEmpty()) {
+    return true;
+  }
+  return JS_ParseJSON(aCx, PromiseFlatString(aJSON).get(), aJSON.Length(), aVal);
+}
+
+bool
+DictionaryBase::StringifyToJSON(JSContext* aCx,
+                                JS::Handle<JSObject*> aObj,
+                                nsAString& aJSON) const
+{
+  return JS::ToJSONMaybeSafely(aCx, aObj, AppendJSONToString, &aJSON);
+}
+
+/* static */
+bool
+DictionaryBase::AppendJSONToString(const char16_t* aJSONData,
+                                   uint32_t aDataLength,
+                                   void* aString)
+{
+  nsAString* string = static_cast<nsAString*>(aString);
+  string->Append(aJSONData, aDataLength);
+  return true;
+}
+
+nsresult
+ReparentWrapper(JSContext* aCx, JS::Handle<JSObject*> aObjArg)
+{
+  js::AssertSameCompartment(aCx, aObjArg);
+
+  // Check if we're anywhere near the stack limit before we reach the
+  // transplanting code, since it has no good way to handle errors. This uses
+  // the untrusted script limit, which is not strictly necessary since no
+  // actual script should run.
+  JS_CHECK_RECURSION_CONSERVATIVE(aCx, return NS_ERROR_FAILURE);
+
+  JS::Rooted<JSObject*> aObj(aCx, aObjArg);
+  const DOMJSClass* domClass = GetDOMClass(aObj);
+
+  // DOM things are always parented to globals.
+  JS::Rooted<JSObject*> oldParent(aCx,
+                                  js::GetGlobalForObjectCrossCompartment(aObj));
+  MOZ_ASSERT(js::GetGlobalForObjectCrossCompartment(oldParent) == oldParent);
+
+  JS::Rooted<JSObject*> newParent(aCx,
+                                  domClass->mGetAssociatedGlobal(aCx, aObj));
+  MOZ_ASSERT(JS_IsGlobalObject(newParent));
+
+  JSAutoCompartment oldAc(aCx, oldParent);
+
+  JSCompartment* oldCompartment = js::GetObjectCompartment(oldParent);
+  JSCompartment* newCompartment = js::GetObjectCompartment(newParent);
+  if (oldCompartment == newCompartment) {
+    MOZ_ASSERT(oldParent == newParent);
+    return NS_OK;
+  }
+
+  nsISupports* native = UnwrapDOMObjectToISupports(aObj);
+  if (!native) {
+    return NS_OK;
+  }
+
+  bool isProxy = js::IsProxy(aObj);
+  JS::Rooted<JSObject*> expandoObject(aCx);
+  if (isProxy) {
+    expandoObject = DOMProxyHandler::GetAndClearExpandoObject(aObj);
+  }
+
+  JSAutoCompartment newAc(aCx, newParent);
+
+  // First we clone the reflector. We get a copy of its properties and clone its
+  // expando chain.
+
+  JS::Handle<JSObject*> proto = (domClass->mGetProto)(aCx);
+  if (!proto) {
+    return NS_ERROR_FAILURE;
+  }
+
+  JS::Rooted<JSObject*> newobj(aCx, JS_CloneObject(aCx, aObj, proto));
+  if (!newobj) {
+    return NS_ERROR_FAILURE;
+  }
+
+  JS::Rooted<JSObject*> propertyHolder(aCx);
+  JS::Rooted<JSObject*> copyFrom(aCx, isProxy ? expandoObject : aObj);
+  if (copyFrom) {
+    propertyHolder = JS_NewObjectWithGivenProto(aCx, nullptr, nullptr);
+    if (!propertyHolder) {
+      return NS_ERROR_OUT_OF_MEMORY;
+    }
+
+    if (!JS_CopyPropertiesFrom(aCx, propertyHolder, copyFrom)) {
+      return NS_ERROR_FAILURE;
+    }
+  } else {
+    propertyHolder = nullptr;
+  }
+
+  // Expandos from other compartments are attached to the target JS object.
+  // Copy them over, and let the old ones die a natural death.
+
+  // Note that at this point the DOM_OBJECT_SLOT for |newobj| has not been set.
+  // CloneExpandoChain() will use this property of |newobj| when it calls
+  // preserveWrapper() via attachExpandoObject() if |aObj| has expandos set, and
+  // preserveWrapper() will not do anything in this case.  This is safe because
+  // if expandos are present then the wrapper will already have been preserved
+  // for this native.
+  if (!xpc::XrayUtils::CloneExpandoChain(aCx, newobj, aObj)) {
+    return NS_ERROR_FAILURE;
+  }
+
+  // We've set up |newobj|, so we make it own the native by setting its reserved
+  // slot and nulling out the reserved slot of |obj|.
+  //
+  // NB: It's important to do this _after_ copying the properties to
+  // propertyHolder. Otherwise, an object with |foo.x === foo| will
+  // crash when JS_CopyPropertiesFrom tries to call wrap() on foo.x.
+  js::SetReservedOrProxyPrivateSlot(newobj, DOM_OBJECT_SLOT,
+                                    js::GetReservedOrProxyPrivateSlot(aObj, DOM_OBJECT_SLOT));
+  js::SetReservedOrProxyPrivateSlot(aObj, DOM_OBJECT_SLOT, JS::PrivateValue(nullptr));
+
+  aObj = xpc::TransplantObject(aCx, aObj, newobj);
+  if (!aObj) {
+    MOZ_CRASH();
+  }
+
+  nsWrapperCache* cache = nullptr;
+  CallQueryInterface(native, &cache);
+  bool preserving = cache->PreservingWrapper();
+  cache->SetPreservingWrapper(false);
+  cache->SetWrapper(aObj);
+  cache->SetPreservingWrapper(preserving);
+
+  if (propertyHolder) {
+    JS::Rooted<JSObject*> copyTo(aCx);
+    if (isProxy) {
+      copyTo = DOMProxyHandler::EnsureExpandoObject(aCx, aObj);
+    } else {
+      copyTo = aObj;
+    }
+
+    if (!copyTo || !JS_CopyPropertiesFrom(aCx, copyTo, propertyHolder)) {
+      MOZ_CRASH();
+    }
+  }
+
+  JS::Rooted<JSObject*> maybeObjLC(aCx, aObj);
+  nsObjectLoadingContent* htmlobject;
+  nsresult rv = UNWRAP_OBJECT(HTMLObjectElement, &maybeObjLC, htmlobject);
+  if (NS_FAILED(rv)) {
+    rv = UnwrapObject<prototypes::id::HTMLEmbedElement,
+                      HTMLSharedObjectElement>(&maybeObjLC, htmlobject);
+    if (NS_FAILED(rv)) {
+      rv = UnwrapObject<prototypes::id::HTMLAppletElement,
+                        HTMLSharedObjectElement>(&maybeObjLC, htmlobject);
+      if (NS_FAILED(rv)) {
+        htmlobject = nullptr;
+      }
+    }
+  }
+  if (htmlobject) {
+    htmlobject->SetupProtoChain(aCx, aObj);
+  }
+
+  // Now we can just return the wrapper
+  return NS_OK;
+}
+
+GlobalObject::GlobalObject(JSContext* aCx, JSObject* aObject)
+  : mGlobalJSObject(aCx),
+    mCx(aCx),
+    mGlobalObject(nullptr)
+{
+  MOZ_ASSERT(mCx);
+  JS::Rooted<JSObject*> obj(aCx, aObject);
+  if (js::IsWrapper(obj)) {
+    obj = js::CheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+    if (!obj) {
+      // We should never end up here on a worker thread, since there shouldn't
+      // be any security wrappers to worry about.
+      if (!MOZ_LIKELY(NS_IsMainThread())) {
+        MOZ_CRASH();
+      }
+
+      Throw(aCx, NS_ERROR_XPC_SECURITY_MANAGER_VETO);
+      return;
+    }
+  }
+
+  mGlobalJSObject = js::GetGlobalForObjectCrossCompartment(obj);
+}
+
+nsISupports*
+GlobalObject::GetAsSupports() const
+{
+  if (mGlobalObject) {
+    return mGlobalObject;
+  }
+
+  MOZ_ASSERT(!js::IsWrapper(mGlobalJSObject));
+
+  // Most of our globals are DOM objects.  Try that first.  Note that this
+  // assumes that either the first nsISupports in the object is the canonical
+  // one or that we don't care about the canonical nsISupports here.
+  mGlobalObject = UnwrapDOMObjectToISupports(mGlobalJSObject);
+  if (mGlobalObject) {
+    return mGlobalObject;
+  }
+
+  MOZ_ASSERT(NS_IsMainThread(), "All our worker globals are DOM objects");
+
+  // Remove everything below here once all our global objects are using new
+  // bindings.  If that ever happens; it would need to include Sandbox and
+  // BackstagePass.
+
+  // See whether mGlobalJSObject is an XPCWrappedNative.  This will redo the
+  // IsWrapper bit above and the UnwrapDOMObjectToISupports in the case when
+  // we're not actually an XPCWrappedNative, but this should be a rare-ish case
+  // anyway.
+  nsCOMPtr<nsISupports> supp = xpc::UnwrapReflectorToISupports(mGlobalJSObject);
+  if (supp) {
+    // See documentation for mGlobalJSObject for why this assignment is OK.
+    mGlobalObject = supp;
+    return mGlobalObject;
+  }
+
+  // And now a final hack.  Sandbox is not a reflector, but it does have an
+  // nsIGlobalObject hanging out in its private slot.  Handle that case here,
+  // (though again, this will do the useless UnwrapDOMObjectToISupports if we
+  // got here for something that is somehow not a DOM object, not an
+  // XPCWrappedNative _and_ not a Sandbox).
+  if (XPCConvert::GetISupportsFromJSObject(mGlobalJSObject, &mGlobalObject)) {
+    return mGlobalObject;
+  }
+
+  MOZ_ASSERT(!mGlobalObject);
+
+  Throw(mCx, NS_ERROR_XPC_BAD_CONVERT_JS);
+  return nullptr;
+}
+
+nsIPrincipal*
+GlobalObject::GetSubjectPrincipal() const
+{
+  if (!NS_IsMainThread()) {
+    return nullptr;
+  }
+
+  JSCompartment* compartment = js::GetContextCompartment(mCx);
+  MOZ_ASSERT(compartment);
+  JSPrincipals* principals = JS_GetCompartmentPrincipals(compartment);
+  return nsJSPrincipals::get(principals);
+}
+
+static bool
+CallOrdinaryHasInstance(JSContext* cx, JS::CallArgs& args)
+{
+    JS::Rooted<JSObject*> thisObj(cx, &args.thisv().toObject());
+    bool isInstance;
+    if (!JS::OrdinaryHasInstance(cx, thisObj, args.get(0), &isInstance)) {
+      return false;
+    }
+    args.rval().setBoolean(isInstance);
+    return true;
+}
+
+bool
+InterfaceHasInstance(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  // If the thing we were passed is not an object, return false like
+  // OrdinaryHasInstance does.
+  if (!args.get(0).isObject()) {
+    args.rval().setBoolean(false);
+    return true;
+  }
+
+  // If "this" is not an object, likewise return false (again, like
+  // OrdinaryHasInstance).
+  if (!args.thisv().isObject()) {
+    args.rval().setBoolean(false);
+    return true;
+  }
+
+  // If "this" doesn't have a DOMIfaceAndProtoJSClass, it's not a DOM
+  // constructor, so just fall back to OrdinaryHasInstance.  But note that we
+  // should CheckedUnwrap here, because otherwise we won't get the right
+  // answers.
+  JS::Rooted<JSObject*> thisObj(cx, js::CheckedUnwrap(&args.thisv().toObject()));
+  if (!thisObj) {
+    // Just fall back on the normal thing, in case it still happens to work.
+    return CallOrdinaryHasInstance(cx, args);
+  }
+
+  const js::Class* thisClass = js::GetObjectClass(thisObj);
+
+  if (!IsDOMIfaceAndProtoClass(thisClass)) {
+    return CallOrdinaryHasInstance(cx, args);
+  }
+
+  const DOMIfaceAndProtoJSClass* clasp =
+    DOMIfaceAndProtoJSClass::FromJSClass(thisClass);
+
+  // If "this" isn't a DOM constructor or is a constructor for an interface
+  // without a prototype, just fall back to OrdinaryHasInstance.
+  if (clasp->mType != eInterface ||
+      clasp->mPrototypeID == prototypes::id::_ID_Count) {
+    return CallOrdinaryHasInstance(cx, args);
+  }
+
+  JS::Rooted<JSObject*> instance(cx, &args[0].toObject());
+  const DOMJSClass* domClass =
+    GetDOMClass(js::UncheckedUnwrap(instance, /* stopAtWindowProxy = */ false));
+
+  if (domClass &&
+      domClass->mInterfaceChain[clasp->mDepth] == clasp->mPrototypeID) {
+    args.rval().setBoolean(true);
+    return true;
+  }
+
+  if (jsipc::IsWrappedCPOW(instance)) {
+    bool boolp = false;
+    if (!jsipc::DOMInstanceOf(cx, js::UncheckedUnwrap(instance), clasp->mPrototypeID,
+                              clasp->mDepth, &boolp)) {
+      return false;
+    }
+    args.rval().setBoolean(boolp);
+    return true;
+  }
+
+  return CallOrdinaryHasInstance(cx, args);
+}
+
+bool
+InterfaceHasInstance(JSContext* cx, int prototypeID, int depth,
+                     JS::Handle<JSObject*> instance,
+                     bool* bp)
+{
+  const DOMJSClass* domClass = GetDOMClass(js::UncheckedUnwrap(instance));
+
+  MOZ_ASSERT(!domClass || prototypeID != prototypes::id::_ID_Count,
+             "Why do we have a hasInstance hook if we don't have a prototype "
+             "ID?");
+
+  *bp = (domClass && domClass->mInterfaceChain[depth] == prototypeID);
+  return true;
+}
+
+bool
+ReportLenientThisUnwrappingFailure(JSContext* cx, JSObject* obj)
+{
+  JS::Rooted<JSObject*> rootedObj(cx, obj);
+  GlobalObject global(cx, rootedObj);
+  if (global.Failed()) {
+    return false;
+  }
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global.GetAsSupports());
+  if (window && window->GetDoc()) {
+    window->GetDoc()->WarnOnceAbout(nsIDocument::eLenientThis);
+  }
+  return true;
+}
+
+bool
+GetContentGlobalForJSImplementedObject(JSContext* cx, JS::Handle<JSObject*> obj,
+                                       nsIGlobalObject** globalObj)
+{
+  // Be very careful to not get tricked here.
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!xpc::AccessCheck::isChrome(js::GetObjectCompartment(obj))) {
+    NS_RUNTIMEABORT("Should have a chrome object here");
+  }
+
+  // Look up the content-side object.
+  JS::Rooted<JS::Value> domImplVal(cx);
+  if (!JS_GetProperty(cx, obj, "__DOM_IMPL__", &domImplVal)) {
+    return false;
+  }
+
+  if (!domImplVal.isObject()) {
+    ThrowErrorMessage(cx, MSG_NOT_OBJECT, "Value");
+    return false;
+  }
+
+  // Go ahead and get the global from it.  GlobalObject will handle
+  // doing unwrapping as needed.
+  GlobalObject global(cx, &domImplVal.toObject());
+  if (global.Failed()) {
+    return false;
+  }
+
+  DebugOnly<nsresult> rv = CallQueryInterface(global.GetAsSupports(), globalObj);
+  MOZ_ASSERT(NS_SUCCEEDED(rv));
+  MOZ_ASSERT(*globalObj);
+  return true;
+}
+
+already_AddRefed<nsIGlobalObject>
+ConstructJSImplementation(const char* aContractId,
+                          const GlobalObject& aGlobal,
+                          JS::MutableHandle<JSObject*> aObject,
+                          ErrorResult& aRv)
+{
+  // Get the global object to use as a parent and for initialization.
+  nsCOMPtr<nsIGlobalObject> global = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!global) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  ConstructJSImplementation(aContractId, global, aObject, aRv);
+
+  if (aRv.Failed()) {
+    return nullptr;
+  }
+  return global.forget();
+}
+
+void
+ConstructJSImplementation(const char* aContractId,
+                          nsIGlobalObject* aGlobal,
+                          JS::MutableHandle<JSObject*> aObject,
+                          ErrorResult& aRv)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  // Make sure to divorce ourselves from the calling JS while creating and
+  // initializing the object, so exceptions from that will get reported
+  // properly, since those are never exceptions that a spec wants to be thrown.
+  {
+    AutoNoJSAPI nojsapi;
+
+    // Get the XPCOM component containing the JS implementation.
+    nsresult rv;
+    nsCOMPtr<nsISupports> implISupports = do_CreateInstance(aContractId, &rv);
+    if (!implISupports) {
+      nsPrintfCString msg("Failed to get JS implementation for contract \"%s\"",
+                          aContractId);
+      NS_WARNING(msg.get());
+      aRv.Throw(rv);
+      return;
+    }
+    // Initialize the object, if it implements nsIDOMGlobalPropertyInitializer
+    // and our global is a window.
+    nsCOMPtr<nsIDOMGlobalPropertyInitializer> gpi =
+      do_QueryInterface(implISupports);
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal);
+    if (gpi) {
+      JS::Rooted<JS::Value> initReturn(RootingCx());
+      rv = gpi->Init(window, &initReturn);
+      if (NS_FAILED(rv)) {
+        aRv.Throw(rv);
+        return;
+      }
+      // With JS-implemented WebIDL, the return value of init() is not used to determine
+      // if init() failed, so init() should only return undefined. Any kind of permission
+      // or pref checking must happen by adding an attribute to the WebIDL interface.
+      if (!initReturn.isUndefined()) {
+        MOZ_ASSERT(false, "The init() method for JS-implemented WebIDL should not return anything");
+        MOZ_CRASH();
+      }
+    }
+    // Extract the JS implementation from the XPCOM object.
+    nsCOMPtr<nsIXPConnectWrappedJS> implWrapped =
+      do_QueryInterface(implISupports, &rv);
+    MOZ_ASSERT(implWrapped, "Failed to get wrapped JS from XPCOM component.");
+    if (!implWrapped) {
+      aRv.Throw(rv);
+      return;
+    }
+    aObject.set(implWrapped->GetJSObject());
+    if (!aObject) {
+      aRv.Throw(NS_ERROR_FAILURE);
+    }
+  }
+}
+
+bool
+NonVoidByteStringToJsval(JSContext *cx, const nsACString &str,
+                         JS::MutableHandle<JS::Value> rval)
+{
+    // ByteStrings are not UTF-8 encoded.
+    JSString* jsStr = JS_NewStringCopyN(cx, str.Data(), str.Length());
+
+    if (!jsStr)
+        return false;
+
+    rval.setString(jsStr);
+    return true;
+}
+
+
+template<typename T> static void
+NormalizeUSVStringInternal(JSContext* aCx, T& aString)
+{
+  char16_t* start = aString.BeginWriting();
+  // Must use const here because we can't pass char** to UTF16CharEnumerator as
+  // it expects const char**.  Unclear why this is illegal...
+  const char16_t* nextChar = start;
+  const char16_t* end = aString.Data() + aString.Length();
+  while (nextChar < end) {
+    uint32_t enumerated = UTF16CharEnumerator::NextChar(&nextChar, end);
+    if (enumerated == UCS2_REPLACEMENT_CHAR) {
+      int32_t lastCharIndex = (nextChar - start) - 1;
+      start[lastCharIndex] = static_cast<char16_t>(enumerated);
+    }
+  }
+}
+
+void
+NormalizeUSVString(JSContext* aCx, nsAString& aString)
+{
+  NormalizeUSVStringInternal(aCx, aString);
+}
+
+void
+NormalizeUSVString(JSContext* aCx, binding_detail::FakeString& aString)
+{
+  NormalizeUSVStringInternal(aCx, aString);
+}
+
+bool
+ConvertJSValueToByteString(JSContext* cx, JS::Handle<JS::Value> v,
+                           bool nullable, nsACString& result)
+{
+  JS::Rooted<JSString*> s(cx);
+  if (v.isString()) {
+    s = v.toString();
+  } else {
+
+    if (nullable && v.isNullOrUndefined()) {
+      result.SetIsVoid(true);
+      return true;
+    }
+
+    s = JS::ToString(cx, v);
+    if (!s) {
+      return false;
+    }
+  }
+
+  // Conversion from Javascript string to ByteString is only valid if all
+  // characters < 256. This is always the case for Latin1 strings.
+  size_t length;
+  if (!js::StringHasLatin1Chars(s)) {
+    // ThrowErrorMessage can GC, so we first scan the string for bad chars
+    // and report the error outside the AutoCheckCannotGC scope.
+    bool foundBadChar = false;
+    size_t badCharIndex;
+    char16_t badChar;
+    {
+      JS::AutoCheckCannotGC nogc;
+      const char16_t* chars = JS_GetTwoByteStringCharsAndLength(cx, nogc, s, &length);
+      if (!chars) {
+        return false;
+      }
+
+      for (size_t i = 0; i < length; i++) {
+        if (chars[i] > 255) {
+          badCharIndex = i;
+          badChar = chars[i];
+          foundBadChar = true;
+          break;
+        }
+      }
+    }
+
+    if (foundBadChar) {
+      MOZ_ASSERT(badCharIndex < length);
+      MOZ_ASSERT(badChar > 255);
+      // The largest unsigned 64 bit number (18,446,744,073,709,551,615) has
+      // 20 digits, plus one more for the null terminator.
+      char index[21];
+      static_assert(sizeof(size_t) <= 8, "index array too small");
+      SprintfLiteral(index, "%" PRIuSIZE, badCharIndex);
+      // A char16_t is 16 bits long.  The biggest unsigned 16 bit
+      // number (65,535) has 5 digits, plus one more for the null
+      // terminator.
+      char badCharArray[6];
+      static_assert(sizeof(char16_t) <= 2, "badCharArray too small");
+      SprintfLiteral(badCharArray, "%d", badChar);
+      ThrowErrorMessage(cx, MSG_INVALID_BYTESTRING, index, badCharArray);
+      return false;
+    }
+  } else {
+    length = js::GetStringLength(s);
+  }
+
+  static_assert(js::MaxStringLength < UINT32_MAX,
+                "length+1 shouldn't overflow");
+
+  if (!result.SetLength(length, fallible)) {
+    return false;
+  }
+
+  JS_EncodeStringToBuffer(cx, s, result.BeginWriting(), length);
+
+  return true;
+}
+
+void
+FinalizeGlobal(JSFreeOp* aFreeOp, JSObject* aObj)
+{
+  MOZ_ASSERT(js::GetObjectClass(aObj)->flags & JSCLASS_DOM_GLOBAL);
+  mozilla::dom::DestroyProtoAndIfaceCache(aObj);
+}
+
+bool
+ResolveGlobal(JSContext* aCx, JS::Handle<JSObject*> aObj,
+              JS::Handle<jsid> aId, bool* aResolvedp)
+{
+  MOZ_ASSERT(JS_IsGlobalObject(aObj),
+             "Should have a global here, since we plan to resolve standard "
+             "classes!");
+
+  return JS_ResolveStandardClass(aCx, aObj, aId, aResolvedp);
+}
+
+bool
+MayResolveGlobal(const JSAtomState& aNames, jsid aId, JSObject* aMaybeObj)
+{
+  return JS_MayResolveStandardClass(aNames, aId, aMaybeObj);
+}
+
+bool
+EnumerateGlobal(JSContext* aCx, JS::Handle<JSObject*> aObj)
+{
+  MOZ_ASSERT(JS_IsGlobalObject(aObj),
+             "Should have a global here, since we plan to enumerate standard "
+             "classes!");
+
+  return JS_EnumerateStandardClasses(aCx, aObj);
+}
+
+bool
+IsNonExposedGlobal(JSContext* aCx, JSObject* aGlobal,
+                   uint32_t aNonExposedGlobals)
+{
+  MOZ_ASSERT(aNonExposedGlobals, "Why did we get called?");
+  MOZ_ASSERT((aNonExposedGlobals &
+              ~(GlobalNames::Window |
+                GlobalNames::BackstagePass |
+                GlobalNames::DedicatedWorkerGlobalScope |
+                GlobalNames::SharedWorkerGlobalScope |
+                GlobalNames::ServiceWorkerGlobalScope |
+                GlobalNames::WorkerDebuggerGlobalScope |
+                GlobalNames::WorkletGlobalScope)) == 0,
+             "Unknown non-exposed global type");
+
+  const char* name = js::GetObjectClass(aGlobal)->name;
+
+  if ((aNonExposedGlobals & GlobalNames::Window) &&
+      !strcmp(name, "Window")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::BackstagePass) &&
+      !strcmp(name, "BackstagePass")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::DedicatedWorkerGlobalScope) &&
+      !strcmp(name, "DedicatedWorkerGlobalScope")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::SharedWorkerGlobalScope) &&
+      !strcmp(name, "SharedWorkerGlobalScope")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::ServiceWorkerGlobalScope) &&
+      !strcmp(name, "ServiceWorkerGlobalScope")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::WorkerDebuggerGlobalScope) &&
+      !strcmp(name, "WorkerDebuggerGlobalScopex")) {
+    return true;
+  }
+
+  if ((aNonExposedGlobals & GlobalNames::WorkletGlobalScope) &&
+      !strcmp(name, "WorkletGlobalScope")) {
+    return true;
+  }
+
+  return false;
+}
+
+void
+HandlePrerenderingViolation(nsPIDOMWindowInner* aWindow)
+{
+  // Freeze the window and its workers, and its children too.
+  aWindow->Freeze();
+
+  // Suspend event handling on the document
+  nsCOMPtr<nsIDocument> doc = aWindow->GetExtantDoc();
+  if (doc) {
+    doc->SuppressEventHandling(nsIDocument::eEvents);
+  }
+}
+
+bool
+EnforceNotInPrerendering(JSContext* aCx, JSObject* aObj)
+{
+  JS::Rooted<JSObject*> thisObj(aCx, js::CheckedUnwrap(aObj));
+  if (!thisObj) {
+    // Without a this object, we cannot check the safety.
+    return true;
+  }
+  nsGlobalWindow* window = xpc::WindowGlobalOrNull(thisObj);
+  if (!window) {
+    // Without a window, we cannot check the safety.
+    return true;
+  }
+
+  if (window->GetIsPrerendered()) {
+    HandlePrerenderingViolation(window->AsInner());
+    // When the bindings layer sees a false return value, it returns false form
+    // the JSNative in order to trigger an uncatchable exception.
+    return false;
+  }
+
+  return true;
+}
+
+bool
+GenericBindingGetter(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+  prototypes::ID protoID = static_cast<prototypes::ID>(info->protoID);
+  if (!args.thisv().isObject()) {
+    return ThrowInvalidThis(cx, args, false, protoID);
+  }
+  JS::Rooted<JSObject*> obj(cx, &args.thisv().toObject());
+
+  // NOTE: we want to leave obj in its initial compartment, so don't want to
+  // pass it to UnwrapObject.
+  JS::Rooted<JSObject*> rootSelf(cx, obj);
+  void* self;
+  {
+    binding_detail::MutableObjectHandleWrapper wrapper(&rootSelf);
+    nsresult rv = binding_detail::UnwrapObjectInternal<void, true>(wrapper,
+                                                                   self,
+                                                                   protoID,
+                                                                   info->depth);
+    if (NS_FAILED(rv)) {
+      return ThrowInvalidThis(cx, args,
+                              rv == NS_ERROR_XPC_SECURITY_MANAGER_VETO,
+                              protoID);
+    }
+  }
+
+  MOZ_ASSERT(info->type() == JSJitInfo::Getter);
+  JSJitGetterOp getter = info->getter;
+  bool ok = getter(cx, obj, self, JSJitGetterCallArgs(args));
+#ifdef DEBUG
+  if (ok) {
+    AssertReturnTypeMatchesJitinfo(info, args.rval());
+  }
+#endif
+  return ok;
+}
+
+bool
+GenericBindingSetter(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+  prototypes::ID protoID = static_cast<prototypes::ID>(info->protoID);
+  if (!args.thisv().isObject()) {
+    return ThrowInvalidThis(cx, args, false, protoID);
+  }
+  JS::Rooted<JSObject*> obj(cx, &args.thisv().toObject());
+
+  // NOTE: we want to leave obj in its initial compartment, so don't want to
+  // pass it to UnwrapObject.
+  JS::Rooted<JSObject*> rootSelf(cx, obj);
+  void* self;
+  {
+    binding_detail::MutableObjectHandleWrapper wrapper(&rootSelf);
+    nsresult rv = binding_detail::UnwrapObjectInternal<void, true>(wrapper,
+                                                                   self,
+                                                                   protoID,
+                                                                   info->depth);
+    if (NS_FAILED(rv)) {
+      return ThrowInvalidThis(cx, args,
+                              rv == NS_ERROR_XPC_SECURITY_MANAGER_VETO,
+                              protoID);
+    }
+  }
+  if (args.length() == 0) {
+    return ThrowNoSetterArg(cx, protoID);
+  }
+  MOZ_ASSERT(info->type() == JSJitInfo::Setter);
+  JSJitSetterOp setter = info->setter;
+  if (!setter(cx, obj, self, JSJitSetterCallArgs(args))) {
+    return false;
+  }
+  args.rval().setUndefined();
+#ifdef DEBUG
+  AssertReturnTypeMatchesJitinfo(info, args.rval());
+#endif
+  return true;
+}
+
+bool
+GenericBindingMethod(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+  prototypes::ID protoID = static_cast<prototypes::ID>(info->protoID);
+  if (!args.thisv().isObject()) {
+    return ThrowInvalidThis(cx, args, false, protoID);
+  }
+  JS::Rooted<JSObject*> obj(cx, &args.thisv().toObject());
+
+  // NOTE: we want to leave obj in its initial compartment, so don't want to
+  // pass it to UnwrapObject.
+  JS::Rooted<JSObject*> rootSelf(cx, obj);
+  void* self;
+  {
+    binding_detail::MutableObjectHandleWrapper wrapper(&rootSelf);
+    nsresult rv = binding_detail::UnwrapObjectInternal<void, true>(wrapper,
+                                                                   self,
+                                                                   protoID,
+                                                                   info->depth);
+    if (NS_FAILED(rv)) {
+      return ThrowInvalidThis(cx, args,
+                              rv == NS_ERROR_XPC_SECURITY_MANAGER_VETO,
+                              protoID);
+    }
+  }
+  MOZ_ASSERT(info->type() == JSJitInfo::Method);
+  JSJitMethodOp method = info->method;
+  bool ok = method(cx, obj, self, JSJitMethodCallArgs(args));
+#ifdef DEBUG
+  if (ok) {
+    AssertReturnTypeMatchesJitinfo(info, args.rval());
+  }
+#endif
+  return ok;
+}
+
+bool
+GenericPromiseReturningBindingMethod(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  // Make sure to save the callee before someone maybe messes with rval().
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  JS::Rooted<JSObject*> callee(cx, &args.callee());
+
+  // We could invoke GenericBindingMethod here, but that involves an
+  // extra call.  Manually inline it instead.
+  const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+  prototypes::ID protoID = static_cast<prototypes::ID>(info->protoID);
+  if (!args.thisv().isObject()) {
+    ThrowInvalidThis(cx, args, false, protoID);
+    return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                     args.rval());
+  }
+  JS::Rooted<JSObject*> obj(cx, &args.thisv().toObject());
+
+  // NOTE: we want to leave obj in its initial compartment, so don't want to
+  // pass it to UnwrapObject.
+  JS::Rooted<JSObject*> rootSelf(cx, obj);
+  void* self;
+  {
+    binding_detail::MutableObjectHandleWrapper wrapper(&rootSelf);
+    nsresult rv = binding_detail::UnwrapObjectInternal<void, true>(wrapper,
+                                                                   self,
+                                                                   protoID,
+                                                                   info->depth);
+    if (NS_FAILED(rv)) {
+      ThrowInvalidThis(cx, args, rv == NS_ERROR_XPC_SECURITY_MANAGER_VETO,
+                       protoID);
+      return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                       args.rval());
+    }
+  }
+  MOZ_ASSERT(info->type() == JSJitInfo::Method);
+  JSJitMethodOp method = info->method;
+  bool ok = method(cx, obj, self, JSJitMethodCallArgs(args));
+  if (ok) {
+#ifdef DEBUG
+    AssertReturnTypeMatchesJitinfo(info, args.rval());
+#endif
+    return true;
+  }
+
+  // Promise-returning methods always return objects
+  MOZ_ASSERT(info->returnType() == JSVAL_TYPE_OBJECT);
+  return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                   args.rval());
+}
+
+bool
+StaticMethodPromiseWrapper(JSContext* cx, unsigned argc, JS::Value* vp)
+{
+  // Make sure to save the callee before someone maybe messes with rval().
+  JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+  JS::Rooted<JSObject*> callee(cx, &args.callee());
+
+  const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+  MOZ_ASSERT(info);
+  MOZ_ASSERT(info->type() == JSJitInfo::StaticMethod);
+
+  bool ok = info->staticMethod(cx, argc, vp);
+  if (ok) {
+    return true;
+  }
+
+  return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                   args.rval());
+}
+
+bool
+ConvertExceptionToPromise(JSContext* cx,
+                          JSObject* promiseScope,
+                          JS::MutableHandle<JS::Value> rval)
+{
+#ifndef SPIDERMONKEY_PROMISE
+  GlobalObject global(cx, promiseScope);
+  if (global.Failed()) {
+    return false;
+  }
+
+  JS::Rooted<JS::Value> exn(cx);
+  if (!JS_GetPendingException(cx, &exn)) {
+    // This is very important: if there is no pending exception here but we're
+    // ending up in this code, that means the callee threw an uncatchable
+    // exception.  Just propagate that out as-is.
+    return false;
+  }
+
+  JS_ClearPendingException(cx);
+
+  nsCOMPtr<nsIGlobalObject> globalObj =
+    do_QueryInterface(global.GetAsSupports());
+  if (!globalObj) {
+    ErrorResult rv;
+    rv.Throw(NS_ERROR_UNEXPECTED);
+    return !rv.MaybeSetPendingException(cx);
+  }
+
+  ErrorResult rv;
+  RefPtr<Promise> promise = Promise::Reject(globalObj, cx, exn, rv);
+  if (rv.MaybeSetPendingException(cx)) {
+    // We just give up.  We put the exception from the ErrorResult on
+    // the JSContext just to make sure to not leak memory on the
+    // ErrorResult, but now just put the original exception back.
+    JS_SetPendingException(cx, exn);
+    return false;
+  }
+
+  return GetOrCreateDOMReflector(cx, promise, rval);
+#else // SPIDERMONKEY_PROMISE
+  {
+    JSAutoCompartment ac(cx, promiseScope);
+
+    JS::Rooted<JS::Value> exn(cx);
+    if (!JS_GetPendingException(cx, &exn)) {
+      // This is very important: if there is no pending exception here but we're
+      // ending up in this code, that means the callee threw an uncatchable
+      // exception.  Just propagate that out as-is.
+      return false;
+    }
+
+    JS_ClearPendingException(cx);
+
+    JSObject* promise = JS::CallOriginalPromiseReject(cx, exn);
+    if (!promise) {
+      // We just give up.  Put the exception back.
+      JS_SetPendingException(cx, exn);
+      return false;
+    }
+
+    rval.setObject(*promise);
+  }
+
+  // Now make sure we rewrap promise back into the compartment we want
+  return JS_WrapValue(cx, rval);
+#endif // SPIDERMONKEY_PROMISE
+}
+
+/* static */
+void
+CreateGlobalOptions<nsGlobalWindow>::TraceGlobal(JSTracer* aTrc, JSObject* aObj)
+{
+  xpc::TraceXPCGlobal(aTrc, aObj);
+}
+
+static bool sRegisteredDOMNames = false;
+
+nsresult
+RegisterDOMNames()
+{
+  if (sRegisteredDOMNames) {
+    return NS_OK;
+  }
+
+  // Register new DOM bindings
+  WebIDLGlobalNameHash::Init();
+
+  nsresult rv = nsDOMClassInfo::Init();
+  if (NS_FAILED(rv)) {
+    NS_ERROR("Could not initialize nsDOMClassInfo");
+    return rv;
+  }
+
+  sRegisteredDOMNames = true;
+
+  return NS_OK;
+}
+
+/* static */
+bool
+CreateGlobalOptions<nsGlobalWindow>::PostCreateGlobal(JSContext* aCx,
+                                                      JS::Handle<JSObject*> aGlobal)
+{
+  nsresult rv = RegisterDOMNames();
+  if (NS_FAILED(rv)) {
+    return Throw(aCx, rv);
+  }
+
+  // Invoking the XPCWrappedNativeScope constructor automatically hooks it
+  // up to the compartment of aGlobal.
+  (void) new XPCWrappedNativeScope(aCx, aGlobal);
+  return true;
+}
+
+#ifdef DEBUG
+void
+AssertReturnTypeMatchesJitinfo(const JSJitInfo* aJitInfo,
+                               JS::Handle<JS::Value> aValue)
+{
+  switch (aJitInfo->returnType()) {
+  case JSVAL_TYPE_UNKNOWN:
+    // Any value is good.
+    break;
+  case JSVAL_TYPE_DOUBLE:
+    // The value could actually be an int32 value as well.
+    MOZ_ASSERT(aValue.isNumber());
+    break;
+  case JSVAL_TYPE_INT32:
+    MOZ_ASSERT(aValue.isInt32());
+    break;
+  case JSVAL_TYPE_UNDEFINED:
+    MOZ_ASSERT(aValue.isUndefined());
+    break;
+  case JSVAL_TYPE_BOOLEAN:
+    MOZ_ASSERT(aValue.isBoolean());
+    break;
+  case JSVAL_TYPE_STRING:
+    MOZ_ASSERT(aValue.isString());
+    break;
+  case JSVAL_TYPE_NULL:
+    MOZ_ASSERT(aValue.isNull());
+    break;
+  case JSVAL_TYPE_OBJECT:
+    MOZ_ASSERT(aValue.isObject());
+    break;
+  default:
+    // Someone messed up their jitinfo type.
+    MOZ_ASSERT(false, "Unexpected JSValueType stored in jitinfo");
+    break;
+  }
+}
+#endif
+
+bool
+CallerSubsumes(JSObject *aObject)
+{
+  nsIPrincipal* objPrin = nsContentUtils::ObjectPrincipal(js::UncheckedUnwrap(aObject));
+  return nsContentUtils::SubjectPrincipal()->Subsumes(objPrin);
+}
+
+nsresult
+UnwrapArgImpl(JS::Handle<JSObject*> src,
+              const nsIID &iid,
+              void **ppArg)
+{
+  if (!NS_IsMainThread()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCOMPtr<nsISupports> iface = xpc::UnwrapReflectorToISupports(src);
+  if (iface) {
+    if (NS_FAILED(iface->QueryInterface(iid, ppArg))) {
+      return NS_ERROR_XPC_BAD_CONVERT_JS;
+    }
+
+    return NS_OK;
+  }
+
+  // Only allow XPCWrappedJS stuff in system code.  Ideally we would remove this
+  // even there, but that involves converting some things to WebIDL callback
+  // interfaces and making some other things builtinclass...
+  if (!nsContentUtils::IsCallerChrome()) {
+    return NS_ERROR_XPC_BAD_CONVERT_JS;
+  }
+
+  RefPtr<nsXPCWrappedJS> wrappedJS;
+  nsresult rv = nsXPCWrappedJS::GetNewOrUsed(src, iid, getter_AddRefs(wrappedJS));
+  if (NS_FAILED(rv) || !wrappedJS) {
+    return rv;
+  }
+
+  // We need to go through the QueryInterface logic to make this return
+  // the right thing for the various 'special' interfaces; e.g.
+  // nsIPropertyBag. We must use AggregatedQueryInterface in cases where
+  // there is an outer to avoid nasty recursion.
+  return wrappedJS->QueryInterface(iid, ppArg);
+}
+
+nsresult
+UnwrapXPConnectImpl(JSContext* cx,
+                    JS::MutableHandle<JS::Value> src,
+                    const nsIID &iid,
+                    void **ppArg)
+{
+  if (!NS_IsMainThread()) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  MOZ_ASSERT(src.isObject());
+  // Unwrap ourselves, because we're going to want access to the unwrapped
+  // object.
+  JS::Rooted<JSObject*> obj(cx,
+                            js::CheckedUnwrap(&src.toObject(),
+                                              /* stopAtWindowProxy = */ false));
+  if (!obj) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCOMPtr<nsISupports> iface = xpc::UnwrapReflectorToISupports(obj);
+  if (!iface) {
+    return NS_ERROR_XPC_BAD_CONVERT_JS;
+  }
+
+  if (NS_FAILED(iface->QueryInterface(iid, ppArg))) {
+    return NS_ERROR_XPC_BAD_CONVERT_JS;
+  }
+
+  // Now update our source to keep rooting our object.
+  src.setObject(*obj);
+  return NS_OK;
+}
+
+nsresult
+UnwrapWindowProxyImpl(JS::Handle<JSObject*> src,
+                      nsPIDOMWindowOuter** ppArg)
+{
+  nsCOMPtr<nsPIDOMWindowInner> inner;
+  nsresult rv = UnwrapArg<nsPIDOMWindowInner>(src, getter_AddRefs(inner));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsCOMPtr<nsPIDOMWindowOuter> outer = inner->GetOuterWindow();
+  outer.forget(ppArg);
+  return NS_OK;
+}
+
+bool
+SystemGlobalResolve(JSContext* cx, JS::Handle<JSObject*> obj,
+                    JS::Handle<jsid> id, bool* resolvedp)
+{
+  if (!ResolveGlobal(cx, obj, id, resolvedp)) {
+    return false;
+  }
+
+  if (*resolvedp) {
+    return true;
+  }
+
+  return ResolveSystemBinding(cx, obj, id, resolvedp);
+}
+
+bool
+SystemGlobalEnumerate(JSContext* cx, JS::Handle<JSObject*> obj)
+{
+  bool ignored = false;
+  return EnumerateGlobal(cx, obj) &&
+         ResolveSystemBinding(cx, obj, JSID_VOIDHANDLE, &ignored);
+}
+
+template<decltype(JS::NewMapObject) Method>
+bool
+GetMaplikeSetlikeBackingObject(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                               size_t aSlotIndex,
+                               JS::MutableHandle<JSObject*> aBackingObj,
+                               bool* aBackingObjCreated)
+{
+  JS::Rooted<JSObject*> reflector(aCx);
+  reflector = IsDOMObject(aObj) ? aObj : js::UncheckedUnwrap(aObj,
+                                                             /* stopAtWindowProxy = */ false);
+
+  // Retrieve the backing object from the reserved slot on the maplike/setlike
+  // object. If it doesn't exist yet, create it.
+  JS::Rooted<JS::Value> slotValue(aCx);
+  slotValue = js::GetReservedSlot(reflector, aSlotIndex);
+  if (slotValue.isUndefined()) {
+    // Since backing object access can happen in non-originating compartments,
+    // make sure to create the backing object in reflector compartment.
+    {
+      JSAutoCompartment ac(aCx, reflector);
+      JS::Rooted<JSObject*> newBackingObj(aCx);
+      newBackingObj.set(Method(aCx));
+      if (NS_WARN_IF(!newBackingObj)) {
+        return false;
+      }
+      js::SetReservedSlot(reflector, aSlotIndex, JS::ObjectValue(*newBackingObj));
+    }
+    slotValue = js::GetReservedSlot(reflector, aSlotIndex);
+    *aBackingObjCreated = true;
+  } else {
+    *aBackingObjCreated = false;
+  }
+  if (!MaybeWrapNonDOMObjectValue(aCx, &slotValue)) {
+    return false;
+  }
+  aBackingObj.set(&slotValue.toObject());
+  return true;
+}
+
+bool
+GetMaplikeBackingObject(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                        size_t aSlotIndex,
+                        JS::MutableHandle<JSObject*> aBackingObj,
+                        bool* aBackingObjCreated)
+{
+  return GetMaplikeSetlikeBackingObject<JS::NewMapObject>(aCx, aObj, aSlotIndex,
+                                                          aBackingObj,
+                                                          aBackingObjCreated);
+}
+
+bool
+GetSetlikeBackingObject(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                        size_t aSlotIndex,
+                        JS::MutableHandle<JSObject*> aBackingObj,
+                        bool* aBackingObjCreated)
+{
+  return GetMaplikeSetlikeBackingObject<JS::NewSetObject>(aCx, aObj, aSlotIndex,
+                                                          aBackingObj,
+                                                          aBackingObjCreated);
+}
+
+bool
+ForEachHandler(JSContext* aCx, unsigned aArgc, JS::Value* aVp)
+{
+  JS::CallArgs args = CallArgsFromVp(aArgc, aVp);
+  // Unpack callback and object from slots
+  JS::Rooted<JS::Value>
+    callbackFn(aCx, js::GetFunctionNativeReserved(&args.callee(),
+                                                  FOREACH_CALLBACK_SLOT));
+  JS::Rooted<JS::Value>
+    maplikeOrSetlikeObj(aCx,
+                        js::GetFunctionNativeReserved(&args.callee(),
+                                                      FOREACH_MAPLIKEORSETLIKEOBJ_SLOT));
+  MOZ_ASSERT(aArgc == 3);
+  JS::AutoValueVector newArgs(aCx);
+  // Arguments are passed in as value, key, object. Keep value and key, replace
+  // object with the maplike/setlike object.
+  if (!newArgs.append(args.get(0))) {
+    return false;
+  }
+  if (!newArgs.append(args.get(1))) {
+    return false;
+  }
+  if (!newArgs.append(maplikeOrSetlikeObj)) {
+    return false;
+  }
+  JS::Rooted<JS::Value> rval(aCx, JS::UndefinedValue());
+  // Now actually call the user specified callback
+  return JS::Call(aCx, args.thisv(), callbackFn, newArgs, &rval);
+}
+
+static inline prototypes::ID
+GetProtoIdForNewtarget(JS::Handle<JSObject*> aNewTarget)
+{
+  const js::Class* newTargetClass = js::GetObjectClass(aNewTarget);
+  if (IsDOMIfaceAndProtoClass(newTargetClass)) {
+    const DOMIfaceAndProtoJSClass* newTargetIfaceClass =
+      DOMIfaceAndProtoJSClass::FromJSClass(newTargetClass);
+    if (newTargetIfaceClass->mType == eInterface) {
+      return newTargetIfaceClass->mPrototypeID;
+    }
+  } else if (JS_IsNativeFunction(aNewTarget, Constructor)) {
+    return GetNativePropertyHooksFromConstructorFunction(aNewTarget)->mPrototypeID;
+  }
+
+  return prototypes::id::_ID_Count;
+}
+
+bool
+GetDesiredProto(JSContext* aCx, const JS::CallArgs& aCallArgs,
+                JS::MutableHandle<JSObject*> aDesiredProto)
+{
+  if (!aCallArgs.isConstructing()) {
+    aDesiredProto.set(nullptr);
+    return true;
+  }
+
+  // The desired prototype depends on the actual constructor that was invoked,
+  // which is passed to us as the newTarget in the callargs.  We want to do
+  // something akin to the ES6 specification's GetProtototypeFromConstructor (so
+  // get .prototype on the newTarget, with a fallback to some sort of default).
+
+  // First, a fast path for the case when the the constructor is in fact one of
+  // our DOM constructors.  This is safe because on those the "constructor"
+  // property is non-configurable and non-writable, so we don't have to do the
+  // slow JS_GetProperty call.
+  JS::Rooted<JSObject*> newTarget(aCx, &aCallArgs.newTarget().toObject());
+  JS::Rooted<JSObject*> originalNewTarget(aCx, newTarget);
+  // See whether we have a known DOM constructor here, such that we can take a
+  // fast path.
+  prototypes::ID protoID = GetProtoIdForNewtarget(newTarget);
+  if (protoID == prototypes::id::_ID_Count) {
+    // We might still have a cross-compartment wrapper for a known DOM
+    // constructor.
+    newTarget = js::CheckedUnwrap(newTarget);
+    if (newTarget && newTarget != originalNewTarget) {
+      protoID = GetProtoIdForNewtarget(newTarget);
+    }
+  }
+
+  if (protoID != prototypes::id::_ID_Count) {
+    ProtoAndIfaceCache& protoAndIfaceCache =
+      *GetProtoAndIfaceCache(js::GetGlobalForObjectCrossCompartment(newTarget));
+    aDesiredProto.set(protoAndIfaceCache.EntrySlotMustExist(protoID));
+    if (newTarget != originalNewTarget) {
+      return JS_WrapObject(aCx, aDesiredProto);
+    }
+    return true;
+  }
+
+  // Slow path.  This basically duplicates the ES6 spec's
+  // GetPrototypeFromConstructor except that instead of taking a string naming
+  // the fallback prototype we just fall back to using null and assume that our
+  // caller will then pick the right default.  The actual defaulting behavior
+  // here still needs to be defined in the Web IDL specification.
+  //
+  // Note that it's very important to do this property get on originalNewTarget,
+  // not our unwrapped newTarget, since we want to get Xray behavior here as
+  // needed.
+  // XXXbz for speed purposes, using a preinterned id here sure would be nice.
+  JS::Rooted<JS::Value> protoVal(aCx);
+  if (!JS_GetProperty(aCx, originalNewTarget, "prototype", &protoVal)) {
+    return false;
+  }
+
+  if (!protoVal.isObject()) {
+    aDesiredProto.set(nullptr);
+    return true;
+  }
+
+  aDesiredProto.set(&protoVal.toObject());
+  return true;
+}
+
+#ifdef DEBUG
+namespace binding_detail {
+void
+AssertReflectorHasGivenProto(JSContext* aCx, JSObject* aReflector,
+                             JS::Handle<JSObject*> aGivenProto)
+{
+  if (!aGivenProto) {
+    // Nothing to assert here
+    return;
+  }
+
+  JS::Rooted<JSObject*> reflector(aCx, aReflector);
+  JSAutoCompartment ac(aCx, reflector);
+  JS::Rooted<JSObject*> reflectorProto(aCx);
+  bool ok = JS_GetPrototype(aCx, reflector, &reflectorProto);
+  MOZ_ASSERT(ok);
+  // aGivenProto may not be in the right compartment here, so we
+  // have to wrap it to compare.
+  JS::Rooted<JSObject*> givenProto(aCx, aGivenProto);
+  ok = JS_WrapObject(aCx, &givenProto);
+  MOZ_ASSERT(ok);
+  MOZ_ASSERT(givenProto == reflectorProto,
+             "How are we supposed to change the proto now?");
+}
+} // namespace binding_detail
+#endif // DEBUG
+
+void
+SetDocumentAndPageUseCounter(JSContext* aCx, JSObject* aObject,
+                             UseCounter aUseCounter)
+{
+  nsGlobalWindow* win = xpc::WindowGlobalOrNull(js::UncheckedUnwrap(aObject));
+  if (win && win->GetDocument()) {
+    win->GetDocument()->SetDocumentAndPageUseCounter(aUseCounter);
+  }
+}
+
+namespace {
+
+// This runnable is used to write a deprecation message from a worker to the
+// console running on the main-thread.
+class DeprecationWarningRunnable final : public WorkerProxyToMainThreadRunnable
+{
+  nsIDocument::DeprecatedOperations mOperation;
+
+public:
+  DeprecationWarningRunnable(WorkerPrivate* aWorkerPrivate,
+                             nsIDocument::DeprecatedOperations aOperation)
+    : WorkerProxyToMainThreadRunnable(aWorkerPrivate)
+    , mOperation(aOperation)
+  {
+    MOZ_ASSERT(aWorkerPrivate);
+    aWorkerPrivate->AssertIsOnWorkerThread();
+  }
+
+private:
+  void
+  RunOnMainThread() override
+  {
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // Walk up to our containing page
+    WorkerPrivate* wp = mWorkerPrivate;
+    while (wp->GetParent()) {
+      wp = wp->GetParent();
+    }
+
+    nsPIDOMWindowInner* window = wp->GetWindow();
+    if (window && window->GetExtantDoc()) {
+      window->GetExtantDoc()->WarnOnceAbout(mOperation);
+    }
+  }
+
+  void
+  RunBackOnWorkerThread() override
+  {}
+};
+
+} // anonymous namespace
+
+void
+DeprecationWarning(JSContext* aCx, JSObject* aObject,
+                   nsIDocument::DeprecatedOperations aOperation)
+{
+  GlobalObject global(aCx, aObject);
+  if (global.Failed()) {
+    NS_ERROR("Could not create global for DeprecationWarning");
+    return;
+  }
+
+  if (NS_IsMainThread()) {
+    nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(global.GetAsSupports());
+    if (window && window->GetExtantDoc()) {
+      window->GetExtantDoc()->WarnOnceAbout(aOperation);
+    }
+
+    return;
+  }
+
+  WorkerPrivate* workerPrivate = GetWorkerPrivateFromContext(aCx);
+  if (!workerPrivate) {
+    return;
+  }
+
+  RefPtr<DeprecationWarningRunnable> runnable =
+    new DeprecationWarningRunnable(workerPrivate, aOperation);
+  runnable->Dispatch();
+}
+
+namespace binding_detail {
+JSObject*
+UnprivilegedJunkScopeOrWorkerGlobal()
+{
+  if (NS_IsMainThread()) {
+    return xpc::UnprivilegedJunkScope();
+  }
+
+  return GetCurrentThreadWorkerGlobal();
+}
+} // namespace binding_detail
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/BindingUtils.h b/dom/bindings/BindingUtils.h
new file mode 100644
index 000000000..3e58390c9
--- /dev/null
+++ b/dom/bindings/BindingUtils.h
@@ -0,0 +1,3441 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_BindingUtils_h__
+#define mozilla_dom_BindingUtils_h__
+
+#include "jsfriendapi.h"
+#include "jswrapper.h"
+#include "js/Conversions.h"
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Alignment.h"
+#include "mozilla/Array.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/DeferredFinalize.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/CallbackObject.h"
+#include "mozilla/dom/DOMJSClass.h"
+#include "mozilla/dom/DOMJSProxyHandler.h"
+#include "mozilla/dom/Exceptions.h"
+#include "mozilla/dom/NonRefcountedDOMObject.h"
+#include "mozilla/dom/Nullable.h"
+#include "mozilla/dom/RootedDictionary.h"
+#include "mozilla/SegmentedVector.h"
+#include "mozilla/dom/workers/Workers.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MemoryReporting.h"
+#include "nsAutoPtr.h"
+#include "nsIDocument.h"
+#include "nsIGlobalObject.h"
+#include "nsIXPConnect.h"
+#include "nsJSUtils.h"
+#include "nsISupportsImpl.h"
+#include "qsObjectHelper.h"
+#include "xpcpublic.h"
+#include "nsIVariant.h"
+#include "mozilla/dom/FakeString.h"
+
+#include "nsWrapperCacheInlines.h"
+
+class nsIJSID;
+
+namespace mozilla {
+
+enum UseCounter : int16_t;
+
+namespace dom {
+template<typename DataType> class MozMap;
+
+nsresult
+UnwrapArgImpl(JS::Handle<JSObject*> src, const nsIID& iid, void** ppArg);
+
+nsresult
+UnwrapWindowProxyImpl(JS::Handle<JSObject*> src, nsPIDOMWindowOuter** ppArg);
+
+/** Convert a jsval to an XPCOM pointer. Caller must not assume that src will
+    keep the XPCOM pointer rooted. */
+template <class Interface>
+inline nsresult
+UnwrapArg(JS::Handle<JSObject*> src, Interface** ppArg)
+{
+  return UnwrapArgImpl(src, NS_GET_TEMPLATE_IID(Interface),
+                       reinterpret_cast<void**>(ppArg));
+}
+
+template <>
+inline nsresult
+UnwrapArg<nsPIDOMWindowOuter>(JS::Handle<JSObject*> src, nsPIDOMWindowOuter** ppArg)
+{
+  return UnwrapWindowProxyImpl(src, ppArg);
+}
+
+nsresult
+UnwrapXPConnectImpl(JSContext* cx, JS::MutableHandle<JS::Value> src,
+                    const nsIID& iid, void** ppArg);
+
+/*
+ * Convert a jsval being used as a Web IDL interface implementation to an XPCOM
+ * pointer; this is only used for Web IDL interfaces that specify
+ * hasXPConnectImpls.  This is not the same as UnwrapArg because caller _can_
+ * assume that if unwrapping succeeds "val" will be updated so it's rooting the
+ * XPCOM pointer.  Also, UnwrapXPConnect doesn't need to worry about doing
+ * XPCWrappedJS things.
+ *
+ * val must be an ObjectValue.
+ */
+template<class Interface>
+inline nsresult
+UnwrapXPConnect(JSContext* cx, JS::MutableHandle<JS::Value> val,
+                Interface** ppThis)
+{
+  return UnwrapXPConnectImpl(cx, val, NS_GET_TEMPLATE_IID(Interface),
+                             reinterpret_cast<void**>(ppThis));
+}
+
+bool
+ThrowInvalidThis(JSContext* aCx, const JS::CallArgs& aArgs,
+                 bool aSecurityError, const char* aInterfaceName);
+
+bool
+ThrowInvalidThis(JSContext* aCx, const JS::CallArgs& aArgs,
+                 bool aSecurityError, prototypes::ID aProtoId);
+
+// Returns true if the JSClass is used for DOM objects.
+inline bool
+IsDOMClass(const JSClass* clasp)
+{
+  return clasp->flags & JSCLASS_IS_DOMJSCLASS;
+}
+
+inline bool
+IsDOMClass(const js::Class* clasp)
+{
+  return IsDOMClass(Jsvalify(clasp));
+}
+
+// Return true if the JSClass is used for non-proxy DOM objects.
+inline bool
+IsNonProxyDOMClass(const js::Class* clasp)
+{
+  return IsDOMClass(clasp) && !clasp->isProxy();
+}
+
+inline bool
+IsNonProxyDOMClass(const JSClass* clasp)
+{
+  return IsNonProxyDOMClass(js::Valueify(clasp));
+}
+
+// Returns true if the JSClass is used for DOM interface and interface
+// prototype objects.
+inline bool
+IsDOMIfaceAndProtoClass(const JSClass* clasp)
+{
+  return clasp->flags & JSCLASS_IS_DOMIFACEANDPROTOJSCLASS;
+}
+
+inline bool
+IsDOMIfaceAndProtoClass(const js::Class* clasp)
+{
+  return IsDOMIfaceAndProtoClass(Jsvalify(clasp));
+}
+
+static_assert(DOM_OBJECT_SLOT == 0,
+              "DOM_OBJECT_SLOT doesn't match the proxy private slot.  "
+              "Expect bad things");
+template <class T>
+inline T*
+UnwrapDOMObject(JSObject* obj)
+{
+  MOZ_ASSERT(IsDOMClass(js::GetObjectClass(obj)),
+             "Don't pass non-DOM objects to this function");
+
+  JS::Value val = js::GetReservedOrProxyPrivateSlot(obj, DOM_OBJECT_SLOT);
+  return static_cast<T*>(val.toPrivate());
+}
+
+template <class T>
+inline T*
+UnwrapPossiblyNotInitializedDOMObject(JSObject* obj)
+{
+  // This is used by the OjectMoved JSClass hook which can be called before
+  // JS_NewObject has returned and so before we have a chance to set
+  // DOM_OBJECT_SLOT to anything useful.
+
+  MOZ_ASSERT(IsDOMClass(js::GetObjectClass(obj)),
+             "Don't pass non-DOM objects to this function");
+
+  JS::Value val = js::GetReservedOrProxyPrivateSlot(obj, DOM_OBJECT_SLOT);
+  if (val.isUndefined()) {
+    return nullptr;
+  }
+  return static_cast<T*>(val.toPrivate());
+}
+
+inline const DOMJSClass*
+GetDOMClass(const js::Class* clasp)
+{
+  return IsDOMClass(clasp) ? DOMJSClass::FromJSClass(clasp) : nullptr;
+}
+
+inline const DOMJSClass*
+GetDOMClass(JSObject* obj)
+{
+  return GetDOMClass(js::GetObjectClass(obj));
+}
+
+inline nsISupports*
+UnwrapDOMObjectToISupports(JSObject* aObject)
+{
+  const DOMJSClass* clasp = GetDOMClass(aObject);
+  if (!clasp || !clasp->mDOMObjectIsISupports) {
+    return nullptr;
+  }
+
+  return UnwrapPossiblyNotInitializedDOMObject<nsISupports>(aObject);
+}
+
+inline bool
+IsDOMObject(JSObject* obj)
+{
+  return IsDOMClass(js::GetObjectClass(obj));
+}
+
+// There are two valid ways to use UNWRAP_OBJECT: Either obj needs to
+// be a MutableHandle<JSObject*>, or value needs to be a strong-reference
+// smart pointer type (OwningNonNull or RefPtr or nsCOMPtr), in which case obj
+// can be anything that converts to JSObject*.
+#define UNWRAP_OBJECT(Interface, obj, value)                                 \
+  mozilla::dom::UnwrapObject<mozilla::dom::prototypes::id::Interface,        \
+    mozilla::dom::Interface##Binding::NativeType>(obj, value)
+
+// Test whether the given object is an instance of the given interface.
+#define IS_INSTANCE_OF(Interface, obj)                                  \
+  mozilla::dom::IsInstanceOf<mozilla::dom::prototypes::id::Interface,   \
+                             mozilla::dom::Interface##Binding::NativeType>(obj)
+
+// Unwrap the given non-wrapper object.  This can be used with any obj that
+// converts to JSObject*; as long as that JSObject* is live the return value
+// will be valid.
+#define UNWRAP_NON_WRAPPER_OBJECT(Interface, obj, value)                        \
+  mozilla::dom::UnwrapNonWrapperObject<mozilla::dom::prototypes::id::Interface, \
+    mozilla::dom::Interface##Binding::NativeType>(obj, value)
+
+// Some callers don't want to set an exception when unwrapping fails
+// (for example, overload resolution uses unwrapping to tell what sort
+// of thing it's looking at).
+// U must be something that a T* can be assigned to (e.g. T* or an RefPtr<T>).
+//
+// The obj argument will be mutated to point to CheckedUnwrap of itself if the
+// passed-in value is not a DOM object and CheckedUnwrap succeeds.
+//
+// If mayBeWrapper is true, there are three valid ways to invoke
+// UnwrapObjectInternal: Either obj needs to be a class wrapping a
+// MutableHandle<JSObject*>, with an assignment operator that sets the handle to
+// the given object, or U needs to be a strong-reference smart pointer type
+// (OwningNonNull or RefPtr or nsCOMPtr), or the value being stored in "value"
+// must not escape past being tested for falsiness immediately after the
+// UnwrapObjectInternal call.
+//
+// If mayBeWrapper is false, obj can just be a JSObject*, and U anything that a
+// T* can be assigned to.
+namespace binding_detail {
+template <class T, bool mayBeWrapper, typename U, typename V>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObjectInternal(V& obj, U& value, prototypes::ID protoID,
+                     uint32_t protoDepth)
+{
+  /* First check to see whether we have a DOM object */
+  const DOMJSClass* domClass = GetDOMClass(obj);
+  if (domClass) {
+    /* This object is a DOM object.  Double-check that it is safely
+       castable to T by checking whether it claims to inherit from the
+       class identified by protoID. */
+    if (domClass->mInterfaceChain[protoDepth] == protoID) {
+      value = UnwrapDOMObject<T>(obj);
+      return NS_OK;
+    }
+  }
+
+  /* Maybe we have a security wrapper or outer window? */
+  if (!mayBeWrapper || !js::IsWrapper(obj)) {
+    /* Not a DOM object, not a wrapper, just bail */
+    return NS_ERROR_XPC_BAD_CONVERT_JS;
+  }
+
+  JSObject* unwrappedObj =
+    js::CheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+  if (!unwrappedObj) {
+    return NS_ERROR_XPC_SECURITY_MANAGER_VETO;
+  }
+  MOZ_ASSERT(!js::IsWrapper(unwrappedObj));
+  // Recursive call is OK, because now we're using false for mayBeWrapper and
+  // we never reach this code if that boolean is false, so can't keep calling
+  // ourselves.
+  //
+  // Unwrap into a temporary pointer, because in general unwrapping into
+  // something of type U might trigger GC (e.g. release the value currently
+  // stored in there, with arbitrary consequences) and invalidate the
+  // "unwrappedObj" pointer.
+  T* tempValue;
+  nsresult rv = UnwrapObjectInternal<T, false>(unwrappedObj, tempValue,
+                                               protoID, protoDepth);
+  if (NS_SUCCEEDED(rv)) {
+    // It's very important to not update "obj" with the "unwrappedObj" value
+    // until we know the unwrap has succeeded.  Otherwise, in a situation in
+    // which we have an overload of object and primitive we could end up
+    // converting to the primitive from the unwrappedObj, whereas we want to do
+    // it from the original object.
+    obj = unwrappedObj;
+    // And now assign to "value"; at this point we don't care if a GC happens
+    // and invalidates unwrappedObj.
+    value = tempValue;
+    return NS_OK;
+  }
+
+  /* It's the wrong sort of DOM object */
+  return NS_ERROR_XPC_BAD_CONVERT_JS;
+}
+
+struct MutableObjectHandleWrapper {
+  explicit MutableObjectHandleWrapper(JS::MutableHandle<JSObject*> aHandle)
+    : mHandle(aHandle)
+  {
+  }
+
+  void operator=(JSObject* aObject)
+  {
+    MOZ_ASSERT(aObject);
+    mHandle.set(aObject);
+  }
+
+  operator JSObject*() const
+  {
+    return mHandle;
+  }
+
+private:
+  JS::MutableHandle<JSObject*> mHandle;
+};
+
+struct MutableValueHandleWrapper {
+  explicit MutableValueHandleWrapper(JS::MutableHandle<JS::Value> aHandle)
+    : mHandle(aHandle)
+  {
+  }
+
+  void operator=(JSObject* aObject)
+  {
+    MOZ_ASSERT(aObject);
+    mHandle.setObject(*aObject);
+  }
+
+  operator JSObject*() const
+  {
+    return &mHandle.toObject();
+  }
+
+private:
+  JS::MutableHandle<JS::Value> mHandle;
+};
+
+} // namespace binding_detail
+
+// UnwrapObject overloads that ensure we have a MutableHandle to keep it alive.
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JS::MutableHandle<JSObject*> obj, U& value)
+{
+  binding_detail::MutableObjectHandleWrapper wrapper(obj);
+  return binding_detail::UnwrapObjectInternal<T, true>(
+    wrapper, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JS::MutableHandle<JS::Value> obj, U& value)
+{
+  MOZ_ASSERT(obj.isObject());
+  binding_detail::MutableValueHandleWrapper wrapper(obj);
+  return binding_detail::UnwrapObjectInternal<T, true>(
+    wrapper, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+// UnwrapObject overloads that ensure we have a strong ref to keep it alive.
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JSObject* obj, RefPtr<U>& value)
+{
+  return binding_detail::UnwrapObjectInternal<T, true>(
+    obj, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JSObject* obj, nsCOMPtr<U>& value)
+{
+  return binding_detail::UnwrapObjectInternal<T, true>(
+    obj, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JSObject* obj, OwningNonNull<U>& value)
+{
+  return binding_detail::UnwrapObjectInternal<T, true>(
+    obj, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+// An UnwrapObject overload that just calls one of the JSObject* ones.
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapObject(JS::Handle<JS::Value> obj, U& value)
+{
+  MOZ_ASSERT(obj.isObject());
+  return UnwrapObject<PrototypeID, T>(&obj.toObject(), value);
+}
+
+template<prototypes::ID PrototypeID, class T>
+MOZ_ALWAYS_INLINE bool
+IsInstanceOf(JSObject* obj)
+{
+  void* ignored;
+  nsresult unwrapped = binding_detail::UnwrapObjectInternal<T, true>(
+    obj, ignored, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+  return NS_SUCCEEDED(unwrapped);
+}
+
+template<prototypes::ID PrototypeID, class T, typename U>
+MOZ_ALWAYS_INLINE nsresult
+UnwrapNonWrapperObject(JSObject* obj, U& value)
+{
+  MOZ_ASSERT(!js::IsWrapper(obj));
+  return binding_detail::UnwrapObjectInternal<T, false>(
+    obj, value, PrototypeID, PrototypeTraits<PrototypeID>::Depth);
+}
+
+inline bool
+IsNotDateOrRegExp(JSContext* cx, JS::Handle<JSObject*> obj,
+                  bool* notDateOrRegExp)
+{
+  MOZ_ASSERT(obj);
+
+  js::ESClass cls;
+  if (!js::GetBuiltinClass(cx, obj, &cls)) {
+    return false;
+  }
+
+  *notDateOrRegExp = cls != js::ESClass::Date && cls != js::ESClass::RegExp;
+  return true;
+}
+
+MOZ_ALWAYS_INLINE bool
+IsObjectValueConvertibleToDictionary(JSContext* cx,
+                                     JS::Handle<JS::Value> objVal,
+                                     bool* convertible)
+{
+  JS::Rooted<JSObject*> obj(cx, &objVal.toObject());
+  return IsNotDateOrRegExp(cx, obj, convertible);
+}
+
+MOZ_ALWAYS_INLINE bool
+IsConvertibleToDictionary(JSContext* cx, JS::Handle<JS::Value> val,
+                          bool* convertible)
+{
+  if (val.isNullOrUndefined()) {
+    *convertible = true;
+    return true;
+  }
+  if (!val.isObject()) {
+    *convertible = false;
+    return true;
+  }
+  return IsObjectValueConvertibleToDictionary(cx, val, convertible);
+}
+
+MOZ_ALWAYS_INLINE bool
+IsConvertibleToCallbackInterface(JSContext* cx, JS::Handle<JSObject*> obj,
+                                 bool* convertible)
+{
+  return IsNotDateOrRegExp(cx, obj, convertible);
+}
+
+// The items in the protoAndIfaceCache are indexed by the prototypes::id::ID,
+// constructors::id::ID and namedpropertiesobjects::id::ID enums, in that order.
+// The end of the prototype objects should be the start of the interface
+// objects, and the end of the interface objects should be the start of the
+// named properties objects.
+static_assert((size_t)constructors::id::_ID_Start ==
+              (size_t)prototypes::id::_ID_Count &&
+              (size_t)namedpropertiesobjects::id::_ID_Start ==
+              (size_t)constructors::id::_ID_Count,
+              "Overlapping or discontiguous indexes.");
+const size_t kProtoAndIfaceCacheCount = namedpropertiesobjects::id::_ID_Count;
+
+class ProtoAndIfaceCache
+{
+  // The caching strategy we use depends on what sort of global we're dealing
+  // with.  For a window-like global, we want everything to be as fast as
+  // possible, so we use a flat array, indexed by prototype/constructor ID.
+  // For everything else (e.g. globals for JSMs), space is more important than
+  // speed, so we use a two-level lookup table.
+
+  class ArrayCache : public Array<JS::Heap<JSObject*>, kProtoAndIfaceCacheCount>
+  {
+  public:
+    JSObject* EntrySlotIfExists(size_t i) {
+      return (*this)[i];
+    }
+
+    JS::Heap<JSObject*>& EntrySlotOrCreate(size_t i) {
+      return (*this)[i];
+    }
+
+    JS::Heap<JSObject*>& EntrySlotMustExist(size_t i) {
+      return (*this)[i];
+    }
+
+    void Trace(JSTracer* aTracer) {
+      for (size_t i = 0; i < ArrayLength(*this); ++i) {
+        JS::TraceEdge(aTracer, &(*this)[i], "protoAndIfaceCache[i]");
+      }
+    }
+
+    size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) {
+      return aMallocSizeOf(this);
+    }
+  };
+
+  class PageTableCache
+  {
+  public:
+    PageTableCache() {
+      memset(&mPages, 0, sizeof(mPages));
+    }
+
+    ~PageTableCache() {
+      for (size_t i = 0; i < ArrayLength(mPages); ++i) {
+        delete mPages[i];
+      }
+    }
+
+    JSObject* EntrySlotIfExists(size_t i) {
+      MOZ_ASSERT(i < kProtoAndIfaceCacheCount);
+      size_t pageIndex = i / kPageSize;
+      size_t leafIndex = i % kPageSize;
+      Page* p = mPages[pageIndex];
+      if (!p) {
+        return nullptr;
+      }
+      return (*p)[leafIndex];
+    }
+
+    JS::Heap<JSObject*>& EntrySlotOrCreate(size_t i) {
+      MOZ_ASSERT(i < kProtoAndIfaceCacheCount);
+      size_t pageIndex = i / kPageSize;
+      size_t leafIndex = i % kPageSize;
+      Page* p = mPages[pageIndex];
+      if (!p) {
+        p = new Page;
+        mPages[pageIndex] = p;
+      }
+      return (*p)[leafIndex];
+    }
+
+    JS::Heap<JSObject*>& EntrySlotMustExist(size_t i) {
+      MOZ_ASSERT(i < kProtoAndIfaceCacheCount);
+      size_t pageIndex = i / kPageSize;
+      size_t leafIndex = i % kPageSize;
+      Page* p = mPages[pageIndex];
+      MOZ_ASSERT(p);
+      return (*p)[leafIndex];
+    }
+
+    void Trace(JSTracer* trc) {
+      for (size_t i = 0; i < ArrayLength(mPages); ++i) {
+        Page* p = mPages[i];
+        if (p) {
+          for (size_t j = 0; j < ArrayLength(*p); ++j) {
+            JS::TraceEdge(trc, &(*p)[j], "protoAndIfaceCache[i]");
+          }
+        }
+      }
+    }
+
+    size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) {
+      size_t n = aMallocSizeOf(this);
+      for (size_t i = 0; i < ArrayLength(mPages); ++i) {
+        n += aMallocSizeOf(mPages[i]);
+      }
+      return n;
+    }
+
+  private:
+    static const size_t kPageSize = 16;
+    typedef Array<JS::Heap<JSObject*>, kPageSize> Page;
+    static const size_t kNPages = kProtoAndIfaceCacheCount / kPageSize +
+      size_t(bool(kProtoAndIfaceCacheCount % kPageSize));
+    Array<Page*, kNPages> mPages;
+  };
+
+public:
+  enum Kind {
+    WindowLike,
+    NonWindowLike
+  };
+
+  explicit ProtoAndIfaceCache(Kind aKind) : mKind(aKind) {
+    MOZ_COUNT_CTOR(ProtoAndIfaceCache);
+    if (aKind == WindowLike) {
+      mArrayCache = new ArrayCache();
+    } else {
+      mPageTableCache = new PageTableCache();
+    }
+  }
+
+  ~ProtoAndIfaceCache() {
+    if (mKind == WindowLike) {
+      delete mArrayCache;
+    } else {
+      delete mPageTableCache;
+    }
+    MOZ_COUNT_DTOR(ProtoAndIfaceCache);
+  }
+
+#define FORWARD_OPERATION(opName, args)              \
+  do {                                               \
+    if (mKind == WindowLike) {                       \
+      return mArrayCache->opName args;               \
+    } else {                                         \
+      return mPageTableCache->opName args;           \
+    }                                                \
+  } while(0)
+
+  // Return the JSObject stored in slot i, if that slot exists.  If
+  // the slot does not exist, return null.
+  JSObject* EntrySlotIfExists(size_t i) {
+    FORWARD_OPERATION(EntrySlotIfExists, (i));
+  }
+
+  // Return a reference to slot i, creating it if necessary.  There
+  // may not be an object in the returned slot.
+  JS::Heap<JSObject*>& EntrySlotOrCreate(size_t i) {
+    FORWARD_OPERATION(EntrySlotOrCreate, (i));
+  }
+
+  // Return a reference to slot i, which is guaranteed to already
+  // exist.  There may not be an object in the slot, if prototype and
+  // constructor initialization for one of our bindings failed.
+  JS::Heap<JSObject*>& EntrySlotMustExist(size_t i) {
+    FORWARD_OPERATION(EntrySlotMustExist, (i));
+  }
+
+  void Trace(JSTracer *aTracer) {
+    FORWARD_OPERATION(Trace, (aTracer));
+  }
+
+  size_t SizeOfIncludingThis(MallocSizeOf aMallocSizeOf) {
+    size_t n = aMallocSizeOf(this);
+    n += (mKind == WindowLike
+          ? mArrayCache->SizeOfIncludingThis(aMallocSizeOf)
+          : mPageTableCache->SizeOfIncludingThis(aMallocSizeOf));
+    return n;
+  }
+#undef FORWARD_OPERATION
+
+private:
+  union {
+    ArrayCache *mArrayCache;
+    PageTableCache *mPageTableCache;
+  };
+  Kind mKind;
+};
+
+inline void
+AllocateProtoAndIfaceCache(JSObject* obj, ProtoAndIfaceCache::Kind aKind)
+{
+  MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
+  MOZ_ASSERT(js::GetReservedSlot(obj, DOM_PROTOTYPE_SLOT).isUndefined());
+
+  ProtoAndIfaceCache* protoAndIfaceCache = new ProtoAndIfaceCache(aKind);
+
+  js::SetReservedSlot(obj, DOM_PROTOTYPE_SLOT,
+                      JS::PrivateValue(protoAndIfaceCache));
+}
+
+#ifdef DEBUG
+struct VerifyTraceProtoAndIfaceCacheCalledTracer : public JS::CallbackTracer
+{
+  bool ok;
+
+  explicit VerifyTraceProtoAndIfaceCacheCalledTracer(JSContext* cx)
+    : JS::CallbackTracer(cx), ok(false)
+  {}
+
+  void onChild(const JS::GCCellPtr&) override {
+    // We don't do anything here, we only want to verify that
+    // TraceProtoAndIfaceCache was called.
+  }
+
+  TracerKind getTracerKind() const override { return TracerKind::VerifyTraceProtoAndIface; }
+};
+#endif
+
+inline void
+TraceProtoAndIfaceCache(JSTracer* trc, JSObject* obj)
+{
+  MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
+
+#ifdef DEBUG
+  if (trc->isCallbackTracer() &&
+      (trc->asCallbackTracer()->getTracerKind() ==
+       JS::CallbackTracer::TracerKind::VerifyTraceProtoAndIface)) {
+    // We don't do anything here, we only want to verify that
+    // TraceProtoAndIfaceCache was called.
+    static_cast<VerifyTraceProtoAndIfaceCacheCalledTracer*>(trc)->ok = true;
+    return;
+  }
+#endif
+
+  if (!DOMGlobalHasProtoAndIFaceCache(obj))
+    return;
+  ProtoAndIfaceCache* protoAndIfaceCache = GetProtoAndIfaceCache(obj);
+  protoAndIfaceCache->Trace(trc);
+}
+
+inline void
+DestroyProtoAndIfaceCache(JSObject* obj)
+{
+  MOZ_ASSERT(js::GetObjectClass(obj)->flags & JSCLASS_DOM_GLOBAL);
+
+  if (!DOMGlobalHasProtoAndIFaceCache(obj)) {
+    return;
+  }
+
+  ProtoAndIfaceCache* protoAndIfaceCache = GetProtoAndIfaceCache(obj);
+
+  delete protoAndIfaceCache;
+}
+
+/**
+ * Add constants to an object.
+ */
+bool
+DefineConstants(JSContext* cx, JS::Handle<JSObject*> obj,
+                const ConstantSpec* cs);
+
+struct JSNativeHolder
+{
+  JSNative mNative;
+  const NativePropertyHooks* mPropertyHooks;
+};
+
+struct NamedConstructor
+{
+  const char* mName;
+  const JSNativeHolder mHolder;
+  unsigned mNargs;
+};
+
+/*
+ * Create a DOM interface object (if constructorClass is non-null) and/or a
+ * DOM interface prototype object (if protoClass is non-null).
+ *
+ * global is used as the parent of the interface object and the interface
+ *        prototype object
+ * protoProto is the prototype to use for the interface prototype object.
+ * interfaceProto is the prototype to use for the interface object.  This can be
+ *                null if both constructorClass and constructor are null (as in,
+ *                if we're not creating an interface object at all).
+ * protoClass is the JSClass to use for the interface prototype object.
+ *            This is null if we should not create an interface prototype
+ *            object.
+ * protoCache a pointer to a JSObject pointer where we should cache the
+ *            interface prototype object. This must be null if protoClass is and
+ *            vice versa.
+ * constructorClass is the JSClass to use for the interface object.
+ *                  This is null if we should not create an interface object or
+ *                  if it should be a function object.
+ * constructor holds the JSNative to back the interface object which should be a
+ *             Function, unless constructorClass is non-null in which case it is
+ *             ignored. If this is null and constructorClass is also null then
+ *             we should not create an interface object at all.
+ * ctorNargs is the length of the constructor function; 0 if no constructor
+ * constructorCache a pointer to a JSObject pointer where we should cache the
+ *                  interface object. This must be null if both constructorClass
+ *                  and constructor are null, and non-null otherwise.
+ * properties contains the methods, attributes and constants to be defined on
+ *            objects in any compartment.
+ * chromeProperties contains the methods, attributes and constants to be defined
+ *                  on objects in chrome compartments. This must be null if the
+ *                  interface doesn't have any ChromeOnly properties or if the
+ *                  object is being created in non-chrome compartment.
+ * defineOnGlobal controls whether properties should be defined on the given
+ *                global for the interface object (if any) and named
+ *                constructors (if any) for this interface.  This can be
+ *                false in situations where we want the properties to only
+ *                appear on privileged Xrays but not on the unprivileged
+ *                underlying global.
+ * unscopableNames if not null it points to a null-terminated list of const
+ *                 char* names of the unscopable properties for this interface.
+ * isGlobal if true, we're creating interface objects for a [Global] or
+ *        [PrimaryGlobal] interface, and hence shouldn't define properties on
+ *        the prototype object.
+ *
+ * At least one of protoClass, constructorClass or constructor should be
+ * non-null. If constructorClass or constructor are non-null, the resulting
+ * interface object will be defined on the given global with property name
+ * |name|, which must also be non-null.
+ */
+void
+CreateInterfaceObjects(JSContext* cx, JS::Handle<JSObject*> global,
+                       JS::Handle<JSObject*> protoProto,
+                       const js::Class* protoClass, JS::Heap<JSObject*>* protoCache,
+                       JS::Handle<JSObject*> interfaceProto,
+                       const js::Class* constructorClass,
+                       unsigned ctorNargs, const NamedConstructor* namedConstructors,
+                       JS::Heap<JSObject*>* constructorCache,
+                       const NativeProperties* regularProperties,
+                       const NativeProperties* chromeOnlyProperties,
+                       const char* name, bool defineOnGlobal,
+                       const char* const* unscopableNames,
+                       bool isGlobal);
+
+/**
+ * Define the properties (regular and chrome-only) on obj.
+ *
+ * obj the object to instal the properties on. This should be the interface
+ *     prototype object for regular interfaces and the instance object for
+ *     interfaces marked with Global.
+ * properties contains the methods, attributes and constants to be defined on
+ *            objects in any compartment.
+ * chromeProperties contains the methods, attributes and constants to be defined
+ *                  on objects in chrome compartments. This must be null if the
+ *                  interface doesn't have any ChromeOnly properties or if the
+ *                  object is being created in non-chrome compartment.
+ */
+bool
+DefineProperties(JSContext* cx, JS::Handle<JSObject*> obj,
+                 const NativeProperties* properties,
+                 const NativeProperties* chromeOnlyProperties);
+
+/*
+ * Define the unforgeable methods on an object.
+ */
+bool
+DefineUnforgeableMethods(JSContext* cx, JS::Handle<JSObject*> obj,
+                         const Prefable<const JSFunctionSpec>* props);
+
+/*
+ * Define the unforgeable attributes on an object.
+ */
+bool
+DefineUnforgeableAttributes(JSContext* cx, JS::Handle<JSObject*> obj,
+                            const Prefable<const JSPropertySpec>* props);
+
+#define HAS_MEMBER_TYPEDEFS                                               \
+private:                                                                  \
+  typedef char yes[1];                                                    \
+  typedef char no[2]
+
+#ifdef _MSC_VER
+#define HAS_MEMBER_CHECK(_name)                                           \
+  template<typename V> static yes& Check##_name(char (*)[(&V::_name == 0) + 1])
+#else
+#define HAS_MEMBER_CHECK(_name)                                           \
+  template<typename V> static yes& Check##_name(char (*)[sizeof(&V::_name) + 1])
+#endif
+
+#define HAS_MEMBER(_memberName, _valueName)                               \
+private:                                                                  \
+  HAS_MEMBER_CHECK(_memberName);                                          \
+  template<typename V> static no& Check##_memberName(...);                \
+                                                                          \
+public:                                                                   \
+  static bool const _valueName =                                          \
+    sizeof(Check##_memberName<T>(nullptr)) == sizeof(yes)
+
+template<class T>
+struct NativeHasMember
+{
+  HAS_MEMBER_TYPEDEFS;
+
+  HAS_MEMBER(GetParentObject, GetParentObject);
+  HAS_MEMBER(WrapObject, WrapObject);
+};
+
+template<class T>
+struct IsSmartPtr
+{
+  HAS_MEMBER_TYPEDEFS;
+
+  HAS_MEMBER(get, value);
+};
+
+template<class T>
+struct IsRefcounted
+{
+  HAS_MEMBER_TYPEDEFS;
+
+  HAS_MEMBER(AddRef, HasAddref);
+  HAS_MEMBER(Release, HasRelease);
+
+public:
+  static bool const value = HasAddref && HasRelease;
+
+private:
+  // This struct only works if T is fully declared (not just forward declared).
+  // The IsBaseOf check will ensure that, we don't really need it for any other
+  // reason (the static assert will of course always be true).
+  static_assert(!IsBaseOf<nsISupports, T>::value || IsRefcounted::value,
+                "Classes derived from nsISupports are refcounted!");
+
+};
+
+#undef HAS_MEMBER
+#undef HAS_MEMBER_CHECK
+#undef HAS_MEMBER_TYPEDEFS
+
+#ifdef DEBUG
+template <class T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct
+CheckWrapperCacheCast
+{
+  static bool Check()
+  {
+    return reinterpret_cast<uintptr_t>(
+      static_cast<nsWrapperCache*>(
+        reinterpret_cast<T*>(1))) == 1;
+  }
+};
+template <class T>
+struct
+CheckWrapperCacheCast<T, true>
+{
+  static bool Check()
+  {
+    return true;
+  }
+};
+#endif
+
+MOZ_ALWAYS_INLINE bool
+CouldBeDOMBinding(void*)
+{
+  return true;
+}
+
+MOZ_ALWAYS_INLINE bool
+CouldBeDOMBinding(nsWrapperCache* aCache)
+{
+  return aCache->IsDOMBinding();
+}
+
+inline bool
+TryToOuterize(JS::MutableHandle<JS::Value> rval)
+{
+  if (js::IsWindow(&rval.toObject())) {
+    JSObject* obj = js::ToWindowProxyIfWindow(&rval.toObject());
+    MOZ_ASSERT(obj);
+    rval.set(JS::ObjectValue(*obj));
+  }
+
+  return true;
+}
+
+// Make sure to wrap the given string value into the right compartment, as
+// needed.
+MOZ_ALWAYS_INLINE
+bool
+MaybeWrapStringValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(rval.isString());
+  JSString* str = rval.toString();
+  if (JS::GetStringZone(str) != js::GetContextZone(cx)) {
+    return JS_WrapValue(cx, rval);
+  }
+  return true;
+}
+
+// Make sure to wrap the given object value into the right compartment as
+// needed.  This will work correctly, but possibly slowly, on all objects.
+MOZ_ALWAYS_INLINE
+bool
+MaybeWrapObjectValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(rval.isObject());
+
+  // Cross-compartment always requires wrapping.
+  JSObject* obj = &rval.toObject();
+  if (js::GetObjectCompartment(obj) != js::GetContextCompartment(cx)) {
+    return JS_WrapValue(cx, rval);
+  }
+
+  // We're same-compartment, but even then we might need to wrap
+  // objects specially.  Check for that.
+  if (IsDOMObject(obj)) {
+    return TryToOuterize(rval);
+  }
+
+  // It's not a WebIDL object, so it's OK to just leave it as-is: only WebIDL
+  // objects (specifically only windows) require outerization.
+  return true;
+}
+
+// Like MaybeWrapObjectValue, but also allows null
+MOZ_ALWAYS_INLINE
+bool
+MaybeWrapObjectOrNullValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(rval.isObjectOrNull());
+  if (rval.isNull()) {
+    return true;
+  }
+  return MaybeWrapObjectValue(cx, rval);
+}
+
+// Wrapping for objects that are known to not be DOM or XPConnect objects
+MOZ_ALWAYS_INLINE
+bool
+MaybeWrapNonDOMObjectValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(rval.isObject());
+  MOZ_ASSERT(!GetDOMClass(&rval.toObject()));
+  MOZ_ASSERT(!(js::GetObjectClass(&rval.toObject())->flags &
+               JSCLASS_PRIVATE_IS_NSISUPPORTS));
+
+  JSObject* obj = &rval.toObject();
+  if (js::GetObjectCompartment(obj) == js::GetContextCompartment(cx)) {
+    return true;
+  }
+  return JS_WrapValue(cx, rval);
+}
+
+// Like MaybeWrapNonDOMObjectValue but allows null
+MOZ_ALWAYS_INLINE
+bool
+MaybeWrapNonDOMObjectOrNullValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(rval.isObjectOrNull());
+  if (rval.isNull()) {
+    return true;
+  }
+  return MaybeWrapNonDOMObjectValue(cx, rval);
+}
+
+// If rval is a gcthing and is not in the compartment of cx, wrap rval
+// into the compartment of cx (typically by replacing it with an Xray or
+// cross-compartment wrapper around the original object).
+MOZ_ALWAYS_INLINE bool
+MaybeWrapValue(JSContext* cx, JS::MutableHandle<JS::Value> rval)
+{
+  if (rval.isString()) {
+    return MaybeWrapStringValue(cx, rval);
+  }
+
+  if (!rval.isObject()) {
+    return true;
+  }
+
+  return MaybeWrapObjectValue(cx, rval);
+}
+
+namespace binding_detail {
+enum GetOrCreateReflectorWrapBehavior {
+  eWrapIntoContextCompartment,
+  eDontWrapIntoContextCompartment
+};
+
+template <class T>
+struct TypeNeedsOuterization
+{
+  // We only need to outerize Window objects, so anything inheriting from
+  // nsGlobalWindow (which inherits from EventTarget itself).
+  static const bool value =
+    IsBaseOf<nsGlobalWindow, T>::value || IsSame<EventTarget, T>::value;
+};
+
+#ifdef DEBUG
+template<typename T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct CheckWrapperCacheTracing
+{
+  static inline void Check(T* aObject)
+  {
+  }
+};
+
+template<typename T>
+struct CheckWrapperCacheTracing<T, true>
+{
+  static void Check(T* aObject)
+  {
+    // Rooting analysis thinks QueryInterface may GC, but we're dealing with
+    // a subset of QueryInterface, C++ only types here.
+    JS::AutoSuppressGCAnalysis nogc;
+
+    nsWrapperCache* wrapperCacheFromQI = nullptr;
+    aObject->QueryInterface(NS_GET_IID(nsWrapperCache),
+                            reinterpret_cast<void**>(&wrapperCacheFromQI));
+
+    MOZ_ASSERT(wrapperCacheFromQI,
+               "Missing nsWrapperCache from QueryInterface implementation?");
+
+    if (!wrapperCacheFromQI->GetWrapperPreserveColor()) {
+      // Can't assert that we trace the wrapper, since we don't have any
+      // wrapper to trace.
+      return;
+    }
+
+    nsISupports* ccISupports = nullptr;
+    aObject->QueryInterface(NS_GET_IID(nsCycleCollectionISupports),
+                            reinterpret_cast<void**>(&ccISupports));
+    MOZ_ASSERT(ccISupports,
+               "nsWrapperCache object which isn't cycle collectable?");
+
+    nsXPCOMCycleCollectionParticipant* participant = nullptr;
+    CallQueryInterface(ccISupports, &participant);
+    MOZ_ASSERT(participant, "Can't QI to CycleCollectionParticipant?");
+
+    bool wasPreservingWrapper = wrapperCacheFromQI->PreservingWrapper();
+    wrapperCacheFromQI->SetPreservingWrapper(true);
+    wrapperCacheFromQI->CheckCCWrapperTraversal(ccISupports, participant);
+    wrapperCacheFromQI->SetPreservingWrapper(wasPreservingWrapper);
+  }
+};
+
+void
+AssertReflectorHasGivenProto(JSContext* aCx, JSObject* aReflector,
+                             JS::Handle<JSObject*> aGivenProto);
+#endif // DEBUG
+
+template <class T, GetOrCreateReflectorWrapBehavior wrapBehavior>
+MOZ_ALWAYS_INLINE bool
+DoGetOrCreateDOMReflector(JSContext* cx, T* value,
+                          JS::Handle<JSObject*> givenProto,
+                          JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(value);
+  // We can get rid of this when we remove support for hasXPConnectImpls.
+  bool couldBeDOMBinding = CouldBeDOMBinding(value);
+  JSObject* obj = value->GetWrapper();
+  if (obj) {
+#ifdef DEBUG
+    AssertReflectorHasGivenProto(cx, obj, givenProto);
+    // Have to reget obj because AssertReflectorHasGivenProto can
+    // trigger gc so the pointer may now be invalid.
+    obj = value->GetWrapper();
+#endif
+  } else {
+    // Inline this here while we have non-dom objects in wrapper caches.
+    if (!couldBeDOMBinding) {
+      return false;
+    }
+
+    obj = value->WrapObject(cx, givenProto);
+    if (!obj) {
+      // At this point, obj is null, so just return false.
+      // Callers seem to be testing JS_IsExceptionPending(cx) to
+      // figure out whether WrapObject() threw.
+      return false;
+    }
+
+#ifdef DEBUG
+    if (IsBaseOf<nsWrapperCache, T>::value) {
+      CheckWrapperCacheTracing<T>::Check(value);
+    }
+#endif
+  }
+
+#ifdef DEBUG
+  const DOMJSClass* clasp = GetDOMClass(obj);
+  // clasp can be null if the cache contained a non-DOM object.
+  if (clasp) {
+    // Some sanity asserts about our object.  Specifically:
+    // 1)  If our class claims we're nsISupports, we better be nsISupports
+    //     XXXbz ideally, we could assert that reinterpret_cast to nsISupports
+    //     does the right thing, but I don't see a way to do it.  :(
+    // 2)  If our class doesn't claim we're nsISupports we better be
+    //     reinterpret_castable to nsWrapperCache.
+    MOZ_ASSERT(clasp, "What happened here?");
+    MOZ_ASSERT_IF(clasp->mDOMObjectIsISupports, (IsBaseOf<nsISupports, T>::value));
+    MOZ_ASSERT(CheckWrapperCacheCast<T>::Check());
+  }
+#endif
+
+  rval.set(JS::ObjectValue(*obj));
+
+  bool sameCompartment =
+    js::GetObjectCompartment(obj) == js::GetContextCompartment(cx);
+  if (sameCompartment && couldBeDOMBinding) {
+    return TypeNeedsOuterization<T>::value ? TryToOuterize(rval) : true;
+  }
+
+  if (wrapBehavior == eDontWrapIntoContextCompartment) {
+    if (TypeNeedsOuterization<T>::value) {
+      JSAutoCompartment ac(cx, obj);
+      return TryToOuterize(rval);
+    }
+
+    return true;
+  }
+
+  return JS_WrapValue(cx, rval);
+}
+
+} // namespace binding_detail
+
+// Create a JSObject wrapping "value", if there isn't one already, and store it
+// in rval.  "value" must be a concrete class that implements a
+// GetWrapperPreserveColor() which can return its existing wrapper, if any, and
+// a WrapObject() which will try to create a wrapper. Typically, this is done by
+// having "value" inherit from nsWrapperCache.
+//
+// The value stored in rval will be ready to be exposed to whatever JS
+// is running on cx right now.  In particular, it will be in the
+// compartment of cx, and outerized as needed.
+template <class T>
+MOZ_ALWAYS_INLINE bool
+GetOrCreateDOMReflector(JSContext* cx, T* value,
+                        JS::MutableHandle<JS::Value> rval,
+                        JS::Handle<JSObject*> givenProto = nullptr)
+{
+  using namespace binding_detail;
+  return DoGetOrCreateDOMReflector<T, eWrapIntoContextCompartment>(cx, value,
+                                                                   givenProto,
+                                                                   rval);
+}
+
+// Like GetOrCreateDOMReflector but doesn't wrap into the context compartment,
+// and hence does not actually require cx to be in a compartment.
+template <class T>
+MOZ_ALWAYS_INLINE bool
+GetOrCreateDOMReflectorNoWrap(JSContext* cx, T* value,
+                              JS::MutableHandle<JS::Value> rval)
+{
+  using namespace binding_detail;
+  return DoGetOrCreateDOMReflector<T, eDontWrapIntoContextCompartment>(cx,
+                                                                       value,
+                                                                       nullptr,
+                                                                       rval);
+}
+
+// Create a JSObject wrapping "value", for cases when "value" is a
+// non-wrapper-cached object using WebIDL bindings.  "value" must implement a
+// WrapObject() method taking a JSContext and a scope.
+template <class T>
+inline bool
+WrapNewBindingNonWrapperCachedObject(JSContext* cx,
+                                     JS::Handle<JSObject*> scopeArg,
+                                     T* value,
+                                     JS::MutableHandle<JS::Value> rval,
+                                     JS::Handle<JSObject*> givenProto = nullptr)
+{
+  static_assert(IsRefcounted<T>::value, "Don't pass owned classes in here.");
+  MOZ_ASSERT(value);
+  // We try to wrap in the compartment of the underlying object of "scope"
+  JS::Rooted<JSObject*> obj(cx);
+  {
+    // scope for the JSAutoCompartment so that we restore the compartment
+    // before we call JS_WrapValue.
+    Maybe<JSAutoCompartment> ac;
+    // Maybe<Handle> doesn't so much work, and in any case, adding
+    // more Maybe (one for a Rooted and one for a Handle) adds more
+    // code (and branches!) than just adding a single rooted.
+    JS::Rooted<JSObject*> scope(cx, scopeArg);
+    JS::Rooted<JSObject*> proto(cx, givenProto);
+    if (js::IsWrapper(scope)) {
+      scope = js::CheckedUnwrap(scope, /* stopAtWindowProxy = */ false);
+      if (!scope)
+        return false;
+      ac.emplace(cx, scope);
+      if (!JS_WrapObject(cx, &proto)) {
+        return false;
+      }
+    }
+
+    MOZ_ASSERT(js::IsObjectInContextCompartment(scope, cx));
+    if (!value->WrapObject(cx, proto, &obj)) {
+      return false;
+    }
+  }
+
+  // We can end up here in all sorts of compartments, per above.  Make
+  // sure to JS_WrapValue!
+  rval.set(JS::ObjectValue(*obj));
+  return MaybeWrapObjectValue(cx, rval);
+}
+
+// Create a JSObject wrapping "value", for cases when "value" is a
+// non-wrapper-cached owned object using WebIDL bindings.  "value" must implement a
+// WrapObject() method taking a JSContext, a scope, and a boolean outparam that
+// is true if the JSObject took ownership
+template <class T>
+inline bool
+WrapNewBindingNonWrapperCachedObject(JSContext* cx,
+                                     JS::Handle<JSObject*> scopeArg,
+                                     nsAutoPtr<T>& value,
+                                     JS::MutableHandle<JS::Value> rval,
+                                     JS::Handle<JSObject*> givenProto = nullptr)
+{
+  static_assert(!IsRefcounted<T>::value, "Only pass owned classes in here.");
+  // We do a runtime check on value, because otherwise we might in
+  // fact end up wrapping a null and invoking methods on it later.
+  if (!value) {
+    NS_RUNTIMEABORT("Don't try to wrap null objects");
+  }
+  // We try to wrap in the compartment of the underlying object of "scope"
+  JS::Rooted<JSObject*> obj(cx);
+  {
+    // scope for the JSAutoCompartment so that we restore the compartment
+    // before we call JS_WrapValue.
+    Maybe<JSAutoCompartment> ac;
+    // Maybe<Handle> doesn't so much work, and in any case, adding
+    // more Maybe (one for a Rooted and one for a Handle) adds more
+    // code (and branches!) than just adding a single rooted.
+    JS::Rooted<JSObject*> scope(cx, scopeArg);
+    JS::Rooted<JSObject*> proto(cx, givenProto);
+    if (js::IsWrapper(scope)) {
+      scope = js::CheckedUnwrap(scope, /* stopAtWindowProxy = */ false);
+      if (!scope)
+        return false;
+      ac.emplace(cx, scope);
+      if (!JS_WrapObject(cx, &proto)) {
+        return false;
+      }
+    }
+
+    MOZ_ASSERT(js::IsObjectInContextCompartment(scope, cx));
+    if (!value->WrapObject(cx, proto, &obj)) {
+      return false;
+    }
+
+    value.forget();
+  }
+
+  // We can end up here in all sorts of compartments, per above.  Make
+  // sure to JS_WrapValue!
+  rval.set(JS::ObjectValue(*obj));
+  return MaybeWrapObjectValue(cx, rval);
+}
+
+// Helper for smart pointers (nsRefPtr/nsCOMPtr).
+template <template <typename> class SmartPtr, typename T,
+          typename U=typename EnableIf<IsRefcounted<T>::value, T>::Type,
+          typename V=typename EnableIf<IsSmartPtr<SmartPtr<T>>::value, T>::Type>
+inline bool
+WrapNewBindingNonWrapperCachedObject(JSContext* cx, JS::Handle<JSObject*> scope,
+                                     const SmartPtr<T>& value,
+                                     JS::MutableHandle<JS::Value> rval,
+                                     JS::Handle<JSObject*> givenProto = nullptr)
+{
+  return WrapNewBindingNonWrapperCachedObject(cx, scope, value.get(), rval,
+                                              givenProto);
+}
+
+// Helper for object references (as opposed to pointers).
+template <typename T,
+          typename U=typename EnableIf<!IsSmartPtr<T>::value, T>::Type>
+inline bool
+WrapNewBindingNonWrapperCachedObject(JSContext* cx, JS::Handle<JSObject*> scope,
+                                     T& value,
+                                     JS::MutableHandle<JS::Value> rval,
+                                     JS::Handle<JSObject*> givenProto = nullptr)
+{
+  return WrapNewBindingNonWrapperCachedObject(cx, scope, &value, rval,
+                                              givenProto);
+}
+
+// Only set allowNativeWrapper to false if you really know you need it, if in
+// doubt use true. Setting it to false disables security wrappers.
+bool
+NativeInterface2JSObjectAndThrowIfFailed(JSContext* aCx,
+                                         JS::Handle<JSObject*> aScope,
+                                         JS::MutableHandle<JS::Value> aRetval,
+                                         xpcObjectHelper& aHelper,
+                                         const nsIID* aIID,
+                                         bool aAllowNativeWrapper);
+
+/**
+ * A method to handle new-binding wrap failure, by possibly falling back to
+ * wrapping as a non-new-binding object.
+ */
+template <class T>
+MOZ_ALWAYS_INLINE bool
+HandleNewBindingWrappingFailure(JSContext* cx, JS::Handle<JSObject*> scope,
+                                T* value, JS::MutableHandle<JS::Value> rval)
+{
+  if (JS_IsExceptionPending(cx)) {
+    return false;
+  }
+
+  qsObjectHelper helper(value, GetWrapperCache(value));
+  return NativeInterface2JSObjectAndThrowIfFailed(cx, scope, rval,
+                                                  helper, nullptr, true);
+}
+
+// Helper for calling HandleNewBindingWrappingFailure with smart pointers
+// (nsAutoPtr/nsRefPtr/nsCOMPtr) or references.
+
+template <class T, bool isSmartPtr=IsSmartPtr<T>::value>
+struct HandleNewBindingWrappingFailureHelper
+{
+  static inline bool Wrap(JSContext* cx, JS::Handle<JSObject*> scope,
+                          const T& value, JS::MutableHandle<JS::Value> rval)
+  {
+    return HandleNewBindingWrappingFailure(cx, scope, value.get(), rval);
+  }
+};
+
+template <class T>
+struct HandleNewBindingWrappingFailureHelper<T, false>
+{
+  static inline bool Wrap(JSContext* cx, JS::Handle<JSObject*> scope, T& value,
+                          JS::MutableHandle<JS::Value> rval)
+  {
+    return HandleNewBindingWrappingFailure(cx, scope, &value, rval);
+  }
+};
+
+template<class T>
+inline bool
+HandleNewBindingWrappingFailure(JSContext* cx, JS::Handle<JSObject*> scope,
+                                T& value, JS::MutableHandle<JS::Value> rval)
+{
+  return HandleNewBindingWrappingFailureHelper<T>::Wrap(cx, scope, value, rval);
+}
+
+template<bool Fatal>
+inline bool
+EnumValueNotFound(JSContext* cx, JS::HandleString str, const char* type,
+                  const char* sourceDescription);
+
+template<>
+inline bool
+EnumValueNotFound<false>(JSContext* cx, JS::HandleString str, const char* type,
+                         const char* sourceDescription)
+{
+  // TODO: Log a warning to the console.
+  return true;
+}
+
+template<>
+inline bool
+EnumValueNotFound<true>(JSContext* cx, JS::HandleString str, const char* type,
+                        const char* sourceDescription)
+{
+  JSAutoByteString deflated;
+  if (!deflated.encodeUtf8(cx, str)) {
+    return false;
+  }
+  return ThrowErrorMessage(cx, MSG_INVALID_ENUM_VALUE, sourceDescription,
+                           deflated.ptr(), type);
+}
+
+template<typename CharT>
+inline int
+FindEnumStringIndexImpl(const CharT* chars, size_t length, const EnumEntry* values)
+{
+  int i = 0;
+  for (const EnumEntry* value = values; value->value; ++value, ++i) {
+    if (length != value->length) {
+      continue;
+    }
+
+    bool equal = true;
+    const char* val = value->value;
+    for (size_t j = 0; j != length; ++j) {
+      if (unsigned(val[j]) != unsigned(chars[j])) {
+        equal = false;
+        break;
+      }
+    }
+
+    if (equal) {
+      return i;
+    }
+  }
+
+  return -1;
+}
+
+template<bool InvalidValueFatal>
+inline bool
+FindEnumStringIndex(JSContext* cx, JS::Handle<JS::Value> v, const EnumEntry* values,
+                    const char* type, const char* sourceDescription, int* index)
+{
+  // JS_StringEqualsAscii is slow as molasses, so don't use it here.
+  JS::RootedString str(cx, JS::ToString(cx, v));
+  if (!str) {
+    return false;
+  }
+
+  {
+    size_t length;
+    JS::AutoCheckCannotGC nogc;
+    if (js::StringHasLatin1Chars(str)) {
+      const JS::Latin1Char* chars = JS_GetLatin1StringCharsAndLength(cx, nogc, str,
+                                                                     &length);
+      if (!chars) {
+        return false;
+      }
+      *index = FindEnumStringIndexImpl(chars, length, values);
+    } else {
+      const char16_t* chars = JS_GetTwoByteStringCharsAndLength(cx, nogc, str,
+                                                                &length);
+      if (!chars) {
+        return false;
+      }
+      *index = FindEnumStringIndexImpl(chars, length, values);
+    }
+    if (*index >= 0) {
+      return true;
+    }
+  }
+
+  return EnumValueNotFound<InvalidValueFatal>(cx, str, type, sourceDescription);
+}
+
+inline nsWrapperCache*
+GetWrapperCache(const ParentObject& aParentObject)
+{
+  return aParentObject.mWrapperCache;
+}
+
+template<class T>
+inline T*
+GetParentPointer(T* aObject)
+{
+  return aObject;
+}
+
+inline nsISupports*
+GetParentPointer(const ParentObject& aObject)
+{
+  return aObject.mObject;
+}
+
+template <typename T>
+inline bool
+GetUseXBLScope(T* aParentObject)
+{
+  return false;
+}
+
+inline bool
+GetUseXBLScope(const ParentObject& aParentObject)
+{
+  return aParentObject.mUseXBLScope;
+}
+
+template<class T>
+inline void
+ClearWrapper(T* p, nsWrapperCache* cache)
+{
+  cache->ClearWrapper();
+}
+
+template<class T>
+inline void
+ClearWrapper(T* p, void*)
+{
+  nsWrapperCache* cache;
+  CallQueryInterface(p, &cache);
+  ClearWrapper(p, cache);
+}
+
+template<class T>
+inline void
+UpdateWrapper(T* p, nsWrapperCache* cache, JSObject* obj, const JSObject* old)
+{
+  JS::AutoAssertGCCallback inCallback(obj);
+  cache->UpdateWrapper(obj, old);
+}
+
+template<class T>
+inline void
+UpdateWrapper(T* p, void*, JSObject* obj, const JSObject* old)
+{
+  JS::AutoAssertGCCallback inCallback(obj);
+  nsWrapperCache* cache;
+  CallQueryInterface(p, &cache);
+  UpdateWrapper(p, cache, obj, old);
+}
+
+// Attempt to preserve the wrapper, if any, for a Paris DOM bindings object.
+// Return true if we successfully preserved the wrapper, or there is no wrapper
+// to preserve. In the latter case we don't need to preserve the wrapper, because
+// the object can only be obtained by JS once, or they cannot be meaningfully
+// owned from the native side.
+//
+// This operation will return false only for non-nsISupports cycle-collected
+// objects, because we cannot determine if they are wrappercached or not.
+bool
+TryPreserveWrapper(JSObject* obj);
+
+// Can only be called with a DOM JSClass.
+bool
+InstanceClassHasProtoAtDepth(const js::Class* clasp,
+                             uint32_t protoID, uint32_t depth);
+
+// Only set allowNativeWrapper to false if you really know you need it, if in
+// doubt use true. Setting it to false disables security wrappers.
+bool
+XPCOMObjectToJsval(JSContext* cx, JS::Handle<JSObject*> scope,
+                   xpcObjectHelper& helper, const nsIID* iid,
+                   bool allowNativeWrapper, JS::MutableHandle<JS::Value> rval);
+
+// Special-cased wrapping for variants
+bool
+VariantToJsval(JSContext* aCx, nsIVariant* aVariant,
+               JS::MutableHandle<JS::Value> aRetval);
+
+// Wrap an object "p" which is not using WebIDL bindings yet.  This _will_
+// actually work on WebIDL binding objects that are wrappercached, but will be
+// much slower than GetOrCreateDOMReflector.  "cache" must either be null or be
+// the nsWrapperCache for "p".
+template<class T>
+inline bool
+WrapObject(JSContext* cx, T* p, nsWrapperCache* cache, const nsIID* iid,
+           JS::MutableHandle<JS::Value> rval)
+{
+  if (xpc_FastGetCachedWrapper(cx, cache, rval))
+    return true;
+  qsObjectHelper helper(p, cache);
+  JS::Rooted<JSObject*> scope(cx, JS::CurrentGlobalOrNull(cx));
+  return XPCOMObjectToJsval(cx, scope, helper, iid, true, rval);
+}
+
+// A specialization of the above for nsIVariant, because that needs to
+// do something different.
+template<>
+inline bool
+WrapObject<nsIVariant>(JSContext* cx, nsIVariant* p,
+                       nsWrapperCache* cache, const nsIID* iid,
+                       JS::MutableHandle<JS::Value> rval)
+{
+  MOZ_ASSERT(iid);
+  MOZ_ASSERT(iid->Equals(NS_GET_IID(nsIVariant)));
+  return VariantToJsval(cx, p, rval);
+}
+
+// Wrap an object "p" which is not using WebIDL bindings yet.  Just like the
+// variant that takes an nsWrapperCache above, but will try to auto-derive the
+// nsWrapperCache* from "p".
+template<class T>
+inline bool
+WrapObject(JSContext* cx, T* p, const nsIID* iid,
+           JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p, GetWrapperCache(p), iid, rval);
+}
+
+// Just like the WrapObject above, but without requiring you to pick which
+// interface you're wrapping as.  This should only be used for objects that have
+// classinfo, for which it doesn't matter what IID is used to wrap.
+template<class T>
+inline bool
+WrapObject(JSContext* cx, T* p, JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p, nullptr, rval);
+}
+
+// Helper to make it possible to wrap directly out of an nsCOMPtr
+template<class T>
+inline bool
+WrapObject(JSContext* cx, const nsCOMPtr<T>& p,
+           const nsIID* iid, JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p.get(), iid, rval);
+}
+
+// Helper to make it possible to wrap directly out of an nsCOMPtr
+template<class T>
+inline bool
+WrapObject(JSContext* cx, const nsCOMPtr<T>& p,
+           JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p, nullptr, rval);
+}
+
+// Helper to make it possible to wrap directly out of an nsRefPtr
+template<class T>
+inline bool
+WrapObject(JSContext* cx, const RefPtr<T>& p,
+           const nsIID* iid, JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p.get(), iid, rval);
+}
+
+// Helper to make it possible to wrap directly out of an nsRefPtr
+template<class T>
+inline bool
+WrapObject(JSContext* cx, const RefPtr<T>& p,
+           JS::MutableHandle<JS::Value> rval)
+{
+  return WrapObject(cx, p, nullptr, rval);
+}
+
+// Specialization to make it easy to use WrapObject in codegen.
+template<>
+inline bool
+WrapObject<JSObject>(JSContext* cx, JSObject* p,
+                     JS::MutableHandle<JS::Value> rval)
+{
+  rval.set(JS::ObjectOrNullValue(p));
+  return true;
+}
+
+inline bool
+WrapObject(JSContext* cx, JSObject& p, JS::MutableHandle<JS::Value> rval)
+{
+  rval.set(JS::ObjectValue(p));
+  return true;
+}
+
+// Given an object "p" that inherits from nsISupports, wrap it and return the
+// result.  Null is returned on wrapping failure.  This is somewhat similar to
+// WrapObject() above, but does NOT allow Xrays around the result, since we
+// don't want those for our parent object.
+template<typename T>
+static inline JSObject*
+WrapNativeISupports(JSContext* cx, T* p, nsWrapperCache* cache)
+{
+  qsObjectHelper helper(ToSupports(p), cache);
+  JS::Rooted<JSObject*> scope(cx, JS::CurrentGlobalOrNull(cx));
+  JS::Rooted<JS::Value> v(cx);
+  return XPCOMObjectToJsval(cx, scope, helper, nullptr, false, &v) ?
+         v.toObjectOrNull() :
+         nullptr;
+}
+
+
+// Fallback for when our parent is not a WebIDL binding object.
+template<typename T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct WrapNativeFallback
+{
+  static inline JSObject* Wrap(JSContext* cx, T* parent, nsWrapperCache* cache)
+  {
+    return nullptr;
+  }
+};
+
+// Fallback for when our parent is not a WebIDL binding object but _is_ an
+// nsISupports object.
+template<typename T >
+struct WrapNativeFallback<T, true >
+{
+  static inline JSObject* Wrap(JSContext* cx, T* parent, nsWrapperCache* cache)
+  {
+    return WrapNativeISupports(cx, parent, cache);
+  }
+};
+
+// Wrapping of our native parent, for cases when it's a WebIDL object (though
+// possibly preffed off).
+template<typename T, bool hasWrapObject=NativeHasMember<T>::WrapObject>
+struct WrapNativeHelper
+{
+  static inline JSObject* Wrap(JSContext* cx, T* parent, nsWrapperCache* cache)
+  {
+    MOZ_ASSERT(cache);
+
+    JSObject* obj;
+    if ((obj = cache->GetWrapper())) {
+      // GetWrapper always unmarks gray.
+      MOZ_ASSERT(!JS::ObjectIsMarkedGray(obj));
+      return obj;
+    }
+
+    // Inline this here while we have non-dom objects in wrapper caches.
+    if (!CouldBeDOMBinding(parent)) {
+      // WrapNativeFallback never returns a gray thing.
+      obj = WrapNativeFallback<T>::Wrap(cx, parent, cache);
+      MOZ_ASSERT_IF(obj, !JS::ObjectIsMarkedGray(obj));
+    } else {
+      // WrapObject never returns a gray thing.
+      obj = parent->WrapObject(cx, nullptr);
+      MOZ_ASSERT_IF(obj, !JS::ObjectIsMarkedGray(obj));
+    }
+
+    return obj;
+  }
+};
+
+// Wrapping of our native parent, for cases when it's not a WebIDL object.  In
+// this case it must be nsISupports.
+template<typename T>
+struct WrapNativeHelper<T, false>
+{
+  static inline JSObject* Wrap(JSContext* cx, T* parent, nsWrapperCache* cache)
+  {
+    JSObject* obj;
+    if (cache && (obj = cache->GetWrapper())) {
+#ifdef DEBUG
+      JS::Rooted<JSObject*> rootedObj(cx, obj);
+      NS_ASSERTION(WrapNativeISupports(cx, parent, cache) == rootedObj,
+                   "Unexpected object in nsWrapperCache");
+      obj = rootedObj;
+#endif
+      MOZ_ASSERT(!JS::ObjectIsMarkedGray(obj));
+      return obj;
+    }
+
+    obj = WrapNativeISupports(cx, parent, cache);
+    MOZ_ASSERT_IF(obj, !JS::ObjectIsMarkedGray(obj));
+    return obj;
+  }
+};
+
+// Finding the associated global for an object.
+template<typename T>
+static inline JSObject*
+FindAssociatedGlobal(JSContext* cx, T* p, nsWrapperCache* cache,
+                     bool useXBLScope = false)
+{
+  if (!p) {
+    return JS::CurrentGlobalOrNull(cx);
+  }
+
+  JSObject* obj = WrapNativeHelper<T>::Wrap(cx, p, cache);
+  if (!obj) {
+    return nullptr;
+  }
+  MOZ_ASSERT(!JS::ObjectIsMarkedGray(obj));
+
+  obj = js::GetGlobalForObjectCrossCompartment(obj);
+
+  if (!useXBLScope) {
+    return obj;
+  }
+
+  // If useXBLScope is true, it means that the canonical reflector for this
+  // native object should live in the content XBL scope. Note that we never put
+  // anonymous content inside an add-on scope.
+  if (xpc::IsInContentXBLScope(obj)) {
+    return obj;
+  }
+  JS::Rooted<JSObject*> rootedObj(cx, obj);
+  JSObject* xblScope = xpc::GetXBLScope(cx, rootedObj);
+  MOZ_ASSERT_IF(xblScope, JS_IsGlobalObject(xblScope));
+  MOZ_ASSERT_IF(xblScope, !JS::ObjectIsMarkedGray(xblScope));
+  return xblScope;
+}
+
+// Finding of the associated global for an object, when we don't want to
+// explicitly pass in things like the nsWrapperCache for it.
+template<typename T>
+static inline JSObject*
+FindAssociatedGlobal(JSContext* cx, const T& p)
+{
+  return FindAssociatedGlobal(cx, GetParentPointer(p), GetWrapperCache(p), GetUseXBLScope(p));
+}
+
+// Specialization for the case of nsIGlobalObject, since in that case
+// we can just get the JSObject* directly.
+template<>
+inline JSObject*
+FindAssociatedGlobal(JSContext* cx, nsIGlobalObject* const& p)
+{
+  if (!p) {
+    return JS::CurrentGlobalOrNull(cx);
+  }
+
+  JSObject* global = p->GetGlobalJSObject();
+  if (!global) {
+    return nullptr;
+  }
+
+  MOZ_ASSERT(JS_IsGlobalObject(global));
+  // This object could be gray if the nsIGlobalObject is the only thing keeping
+  // it alive.
+  JS::ExposeObjectToActiveJS(global);
+  return global;
+}
+
+template<typename T,
+         bool hasAssociatedGlobal=NativeHasMember<T>::GetParentObject>
+struct FindAssociatedGlobalForNative
+{
+  static JSObject* Get(JSContext* cx, JS::Handle<JSObject*> obj)
+  {
+    MOZ_ASSERT(js::IsObjectInContextCompartment(obj, cx));
+    T* native = UnwrapDOMObject<T>(obj);
+    return FindAssociatedGlobal(cx, native->GetParentObject());
+  }
+};
+
+template<typename T>
+struct FindAssociatedGlobalForNative<T, false>
+{
+  static JSObject* Get(JSContext* cx, JS::Handle<JSObject*> obj)
+  {
+    MOZ_CRASH();
+    return nullptr;
+  }
+};
+
+// Helper for calling GetOrCreateDOMReflector with smart pointers
+// (nsAutoPtr/nsRefPtr/nsCOMPtr) or references.
+template <class T, bool isSmartPtr=IsSmartPtr<T>::value>
+struct GetOrCreateDOMReflectorHelper
+{
+  static inline bool GetOrCreate(JSContext* cx, const T& value,
+                                 JS::Handle<JSObject*> givenProto,
+                                 JS::MutableHandle<JS::Value> rval)
+  {
+    return GetOrCreateDOMReflector(cx, value.get(), rval, givenProto);
+  }
+};
+
+template <class T>
+struct GetOrCreateDOMReflectorHelper<T, false>
+{
+  static inline bool GetOrCreate(JSContext* cx, T& value,
+                                 JS::Handle<JSObject*> givenProto,
+                                 JS::MutableHandle<JS::Value> rval)
+  {
+    static_assert(IsRefcounted<T>::value, "Don't pass owned classes in here.");
+    return GetOrCreateDOMReflector(cx, &value, rval, givenProto);
+  }
+};
+
+template<class T>
+inline bool
+GetOrCreateDOMReflector(JSContext* cx, T& value,
+                        JS::MutableHandle<JS::Value> rval,
+                        JS::Handle<JSObject*> givenProto = nullptr)
+{
+  return GetOrCreateDOMReflectorHelper<T>::GetOrCreate(cx, value, givenProto,
+                                                       rval);
+}
+
+// Helper for calling GetOrCreateDOMReflectorNoWrap with smart pointers
+// (nsAutoPtr/nsRefPtr/nsCOMPtr) or references.
+template <class T, bool isSmartPtr=IsSmartPtr<T>::value>
+struct GetOrCreateDOMReflectorNoWrapHelper
+{
+  static inline bool GetOrCreate(JSContext* cx, const T& value,
+                                 JS::MutableHandle<JS::Value> rval)
+  {
+    return GetOrCreateDOMReflectorNoWrap(cx, value.get(), rval);
+  }
+};
+
+template <class T>
+struct GetOrCreateDOMReflectorNoWrapHelper<T, false>
+{
+  static inline bool GetOrCreate(JSContext* cx, T& value,
+                                 JS::MutableHandle<JS::Value> rval)
+  {
+    return GetOrCreateDOMReflectorNoWrap(cx, &value, rval);
+  }
+};
+
+template<class T>
+inline bool
+GetOrCreateDOMReflectorNoWrap(JSContext* cx, T& value,
+                              JS::MutableHandle<JS::Value> rval)
+{
+  return
+    GetOrCreateDOMReflectorNoWrapHelper<T>::GetOrCreate(cx, value, rval);
+}
+
+template <class T>
+inline JSObject*
+GetCallbackFromCallbackObject(T* aObj)
+{
+  return aObj->Callback();
+}
+
+// Helper for getting the callback JSObject* of a smart ptr around a
+// CallbackObject or a reference to a CallbackObject or something like
+// that.
+template <class T, bool isSmartPtr=IsSmartPtr<T>::value>
+struct GetCallbackFromCallbackObjectHelper
+{
+  static inline JSObject* Get(const T& aObj)
+  {
+    return GetCallbackFromCallbackObject(aObj.get());
+  }
+};
+
+template <class T>
+struct GetCallbackFromCallbackObjectHelper<T, false>
+{
+  static inline JSObject* Get(T& aObj)
+  {
+    return GetCallbackFromCallbackObject(&aObj);
+  }
+};
+
+template<class T>
+inline JSObject*
+GetCallbackFromCallbackObject(T& aObj)
+{
+  return GetCallbackFromCallbackObjectHelper<T>::Get(aObj);
+}
+
+static inline bool
+AtomizeAndPinJSString(JSContext* cx, jsid& id, const char* chars)
+{
+  if (JSString *str = ::JS_AtomizeAndPinString(cx, chars)) {
+    id = INTERNED_STRING_TO_JSID(cx, str);
+    return true;
+  }
+  return false;
+}
+
+// Spec needs a name property
+template <typename Spec>
+static bool
+InitIds(JSContext* cx, const Prefable<Spec>* prefableSpecs, jsid* ids)
+{
+  MOZ_ASSERT(prefableSpecs);
+  MOZ_ASSERT(prefableSpecs->specs);
+  do {
+    // We ignore whether the set of ids is enabled and just intern all the IDs,
+    // because this is only done once per application runtime.
+    Spec* spec = prefableSpecs->specs;
+    do {
+      if (!JS::PropertySpecNameToPermanentId(cx, spec->name, ids)) {
+        return false;
+      }
+    } while (++ids, (++spec)->name);
+
+    // We ran out of ids for that pref.  Put a JSID_VOID in on the id
+    // corresponding to the list terminator for the pref.
+    *ids = JSID_VOID;
+    ++ids;
+  } while ((++prefableSpecs)->specs);
+
+  return true;
+}
+
+bool
+QueryInterface(JSContext* cx, unsigned argc, JS::Value* vp);
+
+template <class T>
+struct
+WantsQueryInterface
+{
+  static_assert(IsBaseOf<nsISupports, T>::value,
+                "QueryInterface can't work without an nsISupports.");
+  static bool Enabled(JSContext* aCx, JSObject* aGlobal)
+  {
+    return NS_IsMainThread() && IsChromeOrXBL(aCx, aGlobal);
+  }
+};
+
+void
+GetInterfaceImpl(JSContext* aCx, nsIInterfaceRequestor* aRequestor,
+                 nsWrapperCache* aCache, nsIJSID* aIID,
+                 JS::MutableHandle<JS::Value> aRetval, ErrorResult& aError);
+
+template<class T>
+void
+GetInterface(JSContext* aCx, T* aThis, nsIJSID* aIID,
+             JS::MutableHandle<JS::Value> aRetval, ErrorResult& aError)
+{
+  GetInterfaceImpl(aCx, aThis, aThis, aIID, aRetval, aError);
+}
+
+bool
+UnforgeableValueOf(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+ThrowingConstructor(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+ThrowConstructorWithoutNew(JSContext* cx, const char* name);
+
+bool
+GetPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       JS::Handle<JS::Value> receiver, JS::Handle<jsid> id,
+                       bool* found, JS::MutableHandle<JS::Value> vp);
+
+//
+bool
+HasPropertyOnPrototype(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       JS::Handle<jsid> id, bool* has);
+
+
+// Append the property names in "names" to "props". If
+// shadowPrototypeProperties is false then skip properties that are also
+// present on the proto chain of proxy.  If shadowPrototypeProperties is true,
+// then the "proxy" argument is ignored.
+bool
+AppendNamedPropertyIds(JSContext* cx, JS::Handle<JSObject*> proxy,
+                       nsTArray<nsString>& names,
+                       bool shadowPrototypeProperties, JS::AutoIdVector& props);
+
+namespace binding_detail {
+
+class FastErrorResult :
+    public mozilla::binding_danger::TErrorResult<
+      mozilla::binding_danger::JustAssertCleanupPolicy>
+{
+};
+
+} // namespace binding_detail
+
+enum StringificationBehavior {
+  eStringify,
+  eEmpty,
+  eNull
+};
+
+template<typename T>
+static inline bool
+ConvertJSValueToString(JSContext* cx, JS::Handle<JS::Value> v,
+                       StringificationBehavior nullBehavior,
+                       StringificationBehavior undefinedBehavior,
+                       T& result)
+{
+  JSString *s;
+  if (v.isString()) {
+    s = v.toString();
+  } else {
+    StringificationBehavior behavior;
+    if (v.isNull()) {
+      behavior = nullBehavior;
+    } else if (v.isUndefined()) {
+      behavior = undefinedBehavior;
+    } else {
+      behavior = eStringify;
+    }
+
+    if (behavior != eStringify) {
+      if (behavior == eEmpty) {
+        result.Truncate();
+      } else {
+        result.SetIsVoid(true);
+      }
+      return true;
+    }
+
+    s = JS::ToString(cx, v);
+    if (!s) {
+      return false;
+    }
+  }
+
+  return AssignJSString(cx, result, s);
+}
+
+void
+NormalizeUSVString(JSContext* aCx, nsAString& aString);
+
+void
+NormalizeUSVString(JSContext* aCx, binding_detail::FakeString& aString);
+
+template<typename T>
+inline bool
+ConvertIdToString(JSContext* cx, JS::HandleId id, T& result, bool& isSymbol)
+{
+  if (MOZ_LIKELY(JSID_IS_STRING(id))) {
+    if (!AssignJSString(cx, result, JSID_TO_STRING(id))) {
+      return false;
+    }
+  } else if (JSID_IS_SYMBOL(id)) {
+    isSymbol = true;
+    return true;
+  } else {
+    JS::RootedValue nameVal(cx, js::IdToValue(id));
+    if (!ConvertJSValueToString(cx, nameVal, eStringify, eStringify, result)) {
+      return false;
+    }
+  }
+  isSymbol = false;
+  return true;
+}
+
+bool
+ConvertJSValueToByteString(JSContext* cx, JS::Handle<JS::Value> v,
+                           bool nullable, nsACString& result);
+
+template<typename T>
+void DoTraceSequence(JSTracer* trc, FallibleTArray<T>& seq);
+template<typename T>
+void DoTraceSequence(JSTracer* trc, InfallibleTArray<T>& seq);
+
+// Class used to trace sequences, with specializations for various
+// sequence types.
+template<typename T,
+         bool isDictionary=IsBaseOf<DictionaryBase, T>::value,
+         bool isTypedArray=IsBaseOf<AllTypedArraysBase, T>::value,
+         bool isOwningUnion=IsBaseOf<AllOwningUnionBase, T>::value>
+class SequenceTracer
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+};
+
+// sequence<object> or sequence<object?>
+template<>
+class SequenceTracer<JSObject*, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, JSObject** objp, JSObject** end) {
+    for (; objp != end; ++objp) {
+      JS::UnsafeTraceRoot(trc, objp, "sequence<object>");
+    }
+  }
+};
+
+// sequence<any>
+template<>
+class SequenceTracer<JS::Value, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, JS::Value* valp, JS::Value* end) {
+    for (; valp != end; ++valp) {
+      JS::UnsafeTraceRoot(trc, valp, "sequence<any>");
+    }
+  }
+};
+
+// sequence<sequence<T>>
+template<typename T>
+class SequenceTracer<Sequence<T>, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, Sequence<T>* seqp, Sequence<T>* end) {
+    for (; seqp != end; ++seqp) {
+      DoTraceSequence(trc, *seqp);
+    }
+  }
+};
+
+// sequence<sequence<T>> as return value
+template<typename T>
+class SequenceTracer<nsTArray<T>, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, nsTArray<T>* seqp, nsTArray<T>* end) {
+    for (; seqp != end; ++seqp) {
+      DoTraceSequence(trc, *seqp);
+    }
+  }
+};
+
+// sequence<someDictionary>
+template<typename T>
+class SequenceTracer<T, true, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, T* dictp, T* end) {
+    for (; dictp != end; ++dictp) {
+      dictp->TraceDictionary(trc);
+    }
+  }
+};
+
+// sequence<SomeTypedArray>
+template<typename T>
+class SequenceTracer<T, false, true, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, T* arrayp, T* end) {
+    for (; arrayp != end; ++arrayp) {
+      arrayp->TraceSelf(trc);
+    }
+  }
+};
+
+// sequence<SomeOwningUnion>
+template<typename T>
+class SequenceTracer<T, false, false, true>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, T* arrayp, T* end) {
+    for (; arrayp != end; ++arrayp) {
+      arrayp->TraceUnion(trc);
+    }
+  }
+};
+
+// sequence<T?> with T? being a Nullable<T>
+template<typename T>
+class SequenceTracer<Nullable<T>, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, Nullable<T>* seqp,
+                            Nullable<T>* end) {
+    for (; seqp != end; ++seqp) {
+      if (!seqp->IsNull()) {
+        // Pretend like we actually have a length-one sequence here so
+        // we can do template instantiation correctly for T.
+        T& val = seqp->Value();
+        T* ptr = &val;
+        SequenceTracer<T>::TraceSequence(trc, ptr, ptr+1);
+      }
+    }
+  }
+};
+
+template<typename T>
+static void
+TraceMozMapValue(T* aValue, void* aClosure)
+{
+  JSTracer* trc = static_cast<JSTracer*>(aClosure);
+  // Act like it's a one-element sequence to leverage all that infrastructure.
+  SequenceTracer<T>::TraceSequence(trc, aValue, aValue + 1);
+}
+
+template<typename T>
+void TraceMozMap(JSTracer* trc, MozMap<T>& map)
+{
+  map.EnumerateValues(TraceMozMapValue<T>, trc);
+}
+
+// sequence<MozMap>
+template<typename T>
+class SequenceTracer<MozMap<T>, false, false, false>
+{
+  explicit SequenceTracer() = delete; // Should never be instantiated
+
+public:
+  static void TraceSequence(JSTracer* trc, MozMap<T>* seqp, MozMap<T>* end) {
+    for (; seqp != end; ++seqp) {
+      seqp->EnumerateValues(TraceMozMapValue<T>, trc);
+    }
+  }
+};
+
+template<typename T>
+void DoTraceSequence(JSTracer* trc, FallibleTArray<T>& seq)
+{
+  SequenceTracer<T>::TraceSequence(trc, seq.Elements(),
+                                   seq.Elements() + seq.Length());
+}
+
+template<typename T>
+void DoTraceSequence(JSTracer* trc, InfallibleTArray<T>& seq)
+{
+  SequenceTracer<T>::TraceSequence(trc, seq.Elements(),
+                                   seq.Elements() + seq.Length());
+}
+
+// Rooter class for sequences; this is what we mostly use in the codegen
+template<typename T>
+class MOZ_RAII SequenceRooter final : private JS::CustomAutoRooter
+{
+public:
+  SequenceRooter(JSContext *aCx, FallibleTArray<T>* aSequence
+                 MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : JS::CustomAutoRooter(aCx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+      mFallibleArray(aSequence),
+      mSequenceType(eFallibleArray)
+  {
+  }
+
+  SequenceRooter(JSContext *aCx, InfallibleTArray<T>* aSequence
+                 MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : JS::CustomAutoRooter(aCx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+      mInfallibleArray(aSequence),
+      mSequenceType(eInfallibleArray)
+  {
+  }
+
+  SequenceRooter(JSContext *aCx, Nullable<nsTArray<T> >* aSequence
+                 MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : JS::CustomAutoRooter(aCx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+      mNullableArray(aSequence),
+      mSequenceType(eNullableArray)
+  {
+  }
+
+ private:
+  enum SequenceType {
+    eInfallibleArray,
+    eFallibleArray,
+    eNullableArray
+  };
+
+  virtual void trace(JSTracer *trc) override
+  {
+    if (mSequenceType == eFallibleArray) {
+      DoTraceSequence(trc, *mFallibleArray);
+    } else if (mSequenceType == eInfallibleArray) {
+      DoTraceSequence(trc, *mInfallibleArray);
+    } else {
+      MOZ_ASSERT(mSequenceType == eNullableArray);
+      if (!mNullableArray->IsNull()) {
+        DoTraceSequence(trc, mNullableArray->Value());
+      }
+    }
+  }
+
+  union {
+    InfallibleTArray<T>* mInfallibleArray;
+    FallibleTArray<T>* mFallibleArray;
+    Nullable<nsTArray<T> >* mNullableArray;
+  };
+
+  SequenceType mSequenceType;
+};
+
+// Rooter class for MozMap; this is what we mostly use in the codegen.
+template<typename T>
+class MOZ_RAII MozMapRooter final : private JS::CustomAutoRooter
+{
+public:
+  MozMapRooter(JSContext *aCx, MozMap<T>* aMozMap
+               MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : JS::CustomAutoRooter(aCx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+      mMozMap(aMozMap),
+      mMozMapType(eMozMap)
+  {
+  }
+
+  MozMapRooter(JSContext *aCx, Nullable<MozMap<T>>* aMozMap
+                 MOZ_GUARD_OBJECT_NOTIFIER_PARAM)
+    : JS::CustomAutoRooter(aCx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+      mNullableMozMap(aMozMap),
+      mMozMapType(eNullableMozMap)
+  {
+  }
+
+private:
+  enum MozMapType {
+    eMozMap,
+    eNullableMozMap
+  };
+
+  virtual void trace(JSTracer *trc) override
+  {
+    if (mMozMapType == eMozMap) {
+      TraceMozMap(trc, *mMozMap);
+    } else {
+      MOZ_ASSERT(mMozMapType == eNullableMozMap);
+      if (!mNullableMozMap->IsNull()) {
+        TraceMozMap(trc, mNullableMozMap->Value());
+      }
+    }
+  }
+
+  union {
+    MozMap<T>* mMozMap;
+    Nullable<MozMap<T>>* mNullableMozMap;
+  };
+
+  MozMapType mMozMapType;
+};
+
+template<typename T>
+class MOZ_RAII RootedUnion : public T,
+                             private JS::CustomAutoRooter
+{
+public:
+  explicit RootedUnion(JSContext* cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    T(),
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+
+  virtual void trace(JSTracer *trc) override
+  {
+    this->TraceUnion(trc);
+  }
+};
+
+template<typename T>
+class MOZ_STACK_CLASS NullableRootedUnion : public Nullable<T>,
+                                            private JS::CustomAutoRooter
+{
+public:
+  explicit NullableRootedUnion(JSContext* cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    Nullable<T>(),
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+
+  virtual void trace(JSTracer *trc) override
+  {
+    if (!this->IsNull()) {
+      this->Value().TraceUnion(trc);
+    }
+  }
+};
+
+inline bool
+IdEquals(jsid id, const char* string)
+{
+  return JSID_IS_STRING(id) &&
+         JS_FlatStringEqualsAscii(JSID_TO_FLAT_STRING(id), string);
+}
+
+inline bool
+AddStringToIDVector(JSContext* cx, JS::AutoIdVector& vector, const char* name)
+{
+  return vector.growBy(1) &&
+         AtomizeAndPinJSString(cx, *(vector[vector.length() - 1]).address(), name);
+}
+
+// We use one constructor JSNative to represent all DOM interface objects (so
+// we can easily detect when we need to wrap them in an Xray wrapper). We store
+// the real JSNative in the mNative member of a JSNativeHolder in the
+// CONSTRUCTOR_NATIVE_HOLDER_RESERVED_SLOT slot of the JSFunction object for a
+// specific interface object. We also store the NativeProperties in the
+// JSNativeHolder.
+// Note that some interface objects are not yet a JSFunction but a normal
+// JSObject with a DOMJSClass, those do not use these slots.
+
+enum {
+  CONSTRUCTOR_NATIVE_HOLDER_RESERVED_SLOT = 0
+};
+
+bool
+Constructor(JSContext* cx, unsigned argc, JS::Value* vp);
+
+// Implementation of the bits that XrayWrapper needs
+
+/**
+ * This resolves operations, attributes and constants of the interfaces for obj.
+ *
+ * wrapper is the Xray JS object.
+ * obj is the target object of the Xray, a binding's instance object or a
+ *     interface or interface prototype object.
+ */
+bool
+XrayResolveOwnProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                       JS::Handle<JSObject*> obj,
+                       JS::Handle<jsid> id,
+                       JS::MutableHandle<JS::PropertyDescriptor> desc,
+                       bool& cacheOnHolder);
+
+/**
+ * Define a property on obj through an Xray wrapper.
+ *
+ * wrapper is the Xray JS object.
+ * obj is the target object of the Xray, a binding's instance object or a
+ *     interface or interface prototype object.
+ * id and desc are the parameters for the property to be defined.
+ * result is the out-parameter indicating success (read it only if
+ *     this returns true and also sets *defined to true).
+ * defined will be set to true if a property was set as a result of this call.
+ */
+bool
+XrayDefineProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                   JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                   JS::Handle<JS::PropertyDescriptor> desc,
+                   JS::ObjectOpResult &result,
+                   bool *defined);
+
+/**
+ * Add to props the property keys of all indexed or named properties of obj and
+ * operations, attributes and constants of the interfaces for obj.
+ *
+ * wrapper is the Xray JS object.
+ * obj is the target object of the Xray, a binding's instance object or a
+ *     interface or interface prototype object.
+ * flags are JSITER_* flags.
+ */
+bool
+XrayOwnPropertyKeys(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                    JS::Handle<JSObject*> obj,
+                    unsigned flags, JS::AutoIdVector& props);
+
+/**
+ * Returns the prototype to use for an Xray for a DOM object, wrapped in cx's
+ * compartment. This always returns the prototype that would be used for a DOM
+ * object if we ignore any changes that might have been done to the prototype
+ * chain by JS, the XBL code or plugins.
+ *
+ * cx should be in the Xray's compartment.
+ * obj is the target object of the Xray, a binding's instance object or an
+ *     interface or interface prototype object.
+ */
+inline bool
+XrayGetNativeProto(JSContext* cx, JS::Handle<JSObject*> obj,
+                   JS::MutableHandle<JSObject*> protop)
+{
+  JS::Rooted<JSObject*> global(cx, js::GetGlobalForObjectCrossCompartment(obj));
+  {
+    JSAutoCompartment ac(cx, global);
+    const DOMJSClass* domClass = GetDOMClass(obj);
+    if (domClass) {
+      ProtoHandleGetter protoGetter = domClass->mGetProto;
+      if (protoGetter) {
+        protop.set(protoGetter(cx));
+      } else {
+        protop.set(JS::GetRealmObjectPrototype(cx));
+      }
+    } else if (JS_ObjectIsFunction(cx, obj)) {
+      MOZ_ASSERT(JS_IsNativeFunction(obj, Constructor));
+      protop.set(JS::GetRealmFunctionPrototype(cx));
+    } else {
+      const js::Class* clasp = js::GetObjectClass(obj);
+      MOZ_ASSERT(IsDOMIfaceAndProtoClass(clasp));
+      ProtoGetter protoGetter =
+        DOMIfaceAndProtoJSClass::FromJSClass(clasp)->mGetParentProto;
+      protop.set(protoGetter(cx));
+    }
+  }
+
+  return JS_WrapObject(cx, protop);
+}
+
+/**
+ * Get the Xray expando class to use for the given DOM object.
+ */
+const JSClass*
+XrayGetExpandoClass(JSContext* cx, JS::Handle<JSObject*> obj);
+
+/**
+ * Delete a named property, if any.  Return value is false if exception thrown,
+ * true otherwise.  The caller should not do any more work after calling this
+ * function, because it has no way whether a deletion was performed and hence
+ * opresult already has state set on it.  If callers ever need to change that,
+ * add a "bool* found" argument and change the generated DeleteNamedProperty to
+ * use it instead of a local variable.
+ */
+bool
+XrayDeleteNamedProperty(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                        JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                        JS::ObjectOpResult& opresult);
+
+/**
+ * Get the object which should be used to cache the return value of a property
+ * getter in the case of a [Cached] or [StoreInSlot] property.  `obj` is the
+ * `this` value for our property getter that we're working with.
+ *
+ * This function can return null on failure to allocate the object, throwing on
+ * the JSContext in the process.
+ *
+ * The isXray outparam will be set to true if obj is an Xray and false
+ * otherwise.
+ *
+ * Note that the Slow version should only be called from
+ * GetCachedSlotStorageObject.
+ */
+JSObject*
+GetCachedSlotStorageObjectSlow(JSContext* cx, JS::Handle<JSObject*> obj,
+                               bool* isXray);
+
+inline JSObject*
+GetCachedSlotStorageObject(JSContext* cx, JS::Handle<JSObject*> obj,
+                           bool* isXray) {
+  if (IsDOMObject(obj)) {
+    *isXray = false;
+    return obj;
+  }
+
+  return GetCachedSlotStorageObjectSlow(cx, obj, isXray);
+}
+
+extern NativePropertyHooks sEmptyNativePropertyHooks;
+
+extern const js::ClassOps sBoringInterfaceObjectClassClassOps;
+
+extern const js::ObjectOps sInterfaceObjectClassObjectOps;
+
+inline bool
+UseDOMXray(JSObject* obj)
+{
+  const js::Class* clasp = js::GetObjectClass(obj);
+  return IsDOMClass(clasp) ||
+         JS_IsNativeFunction(obj, Constructor) ||
+         IsDOMIfaceAndProtoClass(clasp);
+}
+
+#ifdef DEBUG
+inline bool
+HasConstructor(JSObject* obj)
+{
+  return JS_IsNativeFunction(obj, Constructor) ||
+         js::GetObjectClass(obj)->getConstruct();
+}
+#endif
+
+// Helpers for creating a const version of a type.
+template<typename T>
+const T& Constify(T& arg)
+{
+  return arg;
+}
+
+// Helper for turning (Owning)NonNull<T> into T&
+template<typename T>
+T& NonNullHelper(T& aArg)
+{
+  return aArg;
+}
+
+template<typename T>
+T& NonNullHelper(NonNull<T>& aArg)
+{
+  return aArg;
+}
+
+template<typename T>
+const T& NonNullHelper(const NonNull<T>& aArg)
+{
+  return aArg;
+}
+
+template<typename T>
+T& NonNullHelper(OwningNonNull<T>& aArg)
+{
+  return aArg;
+}
+
+template<typename T>
+const T& NonNullHelper(const OwningNonNull<T>& aArg)
+{
+  return aArg;
+}
+
+inline
+void NonNullHelper(NonNull<binding_detail::FakeString>& aArg)
+{
+  // This overload is here to make sure that we never end up applying
+  // NonNullHelper to a NonNull<binding_detail::FakeString>. If we
+  // try to, it should fail to compile, since presumably the caller will try to
+  // use our nonexistent return value.
+}
+
+inline
+void NonNullHelper(const NonNull<binding_detail::FakeString>& aArg)
+{
+  // This overload is here to make sure that we never end up applying
+  // NonNullHelper to a NonNull<binding_detail::FakeString>. If we
+  // try to, it should fail to compile, since presumably the caller will try to
+  // use our nonexistent return value.
+}
+
+inline
+void NonNullHelper(binding_detail::FakeString& aArg)
+{
+  // This overload is here to make sure that we never end up applying
+  // NonNullHelper to a FakeString before we've constified it.  If we
+  // try to, it should fail to compile, since presumably the caller will try to
+  // use our nonexistent return value.
+}
+
+MOZ_ALWAYS_INLINE
+const nsAString& NonNullHelper(const binding_detail::FakeString& aArg)
+{
+  return aArg;
+}
+
+// Reparent the wrapper of aObj to whatever its native now thinks its
+// parent should be.
+nsresult
+ReparentWrapper(JSContext* aCx, JS::Handle<JSObject*> aObj);
+
+/**
+ * Used to implement the Symbol.hasInstance property of an interface object.
+ */
+bool
+InterfaceHasInstance(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+InterfaceHasInstance(JSContext* cx, int prototypeID, int depth,
+                     JS::Handle<JSObject*> instance,
+                     bool* bp);
+
+// Helper for lenient getters/setters to report to console.  If this
+// returns false, we couldn't even get a global.
+bool
+ReportLenientThisUnwrappingFailure(JSContext* cx, JSObject* obj);
+
+// Given a JSObject* that represents the chrome side of a JS-implemented WebIDL
+// interface, get the nsIGlobalObject corresponding to the content side, if any.
+// A false return means an exception was thrown.
+bool
+GetContentGlobalForJSImplementedObject(JSContext* cx, JS::Handle<JSObject*> obj,
+                                       nsIGlobalObject** global);
+
+void
+ConstructJSImplementation(const char* aContractId,
+                          nsIGlobalObject* aGlobal,
+                          JS::MutableHandle<JSObject*> aObject,
+                          ErrorResult& aRv);
+
+already_AddRefed<nsIGlobalObject>
+ConstructJSImplementation(const char* aContractId,
+                          const GlobalObject& aGlobal,
+                          JS::MutableHandle<JSObject*> aObject,
+                          ErrorResult& aRv);
+
+/**
+ * Convert an nsCString to jsval, returning true on success.
+ * These functions are intended for ByteString implementations.
+ * As such, the string is not UTF-8 encoded.  Any UTF8 strings passed to these
+ * methods will be mangled.
+ */
+bool NonVoidByteStringToJsval(JSContext *cx, const nsACString &str,
+                              JS::MutableHandle<JS::Value> rval);
+inline bool ByteStringToJsval(JSContext *cx, const nsACString &str,
+                              JS::MutableHandle<JS::Value> rval)
+{
+    if (str.IsVoid()) {
+        rval.setNull();
+        return true;
+    }
+    return NonVoidByteStringToJsval(cx, str, rval);
+}
+
+template<class T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct PreserveWrapperHelper
+{
+  static void PreserveWrapper(T* aObject)
+  {
+    aObject->PreserveWrapper(aObject, NS_CYCLE_COLLECTION_PARTICIPANT(T));
+  }
+};
+
+template<class T>
+struct PreserveWrapperHelper<T, true>
+{
+  static void PreserveWrapper(T* aObject)
+  {
+    aObject->PreserveWrapper(reinterpret_cast<nsISupports*>(aObject));
+  }
+};
+
+template<class T>
+void PreserveWrapper(T* aObject)
+{
+  PreserveWrapperHelper<T>::PreserveWrapper(aObject);
+}
+
+template<class T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct CastingAssertions
+{
+  static bool ToSupportsIsCorrect(T*)
+  {
+    return true;
+  }
+  static bool ToSupportsIsOnPrimaryInheritanceChain(T*, nsWrapperCache*)
+  {
+    return true;
+  }
+};
+
+template<class T>
+struct CastingAssertions<T, true>
+{
+  static bool ToSupportsIsCorrect(T* aObject)
+  {
+    return ToSupports(aObject) ==  reinterpret_cast<nsISupports*>(aObject);
+  }
+  static bool ToSupportsIsOnPrimaryInheritanceChain(T* aObject,
+                                                    nsWrapperCache* aCache)
+  {
+    return reinterpret_cast<void*>(aObject) != aCache;
+  }
+};
+
+template<class T>
+bool
+ToSupportsIsCorrect(T* aObject)
+{
+  return CastingAssertions<T>::ToSupportsIsCorrect(aObject);
+}
+
+template<class T>
+bool
+ToSupportsIsOnPrimaryInheritanceChain(T* aObject, nsWrapperCache* aCache)
+{
+  return CastingAssertions<T>::ToSupportsIsOnPrimaryInheritanceChain(aObject,
+                                                                     aCache);
+}
+
+// The BindingJSObjectCreator class is supposed to be used by a caller that
+// wants to create and initialise a binding JSObject. After initialisation has
+// been successfully completed it should call ForgetObject().
+// The BindingJSObjectCreator object will root the JSObject until ForgetObject()
+// is called on it. If the native object for the binding is refcounted it will
+// also hold a strong reference to it, that reference is transferred to the
+// JSObject (which holds the native in a slot) when ForgetObject() is called. If
+// the BindingJSObjectCreator object is destroyed and ForgetObject() was never
+// called on it then the JSObject's slot holding the native will be set to
+// undefined, and for a refcounted native the strong reference will be released.
+template<class T>
+class MOZ_STACK_CLASS BindingJSObjectCreator
+{
+public:
+  explicit BindingJSObjectCreator(JSContext* aCx)
+    : mReflector(aCx)
+  {
+  }
+
+  ~BindingJSObjectCreator()
+  {
+    if (mReflector) {
+      js::SetReservedOrProxyPrivateSlot(mReflector, DOM_OBJECT_SLOT,
+                                        JS::UndefinedValue());
+    }
+  }
+
+  void
+  CreateProxyObject(JSContext* aCx, const js::Class* aClass,
+                    const DOMProxyHandler* aHandler,
+                    JS::Handle<JSObject*> aProto, T* aNative,
+                    JS::MutableHandle<JSObject*> aReflector)
+  {
+    js::ProxyOptions options;
+    options.setClass(aClass);
+    JS::Rooted<JS::Value> proxyPrivateVal(aCx, JS::PrivateValue(aNative));
+    aReflector.set(js::NewProxyObject(aCx, aHandler, proxyPrivateVal, aProto,
+                                      options));
+    if (aReflector) {
+      mNative = aNative;
+      mReflector = aReflector;
+    }
+  }
+
+  void
+  CreateObject(JSContext* aCx, const JSClass* aClass,
+               JS::Handle<JSObject*> aProto,
+               T* aNative, JS::MutableHandle<JSObject*> aReflector)
+  {
+    aReflector.set(JS_NewObjectWithGivenProto(aCx, aClass, aProto));
+    if (aReflector) {
+      js::SetReservedSlot(aReflector, DOM_OBJECT_SLOT, JS::PrivateValue(aNative));
+      mNative = aNative;
+      mReflector = aReflector;
+    }
+  }
+
+  void
+  InitializationSucceeded()
+  {
+    void* dummy;
+    mNative.forget(&dummy);
+    mReflector = nullptr;
+  }
+
+private:
+  struct OwnedNative
+  {
+    // Make sure the native objects inherit from NonRefcountedDOMObject so
+    // that we log their ctor and dtor.
+    static_assert(IsBaseOf<NonRefcountedDOMObject, T>::value,
+                  "Non-refcounted objects with DOM bindings should inherit "
+                  "from NonRefcountedDOMObject.");
+
+    OwnedNative&
+    operator=(T* aNative)
+    {
+      return *this;
+    }
+
+    // This signature sucks, but it's the only one that will make a nsRefPtr
+    // just forget about its pointer without warning.
+    void
+    forget(void**)
+    {
+    }
+  };
+
+  JS::Rooted<JSObject*> mReflector;
+  typename Conditional<IsRefcounted<T>::value, RefPtr<T>, OwnedNative>::Type mNative;
+};
+
+template<class T>
+struct DeferredFinalizerImpl
+{
+  typedef typename Conditional<IsSame<T, nsISupports>::value,
+                               nsCOMPtr<T>,
+                               typename Conditional<IsRefcounted<T>::value,
+                                                    RefPtr<T>,
+                                                    nsAutoPtr<T>>::Type>::Type SmartPtr;
+  typedef SegmentedVector<SmartPtr> SmartPtrArray;
+
+  static_assert(IsSame<T, nsISupports>::value || !IsBaseOf<nsISupports, T>::value,
+                "nsISupports classes should all use the nsISupports instantiation");
+
+  static inline void
+  AppendAndTake(SegmentedVector<nsCOMPtr<nsISupports>>& smartPtrArray, nsISupports* ptr)
+  {
+    smartPtrArray.InfallibleAppend(dont_AddRef(ptr));
+  }
+  template<class U>
+  static inline void
+  AppendAndTake(SegmentedVector<RefPtr<U>>& smartPtrArray, U* ptr)
+  {
+    smartPtrArray.InfallibleAppend(dont_AddRef(ptr));
+  }
+  template<class U>
+  static inline void
+  AppendAndTake(SegmentedVector<nsAutoPtr<U>>& smartPtrArray, U* ptr)
+  {
+    smartPtrArray.InfallibleAppend(ptr);
+  }
+
+  static void*
+  AppendDeferredFinalizePointer(void* aData, void* aObject)
+  {
+    SmartPtrArray* pointers = static_cast<SmartPtrArray*>(aData);
+    if (!pointers) {
+      pointers = new SmartPtrArray();
+    }
+    AppendAndTake(*pointers, static_cast<T*>(aObject));
+    return pointers;
+  }
+  static bool
+  DeferredFinalize(uint32_t aSlice, void* aData)
+  {
+    MOZ_ASSERT(aSlice > 0, "nonsensical/useless call with aSlice == 0");
+    SmartPtrArray* pointers = static_cast<SmartPtrArray*>(aData);
+    uint32_t oldLen = pointers->Length();
+    if (oldLen < aSlice) {
+      aSlice = oldLen;
+    }
+    uint32_t newLen = oldLen - aSlice;
+    pointers->PopLastN(aSlice);
+    if (newLen == 0) {
+      delete pointers;
+      return true;
+    }
+    return false;
+  }
+};
+
+template<class T,
+         bool isISupports=IsBaseOf<nsISupports, T>::value>
+struct DeferredFinalizer
+{
+  static void
+  AddForDeferredFinalization(T* aObject)
+  {
+    typedef DeferredFinalizerImpl<T> Impl;
+    DeferredFinalize(Impl::AppendDeferredFinalizePointer,
+                     Impl::DeferredFinalize, aObject);
+  }
+};
+
+template<class T>
+struct DeferredFinalizer<T, true>
+{
+  static void
+  AddForDeferredFinalization(T* aObject)
+  {
+    DeferredFinalize(reinterpret_cast<nsISupports*>(aObject));
+  }
+};
+
+template<class T>
+static void
+AddForDeferredFinalization(T* aObject)
+{
+  DeferredFinalizer<T>::AddForDeferredFinalization(aObject);
+}
+
+// This returns T's CC participant if it participates in CC or null if it
+// doesn't. This also returns null for classes that don't inherit from
+// nsISupports (QI should be used to get the participant for those).
+template<class T, bool isISupports=IsBaseOf<nsISupports, T>::value>
+class GetCCParticipant
+{
+  // Helper for GetCCParticipant for classes that participate in CC.
+  template<class U>
+  static constexpr nsCycleCollectionParticipant*
+  GetHelper(int, typename U::NS_CYCLE_COLLECTION_INNERCLASS* dummy=nullptr)
+  {
+    return T::NS_CYCLE_COLLECTION_INNERCLASS::GetParticipant();
+  }
+  // Helper for GetCCParticipant for classes that don't participate in CC.
+  template<class U>
+  static constexpr nsCycleCollectionParticipant*
+  GetHelper(double)
+  {
+    return nullptr;
+  }
+
+public:
+  static constexpr nsCycleCollectionParticipant*
+  Get()
+  {
+    // Passing int() here will try to call the GetHelper that takes an int as
+    // its firt argument. If T doesn't participate in CC then substitution for
+    // the second argument (with a default value) will fail and because of
+    // SFINAE the next best match (the variant taking a double) will be called.
+    return GetHelper<T>(int());
+  }
+};
+
+template<class T>
+class GetCCParticipant<T, true>
+{
+public:
+  static constexpr nsCycleCollectionParticipant*
+  Get()
+  {
+    return nullptr;
+  }
+};
+
+void
+FinalizeGlobal(JSFreeOp* aFop, JSObject* aObj);
+
+bool
+ResolveGlobal(JSContext* aCx, JS::Handle<JSObject*> aObj,
+              JS::Handle<jsid> aId, bool* aResolvedp);
+
+bool
+MayResolveGlobal(const JSAtomState& aNames, jsid aId, JSObject* aMaybeObj);
+
+bool
+EnumerateGlobal(JSContext* aCx, JS::Handle<JSObject*> aObj);
+
+template <class T>
+struct CreateGlobalOptions
+{
+  static constexpr ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
+    ProtoAndIfaceCache::NonWindowLike;
+  static void TraceGlobal(JSTracer* aTrc, JSObject* aObj)
+  {
+    mozilla::dom::TraceProtoAndIfaceCache(aTrc, aObj);
+  }
+  static bool PostCreateGlobal(JSContext* aCx, JS::Handle<JSObject*> aGlobal)
+  {
+    MOZ_ALWAYS_TRUE(TryPreserveWrapper(aGlobal));
+
+    return true;
+  }
+};
+
+template <>
+struct CreateGlobalOptions<nsGlobalWindow>
+{
+  static constexpr ProtoAndIfaceCache::Kind ProtoAndIfaceCacheKind =
+    ProtoAndIfaceCache::WindowLike;
+  static void TraceGlobal(JSTracer* aTrc, JSObject* aObj);
+  static bool PostCreateGlobal(JSContext* aCx, JS::Handle<JSObject*> aGlobal);
+};
+
+nsresult
+RegisterDOMNames();
+
+// The return value is true if we created and successfully performed our part of
+// the setup for the global, false otherwise.
+//
+// Typically this method's caller will want to ensure that
+// xpc::InitGlobalObjectOptions is called before, and xpc::InitGlobalObject is
+// called after, this method, to ensure that this global object and its
+// compartment are consistent with other global objects.
+template <class T, ProtoHandleGetter GetProto>
+bool
+CreateGlobal(JSContext* aCx, T* aNative, nsWrapperCache* aCache,
+             const JSClass* aClass, JS::CompartmentOptions& aOptions,
+             JSPrincipals* aPrincipal, bool aInitStandardClasses,
+             JS::MutableHandle<JSObject*> aGlobal)
+{
+  aOptions.creationOptions().setTrace(CreateGlobalOptions<T>::TraceGlobal);
+  if (xpc::SharedMemoryEnabled()) {
+    aOptions.creationOptions().setSharedMemoryAndAtomicsEnabled(true);
+  }
+
+  aGlobal.set(JS_NewGlobalObject(aCx, aClass, aPrincipal,
+                                 JS::DontFireOnNewGlobalHook, aOptions));
+  if (!aGlobal) {
+    NS_WARNING("Failed to create global");
+    return false;
+  }
+
+  JSAutoCompartment ac(aCx, aGlobal);
+
+  {
+    js::SetReservedSlot(aGlobal, DOM_OBJECT_SLOT, JS::PrivateValue(aNative));
+    NS_ADDREF(aNative);
+
+    aCache->SetWrapper(aGlobal);
+
+    dom::AllocateProtoAndIfaceCache(aGlobal,
+                                    CreateGlobalOptions<T>::ProtoAndIfaceCacheKind);
+
+    if (!CreateGlobalOptions<T>::PostCreateGlobal(aCx, aGlobal)) {
+      return false;
+    }
+  }
+
+  if (aInitStandardClasses &&
+      !JS_InitStandardClasses(aCx, aGlobal)) {
+    NS_WARNING("Failed to init standard classes");
+    return false;
+  }
+
+  JS::Handle<JSObject*> proto = GetProto(aCx);
+  if (!proto || !JS_SplicePrototype(aCx, aGlobal, proto)) {
+    NS_WARNING("Failed to set proto");
+    return false;
+  }
+
+  bool succeeded;
+  if (!JS_SetImmutablePrototype(aCx, aGlobal, &succeeded)) {
+    return false;
+  }
+  MOZ_ASSERT(succeeded,
+             "making a fresh global object's [[Prototype]] immutable can "
+             "internally fail, but it should never be unsuccessful");
+
+  return true;
+}
+
+/*
+ * Holds a jsid that is initialized to a pinned string, with automatic
+ * conversion to Handle<jsid>, as it is held live forever by pinning.
+ */
+class PinnedStringId
+{
+  jsid id;
+
+ public:
+  PinnedStringId() : id(JSID_VOID) {}
+
+  bool init(JSContext *cx, const char *string) {
+    JSString* str = JS_AtomizeAndPinString(cx, string);
+    if (!str)
+      return false;
+    id = INTERNED_STRING_TO_JSID(cx, str);
+    return true;
+  }
+
+  operator const jsid& () {
+    return id;
+  }
+
+  operator JS::Handle<jsid> () {
+    /* This is safe because we have pinned the string. */
+    return JS::Handle<jsid>::fromMarkedLocation(&id);
+  }
+};
+
+bool
+GenericBindingGetter(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+GenericBindingSetter(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+GenericBindingMethod(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+GenericPromiseReturningBindingMethod(JSContext* cx, unsigned argc, JS::Value* vp);
+
+bool
+StaticMethodPromiseWrapper(JSContext* cx, unsigned argc, JS::Value* vp);
+
+// ConvertExceptionToPromise should only be called when we have an error
+// condition (e.g. returned false from a JSAPI method).  Note that there may be
+// no exception on cx, in which case this is an uncatchable failure that will
+// simply be propagated.  Otherwise this method will attempt to convert the
+// exception to a Promise rejected with the exception that it will store in
+// rval.
+//
+// promiseScope should be the scope in which the Promise should be created.
+bool
+ConvertExceptionToPromise(JSContext* cx,
+                          JSObject* promiseScope,
+                          JS::MutableHandle<JS::Value> rval);
+
+#ifdef DEBUG
+void
+AssertReturnTypeMatchesJitinfo(const JSJitInfo* aJitinfo,
+                               JS::Handle<JS::Value> aValue);
+#endif
+
+// This function is called by the bindings layer for methods/getters/setters
+// that are not safe to be called in prerendering mode.  It checks to make sure
+// that the |this| object is not running in a global that is in prerendering
+// mode.  Otherwise, it aborts execution of timers and event handlers, and
+// returns false which gets converted to an uncatchable exception by the
+// bindings layer.
+bool
+EnforceNotInPrerendering(JSContext* aCx, JSObject* aObj);
+
+// Handles the violation of a blacklisted action in prerendering mode by
+// aborting the scripts, and preventing timers and event handlers from running
+// in the window in the future.
+void
+HandlePrerenderingViolation(nsPIDOMWindowInner* aWindow);
+
+bool
+CallerSubsumes(JSObject* aObject);
+
+MOZ_ALWAYS_INLINE bool
+CallerSubsumes(JS::Handle<JS::Value> aValue)
+{
+  if (!aValue.isObject()) {
+    return true;
+  }
+  return CallerSubsumes(&aValue.toObject());
+}
+
+template<class T>
+inline bool
+WrappedJSToDictionary(JSContext* aCx, nsISupports* aObject, T& aDictionary)
+{
+  nsCOMPtr<nsIXPConnectWrappedJS> wrappedObj = do_QueryInterface(aObject);
+  if (!wrappedObj) {
+    return false;
+  }
+
+  JS::Rooted<JSObject*> obj(aCx, wrappedObj->GetJSObject());
+  if (!obj) {
+    return false;
+  }
+
+  JSAutoCompartment ac(aCx, obj);
+  JS::Rooted<JS::Value> v(aCx, JS::ObjectValue(*obj));
+  return aDictionary.Init(aCx, v);
+}
+
+template<class T>
+inline bool
+WrappedJSToDictionary(nsISupports* aObject, T& aDictionary)
+{
+  nsCOMPtr<nsIXPConnectWrappedJS> wrappedObj = do_QueryInterface(aObject);
+  NS_ENSURE_TRUE(wrappedObj, false);
+  JS::Rooted<JSObject*> obj(RootingCx(), wrappedObj->GetJSObject());
+  NS_ENSURE_TRUE(obj, false);
+
+  nsIGlobalObject* global = xpc::NativeGlobal(obj);
+  NS_ENSURE_TRUE(global, false);
+
+  // we need this AutoEntryScript here because the spec requires us to execute
+  // getters when parsing a dictionary
+  AutoEntryScript aes(global, "WebIDL dictionary creation");
+
+  JS::Rooted<JS::Value> v(aes.cx(), JS::ObjectValue(*obj));
+  return aDictionary.Init(aes.cx(), v);
+}
+
+
+template<class T, class S>
+inline RefPtr<T>
+StrongOrRawPtr(already_AddRefed<S>&& aPtr)
+{
+  return aPtr.template downcast<T>();
+}
+
+template<class T,
+         class ReturnType=typename Conditional<IsRefcounted<T>::value, T*,
+                                               nsAutoPtr<T>>::Type>
+inline ReturnType
+StrongOrRawPtr(T* aPtr)
+{
+  return ReturnType(aPtr);
+}
+
+template<class T, template<typename> class SmartPtr, class S>
+inline void
+StrongOrRawPtr(SmartPtr<S>&& aPtr) = delete;
+
+template<class T>
+struct StrongPtrForMember
+{
+  typedef typename Conditional<IsRefcounted<T>::value,
+                               RefPtr<T>, nsAutoPtr<T>>::Type Type;
+};
+
+namespace binding_detail {
+inline
+JSObject*
+GetHackedNamespaceProtoObject(JSContext* aCx)
+{
+  return JS_NewPlainObject(aCx);
+}
+} // namespace binding_detail
+
+// Resolve an id on the given global object that wants to be included in
+// Exposed=System webidl annotations.  False return value means exception
+// thrown.
+bool SystemGlobalResolve(JSContext* cx, JS::Handle<JSObject*> obj,
+                         JS::Handle<jsid> id, bool* resolvedp);
+
+// Enumerate all ids on the given global object that wants to be included in
+// Exposed=System webidl annotations.  False return value means exception
+// thrown.
+bool SystemGlobalEnumerate(JSContext* cx, JS::Handle<JSObject*> obj);
+
+// Slot indexes for maplike/setlike forEach functions
+#define FOREACH_CALLBACK_SLOT 0
+#define FOREACH_MAPLIKEORSETLIKEOBJ_SLOT 1
+
+// Backing function for running .forEach() on maplike/setlike interfaces.
+// Unpacks callback and maplike/setlike object from reserved slots, then runs
+// callback for each key (and value, for maplikes)
+bool ForEachHandler(JSContext* aCx, unsigned aArgc, JS::Value* aVp);
+
+// Unpacks backing object (ES6 map/set) from the reserved slot of a reflector
+// for a maplike/setlike interface. If backing object does not exist, creates
+// backing object in the compartment of the reflector involved, making this safe
+// to use across compartments/via xrays. Return values of these methods will
+// always be in the context compartment.
+bool GetMaplikeBackingObject(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                             size_t aSlotIndex,
+                             JS::MutableHandle<JSObject*> aBackingObj,
+                             bool* aBackingObjCreated);
+bool GetSetlikeBackingObject(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                             size_t aSlotIndex,
+                             JS::MutableHandle<JSObject*> aBackingObj,
+                             bool* aBackingObjCreated);
+
+// Get the desired prototype object for an object construction from the given
+// CallArgs.  Null is returned if the default prototype should be used.
+bool
+GetDesiredProto(JSContext* aCx, const JS::CallArgs& aCallArgs,
+                JS::MutableHandle<JSObject*> aDesiredProto);
+
+void
+SetDocumentAndPageUseCounter(JSContext* aCx, JSObject* aObject,
+                             UseCounter aUseCounter);
+
+// Warnings
+void
+DeprecationWarning(JSContext* aCx, JSObject* aObject,
+                   nsIDocument::DeprecatedOperations aOperation);
+
+// A callback to perform funToString on an interface object
+JSString*
+InterfaceObjectToString(JSContext* aCx, JS::Handle<JSObject*> aObject,
+                        unsigned /* indent */);
+
+namespace binding_detail {
+// Get a JS global object that can be used for some temporary allocations.  The
+// idea is that this should be used for situations when you need to operate in
+// _some_ compartment but don't care which one.  A typical example is when you
+// have non-JS input, non-JS output, but have to go through some sort of JS
+// representation in the middle, so need a compartment to allocate things in.
+//
+// It's VERY important that any consumers of this function only do things that
+// are guaranteed to be side-effect-free, even in the face of a script
+// environment controlled by a hostile adversary.  This is because in the worker
+// case the global is in fact the worker global, so it and its standard objects
+// are controlled by the worker script.  This is why this function is in the
+// binding_detail namespace.  Any use of this function MUST be very carefully
+// reviewed by someone who is sufficiently devious and has a very good
+// understanding of all the code that will run while we're using the return
+// value, including the SpiderMonkey parts.
+JSObject* UnprivilegedJunkScopeOrWorkerGlobal();
+} // namespace binding_detail
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_BindingUtils_h__ */
diff --git a/dom/bindings/Bindings.conf b/dom/bindings/Bindings.conf
new file mode 100644
index 000000000..aa7f26ad6
--- /dev/null
+++ b/dom/bindings/Bindings.conf
@@ -0,0 +1,1701 @@
+# -*- Mode:Python; tab-width:8; indent-tabs-mode:nil -*- */
+# vim: set ts=8 sts=4 et sw=4 tw=80: */
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# DOM Bindings Configuration.
+#
+# The WebIDL interfaces are defined in dom/webidl. For interfaces requiring
+# special handling, there are corresponding entries in the configuration table
+# below. The configuration table maps each interface name to a |descriptor|.
+#
+# Valid fields for all descriptors:
+#   * nativeType - The native type (concrete class or XPCOM interface) that
+#                  instances of this interface will unwrap to.  If not
+#                  specified, defaults to 'nsIDOM' followed by the interface
+#                  name for external interfaces and
+#                  'mozilla::dom::InterfaceName' for everything else.
+#   * headerFile - The file in which the nativeType is declared (defaults
+#                  to an educated guess).
+#   * concrete - Indicates whether there exist JS objects with this interface as
+#                their primary interface (and hence whose prototype is this
+#                interface's prototype object).  Always False for callback
+#                interfaces.  Defaults to True otherwise.
+#   * notflattened - The native type does not have nsIClassInfo, so when
+#                    wrapping it the right IID needs to be passed in.
+#                    Only relevant for callback interfaces.
+#   * register - True if this binding should be registered.  Defaults to true.
+#   * binaryNames - Dict for mapping method and attribute names to different
+#                   names when calling the native methods (defaults to an empty
+#                   dict). The keys are the property names as they appear in the
+#                   .webidl file and the values are the names as they should be
+#                   in the WebIDL.
+#   * wrapperCache: True if this object is a wrapper cache.  Objects that are
+#                   not can only be returned from a limited set of methods,
+#                   cannot be prefable, and must ensure that they disallow
+#                   XPConnect wrapping.  Always false for callback interfaces.
+#                   Defaults to true for non-callback descriptors.
+#
+# The following fields are either a string, an array (defaults to an empty
+# array) or a dictionary with three possible keys (all, getterOnly and
+# setterOnly) each having such an array as the value
+#
+#   * implicitJSContext - attributes and methods specified in the .webidl file
+#                         that require a JSContext as the first argument
+#
+# The value for an interface is a dictionary which specifies the
+# descriptor to use when generating that interface's binding.
+
+DOMInterfaces = {
+
+'AbstractWorker': {
+    'concrete': False
+},
+
+'AddonManagerPermissions': {
+    'wrapperCache': False,
+    'concrete': False
+},
+
+'AnimationEffectReadOnly': {
+    'concrete': False
+},
+
+'AnimationTimeline': {
+    'concrete': False
+},
+
+'AnonymousContent': {
+    'wrapperCache': False
+},
+
+'ArchiveReader': {
+    'nativeType': 'mozilla::dom::archivereader::ArchiveReader',
+},
+
+'ArchiveRequest': {
+    'nativeType': 'mozilla::dom::archivereader::ArchiveRequest',
+},
+
+'AudioChannelManager': {
+    'nativeType': 'mozilla::dom::system::AudioChannelManager',
+    'headerFile': 'AudioChannelManager.h'
+},
+
+'AudioBuffer': {
+    'implicitJSContext': [ 'copyToChannel' ],
+},
+
+'AudioBufferSourceNode': {
+    'implicitJSContext': [ 'buffer' ],
+},
+
+'AudioNode' : {
+    'concrete': False,
+    'binaryNames': {
+        'channelCountMode': 'channelCountModeValue',
+        'channelInterpretation': 'channelInterpretationValue',
+    },
+},
+
+'BarProp': {
+    'headerFile': 'mozilla/dom/BarProps.h',
+},
+
+'Blob': {
+    'headerFile': 'mozilla/dom/File.h',
+},
+
+'BatteryManager': {
+    'nativeType': 'mozilla::dom::battery::BatteryManager',
+    'headerFile': 'BatteryManager.h'
+},
+
+'BoxObject': {
+    'resultNotAddRefed': ['element'],
+},
+
+'Cache': {
+    'implicitJSContext': [ 'add', 'addAll' ],
+    'nativeType': 'mozilla::dom::cache::Cache',
+},
+
+'CacheStorage': {
+    'nativeType': 'mozilla::dom::cache::CacheStorage',
+},
+
+'CanvasRenderingContext2D': {
+    'implicitJSContext': [
+        'createImageData', 'getImageData'
+    ],
+    'binaryNames': {
+        'mozImageSmoothingEnabled': 'imageSmoothingEnabled'
+    }
+},
+
+'CaretPosition' : {
+    'nativeType': 'nsDOMCaretPosition',
+},
+
+'CharacterData': {
+    'nativeType': 'nsGenericDOMDataNode',
+    'concrete': False
+},
+
+'ChromeUtils': {
+    # The codegen is dumb, and doesn't understand that this interface is only a
+    # collection of static methods, so we have this `concrete: False` hack.
+    'concrete': False,
+},
+
+'ChromeWindow': {
+    'concrete': False,
+},
+
+'ChromeWorker': {
+    'headerFile': 'mozilla/dom/WorkerPrivate.h',
+    'nativeType': 'mozilla::dom::workers::ChromeWorkerPrivate',
+},
+
+'Client': {
+    'nativeType': 'mozilla::dom::workers::ServiceWorkerClient',
+    'headerFile': 'mozilla/dom/workers/bindings/ServiceWorkerClient.h',
+},
+
+'Clients': {
+    'nativeType': 'mozilla::dom::workers::ServiceWorkerClients',
+    'headerFile': 'mozilla/dom/workers/bindings/ServiceWorkerClients.h',
+},
+
+'console': {
+    'nativeType': 'mozilla::dom::Console',
+},
+
+'ConvolverNode': {
+    'implicitJSContext': [ 'buffer' ],
+},
+
+'Coordinates': {
+    'headerFile': 'nsGeoPosition.h'
+},
+
+'Crypto' : {
+    'headerFile': 'Crypto.h'
+},
+
+'CSS': {
+    'concrete': False,
+},
+
+'CSS2Properties': {
+    'nativeType': 'nsDOMCSSDeclaration'
+},
+
+'CSSLexer': {
+    'wrapperCache': False
+},
+
+'CSSPrimitiveValue': {
+    'nativeType': 'nsROCSSPrimitiveValue',
+},
+
+'CSSStyleDeclaration': {
+    'nativeType': 'nsICSSDeclaration'
+},
+
+'CSSStyleSheet': {
+    'nativeType': 'mozilla::StyleSheet',
+    'binaryNames': { 'ownerRule': 'DOMOwnerRule' },
+},
+
+'CSSValue': {
+    'concrete': False
+},
+
+'CSSValueList': {
+    'nativeType': 'nsDOMCSSValueList'
+},
+
+'DataChannel': {
+    'nativeType': 'nsDOMDataChannel',
+},
+
+'DedicatedWorkerGlobalScope': {
+    'headerFile': 'mozilla/dom/WorkerScope.h',
+},
+
+'DeviceAcceleration': {
+    'headerFile': 'mozilla/dom/DeviceMotionEvent.h',
+},
+
+'DeviceRotationRate': {
+    'headerFile': 'mozilla/dom/DeviceMotionEvent.h',
+},
+
+'Document': {
+    'nativeType': 'nsIDocument',
+    'binaryNames': {
+        'documentURI': 'documentURIFromJS',
+        'URL': 'documentURIFromJS'
+    }
+},
+
+'DominatorTree': {
+    'nativeType': 'mozilla::devtools::DominatorTree'
+},
+
+'DOMException': {
+    'binaryNames': {
+        'message': 'messageMoz',
+    },
+    'implicitJSContext': [ 'filename', 'lineNumber', 'stack' ],
+},
+
+'DOMMatrixReadOnly': {
+    'headerFile': 'mozilla/dom/DOMMatrix.h',
+    'concrete': False,
+},
+
+'DOMPointReadOnly': {
+    'headerFile': 'mozilla/dom/DOMPoint.h',
+    'concrete': False,
+},
+
+'DOMRectList': {
+    'headerFile': 'mozilla/dom/DOMRect.h',
+},
+
+'DOMRectReadOnly': {
+    'headerFile': 'mozilla/dom/DOMRect.h',
+},
+
+'DOMRequest': {
+    'implicitJSContext': [ 'then' ],
+},
+
+'DOMStringMap': {
+    'nativeType': 'nsDOMStringMap'
+},
+
+'DOMTokenList': {
+    'nativeType': 'nsDOMTokenList',
+},
+
+'DynamicsCompressorNode': {
+    'binaryNames': {
+        'release': 'getRelease'
+    },
+},
+
+'Event': {
+    'implicitJSContext': [ 'defaultPrevented', 'preventDefault' ],
+},
+
+'EventTarget': {
+    # When we get rid of hasXPConnectImpls, we can get rid of the
+    # couldBeDOMBinding stuff in GetOrCreateDOMReflector.
+    #
+    # We can also get rid of the UnwrapArg bits in
+    # the dom QueryInterface (in BindingUtils.cpp) at that point.
+    'hasXPConnectImpls': True,
+    'concrete': False,
+    'jsImplParent': 'mozilla::DOMEventTargetHelper',
+    'implicitJSContext': [ 'dispatchEvent' ]
+},
+
+'Exception': {
+    'headerFile': 'mozilla/dom/DOMException.h',
+    'binaryNames': {
+        'message': 'messageMoz',
+    },
+    'implicitJSContext': [ '__stringifier', 'filename', 'lineNumber', 'stack' ],
+},
+
+'ExtendableEvent': {
+    'headerFile': 'mozilla/dom/ServiceWorkerEvents.h',
+    'nativeType': 'mozilla::dom::workers::ExtendableEvent',
+    'implicitJSContext': [ 'waitUntil' ],
+},
+
+'ExtendableMessageEvent': {
+    'headerFile': 'mozilla/dom/ServiceWorkerEvents.h',
+    'nativeType': 'mozilla::dom::workers::ExtendableMessageEvent',
+},
+
+'FetchEvent': {
+    'headerFile': 'ServiceWorkerEvents.h',
+    'nativeType': 'mozilla::dom::workers::FetchEvent',
+    'binaryNames': {
+        'request': 'request_'
+    },
+    'implicitJSContext': [ 'respondWith' ],
+},
+
+'FileReader': {
+    'implicitJSContext': [ 'readAsArrayBuffer' ],
+},
+
+'FileReaderSync': {
+    'wrapperCache': False,
+},
+
+'FlyWebFetchEvent': {
+    'headerFile': 'FlyWebServerEvents.h',
+},
+
+'FlyWebWebSocketEvent': {
+    'headerFile': 'FlyWebServerEvents.h',
+},
+
+'FontFaceSet': {
+    'implicitJSContext': [ 'load' ],
+},
+
+'FontFaceSetIterator': {
+    'wrapperCache': False,
+},
+
+'Geolocation': {
+    'headerFile': 'nsGeolocation.h'
+},
+
+'HeapSnapshot': {
+    'nativeType': 'mozilla::devtools::HeapSnapshot'
+},
+
+'History': {
+    'headerFile': 'nsHistory.h',
+    'nativeType': 'nsHistory'
+},
+
+'HTMLAppletElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedObjectElement'
+},
+
+'HTMLBaseElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLCollection': {
+    'nativeType': 'nsIHTMLCollection',
+    # nsContentList.h pulls in nsIHTMLCollection.h
+    'headerFile': 'nsContentList.h',
+},
+
+'HTMLDirectoryElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLDListElement': {
+    'nativeType' : 'mozilla::dom::HTMLSharedListElement'
+},
+
+'HTMLDocument': {
+    'nativeType': 'nsHTMLDocument',
+    'implicitJSContext': [ 'open', 'write', 'writeln' ]
+},
+
+'HTMLElement': {
+    'nativeType': 'nsGenericHTMLElement',
+},
+
+'HTMLEmbedElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedObjectElement'
+},
+
+'HTMLHeadElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLHtmlElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLMediaElement': {
+    'concrete': False
+},
+
+'HTMLOListElement': {
+    'nativeType' : 'mozilla::dom::HTMLSharedListElement'
+},
+
+'HTMLParamElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLQuoteElement': {
+    'nativeType': 'mozilla::dom::HTMLSharedElement'
+},
+
+'HTMLTextAreaElement': {
+    'binaryNames': {
+        'textLength': 'getTextLength'
+    }
+},
+
+'HTMLUListElement': {
+    'nativeType' : 'mozilla::dom::HTMLSharedListElement'
+},
+
+'IDBCursor': {
+    'implicitJSContext': [ 'delete' ],
+    'binaryNames': {
+        'direction': 'getDirection'
+    }
+},
+
+'IDBCursorWithValue': {
+    'nativeType': 'mozilla::dom::IDBCursor',
+},
+
+'IDBDatabase': {
+    'implicitJSContext': [ 'transaction', 'createMutableFile',
+                           'mozCreateFileHandle' ],
+},
+
+'IDBFactory': {
+    'implicitJSContext': [ 'open', 'deleteDatabase', 'openForPrincipal',
+                           'deleteForPrincipal' ],
+},
+
+'IDBIndex': {
+    'binaryNames': {
+        'mozGetAll': 'getAll',
+        'mozGetAllKeys': 'getAllKeys',
+    }
+},
+
+'IDBKeyRange': {
+    'wrapperCache': False,
+},
+
+'IDBLocaleAwareKeyRange': {
+    'headerFile': 'IDBKeyRange.h',
+    'wrapperCache': False,
+},
+
+'IDBObjectStore': {
+    'binaryNames': {
+        'mozGetAll': 'getAll'
+    },
+    'implicitJSContext': [ 'clear' ],
+},
+
+'IDBOpenDBRequest': {
+    'headerFile': 'IDBRequest.h'
+},
+
+'IDBVersionChangeEvent': {
+    'headerFile': 'IDBEvents.h',
+},
+
+'IID': {
+    'nativeType': 'nsIJSID',
+    'headerFile': 'xpcjsid.h',
+},
+
+'ImageBitmap': {
+    'implicitJSContext': [ 'mapDataInto' ],
+},
+
+'ImageCapture': {
+    'binaryNames': { 'videoStreamTrack': 'GetVideoStreamTrack' }
+},
+
+'ImageData': {
+    'wrapperCache': False,
+},
+
+'InputStream': {
+    'nativeType': 'nsIInputStream',
+    'notflattened': True
+},
+
+'IntersectionObserver': {
+    'nativeType': 'mozilla::dom::DOMIntersectionObserver',
+},
+
+'IntersectionObserverEntry': {
+    'nativeType': 'mozilla::dom::DOMIntersectionObserverEntry',
+    'headerFile': 'DOMIntersectionObserver.h',
+},
+
+'KeyEvent': {
+    'concrete': False
+},
+
+'KeyframeEffect': {
+    'implicitJSContext': { 'setterOnly': [ 'spacing' ] }
+},
+
+'LegacyMozTCPSocket': {
+    'headerFile': 'TCPSocket.h',
+    'wrapperCache': False,
+},
+
+'LocalMediaStream': {
+    'headerFile': 'DOMMediaStream.h',
+    'nativeType': 'mozilla::DOMLocalMediaStream'
+},
+
+'MediaList': {
+    'nativeType': 'nsMediaList',
+    'headerFile': 'nsIMediaList.h',
+},
+
+'MediaKeys' : {
+    'implicitJSContext': [ 'createSession']
+},
+
+'MediaStream': {
+    'headerFile': 'DOMMediaStream.h',
+    'nativeType': 'mozilla::DOMMediaStream'
+},
+
+'MediaStreamAudioDestinationNode': {
+    'binaryNames': { 'stream': 'DOMStream' }
+},
+
+'MediaStreamList': {
+    'headerFile': 'MediaStreamList.h',
+},
+
+'MediaStreamTrack': {
+    'concrete': False
+},
+
+'MediaRecorder': {
+    'headerFile': 'MediaRecorder.h',
+},
+
+'MimeType': {
+    'headerFile' : 'nsMimeTypeArray.h',
+    'nativeType': 'nsMimeType',
+},
+
+'MimeTypeArray': {
+    'nativeType': 'nsMimeTypeArray',
+},
+
+'MozCanvasPrintState': {
+    'headerFile': 'mozilla/dom/HTMLCanvasElement.h',
+    'nativeType': 'mozilla::dom::HTMLCanvasPrintState',
+},
+
+'MozChannel': {
+    'nativeType': 'nsIChannel',
+    'notflattened': True
+},
+
+'MozSpeakerManager': {
+    'nativeType': 'mozilla::dom::SpeakerManager',
+    'headerFile': 'SpeakerManager.h'
+},
+
+'MozPowerManager': {
+    'nativeType': 'mozilla::dom::PowerManager',
+},
+
+'MozWakeLock': {
+    'nativeType': 'mozilla::dom::WakeLock',
+},
+
+'MozTimeManager': {
+    'nativeType': 'mozilla::dom::time::TimeManager',
+},
+
+'MutationObserver': {
+    'nativeType': 'nsDOMMutationObserver',
+},
+
+'MutationRecord': {
+    'nativeType': 'nsDOMMutationRecord',
+    'headerFile': 'nsDOMMutationObserver.h',
+},
+
+'NamedNodeMap': {
+    'nativeType': 'nsDOMAttributeMap',
+},
+
+'NetworkInformation': {
+    'nativeType': 'mozilla::dom::network::Connection',
+},
+
+'Node': {
+    'nativeType': 'nsINode',
+    'concrete': False,
+    'binaryNames': {
+        'baseURI': 'baseURIFromJS'
+    }
+},
+
+'NodeIterator': {
+    'wrapperCache': False,
+},
+
+'NodeList': {
+    'nativeType': 'nsINodeList',
+},
+
+'NotificationEvent': {
+    'headerFile': 'mozilla/dom/NotificationEvent.h',
+    'nativeType': 'mozilla::dom::workers::NotificationEvent',
+    'binaryNames': {
+        'notification': 'notification_'
+    }
+},
+
+'OfflineAudioContext': {
+    'nativeType': 'mozilla::dom::AudioContext',
+},
+
+'OfflineResourceList': {
+    'nativeType': 'nsDOMOfflineResourceList',
+},
+
+'PaintRequestList': {
+    'headerFile': 'mozilla/dom/PaintRequest.h',
+},
+
+'Path2D': {
+    'nativeType': 'mozilla::dom::CanvasPath',
+    'headerFile': 'CanvasPath.h'
+},
+
+'PeerConnectionImpl': {
+    'nativeType': 'mozilla::PeerConnectionImpl',
+    'headerFile': 'PeerConnectionImpl.h',
+    'wrapperCache': False
+},
+
+'Plugin': {
+    'headerFile' : 'nsPluginArray.h',
+    'nativeType': 'nsPluginElement',
+},
+
+'PluginArray': {
+    'nativeType': 'nsPluginArray',
+},
+
+'PluginTag': {
+    'nativeType': 'nsIPluginTag',
+},
+
+'PopupBoxObject': {
+    'resultNotAddRefed': ['triggerNode', 'anchorNode'],
+},
+
+'Position': {
+    'headerFile': 'nsGeoPosition.h'
+},
+
+'PositionError': {
+    'headerFile': 'nsGeolocation.h'
+},
+
+'Promise': {
+    'implicitJSContext': [ 'then', 'catch' ],
+},
+
+'PromiseDebugging': {
+    'concrete': False,
+},
+
+'PromiseNativeHandler': {
+    'wrapperCache': False,
+},
+
+'PushEvent': {
+    'headerFile': 'ServiceWorkerEvents.h',
+    'nativeType': 'mozilla::dom::workers::PushEvent',
+},
+
+'PushMessageData': {
+    'headerFile': 'ServiceWorkerEvents.h',
+    'nativeType': 'mozilla::dom::workers::PushMessageData',
+},
+
+'Range': {
+    'nativeType': 'nsRange',
+    'binaryNames': {
+        '__stringifier': 'ToString'
+    }
+},
+
+'Rect': {
+    'nativeType': 'nsDOMCSSRect',
+},
+
+'Request': {
+    'binaryNames': {
+        'headers': 'headers_',
+        'referrerPolicy': 'referrerPolicy_'
+    },
+},
+
+'Response': {
+    'binaryNames': { 'headers': 'headers_' },
+},
+
+'RGBColor': {
+    'nativeType': 'nsDOMCSSRGBColor',
+},
+
+'Screen': {
+    'nativeType': 'nsScreen',
+},
+
+'ServiceWorker': {
+    'nativeType': 'mozilla::dom::workers::ServiceWorker',
+    'headerFile': 'mozilla/dom/workers/bindings/ServiceWorker.h',
+},
+
+'ServiceWorkerGlobalScope': {
+    'headerFile': 'mozilla/dom/WorkerScope.h',
+},
+
+'ServiceWorkerRegistration': {
+    'implicitJSContext': [ 'pushManager' ],
+},
+
+'SharedWorker': {
+    'nativeType': 'mozilla::dom::workers::SharedWorker',
+    'headerFile': 'mozilla/dom/workers/bindings/SharedWorker.h',
+    'implicitJSContext': [ 'constructor' ],
+},
+
+'SharedWorkerGlobalScope': {
+    'headerFile': 'mozilla/dom/WorkerScope.h',
+},
+
+'Storage': {
+    'nativeType': 'mozilla::dom::DOMStorage',
+},
+
+'StyleSheet': {
+    'nativeType': 'mozilla::StyleSheet',
+    'headerFile': 'mozilla/StyleSheetInlines.h',
+},
+
+'SVGAnimatedLengthList': {
+    'nativeType': 'mozilla::DOMSVGAnimatedLengthList',
+    'headerFile': 'DOMSVGAnimatedLengthList.h',
+},
+
+'SVGAnimatedNumberList': {
+    'nativeType': 'mozilla::DOMSVGAnimatedNumberList',
+    'headerFile': 'DOMSVGAnimatedNumberList.h'
+},
+
+'SVGAnimatedPreserveAspectRatio': {
+    'nativeType': 'mozilla::dom::DOMSVGAnimatedPreserveAspectRatio',
+    'headerFile': 'SVGAnimatedPreserveAspectRatio.h'
+},
+
+'SVGAnimationElement': {
+    'concrete': False
+},
+
+'SVGComponentTransferFunctionElement': {
+    'concrete': False,
+},
+
+'SVGElement': {
+    'nativeType': 'nsSVGElement',
+},
+
+'SVGFEFuncAElement': {
+    'headerFile': 'mozilla/dom/SVGComponentTransferFunctionElement.h',
+},
+
+'SVGFEFuncBElement': {
+    'headerFile': 'mozilla/dom/SVGComponentTransferFunctionElement.h',
+},
+
+'SVGFEFuncGElement': {
+    'headerFile': 'mozilla/dom/SVGComponentTransferFunctionElement.h',
+},
+
+'SVGFEFuncRElement': {
+    'headerFile': 'mozilla/dom/SVGComponentTransferFunctionElement.h',
+},
+
+'SVGGraphicsElement': {
+    'concrete': False,
+},
+
+'SVGGradientElement': {
+    'concrete': False,
+},
+
+'SVGLength': {
+    'nativeType': 'mozilla::DOMSVGLength',
+    'headerFile': 'DOMSVGLength.h'
+},
+
+'SVGLengthList': {
+    'nativeType': 'mozilla::DOMSVGLengthList',
+    'headerFile': 'DOMSVGLengthList.h'
+},
+
+'SVGLinearGradientElement': {
+    'headerFile': 'mozilla/dom/SVGGradientElement.h',
+},
+
+'SVGNumber': {
+    'nativeType': 'mozilla::DOMSVGNumber',
+    'headerFile': 'DOMSVGNumber.h',
+},
+
+'SVGNumberList': {
+    'nativeType': 'mozilla::DOMSVGNumberList',
+    'headerFile': 'DOMSVGNumberList.h'
+},
+
+'SVGPathSeg': {
+    'nativeType': 'mozilla::DOMSVGPathSeg',
+    'headerFile': 'DOMSVGPathSeg.h',
+    'concrete': False,
+},
+
+'SVGPathSegClosePath': {
+    'nativeType': 'mozilla::DOMSVGPathSegClosePath',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegMovetoAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegMovetoAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegMovetoRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegMovetoRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoCubicAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoCubicAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoCubicRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoCubicRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoQuadraticAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoQuadraticAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoQuadraticRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoQuadraticRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegArcAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegArcAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegArcRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegArcRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoHorizontalAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoHorizontalAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoHorizontalRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoHorizontalRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoVerticalAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoVerticalAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegLinetoVerticalRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegLinetoVerticalRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoCubicSmoothAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoCubicSmoothAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoCubicSmoothRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoCubicSmoothRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoQuadraticSmoothAbs': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoQuadraticSmoothAbs',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegCurvetoQuadraticSmoothRel': {
+    'nativeType': 'mozilla::DOMSVGPathSegCurvetoQuadraticSmoothRel',
+    'headerFile': 'DOMSVGPathSeg.h'
+},
+
+'SVGPathSegList': {
+    'nativeType': 'mozilla::DOMSVGPathSegList',
+    'headerFile': 'DOMSVGPathSegList.h'
+},
+
+'SVGPoint': {
+    'nativeType': 'mozilla::nsISVGPoint',
+    'headerFile': 'nsISVGPoint.h'
+},
+
+'SVGPointList': {
+    'nativeType': 'mozilla::DOMSVGPointList',
+    'headerFile': 'DOMSVGPointList.h'
+},
+
+'SVGPreserveAspectRatio': {
+    'nativeType': 'mozilla::dom::DOMSVGPreserveAspectRatio',
+    'headerFile': 'SVGPreserveAspectRatio.h'
+},
+
+'SVGRadialGradientElement': {
+    'headerFile': 'mozilla/dom/SVGGradientElement.h',
+},
+
+'SVGRect': {
+    'nativeType': 'mozilla::dom::SVGIRect'
+},
+
+'SVGTextContentElement': {
+    'concrete': False
+},
+
+'SVGTextPositioningElement': {
+    'concrete': False
+},
+
+'SVGTransform': {
+    'binaryNames': {
+        "matrix": "GetMatrix"
+    }
+},
+
+'SVGTransformList': {
+    'nativeType': 'mozilla::DOMSVGTransformList',
+    'headerFile': 'DOMSVGTransformList.h'
+},
+
+'SVGStringList': {
+    'nativeType': 'mozilla::DOMSVGStringList',
+    'headerFile': 'DOMSVGStringList.h',
+},
+
+'SVGUnitTypes' : {
+    'concrete': False,
+},
+
+'SVGZoomAndPan' : {
+    'concrete': False,
+},
+
+'TestFunctions': {
+    'wrapperCache': False
+},
+
+'Text': {
+    # Total hack to allow binding code to realize that nsTextNode can
+    # in fact be cast to Text.
+    'headerFile': 'nsTextNode.h',
+},
+
+'TextDecoder': {
+    'wrapperCache': False
+},
+
+'TextEncoder': {
+    'wrapperCache': False
+},
+
+'TextMetrics': {
+    'wrapperCache': False
+},
+
+'TCPSocket': {
+    'implicitJSContext': ['send']
+},
+
+'ThreadSafeChromeUtils': {
+    # The codegen is dumb, and doesn't understand that this interface is only a
+    # collection of static methods, so we have this `concrete: False` hack.
+    'concrete': False,
+    'headerFile': 'mozilla/dom/ChromeUtils.h',
+},
+
+'TouchList': {
+    'headerFile': 'mozilla/dom/TouchEvent.h',
+},
+
+'TreeColumn': {
+    'nativeType': 'nsTreeColumn',
+    'headerFile': 'nsTreeColumns.h',
+},
+
+'TreeColumns': {
+    'nativeType': 'nsTreeColumns',
+},
+
+'TreeWalker': {
+    'wrapperCache': False,
+},
+
+'VTTCue': {
+    'nativeType': 'mozilla::dom::TextTrackCue'
+},
+
+'VTTRegion': {
+  'nativeType': 'mozilla::dom::TextTrackRegion',
+},
+
+'WindowClient': {
+    'nativeType': 'mozilla::dom::workers::ServiceWorkerWindowClient',
+    'headerFile': 'mozilla/dom/workers/bindings/ServiceWorkerWindowClient.h',
+},
+
+'WebGLActiveInfo': {
+    'nativeType': 'mozilla::WebGLActiveInfo',
+    'headerFile': 'WebGLActiveInfo.h'
+},
+
+'WebGLBuffer': {
+    'nativeType': 'mozilla::WebGLBuffer',
+    'headerFile': 'WebGLBuffer.h'
+},
+
+'WEBGL_compressed_texture_atc': {
+    'nativeType': 'mozilla::WebGLExtensionCompressedTextureATC',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_compressed_texture_etc': {
+    'nativeType': 'mozilla::WebGLExtensionCompressedTextureES3',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_compressed_texture_etc1': {
+    'nativeType': 'mozilla::WebGLExtensionCompressedTextureETC1',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_compressed_texture_pvrtc': {
+    'nativeType': 'mozilla::WebGLExtensionCompressedTexturePVRTC',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_compressed_texture_s3tc': {
+    'nativeType': 'mozilla::WebGLExtensionCompressedTextureS3TC',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_depth_texture': {
+    'nativeType': 'mozilla::WebGLExtensionDepthTexture',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_debug_renderer_info': {
+    'nativeType': 'mozilla::WebGLExtensionDebugRendererInfo',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_debug_shaders': {
+    'nativeType': 'mozilla::WebGLExtensionDebugShaders',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_element_index_uint': {
+    'nativeType': 'mozilla::WebGLExtensionElementIndexUint',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_frag_depth': {
+    'nativeType': 'mozilla::WebGLExtensionFragDepth',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_lose_context': {
+    'nativeType': 'mozilla::WebGLExtensionLoseContext',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_sRGB': {
+    'nativeType': 'mozilla::WebGLExtensionSRGB',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_standard_derivatives': {
+    'nativeType': 'mozilla::WebGLExtensionStandardDerivatives',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_shader_texture_lod': {
+    'nativeType': 'mozilla::WebGLExtensionShaderTextureLod',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_texture_filter_anisotropic': {
+    'nativeType': 'mozilla::WebGLExtensionTextureFilterAnisotropic',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_texture_float': {
+    'nativeType': 'mozilla::WebGLExtensionTextureFloat',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_texture_float_linear': {
+    'nativeType': 'mozilla::WebGLExtensionTextureFloatLinear',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_texture_half_float': {
+   'nativeType': 'mozilla::WebGLExtensionTextureHalfFloat',
+   'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_texture_half_float_linear': {
+   'nativeType': 'mozilla::WebGLExtensionTextureHalfFloatLinear',
+   'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_color_buffer_float': {
+   'nativeType': 'mozilla::WebGLExtensionColorBufferFloat',
+   'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_color_buffer_half_float': {
+   'nativeType': 'mozilla::WebGLExtensionColorBufferHalfFloat',
+   'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_color_buffer_float': {
+   'nativeType': 'mozilla::WebGLExtensionEXTColorBufferFloat',
+   'headerFile': 'WebGLExtensions.h'
+},
+
+'WEBGL_draw_buffers': {
+    'nativeType': 'mozilla::WebGLExtensionDrawBuffers',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'OES_vertex_array_object': {
+    'nativeType': 'mozilla::WebGLExtensionVertexArray',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'ANGLE_instanced_arrays': {
+    'nativeType': 'mozilla::WebGLExtensionInstancedArrays',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_blend_minmax': {
+    'nativeType': 'mozilla::WebGLExtensionBlendMinMax',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'EXT_disjoint_timer_query': {
+    'nativeType': 'mozilla::WebGLExtensionDisjointTimerQuery',
+    'headerFile': 'WebGLExtensions.h'
+},
+
+'WebGLFramebuffer': {
+    'nativeType': 'mozilla::WebGLFramebuffer',
+    'headerFile': 'WebGLFramebuffer.h'
+},
+
+'WebGLProgram': {
+    'nativeType': 'mozilla::WebGLProgram',
+    'headerFile': 'WebGLProgram.h'
+},
+
+'WebGLQuery': {
+    'nativeType': 'mozilla::WebGLQuery',
+    'headerFile': 'WebGLQuery.h'
+},
+
+'WebGLRenderbuffer': {
+    'nativeType': 'mozilla::WebGLRenderbuffer',
+    'headerFile': 'WebGLRenderbuffer.h'
+},
+
+'WebGLRenderingContext': {
+    'nativeType': 'mozilla::WebGLContext',
+    'headerFile': 'WebGLContext.h',
+},
+
+'WebGL2RenderingContext': {
+    'nativeType': 'mozilla::WebGL2Context',
+    'headerFile': 'WebGL2Context.h',
+},
+
+'WebGLSampler': {
+    'nativeType': 'mozilla::WebGLSampler',
+    'headerFile': 'WebGLSampler.h'
+},
+
+'WebGLShader': {
+    'nativeType': 'mozilla::WebGLShader',
+    'headerFile': 'WebGLShader.h'
+},
+
+'WebGLShaderPrecisionFormat': {
+    'nativeType': 'mozilla::WebGLShaderPrecisionFormat',
+    'headerFile': 'WebGLShaderPrecisionFormat.h',
+    'wrapperCache': False
+},
+
+'WebGLSync': {
+    'nativeType': 'mozilla::WebGLSync',
+    'headerFile': 'WebGLSync.h'
+},
+
+'WebGLTexture': {
+    'nativeType': 'mozilla::WebGLTexture',
+    'headerFile': 'WebGLTexture.h'
+},
+
+'WebGLTransformFeedback': {
+    'nativeType': 'mozilla::WebGLTransformFeedback',
+    'headerFile': 'WebGLTransformFeedback.h'
+},
+
+'WebGLUniformLocation': {
+    'nativeType': 'mozilla::WebGLUniformLocation',
+    'headerFile': 'WebGLUniformLocation.h'
+},
+
+'WebGLVertexArrayObject': {
+    'nativeType': 'mozilla::WebGLVertexArray',
+    'headerFile': 'WebGLVertexArray.h'
+},
+
+'WebrtcGlobalInformation': {
+    'nativeType': 'mozilla::dom::WebrtcGlobalInformation',
+    'headerFile': 'WebrtcGlobalInformation.h',
+    'wrapperCache': False,
+    'concrete': False,
+},
+
+'Window': {
+    'nativeType': 'nsGlobalWindow',
+    'binaryNames': {
+        'postMessage': 'postMessageMoz',
+    },
+    'implicitJSContext': [
+        'requestIdleCallback'
+    ],
+},
+
+'WindowProxy': {
+    'nativeType': 'nsPIDOMWindowOuter',
+    'headerFile': 'nsPIDOMWindow.h',
+    'concrete': False
+},
+
+'WindowRoot': {
+    'nativeType': 'nsWindowRoot'
+},
+
+'Worker': {
+    'headerFile': 'mozilla/dom/WorkerPrivate.h',
+    'nativeType': 'mozilla::dom::workers::WorkerPrivate',
+},
+
+'WorkerDebuggerGlobalScope': {
+    'headerFile': 'mozilla/dom/WorkerScope.h',
+    'implicitJSContext': [
+        'dump', 'global', 'reportError', 'setConsoleEventHandler',
+    ],
+},
+
+'WorkerGlobalScope': {
+    'headerFile': 'mozilla/dom/WorkerScope.h',
+    'concrete': False,
+    'implicitJSContext': [
+        'close',
+    ],
+    # Rename a few things so we don't have both classes and methods
+    # with the same name
+    'binaryNames': {
+        'performance': 'getPerformance',
+    },
+},
+
+'XMLHttpRequest': {
+    'implicitJSContext': [ 'send'],
+},
+
+'XMLHttpRequestEventTarget': {
+    'concrete': False
+},
+
+'XMLSerializer': {
+    'nativeType': 'nsDOMSerializer',
+},
+
+'XPathEvaluator': {
+    'wrapperCache': False
+},
+
+'XPathExpression': {
+    'wrapperCache': False,
+},
+
+'XSLTProcessor': {
+    'nativeType': 'txMozillaXSLTProcessor',
+},
+
+'XULDocument': {
+    'headerFile': 'XULDocument.h'
+},
+
+'XULElement': {
+    'nativeType': 'nsXULElement',
+},
+
+####################################
+# Test Interfaces of various sorts #
+####################################
+
+'TestInterface' : {
+        # Keep this in sync with TestExampleInterface
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        'binaryNames': { 'methodRenamedFrom': 'methodRenamedTo',
+                         'attributeGetterRenamedFrom': 'attributeGetterRenamedTo',
+                         'attributeRenamedFrom': 'attributeRenamedTo' }
+        },
+
+'TestParentInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestChildInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestCImplementedInterface' : {
+        'headerFile': 'TestCImplementedInterface.h',
+        'register': False,
+        },
+
+'TestCImplementedInterface2' : {
+        'headerFile': 'TestCImplementedInterface.h',
+        'register': False,
+        },
+
+'TestJSImplInterface' : {
+        # Keep this in sync with TestExampleInterface
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False,
+        'binaryNames': { 'methodRenamedFrom': 'methodRenamedTo',
+                         'attributeGetterRenamedFrom': 'attributeGetterRenamedTo',
+                         'attributeRenamedFrom': 'attributeRenamedTo' }
+        },
+
+'TestJSImplInterface2' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False
+        },
+
+'TestJSImplInterface3' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False
+        },
+
+'TestJSImplInterface4' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False
+        },
+
+'TestJSImplInterface5' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False
+        },
+
+'TestJSImplInterface6' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register': False
+        },
+
+'TestNavigator' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register' : False
+        },
+
+'TestNavigatorWithConstructor' : {
+        'headerFile': 'TestJSImplGenBinding.h',
+        'register' : False
+        },
+
+'TestExternalInterface' : {
+        'nativeType': 'mozilla::dom::TestExternalInterface',
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestNonWrapperCacheInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        'wrapperCache': False
+        },
+
+'IndirectlyImplementedInterface': {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        'castable': False,
+        'concrete': False
+        },
+
+'OnlyForUseInConstructor' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'ImplementedInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False,
+        },
+
+'ImplementedInterfaceParent' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'DiamondImplements' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'DiamondBranch1A' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'DiamondBranch1B' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'DiamondBranch2A' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'DiamondBranch2B' : {
+        'headerFile': 'TestBindingHeader.h',
+        'concrete': False,
+        'register': False
+        },
+
+'TestIndexedGetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestNamedGetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestIndexedGetterAndSetterAndNamedGetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestIndexedAndNamedGetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestIndexedSetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestNamedSetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestIndexedAndNamedSetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestIndexedAndNamedGetterAndSetterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestRenamedInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        'nativeType': 'nsRenamedInterface'
+        },
+
+'TestNamedDeleterInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestNamedDeleterWithRetvalInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestCppKeywordNamedMethodsInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestExampleInterface' : {
+        # Keep this in sync with TestInterface
+        'headerFile': 'TestExampleInterface-example.h',
+        'register': False,
+        'binaryNames': { 'methodRenamedFrom': 'methodRenamedTo',
+                         'attributeGetterRenamedFrom': 'attributeGetterRenamedTo',
+                         'attributeRenamedFrom': 'attributeRenamedTo' }
+        },
+
+'TestExampleWorkerInterface' : {
+        'headerFile': 'TestExampleWorkerInterface-example.h',
+        'register': False,
+        },
+
+'TestExampleProxyInterface' : {
+        'headerFile': 'TestExampleProxyInterface-example.h',
+        'register': False
+        },
+
+'TestDeprecatedInterface' : {
+        # Keep this in sync with TestExampleInterface
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestInterfaceWithPromiseConstructorArg' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestSecureContextInterface' : {
+        # Keep this in sync with TestExampleInterface
+        'headerFile': 'TestBindingHeader.h',
+        'register': False
+        },
+
+'TestNamespace' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestRenamedNamespace' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestProtoObjectHackedNamespace' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+'TestWorkerExposedInterface' : {
+        'headerFile': 'TestBindingHeader.h',
+        'register': False,
+        },
+
+}
+
+# These are temporary, until they've been converted to use new DOM bindings
+def addExternalIface(iface, nativeType=None, headerFile=None,
+                     notflattened=False):
+    if iface in DOMInterfaces:
+        raise Exception('Interface declared both as WebIDL and External interface')
+    domInterface = {
+        'concrete': False
+    }
+    if not nativeType is None:
+        domInterface['nativeType'] = nativeType
+    if not headerFile is None:
+        domInterface['headerFile'] = headerFile
+    domInterface['notflattened'] = notflattened
+    DOMInterfaces[iface] = domInterface
+
+addExternalIface('ApplicationCache', nativeType='nsIDOMOfflineResourceList')
+addExternalIface('Counter')
+addExternalIface('CSSRule')
+addExternalIface('RTCDataChannel', nativeType='nsIDOMDataChannel')
+addExternalIface('HitRegionOptions', nativeType='nsISupports')
+addExternalIface('imgINotificationObserver', nativeType='imgINotificationObserver')
+addExternalIface('imgIRequest', nativeType='imgIRequest', notflattened=True)
+addExternalIface('MenuBuilder', nativeType='nsIMenuBuilder', notflattened=True)
+addExternalIface('MozControllers', nativeType='nsIControllers')
+addExternalIface('MozFrameLoader', nativeType='nsIFrameLoader', notflattened=True)
+addExternalIface('MozObserver', nativeType='nsIObserver', notflattened=True)
+addExternalIface('MozRDFCompositeDataSource', nativeType='nsIRDFCompositeDataSource',
+                 notflattened=True)
+addExternalIface('MozRDFResource', nativeType='nsIRDFResource', notflattened=True)
+addExternalIface('MozTreeView', nativeType='nsITreeView',
+                  headerFile='nsITreeView.h', notflattened=True)
+addExternalIface('MozWakeLockListener', headerFile='nsIDOMWakeLockListener.h')
+addExternalIface('MozXULTemplateBuilder', nativeType='nsIXULTemplateBuilder')
+addExternalIface('nsIBrowserDOMWindow', nativeType='nsIBrowserDOMWindow',
+                 notflattened=True)
+addExternalIface('nsIControllers', nativeType='nsIControllers')
+addExternalIface('nsIDOMCrypto', nativeType='nsIDOMCrypto',
+                 headerFile='Crypto.h')
+addExternalIface('nsIFile', nativeType='nsIFile', notflattened=True)
+addExternalIface('nsILoadGroup', nativeType='nsILoadGroup',
+                 headerFile='nsILoadGroup.h', notflattened=True)
+addExternalIface('nsIMessageBroadcaster', nativeType='nsIMessageBroadcaster',
+                 headerFile='nsIMessageManager.h', notflattened=True)
+addExternalIface('nsISelectionListener', nativeType='nsISelectionListener')
+addExternalIface('nsIStreamListener', nativeType='nsIStreamListener', notflattened=True)
+addExternalIface('nsITransportProvider', nativeType='nsITransportProvider')
+addExternalIface('nsISupports', nativeType='nsISupports')
+addExternalIface('nsIDocShell', nativeType='nsIDocShell', notflattened=True)
+addExternalIface('nsIEditor', nativeType='nsIEditor', notflattened=True)
+addExternalIface('nsIVariant', nativeType='nsIVariant', notflattened=True)
+addExternalIface('nsIScriptableRegion', nativeType='nsIScriptableRegion', notflattened=True)
+addExternalIface('OutputStream', nativeType='nsIOutputStream',
+                 notflattened=True)
+addExternalIface('Principal', nativeType='nsIPrincipal',
+                 headerFile='nsIPrincipal.h', notflattened=True)
+addExternalIface('StackFrame', nativeType='nsIStackFrame',
+                 headerFile='nsIException.h', notflattened=True)
+addExternalIface('URI', nativeType='nsIURI', headerFile='nsIURI.h',
+                 notflattened=True)
+addExternalIface('XULCommandDispatcher')
diff --git a/dom/bindings/CallbackFunction.h b/dom/bindings/CallbackFunction.h
new file mode 100644
index 000000000..ac2b3e8b3
--- /dev/null
+++ b/dom/bindings/CallbackFunction.h
@@ -0,0 +1,78 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A common base class for representing WebIDL callback function types in C++.
+ *
+ * This class implements common functionality like lifetime
+ * management, initialization with the callable, and setup of the call
+ * environment.  Subclasses corresponding to particular callback
+ * function types should provide a Call() method that actually does
+ * the call.
+ */
+
+#ifndef mozilla_dom_CallbackFunction_h
+#define mozilla_dom_CallbackFunction_h
+
+#include "mozilla/dom/CallbackObject.h"
+
+namespace mozilla {
+namespace dom {
+
+class CallbackFunction : public CallbackObject
+{
+public:
+  // See CallbackObject for an explanation of the arguments.
+  explicit CallbackFunction(JSContext* aCx, JS::Handle<JSObject*> aCallable,
+                            nsIGlobalObject* aIncumbentGlobal)
+    : CallbackObject(aCx, aCallable, aIncumbentGlobal)
+  {
+  }
+
+  // See CallbackObject for an explanation of the arguments.
+  explicit CallbackFunction(JS::Handle<JSObject*> aCallable,
+                            JS::Handle<JSObject*> aAsyncStack,
+                            nsIGlobalObject* aIncumbentGlobal)
+    : CallbackObject(aCallable, aAsyncStack, aIncumbentGlobal)
+  {
+  }
+
+  JS::Handle<JSObject*> Callable() const
+  {
+    return Callback();
+  }
+
+  JS::Handle<JSObject*> CallablePreserveColor() const
+  {
+    return CallbackPreserveColor();
+  }
+
+  bool HasGrayCallable() const
+  {
+    // Play it safe in case this gets called after unlink.
+    return mCallback && JS::ObjectIsMarkedGray(mCallback);
+  }
+
+protected:
+  explicit CallbackFunction(CallbackFunction* aCallbackFunction)
+    : CallbackObject(aCallbackFunction)
+  {
+  }
+
+  // See CallbackObject for an explanation of the arguments.
+  CallbackFunction(JSContext* aCx, JS::Handle<JSObject*> aCallable,
+                   nsIGlobalObject* aIncumbentGlobal,
+                   const FastCallbackConstructor&)
+    : CallbackObject(aCx, aCallable, aIncumbentGlobal,
+                     FastCallbackConstructor())
+  {
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_CallbackFunction_h
diff --git a/dom/bindings/CallbackInterface.cpp b/dom/bindings/CallbackInterface.cpp
new file mode 100644
index 000000000..55c1d4d7a
--- /dev/null
+++ b/dom/bindings/CallbackInterface.cpp
@@ -0,0 +1,36 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/CallbackInterface.h"
+#include "jsapi.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "nsPrintfCString.h"
+
+namespace mozilla {
+namespace dom {
+
+bool
+CallbackInterface::GetCallableProperty(JSContext* cx, JS::Handle<jsid> aPropId,
+                                       JS::MutableHandle<JS::Value> aCallable)
+{
+  if (!JS_GetPropertyById(cx, CallbackKnownNotGray(), aPropId, aCallable)) {
+    return false;
+  }
+  if (!aCallable.isObject() ||
+      !JS::IsCallable(&aCallable.toObject())) {
+    char* propName =
+      JS_EncodeString(cx, JS_FORGET_STRING_FLATNESS(JSID_TO_FLAT_STRING(aPropId)));
+    nsPrintfCString description("Property '%s'", propName);
+    JS_free(cx, propName);
+    ThrowErrorMessage(cx, MSG_NOT_CALLABLE, description.get());
+    return false;
+  }
+
+  return true;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/CallbackInterface.h b/dom/bindings/CallbackInterface.h
new file mode 100644
index 000000000..3ba5182e7
--- /dev/null
+++ b/dom/bindings/CallbackInterface.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A common base class for representing WebIDL callback interface types in C++.
+ *
+ * This class implements common functionality like lifetime management,
+ * initialization with the callback object, and setup of the call environment.
+ * Subclasses corresponding to particular callback interface types should
+ * provide methods that actually do the various necessary calls.
+ */
+
+#ifndef mozilla_dom_CallbackInterface_h
+#define mozilla_dom_CallbackInterface_h
+
+#include "mozilla/dom/CallbackObject.h"
+
+namespace mozilla {
+namespace dom {
+
+class CallbackInterface : public CallbackObject
+{
+public:
+  // See CallbackObject for an explanation of the arguments.
+  explicit CallbackInterface(JSContext* aCx, JS::Handle<JSObject*> aCallback,
+                             nsIGlobalObject* aIncumbentGlobal)
+    : CallbackObject(aCx, aCallback, aIncumbentGlobal)
+  {
+  }
+
+  // See CallbackObject for an explanation of the arguments.
+  explicit CallbackInterface(JS::Handle<JSObject*> aCallback,
+                             JS::Handle<JSObject*> aAsyncStack,
+                             nsIGlobalObject* aIncumbentGlobal)
+    : CallbackObject(aCallback, aAsyncStack, aIncumbentGlobal)
+  {
+  }
+
+protected:
+  bool GetCallableProperty(JSContext* cx, JS::Handle<jsid> aPropId,
+                           JS::MutableHandle<JS::Value> aCallable);
+
+  // See CallbackObject for an explanation of the arguments.
+  CallbackInterface(JSContext* aCx, JS::Handle<JSObject*> aCallable,
+                    nsIGlobalObject* aIncumbentGlobal,
+                    const FastCallbackConstructor&)
+    : CallbackObject(aCx, aCallable, aIncumbentGlobal,
+                     FastCallbackConstructor())
+  {
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_CallbackFunction_h
diff --git a/dom/bindings/CallbackObject.cpp b/dom/bindings/CallbackObject.cpp
new file mode 100644
index 000000000..7c7d2c6b4
--- /dev/null
+++ b/dom/bindings/CallbackObject.cpp
@@ -0,0 +1,331 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/CallbackObject.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "jsfriendapi.h"
+#include "nsIScriptGlobalObject.h"
+#include "nsIXPConnect.h"
+#include "nsIScriptContext.h"
+#include "nsPIDOMWindow.h"
+#include "nsJSUtils.h"
+#include "xpcprivate.h"
+#include "WorkerPrivate.h"
+#include "nsGlobalWindow.h"
+#include "WorkerScope.h"
+#include "jsapi.h"
+#include "nsJSPrincipals.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(CallbackObject)
+  NS_INTERFACE_MAP_ENTRY(mozilla::dom::CallbackObject)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(CallbackObject)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(CallbackObject)
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(CallbackObject)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(CallbackObject)
+  tmp->DropJSObjects();
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mIncumbentGlobal)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(CallbackObject)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mIncumbentGlobal)
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(CallbackObject)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mCallback)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mCreationStack)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mIncumbentJSGlobal)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+void
+CallbackObject::Trace(JSTracer* aTracer)
+{
+  JS::TraceEdge(aTracer, &mCallback, "CallbackObject.mCallback");
+  JS::TraceEdge(aTracer, &mCreationStack, "CallbackObject.mCreationStack");
+  JS::TraceEdge(aTracer, &mIncumbentJSGlobal,
+                "CallbackObject.mIncumbentJSGlobal");
+}
+
+void
+CallbackObject::HoldJSObjectsIfMoreThanOneOwner()
+{
+  MOZ_ASSERT(mRefCnt.get() > 0);
+  if (mRefCnt.get() > 1) {
+    mozilla::HoldJSObjects(this);
+  } else {
+    // We can just forget all our stuff.
+    ClearJSReferences();
+  }
+}
+
+CallbackObject::CallSetup::CallSetup(CallbackObject* aCallback,
+                                     ErrorResult& aRv,
+                                     const char* aExecutionReason,
+                                     ExceptionHandling aExceptionHandling,
+                                     JSCompartment* aCompartment,
+                                     bool aIsJSImplementedWebIDL)
+  : mCx(nullptr)
+  , mCompartment(aCompartment)
+  , mErrorResult(aRv)
+  , mExceptionHandling(aExceptionHandling)
+  , mIsMainThread(NS_IsMainThread())
+{
+  if (mIsMainThread) {
+    nsContentUtils::EnterMicroTask();
+  }
+
+  // Compute the caller's subject principal (if necessary) early, before we
+  // do anything that might perturb the relevant state.
+  nsIPrincipal* webIDLCallerPrincipal = nullptr;
+  if (aIsJSImplementedWebIDL) {
+    webIDLCallerPrincipal = nsContentUtils::SubjectPrincipalOrSystemIfNativeCaller();
+  }
+
+  // First, find the real underlying callback.
+  JSObject* realCallback = js::UncheckedUnwrap(aCallback->CallbackPreserveColor());
+  nsIGlobalObject* globalObject = nullptr;
+
+  JSContext* cx;
+  {
+    // Bug 955660: we cannot do "proper" rooting here because we need the
+    // global to get a context. Everything here is simple getters that cannot
+    // GC, so just paper over the necessary dataflow inversion.
+    JS::AutoSuppressGCAnalysis nogc;
+
+    // Now get the global for this callback. Note that for the case of
+    // JS-implemented WebIDL we never have a window here.
+    nsGlobalWindow* win = mIsMainThread && !aIsJSImplementedWebIDL
+                        ? xpc::WindowGlobalOrNull(realCallback)
+                        : nullptr;
+    if (win) {
+      MOZ_ASSERT(win->IsInnerWindow());
+      // We don't want to run script in windows that have been navigated away
+      // from.
+      if (!win->AsInner()->HasActiveDocument()) {
+        aRv.ThrowDOMException(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
+          NS_LITERAL_CSTRING("Refusing to execute function from window "
+                             "whose document is no longer active."));
+        return;
+      }
+      globalObject = win;
+    } else {
+      // No DOM Window. Store the global.
+      JSObject* global = js::GetGlobalForObjectCrossCompartment(realCallback);
+      globalObject = xpc::NativeGlobal(global);
+      MOZ_ASSERT(globalObject);
+    }
+
+    // Bail out if there's no useful global. This seems to happen intermittently
+    // on gaia-ui tests, probably because nsInProcessTabChildGlobal is returning
+    // null in some kind of teardown state.
+    if (!globalObject->GetGlobalJSObject()) {
+      aRv.ThrowDOMException(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
+        NS_LITERAL_CSTRING("Refusing to execute function from global which is "
+                           "being torn down."));
+      return;
+    }
+
+    mAutoEntryScript.emplace(globalObject, aExecutionReason, mIsMainThread);
+    mAutoEntryScript->SetWebIDLCallerPrincipal(webIDLCallerPrincipal);
+    nsIGlobalObject* incumbent = aCallback->IncumbentGlobalOrNull();
+    if (incumbent) {
+      // The callback object traces its incumbent JS global, so in general it
+      // should be alive here. However, it's possible that we could run afoul
+      // of the same IPC global weirdness described above, wherein the
+      // nsIGlobalObject has severed its reference to the JS global. Let's just
+      // be safe here, so that nobody has to waste a day debugging gaia-ui tests.
+      if (!incumbent->GetGlobalJSObject()) {
+      aRv.ThrowDOMException(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
+        NS_LITERAL_CSTRING("Refusing to execute function because our "
+                           "incumbent global is being torn down."));
+        return;
+      }
+      mAutoIncumbentScript.emplace(incumbent);
+    }
+
+    cx = mAutoEntryScript->cx();
+
+    // Unmark the callable (by invoking Callback() and not the CallbackPreserveColor()
+    // variant), and stick it in a Rooted before it can go gray again.
+    // Nothing before us in this function can trigger a CC, so it's safe to wait
+    // until here it do the unmark. This allows us to construct mRootedCallable
+    // with the cx from mAutoEntryScript, avoiding the cost of finding another
+    // JSContext. (Rooted<> does not care about requests or compartments.)
+    mRootedCallable.emplace(cx, aCallback->Callback());
+  }
+
+  // JS-implemented WebIDL is always OK to run, since it runs with Chrome
+  // privileges anyway.
+  if (mIsMainThread && !aIsJSImplementedWebIDL) {
+    // Check that it's ok to run this callback at all.
+    // Make sure to use realCallback to get the global of the callback object,
+    // not the wrapper.
+    bool allowed = xpc::Scriptability::Get(realCallback).Allowed();
+
+    if (!allowed) {
+      aRv.ThrowDOMException(NS_ERROR_DOM_NOT_SUPPORTED_ERR,
+        NS_LITERAL_CSTRING("Refusing to execute function from global in which "
+                           "script is disabled."));
+      return;
+    }
+  }
+
+  mAsyncStack.emplace(cx, aCallback->GetCreationStack());
+  if (*mAsyncStack) {
+    mAsyncStackSetter.emplace(cx, *mAsyncStack, aExecutionReason);
+  }
+
+  // Enter the compartment of our callback, so we can actually work with it.
+  //
+  // Note that if the callback is a wrapper, this will not be the same
+  // compartment that we ended up in with mAutoEntryScript above, because the
+  // entry point is based off of the unwrapped callback (realCallback).
+  mAc.emplace(cx, *mRootedCallable);
+
+  // And now we're ready to go.
+  mCx = cx;
+}
+
+bool
+CallbackObject::CallSetup::ShouldRethrowException(JS::Handle<JS::Value> aException)
+{
+  if (mExceptionHandling == eRethrowExceptions) {
+    if (!mCompartment) {
+      // Caller didn't ask us to filter for only exceptions we subsume.
+      return true;
+    }
+
+    // On workers, we don't have nsIPrincipals to work with.  But we also only
+    // have one compartment, so check whether mCompartment is the same as the
+    // current compartment of mCx.
+    if (mCompartment == js::GetContextCompartment(mCx)) {
+      return true;
+    }
+
+    MOZ_ASSERT(NS_IsMainThread());
+
+    // At this point mCx is in the compartment of our unwrapped callback, so
+    // just check whether the principal of mCompartment subsumes that of the
+    // current compartment/global of mCx.
+    nsIPrincipal* callerPrincipal =
+      nsJSPrincipals::get(JS_GetCompartmentPrincipals(mCompartment));
+    nsIPrincipal* calleePrincipal = nsContentUtils::SubjectPrincipal();
+    if (callerPrincipal->SubsumesConsideringDomain(calleePrincipal)) {
+      return true;
+    }
+  }
+
+  MOZ_ASSERT(mCompartment);
+
+  // Now we only want to throw an exception to the caller if the object that was
+  // thrown is in the caller compartment (which we stored in mCompartment).
+
+  if (!aException.isObject()) {
+    return false;
+  }
+
+  JS::Rooted<JSObject*> obj(mCx, &aException.toObject());
+  obj = js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false);
+  return js::GetObjectCompartment(obj) == mCompartment;
+}
+
+CallbackObject::CallSetup::~CallSetup()
+{
+  // To get our nesting right we have to destroy our JSAutoCompartment first.
+  // In particular, we want to do this before we try reporting any exceptions,
+  // so we end up reporting them while in the compartment of our entry point,
+  // not whatever cross-compartment wrappper mCallback might be.
+  // Be careful: the JSAutoCompartment might not have been constructed at all!
+  mAc.reset();
+
+  // Now, if we have a JSContext, report any pending errors on it, unless we
+  // were told to re-throw them.
+  if (mCx) {
+    bool needToDealWithException = mAutoEntryScript->HasException();
+    if ((mCompartment && mExceptionHandling == eRethrowContentExceptions) ||
+        mExceptionHandling == eRethrowExceptions) {
+      mErrorResult.MightThrowJSException();
+      if (needToDealWithException) {
+        JS::Rooted<JS::Value> exn(mCx);
+        if (mAutoEntryScript->PeekException(&exn) &&
+            ShouldRethrowException(exn)) {
+          mAutoEntryScript->ClearException();
+          MOZ_ASSERT(!mAutoEntryScript->HasException());
+          mErrorResult.ThrowJSException(mCx, exn);
+          needToDealWithException = false;
+        }
+      }
+    }
+
+    if (needToDealWithException) {
+      // Either we're supposed to report our exceptions, or we're supposed to
+      // re-throw them but we failed to get the exception value.  Either way,
+      // we'll just report the pending exception, if any, once ~mAutoEntryScript
+      // runs.  Note that we've already run ~mAc, effectively, so we don't have
+      // to worry about ordering here.
+      if (mErrorResult.IsJSContextException()) {
+        // XXXkhuey bug 1117269.  When this is fixed, please consider fixing
+        // ThrowExceptionValueIfSafe over in Exceptions.cpp in the same way.
+
+        // IsJSContextException shouldn't be true anymore because we will report
+        // the exception on the JSContext ... so throw something else.
+        mErrorResult.Throw(NS_ERROR_UNEXPECTED);
+      }
+    }
+  }
+
+  mAutoIncumbentScript.reset();
+  mAutoEntryScript.reset();
+
+  // It is important that this is the last thing we do, after leaving the
+  // compartment and undoing all our entry/incumbent script changes
+  if (mIsMainThread) {
+    nsContentUtils::LeaveMicroTask();
+  }
+}
+
+already_AddRefed<nsISupports>
+CallbackObjectHolderBase::ToXPCOMCallback(CallbackObject* aCallback,
+                                          const nsIID& aIID) const
+{
+  MOZ_ASSERT(NS_IsMainThread());
+  if (!aCallback) {
+    return nullptr;
+  }
+
+  // We don't init the AutoJSAPI with our callback because we don't want it
+  // reporting errors to its global's onerror handlers.
+  AutoJSAPI jsapi;
+  jsapi.Init();
+  JSContext* cx = jsapi.cx();
+
+  JS::Rooted<JSObject*> callback(cx, aCallback->Callback());
+
+  JSAutoCompartment ac(cx, callback);
+  RefPtr<nsXPCWrappedJS> wrappedJS;
+  nsresult rv =
+    nsXPCWrappedJS::GetNewOrUsed(callback, aIID, getter_AddRefs(wrappedJS));
+  if (NS_FAILED(rv) || !wrappedJS) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsISupports> retval;
+  rv = wrappedJS->QueryInterface(aIID, getter_AddRefs(retval));
+  if (NS_FAILED(rv)) {
+    return nullptr;
+  }
+
+  return retval.forget();
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/CallbackObject.h b/dom/bindings/CallbackObject.h
new file mode 100644
index 000000000..8a3d45dfc
--- /dev/null
+++ b/dom/bindings/CallbackObject.h
@@ -0,0 +1,607 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A common base class for representing WebIDL callback function and
+ * callback interface types in C++.
+ *
+ * This class implements common functionality like lifetime
+ * management, initialization with the JS object, and setup of the
+ * call environment.  Subclasses are responsible for providing methods
+ * that do the call into JS as needed.
+ */
+
+#ifndef mozilla_dom_CallbackObject_h
+#define mozilla_dom_CallbackObject_h
+
+#include "nsISupports.h"
+#include "nsISupportsImpl.h"
+#include "nsCycleCollectionParticipant.h"
+#include "jswrapper.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/HoldDropJSObjects.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/OwningNonNull.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "nsWrapperCache.h"
+#include "nsJSEnvironment.h"
+#include "xpcpublic.h"
+#include "jsapi.h"
+#include "js/TracingAPI.h"
+
+namespace mozilla {
+namespace dom {
+
+#define DOM_CALLBACKOBJECT_IID \
+{ 0xbe74c190, 0x6d76, 0x4991, \
+ { 0x84, 0xb9, 0x65, 0x06, 0x99, 0xe6, 0x93, 0x2b } }
+
+class CallbackObject : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(DOM_CALLBACKOBJECT_IID)
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(CallbackObject)
+
+  // The caller may pass a global object which will act as an override for the
+  // incumbent script settings object when the callback is invoked (overriding
+  // the entry point computed from aCallback). If no override is required, the
+  // caller should pass null.  |aCx| is used to capture the current
+  // stack, which is later used as an async parent when the callback
+  // is invoked.  aCx can be nullptr, in which case no stack is
+  // captured.
+  explicit CallbackObject(JSContext* aCx, JS::Handle<JSObject*> aCallback,
+                          nsIGlobalObject* aIncumbentGlobal)
+  {
+    if (aCx && JS::ContextOptionsRef(aCx).asyncStack()) {
+      JS::RootedObject stack(aCx);
+      if (!JS::CaptureCurrentStack(aCx, &stack)) {
+        JS_ClearPendingException(aCx);
+      }
+      Init(aCallback, stack, aIncumbentGlobal);
+    } else {
+      Init(aCallback, nullptr, aIncumbentGlobal);
+    }
+  }
+
+  // Instead of capturing the current stack to use as an async parent when the
+  // callback is invoked, the caller can use this overload to pass in a stack
+  // for that purpose.
+  explicit CallbackObject(JS::Handle<JSObject*> aCallback,
+                          JS::Handle<JSObject*> aAsyncStack,
+                          nsIGlobalObject* aIncumbentGlobal)
+  {
+    Init(aCallback, aAsyncStack, aIncumbentGlobal);
+  }
+
+  JS::Handle<JSObject*> Callback() const
+  {
+    mCallback.exposeToActiveJS();
+    return CallbackPreserveColor();
+  }
+
+  JSObject* GetCreationStack() const
+  {
+    return mCreationStack;
+  }
+
+  void MarkForCC()
+  {
+    mCallback.exposeToActiveJS();
+    mCreationStack.exposeToActiveJS();
+  }
+
+  /*
+   * This getter does not change the color of the JSObject meaning that the
+   * object returned is not guaranteed to be kept alive past the next CC.
+   *
+   * This should only be called if you are certain that the return value won't
+   * be passed into a JS API function and that it won't be stored without being
+   * rooted (or otherwise signaling the stored value to the CC).
+   */
+  JS::Handle<JSObject*> CallbackPreserveColor() const
+  {
+    // Calling fromMarkedLocation() is safe because we trace our mCallback, and
+    // because the value of mCallback cannot change after if has been set.
+    return JS::Handle<JSObject*>::fromMarkedLocation(mCallback.address());
+  }
+
+  /*
+   * If the callback is known to be non-gray, then this method can be
+   * used instead of Callback() to avoid the overhead of
+   * ExposeObjectToActiveJS().
+   */
+  JS::Handle<JSObject*> CallbackKnownNotGray() const
+  {
+    MOZ_ASSERT(!JS::ObjectIsMarkedGray(mCallback));
+    return CallbackPreserveColor();
+  }
+
+  nsIGlobalObject* IncumbentGlobalOrNull() const
+  {
+    return mIncumbentGlobal;
+  }
+
+  enum ExceptionHandling {
+    // Report any exception and don't throw it to the caller code.
+    eReportExceptions,
+    // Throw an exception to the caller code if the thrown exception is a
+    // binding object for a DOMError or DOMException from the caller's scope,
+    // otherwise report it.
+    eRethrowContentExceptions,
+    // Throw exceptions to the caller code, unless the caller compartment is
+    // provided, the exception is not a DOMError or DOMException from the
+    // caller compartment, and the caller compartment does not subsume our
+    // unwrapped callback.
+    eRethrowExceptions
+  };
+
+  size_t SizeOfIncludingThis(mozilla::MallocSizeOf aMallocSizeOf) const
+  {
+    return aMallocSizeOf(this);
+  }
+
+protected:
+  virtual ~CallbackObject()
+  {
+    DropJSObjects();
+  }
+
+  explicit CallbackObject(CallbackObject* aCallbackObject)
+  {
+    Init(aCallbackObject->mCallback, aCallbackObject->mCreationStack,
+         aCallbackObject->mIncumbentGlobal);
+  }
+
+  bool operator==(const CallbackObject& aOther) const
+  {
+    JSObject* thisObj =
+      js::UncheckedUnwrap(CallbackPreserveColor());
+    JSObject* otherObj =
+      js::UncheckedUnwrap(aOther.CallbackPreserveColor());
+    return thisObj == otherObj;
+  }
+
+private:
+  inline void InitNoHold(JSObject* aCallback, JSObject* aCreationStack,
+                         nsIGlobalObject* aIncumbentGlobal)
+  {
+    MOZ_ASSERT(aCallback && !mCallback);
+    // Set script objects before we hold, on the off chance that a GC could
+    // somehow happen in there... (which would be pretty odd, granted).
+    mCallback = aCallback;
+    mCreationStack = aCreationStack;
+    if (aIncumbentGlobal) {
+      mIncumbentGlobal = aIncumbentGlobal;
+      mIncumbentJSGlobal = aIncumbentGlobal->GetGlobalJSObject();
+    }
+  }
+
+  inline void Init(JSObject* aCallback, JSObject* aCreationStack,
+                   nsIGlobalObject* aIncumbentGlobal)
+  {
+    InitNoHold(aCallback, aCreationStack, aIncumbentGlobal);
+    mozilla::HoldJSObjects(this);
+  }
+
+  inline void ClearJSReferences()
+  {
+    mCallback = nullptr;
+    mCreationStack = nullptr;
+    mIncumbentJSGlobal = nullptr;
+  }
+
+  CallbackObject(const CallbackObject&) = delete;
+  CallbackObject& operator =(const CallbackObject&) = delete;
+
+protected:
+  void DropJSObjects()
+  {
+    MOZ_ASSERT_IF(mIncumbentJSGlobal, mCallback);
+    if (mCallback) {
+      ClearJSReferences();
+      mozilla::DropJSObjects(this);
+    }
+  }
+
+  // For use from subclasses that want to be usable with Rooted.
+  void Trace(JSTracer* aTracer);
+
+  // For use from subclasses that want to be traced for a bit then possibly
+  // switch to HoldJSObjects.  If we have more than one owner, this will
+  // HoldJSObjects; otherwise it will just forget all our JS references.
+  void HoldJSObjectsIfMoreThanOneOwner();
+
+  // Struct used as a way to force a CallbackObject constructor to not call
+  // HoldJSObjects. We're putting it here so that CallbackObject subclasses will
+  // have access to it, but outside code will not.
+  //
+  // Places that use this need to ensure that the callback is traced (e.g. via a
+  // Rooted) until the HoldJSObjects call happens.
+  struct FastCallbackConstructor {
+  };
+
+  // Just like the public version without the FastCallbackConstructor argument,
+  // except for not calling HoldJSObjects.  If you use this, you MUST ensure
+  // that the object is traced until the HoldJSObjects happens!
+  CallbackObject(JSContext* aCx, JS::Handle<JSObject*> aCallback,
+                 nsIGlobalObject* aIncumbentGlobal,
+                 const FastCallbackConstructor&)
+  {
+    if (aCx && JS::ContextOptionsRef(aCx).asyncStack()) {
+      JS::RootedObject stack(aCx);
+      if (!JS::CaptureCurrentStack(aCx, &stack)) {
+        JS_ClearPendingException(aCx);
+      }
+      InitNoHold(aCallback, stack, aIncumbentGlobal);
+    } else {
+      InitNoHold(aCallback, nullptr, aIncumbentGlobal);
+    }
+  }
+
+  // mCallback is not unwrapped, so it can be a cross-compartment-wrapper.
+  // This is done to ensure that, if JS code can't call a callback f(), or get
+  // its members, directly itself, this code won't call f(), or get its members,
+  // on the code's behalf.
+  JS::Heap<JSObject*> mCallback;
+  JS::Heap<JSObject*> mCreationStack;
+  // Ideally, we'd just hold a reference to the nsIGlobalObject, since that's
+  // what we need to pass to AutoIncumbentScript. Unfortunately, that doesn't
+  // hold the actual JS global alive. So we maintain an additional pointer to
+  // the JS global itself so that we can trace it.
+  //
+  // At some point we should consider trying to make native globals hold their
+  // scripted global alive, at which point we can get rid of the duplication
+  // here.
+  nsCOMPtr<nsIGlobalObject> mIncumbentGlobal;
+  JS::TenuredHeap<JSObject*> mIncumbentJSGlobal;
+
+  class MOZ_STACK_CLASS CallSetup
+  {
+    /**
+     * A class that performs whatever setup we need to safely make a
+     * call while this class is on the stack, After the constructor
+     * returns, the call is safe to make if GetContext() returns
+     * non-null.
+     */
+  public:
+    // If aExceptionHandling == eRethrowContentExceptions then aCompartment
+    // needs to be set to the compartment in which exceptions will be rethrown.
+    //
+    // If aExceptionHandling == eRethrowExceptions then aCompartment may be set
+    // to the compartment in which exceptions will be rethrown.  In that case
+    // they will only be rethrown if that compartment's principal subsumes the
+    // principal of our (unwrapped) callback.
+    CallSetup(CallbackObject* aCallback, ErrorResult& aRv,
+              const char* aExecutionReason,
+              ExceptionHandling aExceptionHandling,
+              JSCompartment* aCompartment = nullptr,
+              bool aIsJSImplementedWebIDL = false);
+    ~CallSetup();
+
+    JSContext* GetContext() const
+    {
+      return mCx;
+    }
+
+  private:
+    // We better not get copy-constructed
+    CallSetup(const CallSetup&) = delete;
+
+    bool ShouldRethrowException(JS::Handle<JS::Value> aException);
+
+    // Members which can go away whenever
+    JSContext* mCx;
+
+    // Caller's compartment. This will only have a sensible value if
+    // mExceptionHandling == eRethrowContentExceptions or eRethrowExceptions.
+    JSCompartment* mCompartment;
+
+    // And now members whose construction/destruction order we need to control.
+    Maybe<AutoEntryScript> mAutoEntryScript;
+    Maybe<AutoIncumbentScript> mAutoIncumbentScript;
+
+    Maybe<JS::Rooted<JSObject*> > mRootedCallable;
+
+    // Members which are used to set the async stack.
+    Maybe<JS::Rooted<JSObject*>> mAsyncStack;
+    Maybe<JS::AutoSetAsyncStackForNewCalls> mAsyncStackSetter;
+
+    // Can't construct a JSAutoCompartment without a JSContext either.  Also,
+    // Put mAc after mAutoEntryScript so that we exit the compartment before
+    // we pop the JSContext. Though in practice we'll often manually order
+    // those two things.
+    Maybe<JSAutoCompartment> mAc;
+
+    // An ErrorResult to possibly re-throw exceptions on and whether
+    // we should re-throw them.
+    ErrorResult& mErrorResult;
+    const ExceptionHandling mExceptionHandling;
+    const bool mIsMainThread;
+  };
+};
+
+template<class WebIDLCallbackT, class XPCOMCallbackT>
+class CallbackObjectHolder;
+
+template<class T, class U>
+void ImplCycleCollectionUnlink(CallbackObjectHolder<T, U>& aField);
+
+class CallbackObjectHolderBase
+{
+protected:
+  // Returns null on all failures
+  already_AddRefed<nsISupports> ToXPCOMCallback(CallbackObject* aCallback,
+                                                const nsIID& aIID) const;
+};
+
+template<class WebIDLCallbackT, class XPCOMCallbackT>
+class CallbackObjectHolder : CallbackObjectHolderBase
+{
+  /**
+   * A class which stores either a WebIDLCallbackT* or an XPCOMCallbackT*.  Both
+   * types must inherit from nsISupports.  The pointer that's stored can be
+   * null.
+   *
+   * When storing a WebIDLCallbackT*, mPtrBits is set to the pointer value.
+   * When storing an XPCOMCallbackT*, mPtrBits is the pointer value with low bit
+   * set.
+   */
+public:
+  explicit CallbackObjectHolder(WebIDLCallbackT* aCallback)
+    : mPtrBits(reinterpret_cast<uintptr_t>(aCallback))
+  {
+    NS_IF_ADDREF(aCallback);
+  }
+
+  explicit CallbackObjectHolder(XPCOMCallbackT* aCallback)
+    : mPtrBits(reinterpret_cast<uintptr_t>(aCallback) | XPCOMCallbackFlag)
+  {
+    NS_IF_ADDREF(aCallback);
+  }
+
+  CallbackObjectHolder(CallbackObjectHolder&& aOther)
+    : mPtrBits(aOther.mPtrBits)
+  {
+    aOther.mPtrBits = 0;
+    static_assert(sizeof(CallbackObjectHolder) == sizeof(void*),
+                  "This object is expected to be as small as a pointer, and it "
+                  "is currently passed by value in various places. If it is "
+                  "bloating, we may want to pass it by reference then.");
+  }
+
+  CallbackObjectHolder(const CallbackObjectHolder& aOther) = delete;
+
+  CallbackObjectHolder()
+    : mPtrBits(0)
+  {}
+
+  ~CallbackObjectHolder()
+  {
+    UnlinkSelf();
+  }
+
+  void operator=(WebIDLCallbackT* aCallback)
+  {
+    UnlinkSelf();
+    mPtrBits = reinterpret_cast<uintptr_t>(aCallback);
+    NS_IF_ADDREF(aCallback);
+  }
+
+  void operator=(XPCOMCallbackT* aCallback)
+  {
+    UnlinkSelf();
+    mPtrBits = reinterpret_cast<uintptr_t>(aCallback) | XPCOMCallbackFlag;
+    NS_IF_ADDREF(aCallback);
+  }
+
+  void operator=(CallbackObjectHolder&& aOther)
+  {
+    UnlinkSelf();
+    mPtrBits = aOther.mPtrBits;
+    aOther.mPtrBits = 0;
+  }
+
+  void operator=(const CallbackObjectHolder& aOther) = delete;
+
+  nsISupports* GetISupports() const
+  {
+    return reinterpret_cast<nsISupports*>(mPtrBits & ~XPCOMCallbackFlag);
+  }
+
+  // Boolean conversion operator so people can use this in boolean tests
+  explicit operator bool() const
+  {
+    return GetISupports();
+  }
+
+  CallbackObjectHolder Clone() const
+  {
+    CallbackObjectHolder result;
+    result.mPtrBits = mPtrBits;
+    NS_IF_ADDREF(GetISupports());
+    return result;
+  }
+
+  // Even if HasWebIDLCallback returns true, GetWebIDLCallback() might still
+  // return null.
+  bool HasWebIDLCallback() const
+  {
+    return !(mPtrBits & XPCOMCallbackFlag);
+  }
+
+  WebIDLCallbackT* GetWebIDLCallback() const
+  {
+    MOZ_ASSERT(HasWebIDLCallback());
+    return reinterpret_cast<WebIDLCallbackT*>(mPtrBits);
+  }
+
+  XPCOMCallbackT* GetXPCOMCallback() const
+  {
+    MOZ_ASSERT(!HasWebIDLCallback());
+    return reinterpret_cast<XPCOMCallbackT*>(mPtrBits & ~XPCOMCallbackFlag);
+  }
+
+  bool operator==(WebIDLCallbackT* aOtherCallback) const
+  {
+    if (!aOtherCallback) {
+      // If other is null, then we must be null to be equal.
+      return !GetISupports();
+    }
+
+    if (!HasWebIDLCallback() || !GetWebIDLCallback()) {
+      // If other is non-null, then we can't be equal if we have a
+      // non-WebIDL callback or a null callback.
+      return false;
+    }
+
+    return *GetWebIDLCallback() == *aOtherCallback;
+  }
+
+  bool operator==(XPCOMCallbackT* aOtherCallback) const
+  {
+    return (!aOtherCallback && !GetISupports()) ||
+      (!HasWebIDLCallback() && GetXPCOMCallback() == aOtherCallback);
+  }
+
+  bool operator==(const CallbackObjectHolder& aOtherCallback) const
+  {
+    if (aOtherCallback.HasWebIDLCallback()) {
+      return *this == aOtherCallback.GetWebIDLCallback();
+    }
+
+    return *this == aOtherCallback.GetXPCOMCallback();
+  }
+
+  // Try to return an XPCOMCallbackT version of this object.
+  already_AddRefed<XPCOMCallbackT> ToXPCOMCallback() const
+  {
+    if (!HasWebIDLCallback()) {
+      RefPtr<XPCOMCallbackT> callback = GetXPCOMCallback();
+      return callback.forget();
+    }
+
+    nsCOMPtr<nsISupports> supp =
+      CallbackObjectHolderBase::ToXPCOMCallback(GetWebIDLCallback(),
+                                                NS_GET_TEMPLATE_IID(XPCOMCallbackT));
+    // ToXPCOMCallback already did the right QI for us.
+    return supp.forget().downcast<XPCOMCallbackT>();
+  }
+
+  // Try to return a WebIDLCallbackT version of this object.
+  already_AddRefed<WebIDLCallbackT> ToWebIDLCallback() const
+  {
+    if (HasWebIDLCallback()) {
+      RefPtr<WebIDLCallbackT> callback = GetWebIDLCallback();
+      return callback.forget();
+    }
+    return nullptr;
+  }
+
+private:
+  static const uintptr_t XPCOMCallbackFlag = 1u;
+
+  friend void
+  ImplCycleCollectionUnlink<WebIDLCallbackT,
+                            XPCOMCallbackT>(CallbackObjectHolder& aField);
+
+  void UnlinkSelf()
+  {
+    // NS_IF_RELEASE because we might have been unlinked before
+    nsISupports* ptr = GetISupports();
+    NS_IF_RELEASE(ptr);
+    mPtrBits = 0;
+  }
+
+  uintptr_t mPtrBits;
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(CallbackObject, DOM_CALLBACKOBJECT_IID)
+
+template<class T, class U>
+inline void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            CallbackObjectHolder<T, U>& aField,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  CycleCollectionNoteChild(aCallback, aField.GetISupports(), aName, aFlags);
+}
+
+template<class T, class U>
+void
+ImplCycleCollectionUnlink(CallbackObjectHolder<T, U>& aField)
+{
+  aField.UnlinkSelf();
+}
+
+// T is expected to be a RefPtr or OwningNonNull around a CallbackObject
+// subclass.  This class is used in bindings to safely handle Fast* callbacks;
+// it ensures that the callback is traced, and that if something is holding onto
+// the callback when we're done with it HoldJSObjects is called.
+template<typename T>
+class RootedCallback : public JS::Rooted<T>
+{
+public:
+  explicit RootedCallback(JSContext* cx)
+    : JS::Rooted<T>(cx)
+  {}
+
+  // We need a way to make assignment from pointers (how we're normally used)
+  // work.
+  template<typename S>
+  void operator=(S* arg)
+  {
+    this->get().operator=(arg);
+  }
+
+  // But nullptr can't use the above template, because it doesn't know which S
+  // to select.  So we need a special overload for nullptr.
+  void operator=(decltype(nullptr) arg)
+  {
+    this->get().operator=(arg);
+  }
+
+  // Codegen relies on being able to do Callback() on us.
+  JS::Handle<JSObject*> Callback() const
+  {
+    return this->get()->Callback();
+  }
+
+  ~RootedCallback()
+  {
+    // Ensure that our callback starts holding on to its own JS objects as
+    // needed.  Having to null-check here when T is OwningNonNull is a bit
+    // silly, but it's simpler than creating two separate RootedCallback
+    // instantiations for OwningNonNull and RefPtr.
+    if (IsInitialized(this->get())) {
+      this->get()->HoldJSObjectsIfMoreThanOneOwner();
+    }
+  }
+
+private:
+  template<typename U>
+  static bool IsInitialized(U& aArg); // Not implemented
+
+  template<typename U>
+  static bool IsInitialized(RefPtr<U>& aRefPtr)
+  {
+    return aRefPtr;
+  }
+
+  template<typename U>
+  static bool IsInitialized(OwningNonNull<U>& aOwningNonNull)
+  {
+    return aOwningNonNull.isInitialized();
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_CallbackObject_h
diff --git a/dom/bindings/Codegen.py b/dom/bindings/Codegen.py
new file mode 100644
index 000000000..3174c37dd
--- /dev/null
+++ b/dom/bindings/Codegen.py
@@ -0,0 +1,17364 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# Common codegen classes.
+
+import os
+import re
+import string
+import math
+import textwrap
+import functools
+
+from WebIDL import BuiltinTypes, IDLBuiltinType, IDLNullValue, IDLSequenceType, IDLType, IDLAttribute, IDLInterfaceMember, IDLUndefinedValue, IDLEmptySequenceValue, IDLDictionary
+from Configuration import NoSuchDescriptorError, getTypesFromDescriptor, getTypesFromDictionary, getTypesFromCallback, getAllTypes, Descriptor, MemberIsUnforgeable, iteratorNativeType
+
+AUTOGENERATED_WARNING_COMMENT = \
+    "/* THIS FILE IS AUTOGENERATED BY Codegen.py - DO NOT EDIT */\n\n"
+AUTOGENERATED_WITH_SOURCE_WARNING_COMMENT = \
+    "/* THIS FILE IS AUTOGENERATED FROM %s BY Codegen.py - DO NOT EDIT */\n\n"
+ADDPROPERTY_HOOK_NAME = '_addProperty'
+FINALIZE_HOOK_NAME = '_finalize'
+OBJECT_MOVED_HOOK_NAME = '_objectMoved'
+CONSTRUCT_HOOK_NAME = '_constructor'
+LEGACYCALLER_HOOK_NAME = '_legacycaller'
+HASINSTANCE_HOOK_NAME = '_hasInstance'
+RESOLVE_HOOK_NAME = '_resolve'
+MAY_RESOLVE_HOOK_NAME = '_mayResolve'
+ENUMERATE_HOOK_NAME = '_enumerate'
+ENUM_ENTRY_VARIABLE_NAME = 'strings'
+INSTANCE_RESERVED_SLOTS = 1
+
+
+def memberReservedSlot(member, descriptor):
+    return ("(DOM_INSTANCE_RESERVED_SLOTS + %d)" %
+            member.slotIndices[descriptor.interface.identifier.name])
+
+
+def memberXrayExpandoReservedSlot(member, descriptor):
+    return ("(xpc::JSSLOT_EXPANDO_COUNT + %d)" %
+            member.slotIndices[descriptor.interface.identifier.name])
+
+
+def mayUseXrayExpandoSlots(descriptor, attr):
+    assert not attr.getExtendedAttribute("NewObject")
+    # For attributes whose type is a Gecko interface we always use
+    # slots on the reflector for caching.  Also, for interfaces that
+    # don't want Xrays we obviously never use the Xray expando slot.
+    return descriptor.wantsXrays and not attr.type.isGeckoInterface()
+
+
+def toStringBool(arg):
+    return str(not not arg).lower()
+
+
+def toBindingNamespace(arg):
+    return arg + "Binding"
+
+
+def isTypeCopyConstructible(type):
+    # Nullable and sequence stuff doesn't affect copy-constructibility
+    type = type.unroll()
+    return (type.isPrimitive() or type.isString() or type.isEnum() or
+            (type.isUnion() and
+             CGUnionStruct.isUnionCopyConstructible(type)) or
+            (type.isDictionary() and
+             CGDictionary.isDictionaryCopyConstructible(type.inner)) or
+            # Interface types are only copy-constructible if they're Gecko
+            # interfaces.  SpiderMonkey interfaces are not copy-constructible
+            # because of rooting issues.
+            (type.isInterface() and type.isGeckoInterface()))
+
+
+def idlTypeNeedsCycleCollection(type):
+    type = type.unroll()  # Takes care of sequences and nullables
+    if ((type.isPrimitive() and type.tag() in builtinNames) or
+        type.isEnum() or
+        type.isString() or
+        type.isAny() or
+        type.isObject() or
+        type.isSpiderMonkeyInterface()):
+        return False
+    elif type.isCallback() or type.isGeckoInterface():
+        return True
+    elif type.isUnion():
+        return any(idlTypeNeedsCycleCollection(t) for t in type.flatMemberTypes)
+    elif type.isMozMap():
+        if idlTypeNeedsCycleCollection(type.inner):
+            raise TypeError("Cycle collection for type %s is not supported" % type)
+        return False
+    elif type.isDictionary():
+        if any(idlTypeNeedsCycleCollection(m.type) for m in type.inner.members):
+            raise TypeError("Cycle collection for type %s is not supported" % type)
+        return False
+    else:
+        raise TypeError("Don't know whether to cycle-collect type %s" % type)
+
+
+def wantsAddProperty(desc):
+    return (desc.concrete and desc.wrapperCache and not desc.isGlobal())
+
+
+# We'll want to insert the indent at the beginnings of lines, but we
+# don't want to indent empty lines.  So only indent lines that have a
+# non-newline character on them.
+lineStartDetector = re.compile("^(?=[^\n#])", re.MULTILINE)
+
+
+def indent(s, indentLevel=2):
+    """
+    Indent C++ code.
+
+    Weird secret feature: this doesn't indent lines that start with # (such as
+    #include lines or #ifdef/#endif).
+    """
+    if s == "":
+        return s
+    return re.sub(lineStartDetector, indentLevel * " ", s)
+
+
+# dedent() and fill() are often called on the same string multiple
+# times.  We want to memoize their return values so we don't keep
+# recomputing them all the time.
+def memoize(fn):
+    """
+    Decorator to memoize a function of one argument.  The cache just
+    grows without bound.
+    """
+    cache = {}
+
+    @functools.wraps(fn)
+    def wrapper(arg):
+        retval = cache.get(arg)
+        if retval is None:
+            retval = cache[arg] = fn(arg)
+        return retval
+    return wrapper
+
+
+@memoize
+def dedent(s):
+    """
+    Remove all leading whitespace from s, and remove a blank line
+    at the beginning.
+    """
+    if s.startswith('\n'):
+        s = s[1:]
+    return textwrap.dedent(s)
+
+
+# This works by transforming the fill()-template to an equivalent
+# string.Template.
+fill_multiline_substitution_re = re.compile(r"( *)\$\*{(\w+)}(\n)?")
+
+
+find_substitutions = re.compile(r"\${")
+
+
+@memoize
+def compile_fill_template(template):
+    """
+    Helper function for fill().  Given the template string passed to fill(),
+    do the reusable part of template processing and return a pair (t,
+    argModList) that can be used every time fill() is called with that
+    template argument.
+
+    argsModList is list of tuples that represent modifications to be
+    made to args.  Each modification has, in order: i) the arg name,
+    ii) the modified name, iii) the indent depth.
+    """
+    t = dedent(template)
+    assert t.endswith("\n") or "\n" not in t
+    argModList = []
+
+    def replace(match):
+        """
+        Replaces a line like '  $*{xyz}\n' with '${xyz_n}',
+        where n is the indent depth, and add a corresponding entry to
+        argModList.
+
+        Note that this needs to close over argModList, so it has to be
+        defined inside compile_fill_template().
+        """
+        indentation, name, nl = match.groups()
+        depth = len(indentation)
+
+        # Check that $*{xyz} appears by itself on a line.
+        prev = match.string[:match.start()]
+        if (prev and not prev.endswith("\n")) or nl is None:
+            raise ValueError("Invalid fill() template: $*{%s} must appear by itself on a line" % name)
+
+        # Now replace this whole line of template with the indented equivalent.
+        modified_name = name + "_" + str(depth)
+        argModList.append((name, modified_name, depth))
+        return "${" + modified_name + "}"
+
+    t = re.sub(fill_multiline_substitution_re, replace, t)
+    if not re.search(find_substitutions, t):
+        raise TypeError("Using fill() when dedent() would do.")
+    return (string.Template(t), argModList)
+
+
+def fill(template, **args):
+    """
+    Convenience function for filling in a multiline template.
+
+    `fill(template, name1=v1, name2=v2)` is a lot like
+    `string.Template(template).substitute({"name1": v1, "name2": v2})`.
+
+    However, it's shorter, and has a few nice features:
+
+      * If `template` is indented, fill() automatically dedents it!
+        This makes code using fill() with Python's multiline strings
+        much nicer to look at.
+
+      * If `template` starts with a blank line, fill() strips it off.
+        (Again, convenient with multiline strings.)
+
+      * fill() recognizes a special kind of substitution
+        of the form `$*{name}`.
+
+        Use this to paste in, and automatically indent, multiple lines.
+        (Mnemonic: The `*` is for "multiple lines").
+
+        A `$*` substitution must appear by itself on a line, with optional
+        preceding indentation (spaces only). The whole line is replaced by the
+        corresponding keyword argument, indented appropriately.  If the
+        argument is an empty string, no output is generated, not even a blank
+        line.
+    """
+
+    t, argModList = compile_fill_template(template)
+    # Now apply argModList to args
+    for (name, modified_name, depth) in argModList:
+        if not (args[name] == "" or args[name].endswith("\n")):
+            raise ValueError("Argument %s with value %r is missing a newline" % (name, args[name]))
+        args[modified_name] = indent(args[name], depth)
+
+    return t.substitute(args)
+
+
+class CGThing():
+    """
+    Abstract base class for things that spit out code.
+    """
+    def __init__(self):
+        pass  # Nothing for now
+
+    def declare(self):
+        """Produce code for a header file."""
+        assert False  # Override me!
+
+    def define(self):
+        """Produce code for a cpp file."""
+        assert False  # Override me!
+
+    def deps(self):
+        """Produce the deps for a pp file"""
+        assert False  # Override me!
+
+
+class CGStringTable(CGThing):
+    """
+    Generate a string table for the given strings with a function accessor:
+
+    const char *accessorName(unsigned int index) {
+      static const char table[] = "...";
+      static const uint16_t indices = { ... };
+      return &table[indices[index]];
+    }
+
+    This is more efficient than the more natural:
+
+    const char *table[] = {
+      ...
+    };
+
+    The uint16_t indices are smaller than the pointer equivalents, and the
+    string table requires no runtime relocations.
+    """
+    def __init__(self, accessorName, strings):
+        CGThing.__init__(self)
+        self.accessorName = accessorName
+        self.strings = strings
+
+    def declare(self):
+        return "extern const char *%s(unsigned int aIndex);\n" % self.accessorName
+
+    def define(self):
+        table = ' "\\0" '.join('"%s"' % s for s in self.strings)
+        indices = []
+        currentIndex = 0
+        for s in self.strings:
+            indices.append(currentIndex)
+            currentIndex += len(s) + 1  # for the null terminator
+        return fill(
+            """
+            const char *${name}(unsigned int aIndex)
+            {
+              static const char table[] = ${table};
+              static const uint16_t indices[] = { ${indices} };
+              static_assert(${currentIndex} <= UINT16_MAX, "string table overflow!");
+              return &table[indices[aIndex]];
+            }
+            """,
+            name=self.accessorName,
+            table=table,
+            indices=", ".join("%d" % index for index in indices),
+            currentIndex=currentIndex)
+
+
+class CGNativePropertyHooks(CGThing):
+    """
+    Generate a NativePropertyHooks for a given descriptor
+    """
+    def __init__(self, descriptor, properties):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+        self.properties = properties
+
+    def declare(self):
+        if not self.descriptor.wantsXrays:
+            return ""
+        return dedent("""
+            // We declare this as an array so that retrieving a pointer to this
+            // binding's property hooks only requires compile/link-time resolvable
+            // address arithmetic.  Declaring it as a pointer instead would require
+            // doing a run-time load to fetch a pointer to this binding's property
+            // hooks.  And then structures which embedded a pointer to this structure
+            // would require a run-time load for proper initialization, which would
+            // then induce static constructors.  Lots of static constructors.
+            extern const NativePropertyHooks sNativePropertyHooks[];
+            """)
+
+    def define(self):
+        if not self.descriptor.wantsXrays:
+            return ""
+        deleteNamedProperty = "nullptr"
+        if self.descriptor.concrete and self.descriptor.proxy:
+            resolveOwnProperty = "ResolveOwnProperty"
+            enumerateOwnProperties = "EnumerateOwnProperties"
+            if self.descriptor.needsXrayNamedDeleterHook():
+                deleteNamedProperty = "DeleteNamedProperty"
+        elif self.descriptor.needsXrayResolveHooks():
+            resolveOwnProperty = "ResolveOwnPropertyViaResolve"
+            enumerateOwnProperties = "EnumerateOwnPropertiesViaGetOwnPropertyNames"
+        else:
+            resolveOwnProperty = "nullptr"
+            enumerateOwnProperties = "nullptr"
+        if self.properties.hasNonChromeOnly():
+            regular = "sNativeProperties.Upcast()"
+        else:
+            regular = "nullptr"
+        if self.properties.hasChromeOnly():
+            chrome = "sChromeOnlyNativeProperties.Upcast()"
+        else:
+            chrome = "nullptr"
+        constructorID = "constructors::id::"
+        if self.descriptor.interface.hasInterfaceObject():
+            constructorID += self.descriptor.name
+        else:
+            constructorID += "_ID_Count"
+        prototypeID = "prototypes::id::"
+        if self.descriptor.interface.hasInterfacePrototypeObject():
+            prototypeID += self.descriptor.name
+        else:
+            prototypeID += "_ID_Count"
+        parentProtoName = self.descriptor.parentPrototypeName
+        parentHooks = (toBindingNamespace(parentProtoName) + "::sNativePropertyHooks"
+                       if parentProtoName else 'nullptr')
+
+        if self.descriptor.wantsXrayExpandoClass:
+            expandoClass = "&sXrayExpandoObjectClass"
+        else:
+            expandoClass = "&DefaultXrayExpandoObjectClass"
+
+        return fill(
+            """
+            const NativePropertyHooks sNativePropertyHooks[] = { {
+              ${resolveOwnProperty},
+              ${enumerateOwnProperties},
+              ${deleteNamedProperty},
+              { ${regular}, ${chrome} },
+              ${prototypeID},
+              ${constructorID},
+              ${parentHooks},
+              ${expandoClass}
+            } };
+            """,
+            resolveOwnProperty=resolveOwnProperty,
+            enumerateOwnProperties=enumerateOwnProperties,
+            deleteNamedProperty=deleteNamedProperty,
+            regular=regular,
+            chrome=chrome,
+            prototypeID=prototypeID,
+            constructorID=constructorID,
+            parentHooks=parentHooks,
+            expandoClass=expandoClass)
+
+
+def NativePropertyHooks(descriptor):
+    return "&sEmptyNativePropertyHooks" if not descriptor.wantsXrays else "sNativePropertyHooks"
+
+
+def DOMClass(descriptor):
+    protoList = ['prototypes::id::' + proto for proto in descriptor.prototypeNameChain]
+    # Pad out the list to the right length with _ID_Count so we
+    # guarantee that all the lists are the same length.  _ID_Count
+    # is never the ID of any prototype, so it's safe to use as
+    # padding.
+    protoList.extend(['prototypes::id::_ID_Count'] * (descriptor.config.maxProtoChainLength - len(protoList)))
+
+    return fill(
+        """
+          { ${protoChain} },
+          IsBaseOf<nsISupports, ${nativeType} >::value,
+          ${hooks},
+          FindAssociatedGlobalForNative<${nativeType}>::Get,
+          GetProtoObjectHandle,
+          GetCCParticipant<${nativeType}>::Get()
+        """,
+        protoChain=', '.join(protoList),
+        nativeType=descriptor.nativeType,
+        hooks=NativePropertyHooks(descriptor))
+
+
+class CGDOMJSClass(CGThing):
+    """
+    Generate a DOMJSClass for a given descriptor
+    """
+    def __init__(self, descriptor):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        callHook = LEGACYCALLER_HOOK_NAME if self.descriptor.operations["LegacyCaller"] else 'nullptr'
+        objectMovedHook = OBJECT_MOVED_HOOK_NAME if self.descriptor.wrapperCache else 'nullptr'
+        slotCount = INSTANCE_RESERVED_SLOTS + self.descriptor.interface.totalMembersInSlots
+        classFlags = "JSCLASS_IS_DOMJSCLASS | JSCLASS_FOREGROUND_FINALIZE | "
+        if self.descriptor.isGlobal():
+            classFlags += "JSCLASS_DOM_GLOBAL | JSCLASS_GLOBAL_FLAGS_WITH_SLOTS(DOM_GLOBAL_SLOTS)"
+            traceHook = "JS_GlobalObjectTraceHook"
+            reservedSlots = "JSCLASS_GLOBAL_APPLICATION_SLOTS"
+        else:
+            classFlags += "JSCLASS_HAS_RESERVED_SLOTS(%d)" % slotCount
+            traceHook = 'nullptr'
+            reservedSlots = slotCount
+        if self.descriptor.interface.isProbablyShortLivingObject():
+            classFlags += " | JSCLASS_SKIP_NURSERY_FINALIZE"
+        if self.descriptor.interface.getExtendedAttribute("NeedResolve"):
+            resolveHook = RESOLVE_HOOK_NAME
+            mayResolveHook = MAY_RESOLVE_HOOK_NAME
+            enumerateHook = ENUMERATE_HOOK_NAME
+        elif self.descriptor.isGlobal():
+            resolveHook = "mozilla::dom::ResolveGlobal"
+            mayResolveHook = "mozilla::dom::MayResolveGlobal"
+            enumerateHook = "mozilla::dom::EnumerateGlobal"
+        else:
+            resolveHook = "nullptr"
+            mayResolveHook = "nullptr"
+            enumerateHook = "nullptr"
+
+        return fill(
+            """
+            static const js::ClassOps sClassOps = {
+              ${addProperty}, /* addProperty */
+              nullptr,               /* delProperty */
+              nullptr,               /* getProperty */
+              nullptr,               /* setProperty */
+              ${enumerate}, /* enumerate */
+              ${resolve}, /* resolve */
+              ${mayResolve}, /* mayResolve */
+              ${finalize}, /* finalize */
+              ${call}, /* call */
+              nullptr,               /* hasInstance */
+              nullptr,               /* construct */
+              ${trace}, /* trace */
+            };
+
+            static const js::ClassExtension sClassExtension = {
+              nullptr, /* weakmapKeyDelegateOp */
+              ${objectMoved} /* objectMovedOp */
+            };
+
+            static const DOMJSClass sClass = {
+              { "${name}",
+                ${flags},
+                &sClassOps,
+                JS_NULL_CLASS_SPEC,
+                &sClassExtension,
+                JS_NULL_OBJECT_OPS
+              },
+              $*{descriptor}
+            };
+            static_assert(${instanceReservedSlots} == DOM_INSTANCE_RESERVED_SLOTS,
+                          "Must have the right minimal number of reserved slots.");
+            static_assert(${reservedSlots} >= ${slotCount},
+                          "Must have enough reserved slots.");
+            """,
+            name=self.descriptor.interface.identifier.name,
+            flags=classFlags,
+            addProperty=ADDPROPERTY_HOOK_NAME if wantsAddProperty(self.descriptor) else 'nullptr',
+            enumerate=enumerateHook,
+            resolve=resolveHook,
+            mayResolve=mayResolveHook,
+            finalize=FINALIZE_HOOK_NAME,
+            call=callHook,
+            trace=traceHook,
+            objectMoved=objectMovedHook,
+            descriptor=DOMClass(self.descriptor),
+            instanceReservedSlots=INSTANCE_RESERVED_SLOTS,
+            reservedSlots=reservedSlots,
+            slotCount=slotCount)
+
+
+class CGDOMProxyJSClass(CGThing):
+    """
+    Generate a DOMJSClass for a given proxy descriptor
+    """
+    def __init__(self, descriptor):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        flags = ["JSCLASS_IS_DOMJSCLASS"]
+        # We don't use an IDL annotation for JSCLASS_EMULATES_UNDEFINED because
+        # we don't want people ever adding that to any interface other than
+        # HTMLAllCollection.  So just hardcode it here.
+        if self.descriptor.interface.identifier.name == "HTMLAllCollection":
+            flags.append("JSCLASS_EMULATES_UNDEFINED")
+        objectMovedHook = OBJECT_MOVED_HOOK_NAME if self.descriptor.wrapperCache else 'nullptr'
+        return fill(
+            """
+            static const js::ClassExtension sClassExtension = PROXY_MAKE_EXT(
+                ${objectMoved}
+            );
+
+            static const DOMJSClass sClass = {
+              PROXY_CLASS_WITH_EXT("${name}",
+                                   ${flags},
+                                   &sClassExtension),
+              $*{descriptor}
+            };
+            """,
+            name=self.descriptor.interface.identifier.name,
+            flags=" | ".join(flags),
+            objectMoved=objectMovedHook,
+            descriptor=DOMClass(self.descriptor))
+
+
+class CGXrayExpandoJSClass(CGThing):
+    """
+    Generate a JSClass for an Xray expando object.  This is only
+    needed if we have members in slots (for [Cached] or [StoreInSlot]
+    stuff).
+    """
+    def __init__(self, descriptor):
+        assert descriptor.interface.totalMembersInSlots != 0
+        assert descriptor.wantsXrays
+        assert descriptor.wantsXrayExpandoClass
+        CGThing.__init__(self)
+        self.descriptor = descriptor;
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        return fill(
+            """
+            // This may allocate too many slots, because we only really need
+            // slots for our non-interface-typed members that we cache.  But
+            // allocating slots only for those would make the slot index
+            // computations much more complicated, so let's do this the simple
+            // way for now.
+            DEFINE_XRAY_EXPANDO_CLASS(static, sXrayExpandoObjectClass, ${memberSlots});
+            """,
+            memberSlots=self.descriptor.interface.totalMembersInSlots)
+
+
+def PrototypeIDAndDepth(descriptor):
+    prototypeID = "prototypes::id::"
+    if descriptor.interface.hasInterfacePrototypeObject():
+        prototypeID += descriptor.interface.identifier.name
+        depth = "PrototypeTraits<%s>::Depth" % prototypeID
+    else:
+        prototypeID += "_ID_Count"
+        depth = "0"
+    return (prototypeID, depth)
+
+
+def InterfacePrototypeObjectProtoGetter(descriptor):
+    """
+    Returns a tuple with two elements:
+
+        1) The name of the function to call to get the prototype to use for the
+           interface prototype object as a JSObject*.
+
+        2) The name of the function to call to get the prototype to use for the
+           interface prototype object as a JS::Handle<JSObject*> or None if no
+           such function exists.
+    """
+    parentProtoName = descriptor.parentPrototypeName
+    if descriptor.hasNamedPropertiesObject:
+        protoGetter = "GetNamedPropertiesObject"
+        protoHandleGetter = None
+    elif parentProtoName is None:
+        if descriptor.interface.getExtendedAttribute("ArrayClass"):
+            protoGetter = "JS::GetRealmArrayPrototype"
+        elif descriptor.interface.getExtendedAttribute("ExceptionClass"):
+            protoGetter = "JS::GetRealmErrorPrototype"
+        elif descriptor.interface.isIteratorInterface():
+            protoGetter = "JS::GetRealmIteratorPrototype"
+        else:
+            protoGetter = "JS::GetRealmObjectPrototype"
+        protoHandleGetter = None
+    else:
+        prefix = toBindingNamespace(parentProtoName)
+        protoGetter = prefix + "::GetProtoObject"
+        protoHandleGetter = prefix + "::GetProtoObjectHandle"
+
+    return (protoGetter, protoHandleGetter)
+
+
+class CGPrototypeJSClass(CGThing):
+    def __init__(self, descriptor, properties):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+        self.properties = properties
+
+    def declare(self):
+        # We're purely for internal consumption
+        return ""
+
+    def define(self):
+        prototypeID, depth = PrototypeIDAndDepth(self.descriptor)
+        slotCount = "DOM_INTERFACE_PROTO_SLOTS_BASE"
+        # Globals handle unforgeables directly in Wrap() instead of
+        # via a holder.
+        if (self.descriptor.hasUnforgeableMembers and
+            not self.descriptor.isGlobal()):
+            slotCount += " + 1 /* slot for the JSObject holding the unforgeable properties */"
+        (protoGetter, _) = InterfacePrototypeObjectProtoGetter(self.descriptor)
+        type = "eGlobalInterfacePrototype" if self.descriptor.isGlobal() else "eInterfacePrototype"
+        return fill(
+            """
+            static const DOMIfaceAndProtoJSClass sPrototypeClass = {
+              {
+                "${name}Prototype",
+                JSCLASS_IS_DOMIFACEANDPROTOJSCLASS | JSCLASS_HAS_RESERVED_SLOTS(${slotCount}),
+                JS_NULL_CLASS_OPS,
+                JS_NULL_CLASS_SPEC,
+                JS_NULL_CLASS_EXT,
+                JS_NULL_OBJECT_OPS
+              },
+              ${type},
+              false,
+              ${prototypeID},
+              ${depth},
+              ${hooks},
+              "[object ${name}Prototype]",
+              ${protoGetter}
+            };
+            """,
+            name=self.descriptor.interface.identifier.name,
+            slotCount=slotCount,
+            type=type,
+            hooks=NativePropertyHooks(self.descriptor),
+            prototypeID=prototypeID,
+            depth=depth,
+            protoGetter=protoGetter)
+
+
+def NeedsGeneratedHasInstance(descriptor):
+    assert descriptor.interface.hasInterfaceObject()
+    return descriptor.hasXPConnectImpls or descriptor.interface.isConsequential()
+
+
+def InterfaceObjectProtoGetter(descriptor, forXrays=False):
+    """
+    Returns a tuple with two elements:
+
+        1) The name of the function to call to get the prototype to use for the
+           interface object as a JSObject*.
+
+        2) The name of the function to call to get the prototype to use for the
+           interface prototype as a JS::Handle<JSObject*> or None if no such
+           function exists.
+    """
+    parentInterface = descriptor.interface.parent
+    if parentInterface:
+        assert not descriptor.interface.isNamespace()
+        parentIfaceName = parentInterface.identifier.name
+        parentDesc = descriptor.getDescriptor(parentIfaceName)
+        prefix = toBindingNamespace(parentDesc.name)
+        protoGetter = prefix + "::GetConstructorObject"
+        protoHandleGetter = prefix + "::GetConstructorObjectHandle"
+    elif descriptor.interface.isNamespace():
+        if (forXrays or
+            not descriptor.interface.getExtendedAttribute("ProtoObjectHack")):
+            protoGetter = "JS::GetRealmObjectPrototype"
+        else:
+            protoGetter = "binding_detail::GetHackedNamespaceProtoObject"
+        protoHandleGetter = None
+    else:
+        protoGetter = "JS::GetRealmFunctionPrototype"
+        protoHandleGetter = None
+    return (protoGetter, protoHandleGetter)
+
+
+class CGInterfaceObjectJSClass(CGThing):
+    def __init__(self, descriptor, properties):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+        self.properties = properties
+
+    def declare(self):
+        # We're purely for internal consumption
+        return ""
+
+    def define(self):
+        if self.descriptor.interface.ctor():
+            assert not self.descriptor.interface.isNamespace()
+            ctorname = CONSTRUCT_HOOK_NAME
+        elif self.descriptor.interface.isNamespace():
+            ctorname = "nullptr"
+        else:
+            ctorname = "ThrowingConstructor"
+        needsHasInstance = (
+            not NeedsGeneratedHasInstance(self.descriptor) and
+            self.descriptor.interface.hasInterfacePrototypeObject())
+
+        prototypeID, depth = PrototypeIDAndDepth(self.descriptor)
+        slotCount = "DOM_INTERFACE_SLOTS_BASE"
+        if len(self.descriptor.interface.namedConstructors) > 0:
+            slotCount += (" + %i /* slots for the named constructors */" %
+                          len(self.descriptor.interface.namedConstructors))
+        (protoGetter, _) = InterfaceObjectProtoGetter(self.descriptor,
+                                                      forXrays=True)
+
+        if ctorname == "ThrowingConstructor":
+            ret = ""
+            classOpsPtr = "&sBoringInterfaceObjectClassClassOps"
+        elif ctorname == "nullptr":
+            ret = ""
+            classOpsPtr = "JS_NULL_CLASS_OPS"
+        else:
+            ret = fill(
+                """
+                static const js::ClassOps sInterfaceObjectClassOps = {
+                    nullptr,               /* addProperty */
+                    nullptr,               /* delProperty */
+                    nullptr,               /* getProperty */
+                    nullptr,               /* setProperty */
+                    nullptr,               /* enumerate */
+                    nullptr,               /* resolve */
+                    nullptr,               /* mayResolve */
+                    nullptr,               /* finalize */
+                    ${ctorname}, /* call */
+                    nullptr,               /* hasInstance */
+                    ${ctorname}, /* construct */
+                    nullptr,               /* trace */
+                };
+
+                """,
+                ctorname=ctorname)
+            classOpsPtr = "&sInterfaceObjectClassOps"
+
+        if self.descriptor.interface.isNamespace():
+            classString = self.descriptor.interface.getExtendedAttribute("ClassString")
+            if classString is None:
+                classString = "Object"
+            else:
+                classString = classString[0]
+            toStringResult = "[object %s]" % classString
+            objectOps = "JS_NULL_OBJECT_OPS"
+        else:
+            classString = "Function"
+            toStringResult = ("function %s() {\\n    [native code]\\n}" %
+                              self.descriptor.interface.identifier.name)
+            # We need non-default ObjectOps so we can actually make
+            # use of our toStringResult.
+            objectOps = "&sInterfaceObjectClassObjectOps"
+
+        ret = ret + fill(
+            """
+            static const DOMIfaceAndProtoJSClass sInterfaceObjectClass = {
+              {
+                "${classString}",
+                JSCLASS_IS_DOMIFACEANDPROTOJSCLASS | JSCLASS_HAS_RESERVED_SLOTS(${slotCount}),
+                ${classOpsPtr},
+                JS_NULL_CLASS_SPEC,
+                JS_NULL_CLASS_EXT,
+                ${objectOps}
+              },
+              eInterface,
+              ${needsHasInstance},
+              ${prototypeID},
+              ${depth},
+              ${hooks},
+              "${toStringResult}",
+              ${protoGetter}
+            };
+            """,
+            classString=classString,
+            slotCount=slotCount,
+            classOpsPtr=classOpsPtr,
+            hooks=NativePropertyHooks(self.descriptor),
+            objectOps=objectOps,
+            needsHasInstance=toStringBool(needsHasInstance),
+            prototypeID=prototypeID,
+            depth=depth,
+            toStringResult=toStringResult,
+            protoGetter=protoGetter)
+        return ret
+
+class CGList(CGThing):
+    """
+    Generate code for a list of GCThings.  Just concatenates them together, with
+    an optional joiner string.  "\n" is a common joiner.
+    """
+    def __init__(self, children, joiner=""):
+        CGThing.__init__(self)
+        # Make a copy of the kids into a list, because if someone passes in a
+        # generator we won't be able to both declare and define ourselves, or
+        # define ourselves more than once!
+        self.children = list(children)
+        self.joiner = joiner
+
+    def append(self, child):
+        self.children.append(child)
+
+    def prepend(self, child):
+        self.children.insert(0, child)
+
+    def extend(self, kids):
+        self.children.extend(kids)
+
+    def join(self, iterable):
+        return self.joiner.join(s for s in iterable if len(s) > 0)
+
+    def declare(self):
+        return self.join(child.declare() for child in self.children if child is not None)
+
+    def define(self):
+        return self.join(child.define() for child in self.children if child is not None)
+
+    def deps(self):
+        deps = set()
+        for child in self.children:
+            if child is None:
+                continue
+            deps = deps.union(child.deps())
+        return deps
+
+    def __len__(self):
+        return len(self.children)
+
+
+class CGGeneric(CGThing):
+    """
+    A class that spits out a fixed string into the codegen.  Can spit out a
+    separate string for the declaration too.
+    """
+    def __init__(self, define="", declare=""):
+        self.declareText = declare
+        self.defineText = define
+
+    def declare(self):
+        return self.declareText
+
+    def define(self):
+        return self.defineText
+
+    def deps(self):
+        return set()
+
+
+class CGIndenter(CGThing):
+    """
+    A class that takes another CGThing and generates code that indents that
+    CGThing by some number of spaces.  The default indent is two spaces.
+    """
+    def __init__(self, child, indentLevel=2, declareOnly=False):
+        assert isinstance(child, CGThing)
+        CGThing.__init__(self)
+        self.child = child
+        self.indentLevel = indentLevel
+        self.declareOnly = declareOnly
+
+    def declare(self):
+        return indent(self.child.declare(), self.indentLevel)
+
+    def define(self):
+        defn = self.child.define()
+        if self.declareOnly:
+            return defn
+        else:
+            return indent(defn, self.indentLevel)
+
+
+class CGWrapper(CGThing):
+    """
+    Generic CGThing that wraps other CGThings with pre and post text.
+    """
+    def __init__(self, child, pre="", post="", declarePre=None,
+                 declarePost=None, definePre=None, definePost=None,
+                 declareOnly=False, defineOnly=False, reindent=False):
+        CGThing.__init__(self)
+        self.child = child
+        self.declarePre = declarePre or pre
+        self.declarePost = declarePost or post
+        self.definePre = definePre or pre
+        self.definePost = definePost or post
+        self.declareOnly = declareOnly
+        self.defineOnly = defineOnly
+        self.reindent = reindent
+
+    def declare(self):
+        if self.defineOnly:
+            return ''
+        decl = self.child.declare()
+        if self.reindent:
+            decl = self.reindentString(decl, self.declarePre)
+        return self.declarePre + decl + self.declarePost
+
+    def define(self):
+        if self.declareOnly:
+            return ''
+        defn = self.child.define()
+        if self.reindent:
+            defn = self.reindentString(defn, self.definePre)
+        return self.definePre + defn + self.definePost
+
+    @staticmethod
+    def reindentString(stringToIndent, widthString):
+        # We don't use lineStartDetector because we don't want to
+        # insert whitespace at the beginning of our _first_ line.
+        # Use the length of the last line of width string, in case
+        # it is a multiline string.
+        lastLineWidth = len(widthString.splitlines()[-1])
+        return stripTrailingWhitespace(
+            stringToIndent.replace("\n", "\n" + (" " * lastLineWidth)))
+
+    def deps(self):
+        return self.child.deps()
+
+
+class CGIfWrapper(CGList):
+    def __init__(self, child, condition):
+        CGList.__init__(self, [
+            CGWrapper(CGGeneric(condition), pre="if (", post=") {\n", reindent=True),
+            CGIndenter(child),
+            CGGeneric("}\n")
+        ])
+
+
+class CGIfElseWrapper(CGList):
+    def __init__(self, condition, ifTrue, ifFalse):
+        CGList.__init__(self, [
+            CGWrapper(CGGeneric(condition), pre="if (", post=") {\n", reindent=True),
+            CGIndenter(ifTrue),
+            CGGeneric("} else {\n"),
+            CGIndenter(ifFalse),
+            CGGeneric("}\n")
+        ])
+
+
+class CGElseChain(CGThing):
+    """
+    Concatenate if statements in an if-else-if-else chain.
+    """
+    def __init__(self, children):
+        self.children = [c for c in children if c is not None]
+
+    def declare(self):
+        assert False
+
+    def define(self):
+        if not self.children:
+            return ""
+        s = self.children[0].define()
+        assert s.endswith("\n")
+        for child in self.children[1:]:
+            code = child.define()
+            assert code.startswith("if") or code.startswith("{")
+            assert code.endswith("\n")
+            s = s.rstrip() + " else " + code
+        return s
+
+
+class CGTemplatedType(CGWrapper):
+    def __init__(self, templateName, child, isConst=False, isReference=False):
+        const = "const " if isConst else ""
+        pre = "%s%s<" % (const, templateName)
+        ref = "&" if isReference else ""
+        post = ">%s" % ref
+        CGWrapper.__init__(self, child, pre=pre, post=post)
+
+
+class CGNamespace(CGWrapper):
+    def __init__(self, namespace, child, declareOnly=False):
+        pre = "namespace %s {\n" % namespace
+        post = "} // namespace %s\n" % namespace
+        CGWrapper.__init__(self, child, pre=pre, post=post,
+                           declareOnly=declareOnly)
+
+    @staticmethod
+    def build(namespaces, child, declareOnly=False):
+        """
+        Static helper method to build multiple wrapped namespaces.
+        """
+        if not namespaces:
+            return CGWrapper(child, declareOnly=declareOnly)
+        inner = CGNamespace.build(namespaces[1:], child, declareOnly=declareOnly)
+        return CGNamespace(namespaces[0], inner, declareOnly=declareOnly)
+
+
+class CGIncludeGuard(CGWrapper):
+    """
+    Generates include guards for a header.
+    """
+    def __init__(self, prefix, child):
+        """|prefix| is the filename without the extension."""
+        define = 'mozilla_dom_%s_h' % prefix
+        CGWrapper.__init__(self, child,
+                           declarePre='#ifndef %s\n#define %s\n\n' % (define, define),
+                           declarePost='\n#endif // %s\n' % define)
+
+
+class CGHeaders(CGWrapper):
+    """
+    Generates the appropriate include statements.
+    """
+    def __init__(self, descriptors, dictionaries, callbacks,
+                 callbackDescriptors,
+                 declareIncludes, defineIncludes, prefix, child,
+                 config=None, jsImplementedDescriptors=[]):
+        """
+        Builds a set of includes to cover |descriptors|.
+
+        Also includes the files in |declareIncludes| in the header
+        file and the files in |defineIncludes| in the .cpp.
+
+        |prefix| contains the basename of the file that we generate include
+        statements for.
+        """
+
+        # Determine the filenames for which we need headers.
+        interfaceDeps = [d.interface for d in descriptors]
+        ancestors = []
+        for iface in interfaceDeps:
+            if iface.parent:
+                # We're going to need our parent's prototype, to use as the
+                # prototype of our prototype object.
+                ancestors.append(iface.parent)
+                # And if we have an interface object, we'll need the nearest
+                # ancestor with an interface object too, so we can use its
+                # interface object as the proto of our interface object.
+                if iface.hasInterfaceObject():
+                    parent = iface.parent
+                    while parent and not parent.hasInterfaceObject():
+                        parent = parent.parent
+                    if parent:
+                        ancestors.append(parent)
+        interfaceDeps.extend(ancestors)
+        bindingIncludes = set(self.getDeclarationFilename(d) for d in interfaceDeps)
+
+        # Grab all the implementation declaration files we need.
+        implementationIncludes = set(d.headerFile for d in descriptors if d.needsHeaderInclude())
+
+        # Grab the includes for checking hasInstance
+        interfacesImplementingSelf = set()
+        for d in descriptors:
+            interfacesImplementingSelf |= d.interface.interfacesImplementingSelf
+        implementationIncludes |= set(self.getDeclarationFilename(i) for i in
+                                      interfacesImplementingSelf)
+
+        # Grab the includes for the things that involve XPCOM interfaces
+        hasInstanceIncludes = set("nsIDOM" + d.interface.identifier.name + ".h" for d
+                                  in descriptors if
+                                  d.interface.hasInterfaceObject() and
+                                  NeedsGeneratedHasInstance(d) and
+                                  d.interface.hasInterfacePrototypeObject())
+        if len(hasInstanceIncludes) > 0:
+            hasInstanceIncludes.add("nsContentUtils.h")
+
+        # Now find all the things we'll need as arguments because we
+        # need to wrap or unwrap them.
+        bindingHeaders = set()
+        declareIncludes = set(declareIncludes)
+
+        def addHeadersForType((t, dictionary)):
+            """
+            Add the relevant headers for this type.  We use dictionary, if
+            passed, to decide what to do with interface types.
+            """
+            # Dictionaries have members that need to be actually
+            # declared, not just forward-declared.
+            if dictionary:
+                headerSet = declareIncludes
+            else:
+                headerSet = bindingHeaders
+            if t.nullable():
+                # Need to make sure that Nullable as a dictionary
+                # member works.
+                headerSet.add("mozilla/dom/Nullable.h")
+            unrolled = t.unroll()
+            if unrolled.isUnion():
+                headerSet.add(self.getUnionDeclarationFilename(config, unrolled))
+                bindingHeaders.add("mozilla/dom/UnionConversions.h")
+            elif unrolled.isDate():
+                if dictionary or jsImplementedDescriptors:
+                    declareIncludes.add("mozilla/dom/Date.h")
+                else:
+                    bindingHeaders.add("mozilla/dom/Date.h")
+            elif unrolled.isInterface():
+                if unrolled.isSpiderMonkeyInterface():
+                    bindingHeaders.add("jsfriendapi.h")
+                    if jsImplementedDescriptors:
+                        # Since we can't forward-declare typed array types
+                        # (because they're typedefs), we have to go ahead and
+                        # just include their header if we need to have functions
+                        # taking references to them declared in that header.
+                        headerSet = declareIncludes
+                    headerSet.add("mozilla/dom/TypedArray.h")
+                else:
+                    try:
+                        typeDesc = config.getDescriptor(unrolled.inner.identifier.name)
+                    except NoSuchDescriptorError:
+                        return
+                    # Dictionaries with interface members rely on the
+                    # actual class definition of that interface member
+                    # being visible in the binding header, because they
+                    # store them in RefPtr and have inline
+                    # constructors/destructors.
+                    #
+                    # XXXbz maybe dictionaries with interface members
+                    # should just have out-of-line constructors and
+                    # destructors?
+                    headerSet.add(typeDesc.headerFile)
+            elif unrolled.isDictionary():
+                headerSet.add(self.getDeclarationFilename(unrolled.inner))
+            elif unrolled.isCallback():
+                headerSet.add(self.getDeclarationFilename(unrolled.callback))
+            elif unrolled.isFloat() and not unrolled.isUnrestricted():
+                # Restricted floats are tested for finiteness
+                bindingHeaders.add("mozilla/FloatingPoint.h")
+                bindingHeaders.add("mozilla/dom/PrimitiveConversions.h")
+            elif unrolled.isEnum():
+                filename = self.getDeclarationFilename(unrolled.inner)
+                declareIncludes.add(filename)
+            elif unrolled.isPrimitive():
+                bindingHeaders.add("mozilla/dom/PrimitiveConversions.h")
+            elif unrolled.isMozMap():
+                if dictionary or jsImplementedDescriptors:
+                    declareIncludes.add("mozilla/dom/MozMap.h")
+                else:
+                    bindingHeaders.add("mozilla/dom/MozMap.h")
+                # Also add headers for the type the MozMap is
+                # parametrized over, if needed.
+                addHeadersForType((t.inner, dictionary))
+
+        map(addHeadersForType,
+            getAllTypes(descriptors + callbackDescriptors, dictionaries,
+                        callbacks))
+
+        # Now make sure we're not trying to include the header from inside itself
+        declareIncludes.discard(prefix + ".h")
+
+        def addHeaderForFunc(func, desc):
+            if func is None:
+                return
+            # Include the right class header, which we can only do
+            # if this is a class member function.
+            if desc is not None and not desc.headerIsDefault:
+                # An explicit header file was provided, assume that we know
+                # what we're doing.
+                return
+
+            if "::" in func:
+                # Strip out the function name and convert "::" to "/"
+                bindingHeaders.add("/".join(func.split("::")[:-1]) + ".h")
+
+        # Now for non-callback descriptors make sure we include any
+        # headers needed by Func declarations and other things like that.
+        for desc in descriptors:
+            # If this is an iterator interface generated for a seperate
+            # iterable interface, skip generating type includes, as we have
+            # what we need in IterableIterator.h
+            if desc.interface.isExternal() or desc.interface.isIteratorInterface():
+                continue
+
+            for m in desc.interface.members:
+                addHeaderForFunc(PropertyDefiner.getStringAttr(m, "Func"), desc)
+                staticTypeOverride = PropertyDefiner.getStringAttr(m, "StaticClassOverride")
+                if staticTypeOverride:
+                    bindingHeaders.add("/".join(staticTypeOverride.split("::")) + ".h")
+            # getExtendedAttribute() returns a list, extract the entry.
+            funcList = desc.interface.getExtendedAttribute("Func")
+            if funcList is not None:
+                addHeaderForFunc(funcList[0], desc)
+
+            if desc.interface.maplikeOrSetlikeOrIterable:
+                # We need ToJSValue.h for maplike/setlike type conversions
+                bindingHeaders.add("mozilla/dom/ToJSValue.h")
+                # Add headers for the key and value types of the
+                # maplike/setlike/iterable, since they'll be needed for
+                # convenience functions
+                if desc.interface.maplikeOrSetlikeOrIterable.hasKeyType():
+                    addHeadersForType((desc.interface.maplikeOrSetlikeOrIterable.keyType,
+                                       None))
+                if desc.interface.maplikeOrSetlikeOrIterable.hasValueType():
+                    addHeadersForType((desc.interface.maplikeOrSetlikeOrIterable.valueType,
+                                       None))
+
+        for d in dictionaries:
+            if d.parent:
+                declareIncludes.add(self.getDeclarationFilename(d.parent))
+            bindingHeaders.add(self.getDeclarationFilename(d))
+            for m in d.members:
+                addHeaderForFunc(PropertyDefiner.getStringAttr(m, "Func"),
+                                 None)
+            # No need to worry about Func on members of ancestors, because that
+            # will happen automatically in whatever files those ancestors live
+            # in.
+
+        for c in callbacks:
+            bindingHeaders.add(self.getDeclarationFilename(c))
+
+        for c in callbackDescriptors:
+            bindingHeaders.add(self.getDeclarationFilename(c.interface))
+
+        if len(callbacks) != 0:
+            # We need CallbackFunction to serve as our parent class
+            declareIncludes.add("mozilla/dom/CallbackFunction.h")
+            # And we need ToJSValue.h so we can wrap "this" objects
+            declareIncludes.add("mozilla/dom/ToJSValue.h")
+
+        if len(callbackDescriptors) != 0 or len(jsImplementedDescriptors) != 0:
+            # We need CallbackInterface to serve as our parent class
+            declareIncludes.add("mozilla/dom/CallbackInterface.h")
+            # And we need ToJSValue.h so we can wrap "this" objects
+            declareIncludes.add("mozilla/dom/ToJSValue.h")
+
+        # Also need to include the headers for ancestors of
+        # JS-implemented interfaces.
+        for jsImplemented in jsImplementedDescriptors:
+            jsParent = jsImplemented.interface.parent
+            if jsParent:
+                parentDesc = jsImplemented.getDescriptor(jsParent.identifier.name)
+                declareIncludes.add(parentDesc.jsImplParentHeader)
+
+        # Let the machinery do its thing.
+        def _includeString(includes):
+            return ''.join(['#include "%s"\n' % i for i in includes]) + '\n'
+        CGWrapper.__init__(self, child,
+                           declarePre=_includeString(sorted(declareIncludes)),
+                           definePre=_includeString(sorted(set(defineIncludes) |
+                                                           bindingIncludes |
+                                                           bindingHeaders |
+                                                           hasInstanceIncludes |
+                                                           implementationIncludes)))
+
+    @staticmethod
+    def getDeclarationFilename(decl):
+        # Use our local version of the header, not the exported one, so that
+        # test bindings, which don't export, will work correctly.
+        basename = os.path.basename(decl.filename())
+        return basename.replace('.webidl', 'Binding.h')
+
+    @staticmethod
+    def getUnionDeclarationFilename(config, unionType):
+        assert unionType.isUnion()
+        assert unionType.unroll() == unionType
+        # If a union is "defined" in multiple files, it goes in UnionTypes.h.
+        if len(config.filenamesPerUnion[unionType.name]) > 1:
+            return "mozilla/dom/UnionTypes.h"
+        # If a union is defined by a built-in typedef, it also goes in
+        # UnionTypes.h.
+        assert len(config.filenamesPerUnion[unionType.name]) == 1
+        if "<unknown>" in config.filenamesPerUnion[unionType.name]:
+            return "mozilla/dom/UnionTypes.h"
+        return CGHeaders.getDeclarationFilename(unionType)
+
+
+def SortedDictValues(d):
+    """
+    Returns a list of values from the dict sorted by key.
+    """
+    return [v for k, v in sorted(d.items())]
+
+
+def UnionsForFile(config, webIDLFile):
+    """
+    Returns a list of union types for all union types that are only used in
+    webIDLFile. If webIDLFile is None this will return the list of tuples for
+    union types that are used in more than one WebIDL file.
+    """
+    return config.unionsPerFilename.get(webIDLFile, [])
+
+
+def UnionTypes(unionTypes, config):
+    """
+    The unionTypes argument should be a list of union types. This is typically
+    the list generated by UnionsForFile.
+
+    Returns a tuple containing a set of header filenames to include in
+    the header for the types in unionTypes, a set of header filenames to
+    include in the implementation file for the types in unionTypes, a set
+    of tuples containing a type declaration and a boolean if the type is a
+    struct for member types of the union, a list of traverse methods,
+    unlink methods and a list of union types. These last three lists only
+    contain unique union types.
+    """
+
+    headers = set()
+    implheaders = set()
+    declarations = set()
+    unionStructs = dict()
+    traverseMethods = dict()
+    unlinkMethods = dict()
+
+    for t in unionTypes:
+        name = str(t)
+        if name not in unionStructs:
+            unionStructs[name] = t
+
+            def addHeadersForType(f):
+                if f.nullable():
+                    headers.add("mozilla/dom/Nullable.h")
+                isSequence = f.isSequence()
+                f = f.unroll()
+                if f.isInterface():
+                    if f.isSpiderMonkeyInterface():
+                        headers.add("jsfriendapi.h")
+                        headers.add("mozilla/dom/TypedArray.h")
+                    else:
+                        try:
+                            typeDesc = config.getDescriptor(f.inner.identifier.name)
+                        except NoSuchDescriptorError:
+                            return
+                        if typeDesc.interface.isCallback() or isSequence:
+                            # Callback interfaces always use strong refs, so
+                            # we need to include the right header to be able
+                            # to Release() in our inlined code.
+                            #
+                            # Similarly, sequences always contain strong
+                            # refs, so we'll need the header to handler
+                            # those.
+                            headers.add(typeDesc.headerFile)
+                        else:
+                            declarations.add((typeDesc.nativeType, False))
+                            implheaders.add(typeDesc.headerFile)
+                elif f.isDictionary():
+                    # For a dictionary, we need to see its declaration in
+                    # UnionTypes.h so we have its sizeof and know how big to
+                    # make our union.
+                    headers.add(CGHeaders.getDeclarationFilename(f.inner))
+                    # And if it needs rooting, we need RootedDictionary too
+                    if typeNeedsRooting(f):
+                        headers.add("mozilla/dom/RootedDictionary.h")
+                elif f.isEnum():
+                    # Need to see the actual definition of the enum,
+                    # unfortunately.
+                    headers.add(CGHeaders.getDeclarationFilename(f.inner))
+                elif f.isCallback():
+                    # Callbacks always use strong refs, so we need to include
+                    # the right header to be able to Release() in our inlined
+                    # code.
+                    headers.add(CGHeaders.getDeclarationFilename(f.callback))
+                elif f.isMozMap():
+                    headers.add("mozilla/dom/MozMap.h")
+                    # And add headers for the type we're parametrized over
+                    addHeadersForType(f.inner)
+
+            implheaders.add(CGHeaders.getUnionDeclarationFilename(config, t))
+            for f in t.flatMemberTypes:
+                assert not f.nullable()
+                addHeadersForType(f)
+
+            if idlTypeNeedsCycleCollection(t):
+                declarations.add(("mozilla::dom::%s" % CGUnionStruct.unionTypeName(t, True), False))
+                traverseMethods[name] = CGCycleCollectionTraverseForOwningUnionMethod(t)
+                unlinkMethods[name] = CGCycleCollectionUnlinkForOwningUnionMethod(t)
+
+    # The order of items in CGList is important.
+    # Since the union structs friend the unlinkMethods, the forward-declaration
+    # for these methods should come before the class declaration. Otherwise
+    # some compilers treat the friend declaration as a forward-declaration in
+    # the class scope.
+    return (headers, implheaders, declarations,
+            SortedDictValues(traverseMethods), SortedDictValues(unlinkMethods),
+            SortedDictValues(unionStructs))
+
+
+def UnionConversions(unionTypes, config):
+    """
+    The unionTypes argument should be a list of tuples, each containing two
+    elements: a union type and a descriptor. This is typically the list
+    generated by UnionsForFile.
+
+    Returns a tuple containing a list of headers and a CGThing to declare all
+    union argument conversion helper structs.
+    """
+    headers = set()
+    unionConversions = dict()
+
+    for t in unionTypes:
+        name = str(t)
+        if name not in unionConversions:
+            unionConversions[name] = CGUnionConversionStruct(t, config)
+
+            def addHeadersForType(f):
+                f = f.unroll()
+                if f.isInterface():
+                    if f.isSpiderMonkeyInterface():
+                        headers.add("jsfriendapi.h")
+                        headers.add("mozilla/dom/TypedArray.h")
+                    elif f.inner.isExternal():
+                        try:
+                            typeDesc = config.getDescriptor(f.inner.identifier.name)
+                        except NoSuchDescriptorError:
+                            return
+                        headers.add(typeDesc.headerFile)
+                    else:
+                        headers.add(CGHeaders.getDeclarationFilename(f.inner))
+                elif f.isDictionary():
+                    headers.add(CGHeaders.getDeclarationFilename(f.inner))
+                elif f.isPrimitive():
+                    headers.add("mozilla/dom/PrimitiveConversions.h")
+                elif f.isMozMap():
+                    headers.add("mozilla/dom/MozMap.h")
+                    # And the internal type of the MozMap
+                    addHeadersForType(f.inner)
+
+            # We plan to include UnionTypes.h no matter what, so it's
+            # OK if we throw it into the set here.
+            headers.add(CGHeaders.getUnionDeclarationFilename(config, t))
+
+            for f in t.flatMemberTypes:
+                addHeadersForType(f)
+
+    return (headers,
+            CGWrapper(CGList(SortedDictValues(unionConversions), "\n"),
+                      post="\n\n"))
+
+
+class Argument():
+    """
+    A class for outputting the type and name of an argument
+    """
+    def __init__(self, argType, name, default=None):
+        self.argType = argType
+        self.name = name
+        self.default = default
+
+    def declare(self):
+        string = self.argType + ' ' + self.name
+        if self.default is not None:
+            string += " = " + self.default
+        return string
+
+    def define(self):
+        return self.argType + ' ' + self.name
+
+
+class CGAbstractMethod(CGThing):
+    """
+    An abstract class for generating code for a method.  Subclasses
+    should override definition_body to create the actual code.
+
+    descriptor is the descriptor for the interface the method is associated with
+
+    name is the name of the method as a string
+
+    returnType is the IDLType of the return value
+
+    args is a list of Argument objects
+
+    inline should be True to generate an inline method, whose body is
+    part of the declaration.
+
+    alwaysInline should be True to generate an inline method annotated with
+    MOZ_ALWAYS_INLINE.
+
+    static should be True to generate a static method, which only has
+    a definition.
+
+    If templateArgs is not None it should be a list of strings containing
+    template arguments, and the function will be templatized using those
+    arguments.
+    """
+    def __init__(self, descriptor, name, returnType, args, inline=False, alwaysInline=False, static=False, templateArgs=None):
+        CGThing.__init__(self)
+        self.descriptor = descriptor
+        self.name = name
+        self.returnType = returnType
+        self.args = args
+        self.inline = inline
+        self.alwaysInline = alwaysInline
+        self.static = static
+        self.templateArgs = templateArgs
+
+    def _argstring(self, declare):
+        return ', '.join([a.declare() if declare else a.define() for a in self.args])
+
+    def _template(self):
+        if self.templateArgs is None:
+            return ''
+        return 'template <%s>\n' % ', '.join(self.templateArgs)
+
+    def _decorators(self):
+        decorators = []
+        if self.alwaysInline:
+            decorators.append('MOZ_ALWAYS_INLINE')
+        elif self.inline:
+            decorators.append('inline')
+        if self.static:
+            decorators.append('static')
+        decorators.append(self.returnType)
+        maybeNewline = " " if self.inline else "\n"
+        return ' '.join(decorators) + maybeNewline
+
+    def declare(self):
+        if self.inline:
+            return self._define(True)
+        return "%s%s%s(%s);\n" % (self._template(), self._decorators(), self.name, self._argstring(True))
+
+    def indent_body(self, body):
+        """
+        Indent the code returned by self.definition_body(). Most classes
+        simply indent everything two spaces. This is here for
+        CGRegisterProtos, which needs custom indentation.
+        """
+        return indent(body)
+
+    def _define(self, fromDeclare=False):
+        return (self.definition_prologue(fromDeclare) +
+                self.indent_body(self.definition_body()) +
+                self.definition_epilogue())
+
+    def define(self):
+        return "" if self.inline else self._define()
+
+    def definition_prologue(self, fromDeclare):
+        return "%s%s%s(%s)\n{\n" % (self._template(), self._decorators(),
+                                    self.name, self._argstring(fromDeclare))
+
+    def definition_epilogue(self):
+        return "}\n"
+
+    def definition_body(self):
+        assert False  # Override me!
+
+
+class CGAbstractStaticMethod(CGAbstractMethod):
+    """
+    Abstract base class for codegen of implementation-only (no
+    declaration) static methods.
+    """
+    def __init__(self, descriptor, name, returnType, args):
+        CGAbstractMethod.__init__(self, descriptor, name, returnType, args,
+                                  inline=False, static=True)
+
+    def declare(self):
+        # We only have implementation
+        return ""
+
+
+class CGAbstractClassHook(CGAbstractStaticMethod):
+    """
+    Meant for implementing JSClass hooks, like Finalize or Trace. Does very raw
+    'this' unwrapping as it assumes that the unwrapped type is always known.
+    """
+    def __init__(self, descriptor, name, returnType, args):
+        CGAbstractStaticMethod.__init__(self, descriptor, name, returnType,
+                                        args)
+
+    def definition_body_prologue(self):
+        return ("%s* self = UnwrapPossiblyNotInitializedDOMObject<%s>(obj);\n" %
+                (self.descriptor.nativeType, self.descriptor.nativeType))
+
+    def definition_body(self):
+        return self.definition_body_prologue() + self.generate_code()
+
+    def generate_code(self):
+        assert False  # Override me!
+
+
+class CGGetJSClassMethod(CGAbstractMethod):
+    def __init__(self, descriptor):
+        CGAbstractMethod.__init__(self, descriptor, 'GetJSClass', 'const JSClass*',
+                                  [])
+
+    def definition_body(self):
+        return "return sClass.ToJSClass();\n"
+
+
+class CGAddPropertyHook(CGAbstractClassHook):
+    """
+    A hook for addProperty, used to preserve our wrapper from GC.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::Handle<JS::Value>', 'val')]
+        CGAbstractClassHook.__init__(self, descriptor, ADDPROPERTY_HOOK_NAME,
+                                     'bool', args)
+
+    def generate_code(self):
+        assert self.descriptor.wrapperCache
+        return dedent("""
+            // We don't want to preserve if we don't have a wrapper, and we
+            // obviously can't preserve if we're not initialized.
+            if (self && self->GetWrapperPreserveColor()) {
+              PreserveWrapper(self);
+            }
+            return true;
+            """)
+
+
+def finalizeHook(descriptor, hookName, freeOp):
+    finalize = ""
+    if descriptor.wrapperCache:
+        finalize += "ClearWrapper(self, self);\n"
+    if descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+        finalize += "self->mExpandoAndGeneration.expando = JS::UndefinedValue();\n"
+    if descriptor.isGlobal():
+        finalize += "mozilla::dom::FinalizeGlobal(CastToJSFreeOp(%s), obj);\n" % freeOp
+    finalize += ("AddForDeferredFinalization<%s>(self);\n" %
+                 descriptor.nativeType)
+    return CGIfWrapper(CGGeneric(finalize), "self")
+
+
+class CGClassFinalizeHook(CGAbstractClassHook):
+    """
+    A hook for finalize, used to release our native object.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('js::FreeOp*', 'fop'), Argument('JSObject*', 'obj')]
+        CGAbstractClassHook.__init__(self, descriptor, FINALIZE_HOOK_NAME,
+                                     'void', args)
+
+    def generate_code(self):
+        return finalizeHook(self.descriptor, self.name, self.args[0].name).define()
+
+
+class CGClassObjectMovedHook(CGAbstractClassHook):
+    """
+    A hook for objectMovedOp, used to update the wrapper cache when an object it
+    is holding moves.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSObject*', 'obj'), Argument('const JSObject*', 'old')]
+        CGAbstractClassHook.__init__(self, descriptor, OBJECT_MOVED_HOOK_NAME,
+                                     'void', args)
+
+    def generate_code(self):
+        assert self.descriptor.wrapperCache
+        return CGIfWrapper(CGGeneric("UpdateWrapper(self, self, obj, old);\n"),
+                           "self").define()
+
+
+def JSNativeArguments():
+    return [Argument('JSContext*', 'cx'),
+            Argument('unsigned', 'argc'),
+            Argument('JS::Value*', 'vp')]
+
+
+class CGClassConstructor(CGAbstractStaticMethod):
+    """
+    JS-visible constructor for our objects
+    """
+    def __init__(self, descriptor, ctor, name=CONSTRUCT_HOOK_NAME):
+        CGAbstractStaticMethod.__init__(self, descriptor, name, 'bool',
+                                        JSNativeArguments())
+        self._ctor = ctor
+
+    def define(self):
+        if not self._ctor:
+            return ""
+        return CGAbstractStaticMethod.define(self)
+
+    def definition_body(self):
+        return self.generate_code()
+
+    def generate_code(self):
+        # [ChromeOnly] interfaces may only be constructed by chrome.
+        chromeOnlyCheck = ""
+        if isChromeOnly(self._ctor):
+            chromeOnlyCheck = dedent("""
+                if (!nsContentUtils::ThreadsafeIsCallerChrome()) {
+                  return ThrowingConstructor(cx, argc, vp);
+                }
+
+                """)
+
+        # Additionally, we want to throw if a caller does a bareword invocation
+        # of a constructor without |new|. We don't enforce this for chrome in
+        # realease builds to avoid the addon compat fallout of making that
+        # change. See bug 916644.
+        #
+        # Figure out the name of our constructor for error reporting purposes.
+        # For unnamed webidl constructors, identifier.name is "constructor" but
+        # the name JS sees is the interface name; for named constructors
+        # identifier.name is the actual name.
+        name = self._ctor.identifier.name
+        if name != "constructor":
+            ctorName = name
+        else:
+            ctorName = self.descriptor.interface.identifier.name
+
+        preamble = fill(
+            """
+            JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+            JS::Rooted<JSObject*> obj(cx, &args.callee());
+            $*{chromeOnlyCheck}
+            if (!args.isConstructing()) {
+              // XXXbz wish I could get the name from the callee instead of
+              // Adding more relocations
+              return ThrowConstructorWithoutNew(cx, "${ctorName}");
+            }
+            JS::Rooted<JSObject*> desiredProto(cx);
+            if (!GetDesiredProto(cx, args, &desiredProto)) {
+              return false;
+            }
+            """,
+            chromeOnlyCheck=chromeOnlyCheck,
+            ctorName=ctorName)
+
+        name = self._ctor.identifier.name
+        nativeName = MakeNativeName(self.descriptor.binaryNameFor(name))
+        callGenerator = CGMethodCall(nativeName, True, self.descriptor,
+                                     self._ctor, isConstructor=True,
+                                     constructorName=ctorName)
+        return preamble + "\n" + callGenerator.define()
+
+
+# Encapsulate the constructor in a helper method to share genConstructorBody with CGJSImplMethod.
+class CGConstructNavigatorObject(CGAbstractMethod):
+    """
+    Construct a new JS-implemented WebIDL DOM object, for use on navigator.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('ErrorResult&', 'aRv')]
+        rtype = 'already_AddRefed<%s>' % descriptor.name
+        CGAbstractMethod.__init__(self, descriptor, "ConstructNavigatorObject",
+                                  rtype, args)
+
+    def definition_body(self):
+        if not self.descriptor.interface.isJSImplemented():
+            raise TypeError("Only JS-implemented classes are currently supported "
+                            "on navigator. See bug 856820.")
+
+        return dedent(
+            """
+            GlobalObject global(cx, obj);
+            if (global.Failed()) {
+              aRv.Throw(NS_ERROR_FAILURE);
+              return nullptr;
+            }
+            """) + genConstructorBody(self.descriptor)
+
+
+def NamedConstructorName(m):
+    return '_' + m.identifier.name
+
+
+class CGNamedConstructors(CGThing):
+    def __init__(self, descriptor):
+        self.descriptor = descriptor
+        CGThing.__init__(self)
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        if len(self.descriptor.interface.namedConstructors) == 0:
+            return ""
+
+        constructorID = "constructors::id::"
+        if self.descriptor.interface.hasInterfaceObject():
+            constructorID += self.descriptor.name
+        else:
+            constructorID += "_ID_Count"
+
+        namedConstructors = ""
+        for n in self.descriptor.interface.namedConstructors:
+            namedConstructors += (
+                "{ \"%s\", { %s, &sNamedConstructorNativePropertyHooks }, %i },\n" %
+                (n.identifier.name, NamedConstructorName(n), methodLength(n)))
+
+        return fill(
+            """
+            const NativePropertyHooks sNamedConstructorNativePropertyHooks = {
+                nullptr,
+                nullptr,
+                nullptr,
+                { nullptr, nullptr },
+                prototypes::id::${name},
+                ${constructorID},
+                nullptr
+            };
+
+            static const NamedConstructor namedConstructors[] = {
+              $*{namedConstructors}
+              { nullptr, { nullptr, nullptr }, 0 }
+            };
+            """,
+            name=self.descriptor.name,
+            constructorID=constructorID,
+            namedConstructors=namedConstructors)
+
+
+class CGHasInstanceHook(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('unsigned', 'argc'),
+                Argument('JS::Value*', 'vp')]
+        assert descriptor.interface.hasInterfaceObject()
+        assert NeedsGeneratedHasInstance(descriptor)
+        CGAbstractStaticMethod.__init__(self, descriptor, HASINSTANCE_HOOK_NAME,
+                                        'bool', args)
+
+    def define(self):
+        return CGAbstractStaticMethod.define(self)
+
+    def definition_body(self):
+        return self.generate_code()
+
+    def generate_code(self):
+        header = dedent("""
+            JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+            if (!args.get(0).isObject()) {
+              args.rval().setBoolean(false);
+              return true;
+            }
+
+            JS::Rooted<JSObject*> instance(cx, &args[0].toObject());
+            """)
+        if self.descriptor.interface.hasInterfacePrototypeObject():
+            return (
+                header +
+                fill(
+                    """
+
+                    static_assert(IsBaseOf<nsISupports, ${nativeType}>::value,
+                                  "HasInstance only works for nsISupports-based classes.");
+
+                    bool ok = InterfaceHasInstance(cx, argc, vp);
+                    if (!ok || args.rval().toBoolean()) {
+                      return ok;
+                    }
+
+                    // FIXME Limit this to chrome by checking xpc::AccessCheck::isChrome(obj).
+                    nsCOMPtr<nsISupports> native =
+                      xpc::UnwrapReflectorToISupports(js::UncheckedUnwrap(instance, /* stopAtWindowProxy = */ false));
+                    nsCOMPtr<nsIDOM${name}> qiResult = do_QueryInterface(native);
+                    args.rval().setBoolean(!!qiResult);
+                    return true;
+                    """,
+                    nativeType=self.descriptor.nativeType,
+                    name=self.descriptor.interface.identifier.name))
+
+        hasInstanceCode = dedent("""
+
+            const DOMJSClass* domClass = GetDOMClass(js::UncheckedUnwrap(instance, /* stopAtWindowProxy = */ false));
+            if (!domClass) {
+              // Not a DOM object, so certainly not an instance of this interface
+              args.rval().setBoolean(false);
+              return true;
+            }
+            """)
+        if self.descriptor.interface.identifier.name == "ChromeWindow":
+            setRval = "args.rval().setBoolean(UnwrapDOMObject<nsGlobalWindow>(js::UncheckedUnwrap(instance, /* stopAtWindowProxy = */ false))->IsChromeWindow())"
+        else:
+            setRval = "args.rval().setBoolean(true)"
+        # Sort interaces implementing self by name so we get stable output.
+        for iface in sorted(self.descriptor.interface.interfacesImplementingSelf,
+                            key=lambda iface: iface.identifier.name):
+            hasInstanceCode += fill(
+                """
+
+                if (domClass->mInterfaceChain[PrototypeTraits<prototypes::id::${name}>::Depth] == prototypes::id::${name}) {
+                  ${setRval};
+                  return true;
+                }
+                """,
+                name=iface.identifier.name,
+                setRval=setRval)
+        hasInstanceCode += ("args.rval().setBoolean(false);\n"
+                            "return true;\n")
+        return header + hasInstanceCode
+
+
+def isChromeOnly(m):
+    return m.getExtendedAttribute("ChromeOnly")
+
+
+class MemberCondition:
+    """
+    An object representing the condition for a member to actually be
+    exposed.  Any of the arguments can be None.  If not
+    None, they should have the following types:
+
+    pref: The name of the preference.
+    func: The name of the function.
+    secureContext: A bool indicating whether a secure context is required.
+    nonExposedGlobals: A set of names of globals.  Can be empty, in which case
+                       it's treated the same way as None.
+    """
+    def __init__(self, pref=None, func=None, secureContext=False,
+                 nonExposedGlobals=None):
+        assert pref is None or isinstance(pref, str)
+        assert func is None or isinstance(func, str)
+        assert isinstance(secureContext, bool)
+        assert nonExposedGlobals is None or isinstance(nonExposedGlobals, set)
+        self.pref = pref
+        self.secureContext = secureContext
+
+        def toFuncPtr(val):
+            if val is None:
+                return "nullptr"
+            return "&" + val
+        self.func = toFuncPtr(func)
+
+        if nonExposedGlobals:
+            # Nonempty set
+            self.nonExposedGlobals = " | ".join(
+                map(lambda g: "GlobalNames::%s" % g,
+                    sorted(nonExposedGlobals)))
+        else:
+            self.nonExposedGlobals = "0"
+
+    def __eq__(self, other):
+        return (self.pref == other.pref and self.func == other.func and
+                self.secureContext == other.secureContext and
+                self.nonExposedGlobals == other.nonExposedGlobals)
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def hasDisablers(self):
+        return (self.pref is not None or
+                self.secureContext or
+                self.func != "nullptr" or
+                self.nonExposedGlobals != "0")
+
+
+class PropertyDefiner:
+    """
+    A common superclass for defining things on prototype objects.
+
+    Subclasses should implement generateArray to generate the actual arrays of
+    things we're defining.  They should also set self.chrome to the list of
+    things only exposed to chrome and self.regular to the list of things exposed
+    to both chrome and web pages.
+    """
+    def __init__(self, descriptor, name):
+        self.descriptor = descriptor
+        self.name = name
+        # self.prefCacheData will store an array of (prefname, bool*)
+        # pairs for our bool var caches.  generateArray will fill it
+        # in as needed.
+        self.prefCacheData = []
+
+    def hasChromeOnly(self):
+        return len(self.chrome) > 0
+
+    def hasNonChromeOnly(self):
+        return len(self.regular) > 0
+
+    def variableName(self, chrome):
+        if chrome:
+            if self.hasChromeOnly():
+                return "sChrome" + self.name
+        else:
+            if self.hasNonChromeOnly():
+                return "s" + self.name
+        return "nullptr"
+
+    def usedForXrays(self):
+        return self.descriptor.wantsXrays
+
+    def __str__(self):
+        # We only need to generate id arrays for things that will end
+        # up used via ResolveProperty or EnumerateProperties.
+        str = self.generateArray(self.regular, self.variableName(False),
+                                 self.usedForXrays())
+        if self.hasChromeOnly():
+            str += self.generateArray(self.chrome, self.variableName(True),
+                                      self.usedForXrays())
+        return str
+
+    @staticmethod
+    def getStringAttr(member, name):
+        attr = member.getExtendedAttribute(name)
+        if attr is None:
+            return None
+        # It's a list of strings
+        assert len(attr) == 1
+        assert attr[0] is not None
+        return attr[0]
+
+    @staticmethod
+    def getControllingCondition(interfaceMember, descriptor):
+        interface = descriptor.interface
+        nonExposureSet = interface.exposureSet - interfaceMember.exposureSet
+
+        return MemberCondition(
+            PropertyDefiner.getStringAttr(interfaceMember,
+                                          "Pref"),
+            PropertyDefiner.getStringAttr(interfaceMember,
+                                          "Func"),
+            interfaceMember.getExtendedAttribute("SecureContext") is not None,
+            nonExposureSet)
+
+    def generatePrefableArray(self, array, name, specFormatter, specTerminator,
+                              specType, getCondition, getDataTuple, doIdArrays):
+        """
+        This method generates our various arrays.
+
+        array is an array of interface members as passed to generateArray
+
+        name is the name as passed to generateArray
+
+        specFormatter is a function that takes a single argument, a tuple,
+          and returns a string, a spec array entry
+
+        specTerminator is a terminator for the spec array (inserted every time
+          our controlling pref changes and at the end of the array)
+
+        specType is the actual typename of our spec
+
+        getCondition is a callback function that takes an array entry and
+          returns the corresponding MemberCondition.
+
+        getDataTuple is a callback function that takes an array entry and
+          returns a tuple suitable to be passed to specFormatter.
+        """
+
+        # We want to generate a single list of specs, but with specTerminator
+        # inserted at every point where the pref name controlling the member
+        # changes.  That will make sure the order of the properties as exposed
+        # on the interface and interface prototype objects does not change when
+        # pref control is added to members while still allowing us to define all
+        # the members in the smallest number of JSAPI calls.
+        assert len(array) != 0
+        # So we won't put a specTerminator at the very front of the list:
+        lastCondition = getCondition(array[0], self.descriptor)
+
+        specs = []
+        disablers = []
+        prefableSpecs = []
+
+        disablersTemplate = dedent(
+            """
+            static PrefableDisablers %s_disablers%d = {
+              true, %s, %s, %s
+            };
+            """)
+        prefableWithDisablersTemplate = '  { &%s_disablers%d, &%s_specs[%d] }'
+        prefableWithoutDisablersTemplate = '  { nullptr, &%s_specs[%d] }'
+        prefCacheTemplate = '&%s[%d].disablers->enabled'
+
+        def switchToCondition(props, condition):
+            # Remember the info about where our pref-controlled
+            # booleans live.
+            if condition.pref is not None:
+                props.prefCacheData.append(
+                    (condition.pref,
+                     prefCacheTemplate % (name, len(prefableSpecs))))
+            # Set up pointers to the new sets of specs inside prefableSpecs
+            if condition.hasDisablers():
+                prefableSpecs.append(prefableWithDisablersTemplate %
+                                     (name, len(specs), name, len(specs)))
+                disablers.append(disablersTemplate %
+                                 (name, len(specs),
+                                  toStringBool(condition.secureContext),
+                                  condition.nonExposedGlobals,
+                                  condition.func))
+            else:
+                prefableSpecs.append(prefableWithoutDisablersTemplate %
+                                     (name, len(specs)))
+
+        switchToCondition(self, lastCondition)
+
+        for member in array:
+            curCondition = getCondition(member, self.descriptor)
+            if lastCondition != curCondition:
+                # Terminate previous list
+                specs.append(specTerminator)
+                # And switch to our new condition
+                switchToCondition(self, curCondition)
+                lastCondition = curCondition
+            # And the actual spec
+            specs.append(specFormatter(getDataTuple(member)))
+        specs.append(specTerminator)
+        prefableSpecs.append("  { nullptr, nullptr }")
+
+        specType = "const " + specType
+        arrays = fill(
+            """
+            static ${specType} ${name}_specs[] = {
+            ${specs}
+            };
+
+            ${disablers}
+            // Can't be const because the pref-enabled boolean needs to be writable
+            static Prefable<${specType}> ${name}[] = {
+            ${prefableSpecs}
+            };
+
+            """,
+            specType=specType,
+            name=name,
+            disablers='\n'.join(disablers),
+            specs=',\n'.join(specs),
+            prefableSpecs=',\n'.join(prefableSpecs))
+        if doIdArrays:
+            arrays += "static jsid %s_ids[%i];\n\n" % (name, len(specs))
+        return arrays
+
+
+# The length of a method is the minimum of the lengths of the
+# argument lists of all its overloads.
+def overloadLength(arguments):
+    i = len(arguments)
+    while i > 0 and arguments[i - 1].optional:
+        i -= 1
+    return i
+
+
+def methodLength(method):
+    signatures = method.signatures()
+    return min(overloadLength(arguments) for retType, arguments in signatures)
+
+
+def clearableCachedAttrs(descriptor):
+    return (m for m in descriptor.interface.members if
+            m.isAttr() and
+            # Constants should never need clearing!
+            m.dependsOn != "Nothing" and
+            m.slotIndices is not None)
+
+
+def MakeClearCachedValueNativeName(member):
+    return "ClearCached%sValue" % MakeNativeName(member.identifier.name)
+
+
+def MakeJSImplClearCachedValueNativeName(member):
+    return "_" + MakeClearCachedValueNativeName(member)
+
+
+def IDLToCIdentifier(name):
+    return name.replace("-", "_")
+
+
+class MethodDefiner(PropertyDefiner):
+    """
+    A class for defining methods on a prototype object.
+    """
+    def __init__(self, descriptor, name, static, unforgeable=False):
+        assert not (static and unforgeable)
+        PropertyDefiner.__init__(self, descriptor, name)
+
+        # FIXME https://bugzilla.mozilla.org/show_bug.cgi?id=772822
+        #       We should be able to check for special operations without an
+        #       identifier. For now we check if the name starts with __
+
+        # Ignore non-static methods for interfaces without a proto object
+        if descriptor.interface.hasInterfacePrototypeObject() or static:
+            methods = [m for m in descriptor.interface.members if
+                       m.isMethod() and m.isStatic() == static and
+                       MemberIsUnforgeable(m, descriptor) == unforgeable and
+                       not m.isIdentifierLess()]
+        else:
+            methods = []
+        self.chrome = []
+        self.regular = []
+        for m in methods:
+            if m.identifier.name == 'queryInterface':
+                if m.isStatic():
+                    raise TypeError("Legacy queryInterface member shouldn't be static")
+                signatures = m.signatures()
+
+                def argTypeIsIID(arg):
+                    return arg.type.inner.isExternal() and arg.type.inner.identifier.name == 'IID'
+                if len(signatures) > 1 or len(signatures[0][1]) > 1 or not argTypeIsIID(signatures[0][1][0]):
+                    raise TypeError("There should be only one queryInterface method with 1 argument of type IID")
+
+                # Make sure to not stick QueryInterface on abstract interfaces that
+                # have hasXPConnectImpls (like EventTarget).  So only put it on
+                # interfaces that are concrete and all of whose ancestors are abstract.
+                def allAncestorsAbstract(iface):
+                    if not iface.parent:
+                        return True
+                    desc = self.descriptor.getDescriptor(iface.parent.identifier.name)
+                    if desc.concrete:
+                        return False
+                    return allAncestorsAbstract(iface.parent)
+                if (not self.descriptor.interface.hasInterfacePrototypeObject() or
+                    not self.descriptor.concrete or
+                    not allAncestorsAbstract(self.descriptor.interface)):
+                    raise TypeError("QueryInterface is only supported on "
+                                    "interfaces that are concrete and all "
+                                    "of whose ancestors are abstract: " +
+                                    self.descriptor.name)
+                condition = "WantsQueryInterface<%s>::Enabled" % descriptor.nativeType
+                self.regular.append({
+                    "name": 'QueryInterface',
+                    "methodInfo": False,
+                    "length": 1,
+                    "flags": "0",
+                    "condition": MemberCondition(func=condition)
+                })
+                continue
+
+            # Iterable methods should be enumerable, maplike/setlike methods
+            # should not.
+            isMaplikeOrSetlikeMethod = (m.isMaplikeOrSetlikeOrIterableMethod() and
+                                        (m.maplikeOrSetlikeOrIterable.isMaplike() or
+                                         m.maplikeOrSetlikeOrIterable.isSetlike()))
+            method = {
+                "name": m.identifier.name,
+                "methodInfo": not m.isStatic(),
+                "length": methodLength(m),
+                # Methods generated for a maplike/setlike declaration are not
+                # enumerable.
+                "flags": "JSPROP_ENUMERATE" if not isMaplikeOrSetlikeMethod else "0",
+                "condition": PropertyDefiner.getControllingCondition(m, descriptor),
+                "allowCrossOriginThis": m.getExtendedAttribute("CrossOriginCallable"),
+                "returnsPromise": m.returnsPromise(),
+                "hasIteratorAlias": "@@iterator" in m.aliases
+            }
+
+            if m.isStatic():
+                method["nativeName"] = CppKeywords.checkMethodName(IDLToCIdentifier(m.identifier.name))
+
+            if isChromeOnly(m):
+                self.chrome.append(method)
+            else:
+                self.regular.append(method)
+
+        # TODO: Once iterable is implemented, use tiebreak rules instead of
+        # failing. Also, may be more tiebreak rules to implement once spec bug
+        # is resolved.
+        # https://www.w3.org/Bugs/Public/show_bug.cgi?id=28592
+        def hasIterator(methods, regular):
+            return (any("@@iterator" in m.aliases for m in methods) or
+                    any("@@iterator" == r["name"] for r in regular))
+
+        # Check whether we need to output an @@iterator due to having an indexed
+        # getter.  We only do this while outputting non-static and
+        # non-unforgeable methods, since the @@iterator function will be
+        # neither.
+        if (not static and
+            not unforgeable and
+            descriptor.supportsIndexedProperties()):
+            if hasIterator(methods, self.regular):
+                raise TypeError("Cannot have indexed getter/attr on "
+                                "interface %s with other members "
+                                "that generate @@iterator, such as "
+                                "maplike/setlike or aliased functions." %
+                                self.descriptor.interface.identifier.name)
+            self.regular.append({
+                "name": "@@iterator",
+                "methodInfo": False,
+                "selfHostedName": "ArrayValues",
+                "length": 0,
+                "flags": "JSPROP_ENUMERATE",
+                "condition": MemberCondition()
+            })
+
+        if (static and
+            not unforgeable and
+            descriptor.interface.hasInterfaceObject() and
+            NeedsGeneratedHasInstance(descriptor)):
+            self.regular.append({
+                "name": "@@hasInstance",
+                "methodInfo": False,
+                "nativeName": HASINSTANCE_HOOK_NAME,
+                "length": 1,
+                # Flags match those of Function[Symbol.hasInstance]
+                "flags": "JSPROP_READONLY | JSPROP_PERMANENT",
+                "condition": MemberCondition()
+            })
+
+        # Generate the keys/values/entries aliases for value iterables.
+        maplikeOrSetlikeOrIterable = descriptor.interface.maplikeOrSetlikeOrIterable
+        if (not static and
+            not unforgeable and
+            maplikeOrSetlikeOrIterable and
+            maplikeOrSetlikeOrIterable.isIterable() and
+            maplikeOrSetlikeOrIterable.isValueIterator()):
+            # Add our keys/values/entries/forEach
+            self.regular.append({
+                "name": "keys",
+                "methodInfo": False,
+                "selfHostedName": "ArrayKeys",
+                "length": 0,
+                "flags": "JSPROP_ENUMERATE",
+                "condition": PropertyDefiner.getControllingCondition(m,
+                                                                     descriptor)
+            })
+            self.regular.append({
+                "name": "values",
+                "methodInfo": False,
+                "selfHostedName": "ArrayValues",
+                "length": 0,
+                "flags": "JSPROP_ENUMERATE",
+                "condition": PropertyDefiner.getControllingCondition(m,
+                                                                     descriptor)
+            })
+            self.regular.append({
+                "name": "entries",
+                "methodInfo": False,
+                "selfHostedName": "ArrayEntries",
+                "length": 0,
+                "flags": "JSPROP_ENUMERATE",
+                "condition": PropertyDefiner.getControllingCondition(m,
+                                                                     descriptor)
+            })
+            self.regular.append({
+                "name": "forEach",
+                "methodInfo": False,
+                "selfHostedName": "ArrayForEach",
+                "length": 1,
+                "flags": "JSPROP_ENUMERATE",
+                "condition": PropertyDefiner.getControllingCondition(m,
+                                                                     descriptor)
+            })
+
+        if not static:
+            stringifier = descriptor.operations['Stringifier']
+            if (stringifier and
+                unforgeable == MemberIsUnforgeable(stringifier, descriptor)):
+                toStringDesc = {
+                    "name": "toString",
+                    "nativeName": stringifier.identifier.name,
+                    "length": 0,
+                    "flags": "JSPROP_ENUMERATE",
+                    "condition": PropertyDefiner.getControllingCondition(stringifier, descriptor)
+                }
+                if isChromeOnly(stringifier):
+                    self.chrome.append(toStringDesc)
+                else:
+                    self.regular.append(toStringDesc)
+            jsonifier = descriptor.operations['Jsonifier']
+            if (jsonifier and
+                unforgeable == MemberIsUnforgeable(jsonifier, descriptor)):
+                toJSONDesc = {
+                    "name": "toJSON",
+                    "nativeName": jsonifier.identifier.name,
+                    "length": 0,
+                    "flags": "JSPROP_ENUMERATE",
+                    "condition": PropertyDefiner.getControllingCondition(jsonifier, descriptor)
+                }
+                if isChromeOnly(jsonifier):
+                    self.chrome.append(toJSONDesc)
+                else:
+                    self.regular.append(toJSONDesc)
+            if (unforgeable and
+                descriptor.interface.getExtendedAttribute("Unforgeable")):
+                # Synthesize our valueOf method
+                self.regular.append({
+                    "name": 'valueOf',
+                    "nativeName": "UnforgeableValueOf",
+                    "methodInfo": False,
+                    "length": 0,
+                    "flags": "JSPROP_ENUMERATE",  # readonly/permanent added
+                                                  # automatically.
+                    "condition": MemberCondition()
+                })
+
+        if descriptor.interface.isJSImplemented():
+            if static:
+                if descriptor.interface.hasInterfaceObject():
+                    self.chrome.append({
+                        "name": '_create',
+                        "nativeName": ("%s::_Create" % descriptor.name),
+                        "methodInfo": False,
+                        "length": 2,
+                        "flags": "0",
+                        "condition": MemberCondition()
+                    })
+            else:
+                for m in clearableCachedAttrs(descriptor):
+                    attrName = MakeNativeName(m.identifier.name)
+                    self.chrome.append({
+                        "name": "_clearCached%sValue" % attrName,
+                        "nativeName": MakeJSImplClearCachedValueNativeName(m),
+                        "methodInfo": False,
+                        "length": "0",
+                        "flags": "0",
+                        "condition": MemberCondition()
+                    })
+
+        self.unforgeable = unforgeable
+
+        if static:
+            if not descriptor.interface.hasInterfaceObject():
+                # static methods go on the interface object
+                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
+        else:
+            if not descriptor.interface.hasInterfacePrototypeObject():
+                # non-static methods go on the interface prototype object
+                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
+
+    def generateArray(self, array, name, doIdArrays):
+        if len(array) == 0:
+            return ""
+
+        def condition(m, d):
+            return m["condition"]
+
+        def flags(m):
+            unforgeable = " | JSPROP_PERMANENT | JSPROP_READONLY" if self.unforgeable else ""
+            return m["flags"] + unforgeable
+
+        def specData(m):
+            if "selfHostedName" in m:
+                selfHostedName = '"%s"' % m["selfHostedName"]
+                assert not m.get("methodInfo", True)
+                accessor = "nullptr"
+                jitinfo = "nullptr"
+            else:
+                selfHostedName = "nullptr"
+                # When defining symbols, function name may not match symbol name
+                methodName = m.get("methodName", m["name"])
+                accessor = m.get("nativeName", IDLToCIdentifier(methodName))
+                if m.get("methodInfo", True):
+                    # Cast this in case the methodInfo is a
+                    # JSTypedMethodJitInfo.
+                    jitinfo = ("reinterpret_cast<const JSJitInfo*>(&%s_methodinfo)" % accessor)
+                    if m.get("allowCrossOriginThis", False):
+                        if m.get("returnsPromise", False):
+                            raise TypeError("%s returns a Promise but should "
+                                            "be allowed cross-origin?" %
+                                            accessor)
+                        accessor = "genericCrossOriginMethod"
+                    elif self.descriptor.needsSpecialGenericOps():
+                        if m.get("returnsPromise", False):
+                            accessor = "genericPromiseReturningMethod"
+                        else:
+                            accessor = "genericMethod"
+                    elif m.get("returnsPromise", False):
+                        accessor = "GenericPromiseReturningBindingMethod"
+                    else:
+                        accessor = "GenericBindingMethod"
+                else:
+                    if m.get("returnsPromise", False):
+                        jitinfo = "&%s_methodinfo" % accessor
+                        accessor = "StaticMethodPromiseWrapper"
+                    else:
+                        jitinfo = "nullptr"
+
+            return (m["name"], accessor, jitinfo, m["length"], flags(m), selfHostedName)
+
+        def formatSpec(fields):
+            if fields[0].startswith("@@"):
+                fields = (fields[0][2:],) + fields[1:]
+                return '  JS_SYM_FNSPEC(%s, %s, %s, %s, %s, %s)' % fields
+            return '  JS_FNSPEC("%s", %s, %s, %s, %s, %s)' % fields
+
+        return self.generatePrefableArray(
+            array, name,
+            formatSpec,
+            '  JS_FS_END',
+            'JSFunctionSpec',
+            condition, specData, doIdArrays)
+
+
+def IsCrossOriginWritable(attr, descriptor):
+    """
+    Return whether the IDLAttribute in question is cross-origin writable on the
+    interface represented by descriptor.  This is needed to handle the fact that
+    some, but not all, interfaces implementing URLUtils want a cross-origin
+    writable .href.
+    """
+    crossOriginWritable = attr.getExtendedAttribute("CrossOriginWritable")
+    if not crossOriginWritable:
+        return False
+    if crossOriginWritable is True:
+        return True
+    assert (isinstance(crossOriginWritable, list) and
+            len(crossOriginWritable) == 1)
+    return crossOriginWritable[0] == descriptor.interface.identifier.name
+
+def isNonExposedNavigatorObjectGetter(attr, descriptor):
+    return (attr.navigatorObjectGetter and
+            not descriptor.getDescriptor(attr.type.inner.identifier.name).register)
+
+class AttrDefiner(PropertyDefiner):
+    def __init__(self, descriptor, name, static, unforgeable=False):
+        assert not (static and unforgeable)
+        PropertyDefiner.__init__(self, descriptor, name)
+        self.name = name
+        # Ignore non-static attributes for interfaces without a proto object
+        if descriptor.interface.hasInterfacePrototypeObject() or static:
+            attributes = [m for m in descriptor.interface.members if
+                          m.isAttr() and m.isStatic() == static and
+                          MemberIsUnforgeable(m, descriptor) == unforgeable and
+                          not isNonExposedNavigatorObjectGetter(m, descriptor)]
+        else:
+            attributes = []
+        self.chrome = [m for m in attributes if isChromeOnly(m)]
+        self.regular = [m for m in attributes if not isChromeOnly(m)]
+        self.static = static
+        self.unforgeable = unforgeable
+
+        if static:
+            if not descriptor.interface.hasInterfaceObject():
+                # static attributes go on the interface object
+                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
+        else:
+            if not descriptor.interface.hasInterfacePrototypeObject():
+                # non-static attributes go on the interface prototype object
+                assert not self.hasChromeOnly() and not self.hasNonChromeOnly()
+
+    def generateArray(self, array, name, doIdArrays):
+        if len(array) == 0:
+            return ""
+
+        def flags(attr):
+            unforgeable = " | JSPROP_PERMANENT" if self.unforgeable else ""
+            # Attributes generated as part of a maplike/setlike declaration are
+            # not enumerable.
+            enumerable = " | JSPROP_ENUMERATE" if not attr.isMaplikeOrSetlikeAttr() else ""
+            return ("JSPROP_SHARED" + enumerable + unforgeable)
+
+        def getter(attr):
+            if self.static:
+                accessor = 'get_' + IDLToCIdentifier(attr.identifier.name)
+                jitinfo = "nullptr"
+            else:
+                if attr.hasLenientThis():
+                    accessor = "genericLenientGetter"
+                elif attr.getExtendedAttribute("CrossOriginReadable"):
+                    accessor = "genericCrossOriginGetter"
+                elif self.descriptor.needsSpecialGenericOps():
+                    accessor = "genericGetter"
+                else:
+                    accessor = "GenericBindingGetter"
+                jitinfo = ("&%s_getterinfo" %
+                           IDLToCIdentifier(attr.identifier.name))
+            return "{ { %s, %s } }" % \
+                   (accessor, jitinfo)
+
+        def setter(attr):
+            if (attr.readonly and
+                attr.getExtendedAttribute("PutForwards") is None and
+                attr.getExtendedAttribute("Replaceable") is None and
+                attr.getExtendedAttribute("LenientSetter") is None):
+                return "JSNATIVE_WRAPPER(nullptr)"
+            if self.static:
+                accessor = 'set_' + IDLToCIdentifier(attr.identifier.name)
+                jitinfo = "nullptr"
+            else:
+                if attr.hasLenientThis():
+                    accessor = "genericLenientSetter"
+                elif IsCrossOriginWritable(attr, self.descriptor):
+                    accessor = "genericCrossOriginSetter"
+                elif self.descriptor.needsSpecialGenericOps():
+                    accessor = "genericSetter"
+                else:
+                    accessor = "GenericBindingSetter"
+                jitinfo = "&%s_setterinfo" % IDLToCIdentifier(attr.identifier.name)
+            return "{ { %s, %s } }" % \
+                   (accessor, jitinfo)
+
+        def specData(attr):
+            return (attr.identifier.name, flags(attr), getter(attr),
+                    setter(attr))
+
+        return self.generatePrefableArray(
+            array, name,
+            lambda fields: '  { "%s", %s, { { %s, %s } } }' % fields,
+            '  JS_PS_END',
+            'JSPropertySpec',
+            PropertyDefiner.getControllingCondition, specData, doIdArrays)
+
+
+class ConstDefiner(PropertyDefiner):
+    """
+    A class for definining constants on the interface object
+    """
+    def __init__(self, descriptor, name):
+        PropertyDefiner.__init__(self, descriptor, name)
+        self.name = name
+        constants = [m for m in descriptor.interface.members if m.isConst()]
+        self.chrome = [m for m in constants if isChromeOnly(m)]
+        self.regular = [m for m in constants if not isChromeOnly(m)]
+
+    def generateArray(self, array, name, doIdArrays):
+        if len(array) == 0:
+            return ""
+
+        def specData(const):
+            return (const.identifier.name,
+                    convertConstIDLValueToJSVal(const.value))
+
+        return self.generatePrefableArray(
+            array, name,
+            lambda fields: '  { "%s", %s }' % fields,
+            '  { 0, JS::UndefinedValue() }',
+            'ConstantSpec',
+            PropertyDefiner.getControllingCondition, specData, doIdArrays)
+
+
+class PropertyArrays():
+    def __init__(self, descriptor):
+        self.staticMethods = MethodDefiner(descriptor, "StaticMethods",
+                                           static=True)
+        self.staticAttrs = AttrDefiner(descriptor, "StaticAttributes",
+                                       static=True)
+        self.methods = MethodDefiner(descriptor, "Methods", static=False)
+        self.attrs = AttrDefiner(descriptor, "Attributes", static=False)
+        self.unforgeableMethods = MethodDefiner(descriptor, "UnforgeableMethods",
+                                                static=False, unforgeable=True)
+        self.unforgeableAttrs = AttrDefiner(descriptor, "UnforgeableAttributes",
+                                            static=False, unforgeable=True)
+        self.consts = ConstDefiner(descriptor, "Constants")
+
+    @staticmethod
+    def arrayNames():
+        return ["staticMethods", "staticAttrs", "methods", "attrs",
+                "unforgeableMethods", "unforgeableAttrs", "consts"]
+
+    def hasChromeOnly(self):
+        return any(getattr(self, a).hasChromeOnly() for a in self.arrayNames())
+
+    def hasNonChromeOnly(self):
+        return any(getattr(self, a).hasNonChromeOnly() for a in self.arrayNames())
+
+    def __str__(self):
+        define = ""
+        for array in self.arrayNames():
+            define += str(getattr(self, array))
+        return define
+
+
+class CGNativeProperties(CGList):
+    def __init__(self, descriptor, properties):
+        def generateNativeProperties(name, chrome):
+            def check(p):
+                return p.hasChromeOnly() if chrome else p.hasNonChromeOnly()
+
+            nativePropsInts = []
+            nativePropsTrios = []
+
+            iteratorAliasIndex = -1
+            for index, item in enumerate(properties.methods.regular):
+                if item.get("hasIteratorAlias"):
+                    iteratorAliasIndex = index
+                    break
+            nativePropsInts.append(CGGeneric(str(iteratorAliasIndex)))
+
+            offset = 0
+            for array in properties.arrayNames():
+                propertyArray = getattr(properties, array)
+                if check(propertyArray):
+                    varName = propertyArray.variableName(chrome)
+                    bitfields = "true,  %d /* %s */" % (offset, varName)
+                    offset += 1
+                    nativePropsInts.append(CGGeneric(bitfields))
+
+                    if propertyArray.usedForXrays():
+                        ids = "%(name)s_ids"
+                    else:
+                        ids = "nullptr"
+                    trio = "{ %(name)s, " + ids + ", %(name)s_specs }"
+                    trio = trio % {'name': varName}
+                    nativePropsTrios.append(CGGeneric(trio))
+                else:
+                    bitfields = "false, 0"
+                    nativePropsInts.append(CGGeneric(bitfields))
+
+            nativePropsTrios = \
+                [CGWrapper(CGIndenter(CGList(nativePropsTrios, ",\n")),
+                           pre='{\n', post='\n}')]
+            nativeProps = nativePropsInts + nativePropsTrios
+            pre = ("static const NativePropertiesN<%d> %s = {\n" %
+                   (offset, name))
+            return CGWrapper(CGIndenter(CGList(nativeProps, ",\n")),
+                             pre=pre, post="\n};\n")
+
+        nativeProperties = []
+        if properties.hasNonChromeOnly():
+            nativeProperties.append(
+                generateNativeProperties("sNativeProperties", False))
+        if properties.hasChromeOnly():
+            nativeProperties.append(
+                generateNativeProperties("sChromeOnlyNativeProperties", True))
+
+        CGList.__init__(self, nativeProperties, "\n")
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        return CGList.define(self)
+
+
+class CGJsonifyAttributesMethod(CGAbstractMethod):
+    """
+    Generate the JsonifyAttributes method for an interface descriptor
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'aCx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('%s*' % descriptor.nativeType, 'self'),
+                Argument('JS::Rooted<JSObject*>&', 'aResult')]
+        CGAbstractMethod.__init__(self, descriptor, 'JsonifyAttributes', 'bool', args)
+
+    def definition_body(self):
+        ret = ''
+        interface = self.descriptor.interface
+        for m in interface.members:
+            if m.isAttr() and not m.isStatic() and m.type.isSerializable():
+                ret += fill(
+                    """
+                    { // scope for "temp"
+                      JS::Rooted<JS::Value> temp(aCx);
+                      if (!get_${name}(aCx, obj, self, JSJitGetterCallArgs(&temp))) {
+                        return false;
+                      }
+                      if (!JS_DefineProperty(aCx, aResult, "${name}", temp, JSPROP_ENUMERATE)) {
+                        return false;
+                      }
+                    }
+                    """,
+                    name=IDLToCIdentifier(m.identifier.name))
+        ret += 'return true;\n'
+        return ret
+
+
+class CGCreateInterfaceObjectsMethod(CGAbstractMethod):
+    """
+    Generate the CreateInterfaceObjects method for an interface descriptor.
+
+    properties should be a PropertyArrays instance.
+    """
+    def __init__(self, descriptor, properties, haveUnscopables):
+        args = [Argument('JSContext*', 'aCx'),
+                Argument('JS::Handle<JSObject*>', 'aGlobal'),
+                Argument('ProtoAndIfaceCache&', 'aProtoAndIfaceCache'),
+                Argument('bool', 'aDefineOnGlobal')]
+        CGAbstractMethod.__init__(self, descriptor, 'CreateInterfaceObjects', 'void', args)
+        self.properties = properties
+        self.haveUnscopables = haveUnscopables
+
+    def definition_body(self):
+        (protoGetter, protoHandleGetter) = InterfacePrototypeObjectProtoGetter(self.descriptor)
+        if protoHandleGetter is None:
+            parentProtoType = "Rooted"
+            getParentProto = "aCx, " + protoGetter
+        else:
+            parentProtoType = "Handle"
+            getParentProto = protoHandleGetter
+        getParentProto = getParentProto + "(aCx)"
+
+        (protoGetter, protoHandleGetter) = InterfaceObjectProtoGetter(self.descriptor)
+        if protoHandleGetter is None:
+            getConstructorProto = "aCx, " + protoGetter
+            constructorProtoType = "Rooted"
+        else:
+            getConstructorProto = protoHandleGetter
+            constructorProtoType = "Handle"
+        getConstructorProto += "(aCx)"
+
+        needInterfaceObject = self.descriptor.interface.hasInterfaceObject()
+        needInterfacePrototypeObject = self.descriptor.interface.hasInterfacePrototypeObject()
+
+        # if we don't need to create anything, why are we generating this?
+        assert needInterfaceObject or needInterfacePrototypeObject
+
+        getParentProto = fill(
+            """
+            JS::${type}<JSObject*> parentProto(${getParentProto});
+            if (!parentProto) {
+              return;
+            }
+            """,
+            type=parentProtoType,
+            getParentProto=getParentProto)
+
+        getConstructorProto = fill(
+            """
+            JS::${type}<JSObject*> constructorProto(${getConstructorProto});
+            if (!constructorProto) {
+              return;
+            }
+            """,
+            type=constructorProtoType,
+            getConstructorProto=getConstructorProto)
+
+        idsToInit = []
+        # There is no need to init any IDs in bindings that don't want Xrays.
+        if self.descriptor.wantsXrays:
+            for var in self.properties.arrayNames():
+                props = getattr(self.properties, var)
+                # We only have non-chrome ids to init if we have no chrome ids.
+                if props.hasChromeOnly():
+                    idsToInit.append(props.variableName(True))
+                if props.hasNonChromeOnly():
+                    idsToInit.append(props.variableName(False))
+        if len(idsToInit) > 0:
+            initIdCalls = ["!InitIds(aCx, %s, %s_ids)" % (varname, varname)
+                           for varname in idsToInit]
+            idsInitedFlag = CGGeneric("static bool sIdsInited = false;\n")
+            setFlag = CGGeneric("sIdsInited = true;\n")
+            initIdConditionals = [CGIfWrapper(CGGeneric("return;\n"), call)
+                                  for call in initIdCalls]
+            initIds = CGList([idsInitedFlag,
+                              CGIfWrapper(CGList(initIdConditionals + [setFlag]),
+                                          "!sIdsInited && NS_IsMainThread()")])
+        else:
+            initIds = None
+
+        prefCacheData = []
+        for var in self.properties.arrayNames():
+            props = getattr(self.properties, var)
+            prefCacheData.extend(props.prefCacheData)
+        if len(prefCacheData) != 0:
+            prefCacheData = [
+                CGGeneric('Preferences::AddBoolVarCache(%s, "%s");\n' % (ptr, pref))
+                for pref, ptr in prefCacheData]
+            prefCache = CGWrapper(CGIndenter(CGList(prefCacheData)),
+                                  pre=("static bool sPrefCachesInited = false;\n"
+                                       "if (!sPrefCachesInited && NS_IsMainThread()) {\n"
+                                       "  sPrefCachesInited = true;\n"),
+                                  post="}\n")
+        else:
+            prefCache = None
+
+        if self.descriptor.interface.ctor():
+            constructArgs = methodLength(self.descriptor.interface.ctor())
+        else:
+            constructArgs = 0
+        if len(self.descriptor.interface.namedConstructors) > 0:
+            namedConstructors = "namedConstructors"
+        else:
+            namedConstructors = "nullptr"
+
+        if needInterfacePrototypeObject:
+            protoClass = "&sPrototypeClass.mBase"
+            protoCache = "&aProtoAndIfaceCache.EntrySlotOrCreate(prototypes::id::%s)" % self.descriptor.name
+            parentProto = "parentProto"
+            getParentProto = CGGeneric(getParentProto)
+        else:
+            protoClass = "nullptr"
+            protoCache = "nullptr"
+            parentProto = "nullptr"
+            getParentProto = None
+
+        if needInterfaceObject:
+            interfaceClass = "&sInterfaceObjectClass.mBase"
+            interfaceCache = "&aProtoAndIfaceCache.EntrySlotOrCreate(constructors::id::%s)" % self.descriptor.name
+            getConstructorProto = CGGeneric(getConstructorProto)
+            constructorProto = "constructorProto"
+        else:
+            # We don't have slots to store the named constructors.
+            assert len(self.descriptor.interface.namedConstructors) == 0
+            interfaceClass = "nullptr"
+            interfaceCache = "nullptr"
+            getConstructorProto = None
+            constructorProto = "nullptr"
+
+        isGlobal = self.descriptor.isGlobal() is not None
+        if self.properties.hasNonChromeOnly():
+            properties = "sNativeProperties.Upcast()"
+        else:
+            properties = "nullptr"
+        if self.properties.hasChromeOnly():
+            chromeProperties = "nsContentUtils::ThreadsafeIsCallerChrome() ? sChromeOnlyNativeProperties.Upcast() : nullptr"
+        else:
+            chromeProperties = "nullptr"
+
+        call = fill(
+            """
+            JS::Heap<JSObject*>* protoCache = ${protoCache};
+            JS::Heap<JSObject*>* interfaceCache = ${interfaceCache};
+            dom::CreateInterfaceObjects(aCx, aGlobal, ${parentProto},
+                                        ${protoClass}, protoCache,
+                                        ${constructorProto}, ${interfaceClass}, ${constructArgs}, ${namedConstructors},
+                                        interfaceCache,
+                                        ${properties},
+                                        ${chromeProperties},
+                                        ${name}, aDefineOnGlobal,
+                                        ${unscopableNames},
+                                        ${isGlobal});
+            """,
+            protoClass=protoClass,
+            parentProto=parentProto,
+            protoCache=protoCache,
+            constructorProto=constructorProto,
+            interfaceClass=interfaceClass,
+            constructArgs=constructArgs,
+            namedConstructors=namedConstructors,
+            interfaceCache=interfaceCache,
+            properties=properties,
+            chromeProperties=chromeProperties,
+            name='"' + self.descriptor.interface.identifier.name + '"' if needInterfaceObject else "nullptr",
+            unscopableNames="unscopableNames" if self.haveUnscopables else "nullptr",
+            isGlobal=toStringBool(isGlobal))
+
+        # If we fail after here, we must clear interface and prototype caches
+        # using this code: intermediate failure must not expose the interface in
+        # partially-constructed state.  Note that every case after here needs an
+        # interface prototype object.
+        failureCode = dedent(
+            """
+            *protoCache = nullptr;
+            if (interfaceCache) {
+              *interfaceCache = nullptr;
+            }
+            return;
+            """)
+
+        aliasedMembers = [m for m in self.descriptor.interface.members if m.isMethod() and m.aliases]
+        if aliasedMembers:
+            assert needInterfacePrototypeObject
+
+            def defineAlias(alias):
+                if alias == "@@iterator":
+                    symbolJSID = "SYMBOL_TO_JSID(JS::GetWellKnownSymbol(aCx, JS::SymbolCode::iterator))"
+                    getSymbolJSID = CGGeneric(fill("JS::Rooted<jsid> iteratorId(aCx, ${symbolJSID});",
+                                                   symbolJSID=symbolJSID))
+                    defineFn = "JS_DefinePropertyById"
+                    prop = "iteratorId"
+                elif alias.startswith("@@"):
+                    raise TypeError("Can't handle any well-known Symbol other than @@iterator")
+                else:
+                    getSymbolJSID = None
+                    defineFn = "JS_DefineProperty"
+                    prop = '"%s"' % alias
+                return CGList([
+                    getSymbolJSID,
+                    # XXX If we ever create non-enumerable properties that can
+                    #     be aliased, we should consider making the aliases
+                    #     match the enumerability of the property being aliased.
+                    CGGeneric(fill(
+                        """
+                        if (!${defineFn}(aCx, proto, ${prop}, aliasedVal, JSPROP_ENUMERATE)) {
+                          $*{failureCode}
+                        }
+                        """,
+                        defineFn=defineFn,
+                        prop=prop,
+                        failureCode=failureCode))
+                ], "\n")
+
+            def defineAliasesFor(m):
+                return CGList([
+                    CGGeneric(fill(
+                        """
+                        if (!JS_GetProperty(aCx, proto, \"${prop}\", &aliasedVal)) {
+                          $*{failureCode}
+                        }
+                        """,
+                        failureCode=failureCode,
+                        prop=m.identifier.name))
+                ] + [defineAlias(alias) for alias in sorted(m.aliases)])
+
+            defineAliases = CGList([
+                CGGeneric(fill("""
+                    // Set up aliases on the interface prototype object we just created.
+                    JS::Handle<JSObject*> proto = GetProtoObjectHandle(aCx);
+                    if (!proto) {
+                      $*{failureCode}
+                    }
+
+                    """,
+                    failureCode=failureCode)),
+                CGGeneric("JS::Rooted<JS::Value> aliasedVal(aCx);\n\n")
+            ] + [defineAliasesFor(m) for m in sorted(aliasedMembers)])
+        else:
+            defineAliases = None
+
+        # Globals handle unforgeables directly in Wrap() instead of
+        # via a holder.
+        if self.descriptor.hasUnforgeableMembers and not self.descriptor.isGlobal():
+            assert needInterfacePrototypeObject
+
+            # We want to use the same JSClass and prototype as the object we'll
+            # end up defining the unforgeable properties on in the end, so that
+            # we can use JS_InitializePropertiesFromCompatibleNativeObject to do
+            # a fast copy.  In the case of proxies that's null, because the
+            # expando object is a vanilla object, but in the case of other DOM
+            # objects it's whatever our class is.
+            if self.descriptor.proxy:
+                holderClass = "nullptr"
+                holderProto = "nullptr"
+            else:
+                holderClass = "sClass.ToJSClass()"
+                holderProto = "*protoCache"
+            createUnforgeableHolder = CGGeneric(fill(
+                """
+                JS::Rooted<JSObject*> unforgeableHolder(aCx);
+                {
+                  JS::Rooted<JSObject*> holderProto(aCx, ${holderProto});
+                  unforgeableHolder = JS_NewObjectWithoutMetadata(aCx, ${holderClass}, holderProto);
+                  if (!unforgeableHolder) {
+                    $*{failureCode}
+                  }
+                }
+                """,
+                holderProto=holderProto,
+                holderClass=holderClass,
+                failureCode=failureCode))
+            defineUnforgeables = InitUnforgeablePropertiesOnHolder(self.descriptor,
+                                                                   self.properties,
+                                                                   failureCode)
+            createUnforgeableHolder = CGList(
+                [createUnforgeableHolder, defineUnforgeables])
+
+            installUnforgeableHolder = CGGeneric(dedent(
+                """
+                if (*protoCache) {
+                  js::SetReservedSlot(*protoCache, DOM_INTERFACE_PROTO_SLOTS_BASE,
+                                      JS::ObjectValue(*unforgeableHolder));
+                }
+                """))
+
+            unforgeableHolderSetup = CGList(
+                [createUnforgeableHolder, installUnforgeableHolder], "\n")
+        else:
+            unforgeableHolderSetup = None
+
+        if self.descriptor.name == "Promise":
+            speciesSetup = CGGeneric(fill(
+                """
+                #ifndef SPIDERMONKEY_PROMISE
+                JS::Rooted<JSObject*> promiseConstructor(aCx, *interfaceCache);
+                JS::Rooted<jsid> species(aCx,
+                  SYMBOL_TO_JSID(JS::GetWellKnownSymbol(aCx, JS::SymbolCode::species)));
+                if (!JS_DefinePropertyById(aCx, promiseConstructor, species, JS::UndefinedHandleValue,
+                                           JSPROP_SHARED, Promise::PromiseSpecies, nullptr)) {
+                  $*{failureCode}
+                }
+                #endif // SPIDERMONKEY_PROMISE
+                """,
+                failureCode=failureCode))
+        else:
+            speciesSetup = None
+
+        if (self.descriptor.interface.isOnGlobalProtoChain() and
+            needInterfacePrototypeObject):
+            makeProtoPrototypeImmutable = CGGeneric(fill(
+                """
+                if (*${protoCache}) {
+                  bool succeeded;
+                  JS::Handle<JSObject*> prot = GetProtoObjectHandle(aCx);
+                  if (!JS_SetImmutablePrototype(aCx, prot, &succeeded)) {
+                    $*{failureCode}
+                  }
+
+                  MOZ_ASSERT(succeeded,
+                             "making a fresh prototype object's [[Prototype]] "
+                             "immutable can internally fail, but it should "
+                             "never be unsuccessful");
+                }
+                """,
+                protoCache=protoCache,
+                failureCode=failureCode))
+        else:
+            makeProtoPrototypeImmutable = None
+
+        return CGList(
+            [getParentProto, getConstructorProto, initIds,
+             prefCache, CGGeneric(call), defineAliases, unforgeableHolderSetup,
+             speciesSetup, makeProtoPrototypeImmutable],
+            "\n").define()
+
+
+class CGGetPerInterfaceObject(CGAbstractMethod):
+    """
+    A method for getting a per-interface object (a prototype object or interface
+    constructor object).
+    """
+    def __init__(self, descriptor, name, idPrefix="", extraArgs=[]):
+        args = [Argument('JSContext*', 'aCx')] + extraArgs
+        CGAbstractMethod.__init__(self, descriptor, name,
+                                  'JS::Handle<JSObject*>', args)
+        self.id = idPrefix + "id::" + self.descriptor.name
+
+    def definition_body(self):
+        return fill(
+            """
+            /* Make sure our global is sane.  Hopefully we can remove this sometime */
+            JSObject* global = JS::CurrentGlobalOrNull(aCx);
+            if (!(js::GetObjectClass(global)->flags & JSCLASS_DOM_GLOBAL)) {
+              return nullptr;
+            }
+
+            /* Check to see whether the interface objects are already installed */
+            ProtoAndIfaceCache& protoAndIfaceCache = *GetProtoAndIfaceCache(global);
+            if (!protoAndIfaceCache.EntrySlotIfExists(${id})) {
+              JS::Rooted<JSObject*> rootedGlobal(aCx, global);
+              CreateInterfaceObjects(aCx, rootedGlobal, protoAndIfaceCache, aDefineOnGlobal);
+            }
+
+            /*
+             * The object might _still_ be null, but that's OK.
+             *
+             * Calling fromMarkedLocation() is safe because protoAndIfaceCache is
+             * traced by TraceProtoAndIfaceCache() and its contents are never
+             * changed after they have been set.
+             *
+             * Calling address() avoids the read read barrier that does gray
+             * unmarking, but it's not possible for the object to be gray here.
+             */
+
+            const JS::Heap<JSObject*>& entrySlot = protoAndIfaceCache.EntrySlotMustExist(${id});
+            MOZ_ASSERT_IF(entrySlot, !JS::ObjectIsMarkedGray(entrySlot));
+            return JS::Handle<JSObject*>::fromMarkedLocation(entrySlot.address());
+            """,
+            id=self.id)
+
+
+class CGGetProtoObjectHandleMethod(CGGetPerInterfaceObject):
+    """
+    A method for getting the interface prototype object.
+    """
+    def __init__(self, descriptor):
+        CGGetPerInterfaceObject.__init__(self, descriptor, "GetProtoObjectHandle",
+                                         "prototypes::")
+
+    def definition_body(self):
+        return dedent("""
+            /* Get the interface prototype object for this class.  This will create the
+               object as needed. */
+            bool aDefineOnGlobal = true;
+
+            """) + CGGetPerInterfaceObject.definition_body(self)
+
+
+class CGGetProtoObjectMethod(CGAbstractMethod):
+    """
+    A method for getting the interface prototype object.
+    """
+    def __init__(self, descriptor):
+        CGAbstractMethod.__init__(
+            self, descriptor, "GetProtoObject", "JSObject*",
+            [Argument('JSContext*', 'aCx')])
+
+    def definition_body(self):
+        return "return GetProtoObjectHandle(aCx);\n"
+
+
+class CGGetConstructorObjectHandleMethod(CGGetPerInterfaceObject):
+    """
+    A method for getting the interface constructor object.
+    """
+    def __init__(self, descriptor):
+        CGGetPerInterfaceObject.__init__(
+            self, descriptor, "GetConstructorObjectHandle",
+            "constructors::",
+            extraArgs=[Argument("bool", "aDefineOnGlobal", "true")])
+
+    def definition_body(self):
+        return dedent("""
+            /* Get the interface object for this class.  This will create the object as
+               needed. */
+
+            """) + CGGetPerInterfaceObject.definition_body(self)
+
+
+class CGGetConstructorObjectMethod(CGAbstractMethod):
+    """
+    A method for getting the interface constructor object.
+    """
+    def __init__(self, descriptor):
+        CGAbstractMethod.__init__(
+            self, descriptor, "GetConstructorObject", "JSObject*",
+            [Argument('JSContext*', 'aCx')])
+
+    def definition_body(self):
+        return "return GetConstructorObjectHandle(aCx);\n"
+
+
+class CGGetNamedPropertiesObjectMethod(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'aCx')]
+        CGAbstractStaticMethod.__init__(self, descriptor,
+                                        'GetNamedPropertiesObject',
+                                        'JSObject*', args)
+
+    def definition_body(self):
+        parentProtoName = self.descriptor.parentPrototypeName
+        if parentProtoName is None:
+            getParentProto = ""
+            parentProto = "nullptr"
+        else:
+            getParentProto = fill(
+                """
+                JS::Rooted<JSObject*> parentProto(aCx, ${parent}::GetProtoObjectHandle(aCx));
+                if (!parentProto) {
+                  return nullptr;
+                }
+                """,
+                parent=toBindingNamespace(parentProtoName))
+            parentProto = "parentProto"
+        return fill(
+            """
+            /* Make sure our global is sane.  Hopefully we can remove this sometime */
+            JSObject* global = JS::CurrentGlobalOrNull(aCx);
+            if (!(js::GetObjectClass(global)->flags & JSCLASS_DOM_GLOBAL)) {
+              return nullptr;
+            }
+
+            /* Check to see whether the named properties object has already been created */
+            ProtoAndIfaceCache& protoAndIfaceCache = *GetProtoAndIfaceCache(global);
+
+            JS::Heap<JSObject*>& namedPropertiesObject = protoAndIfaceCache.EntrySlotOrCreate(namedpropertiesobjects::id::${ifaceName});
+            if (!namedPropertiesObject) {
+              $*{getParentProto}
+              namedPropertiesObject = ${nativeType}::CreateNamedPropertiesObject(aCx, ${parentProto});
+              DebugOnly<const DOMIfaceAndProtoJSClass*> clasp =
+                DOMIfaceAndProtoJSClass::FromJSClass(js::GetObjectClass(namedPropertiesObject));
+              MOZ_ASSERT(clasp->mType == eNamedPropertiesObject,
+                         "Expected ${nativeType}::CreateNamedPropertiesObject to return a named properties object");
+              MOZ_ASSERT(clasp->mNativeHooks,
+                         "The named properties object for ${nativeType} should have NativePropertyHooks.");
+              MOZ_ASSERT(clasp->mNativeHooks->mResolveOwnProperty,
+                         "Don't know how to resolve the properties of the named properties object for ${nativeType}.");
+              MOZ_ASSERT(clasp->mNativeHooks->mEnumerateOwnProperties,
+                         "Don't know how to enumerate the properties of the named properties object for ${nativeType}.");
+            }
+            return namedPropertiesObject.get();
+            """,
+            getParentProto=getParentProto,
+            ifaceName=self.descriptor.name,
+            parentProto=parentProto,
+            nativeType=self.descriptor.nativeType)
+
+
+class CGDefineDOMInterfaceMethod(CGAbstractMethod):
+    """
+    A method for resolve hooks to try to lazily define the interface object for
+    a given interface.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'aCx'),
+                Argument('JS::Handle<JSObject*>', 'aGlobal'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('bool', 'aDefineOnGlobal')]
+        CGAbstractMethod.__init__(self, descriptor, 'DefineDOMInterface', 'JSObject*', args)
+
+    def definition_body(self):
+        if len(self.descriptor.interface.namedConstructors) > 0:
+            getConstructor = dedent("""
+                JSObject* interfaceObject = GetConstructorObjectHandle(aCx, aDefineOnGlobal);
+                if (!interfaceObject) {
+                  return nullptr;
+                }
+                for (unsigned slot = DOM_INTERFACE_SLOTS_BASE; slot < JSCLASS_RESERVED_SLOTS(&sInterfaceObjectClass.mBase); ++slot) {
+                  JSObject* constructor = &js::GetReservedSlot(interfaceObject, slot).toObject();
+                  if (JS_GetFunctionId(JS_GetObjectFunction(constructor)) == JSID_TO_STRING(id)) {
+                    return constructor;
+                  }
+                }
+                return interfaceObject;
+                """)
+        else:
+            getConstructor = "return GetConstructorObjectHandle(aCx, aDefineOnGlobal);\n"
+        return getConstructor
+
+
+def getConditionList(idlobj, cxName, objName):
+    """
+    Get the list of conditions for idlobj (to be used in "is this enabled"
+    checks).  This will be returned as a CGList with " &&\n" as the separator,
+    for readability.
+
+    objName is the name of the object that we're working with, because some of
+    our test functions want that.
+    """
+    conditions = []
+    pref = idlobj.getExtendedAttribute("Pref")
+    if pref:
+        assert isinstance(pref, list) and len(pref) == 1
+        conditions.append('Preferences::GetBool("%s")' % pref[0])
+    if idlobj.getExtendedAttribute("ChromeOnly"):
+        conditions.append("nsContentUtils::ThreadsafeIsCallerChrome()")
+    func = idlobj.getExtendedAttribute("Func")
+    if func:
+        assert isinstance(func, list) and len(func) == 1
+        conditions.append("%s(%s, %s)" % (func[0], cxName, objName))
+    if idlobj.getExtendedAttribute("SecureContext"):
+        conditions.append("mozilla::dom::IsSecureContextOrObjectIsFromSecureContext(%s, %s)" % (cxName, objName))
+
+    return CGList((CGGeneric(cond) for cond in conditions), " &&\n")
+
+
+class CGConstructorEnabled(CGAbstractMethod):
+    """
+    A method for testing whether we should be exposing this interface
+    object or navigator property.  This can perform various tests
+    depending on what conditions are specified on the interface.
+    """
+    def __init__(self, descriptor):
+        CGAbstractMethod.__init__(self, descriptor,
+                                  'ConstructorEnabled', 'bool',
+                                  [Argument("JSContext*", "aCx"),
+                                   Argument("JS::Handle<JSObject*>", "aObj")])
+
+    def definition_body(self):
+        body = CGList([], "\n")
+
+        iface = self.descriptor.interface
+
+        if not iface.isExposedOnMainThread():
+            exposedInWindowCheck = dedent(
+                """
+                MOZ_ASSERT(!NS_IsMainThread(), "Why did we even get called?");
+                """)
+            body.append(CGGeneric(exposedInWindowCheck))
+
+        if iface.isExposedInSomeButNotAllWorkers():
+            workerGlobals = sorted(iface.getWorkerExposureSet())
+            workerCondition = CGList((CGGeneric('strcmp(name, "%s")' % workerGlobal)
+                                      for workerGlobal in workerGlobals), " && ")
+            exposedInWorkerCheck = fill(
+                """
+                const char* name = js::GetObjectClass(aObj)->name;
+                if (${workerCondition}) {
+                  return false;
+                }
+                """, workerCondition=workerCondition.define())
+            exposedInWorkerCheck = CGGeneric(exposedInWorkerCheck)
+            if iface.isExposedOnMainThread():
+                exposedInWorkerCheck = CGIfWrapper(exposedInWorkerCheck,
+                                                   "!NS_IsMainThread()")
+            body.append(exposedInWorkerCheck)
+
+        conditions = getConditionList(iface, "aCx", "aObj")
+
+        # We should really have some conditions
+        assert len(body) or len(conditions)
+
+        conditionsWrapper = ""
+        if len(conditions):
+            conditionsWrapper = CGWrapper(conditions,
+                                          pre="return ",
+                                          post=";\n",
+                                          reindent=True)
+        else:
+            conditionsWrapper = CGGeneric("return true;\n")
+
+        body.append(conditionsWrapper)
+        return body.define()
+
+
+def CreateBindingJSObject(descriptor, properties):
+    objDecl = "BindingJSObjectCreator<%s> creator(aCx);\n" % descriptor.nativeType
+
+    # We don't always need to root obj, but there are a variety
+    # of cases where we do, so for simplicity, just always root it.
+    if descriptor.proxy:
+        create = dedent(
+            """
+            creator.CreateProxyObject(aCx, &sClass.mBase, DOMProxyHandler::getInstance(),
+                                      proto, aObject, aReflector);
+            if (!aReflector) {
+              return false;
+            }
+
+            """)
+        if descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+            create += dedent("""
+                js::SetProxyExtra(aReflector, JSPROXYSLOT_EXPANDO,
+                                  JS::PrivateValue(&aObject->mExpandoAndGeneration));
+
+                """)
+    else:
+        create = dedent(
+            """
+            creator.CreateObject(aCx, sClass.ToJSClass(), proto, aObject, aReflector);
+            if (!aReflector) {
+              return false;
+            }
+            """)
+    return objDecl + create
+
+
+def InitUnforgeablePropertiesOnHolder(descriptor, properties, failureCode,
+                                      holderName="unforgeableHolder"):
+    """
+    Define the unforgeable properties on the unforgeable holder for
+    the interface represented by descriptor.
+
+    properties is a PropertyArrays instance.
+
+    """
+    assert (properties.unforgeableAttrs.hasNonChromeOnly() or
+            properties.unforgeableAttrs.hasChromeOnly() or
+            properties.unforgeableMethods.hasNonChromeOnly() or
+            properties.unforgeableMethods.hasChromeOnly())
+
+    unforgeables = []
+
+    defineUnforgeableAttrs = fill(
+        """
+        if (!DefineUnforgeableAttributes(aCx, ${holderName}, %s)) {
+          $*{failureCode}
+        }
+        """,
+        failureCode=failureCode,
+        holderName=holderName)
+    defineUnforgeableMethods = fill(
+        """
+        if (!DefineUnforgeableMethods(aCx, ${holderName}, %s)) {
+          $*{failureCode}
+        }
+        """,
+        failureCode=failureCode,
+        holderName=holderName)
+
+    unforgeableMembers = [
+        (defineUnforgeableAttrs, properties.unforgeableAttrs),
+        (defineUnforgeableMethods, properties.unforgeableMethods)
+    ]
+    for (template, array) in unforgeableMembers:
+        if array.hasNonChromeOnly():
+            unforgeables.append(CGGeneric(template % array.variableName(False)))
+        if array.hasChromeOnly():
+            unforgeables.append(
+                CGIfWrapper(CGGeneric(template % array.variableName(True)),
+                            "nsContentUtils::ThreadsafeIsCallerChrome()"))
+
+    if descriptor.interface.getExtendedAttribute("Unforgeable"):
+        # We do our undefined toJSON and toPrimitive here, not as a regular
+        # property because we don't have a concept of value props anywhere in
+        # IDL.
+        unforgeables.append(CGGeneric(fill(
+            """
+            JS::RootedId toPrimitive(aCx,
+              SYMBOL_TO_JSID(JS::GetWellKnownSymbol(aCx, JS::SymbolCode::toPrimitive)));
+            if (!JS_DefinePropertyById(aCx, ${holderName}, toPrimitive,
+                                       JS::UndefinedHandleValue,
+                                       JSPROP_READONLY | JSPROP_PERMANENT) ||
+                !JS_DefineProperty(aCx, ${holderName}, "toJSON",
+                                   JS::UndefinedHandleValue,
+                                   JSPROP_READONLY | JSPROP_ENUMERATE | JSPROP_PERMANENT)) {
+              $*{failureCode}
+            }
+            """,
+            failureCode=failureCode,
+            holderName=holderName)))
+
+    return CGWrapper(CGList(unforgeables), pre="\n")
+
+
+def CopyUnforgeablePropertiesToInstance(descriptor, failureCode):
+    """
+    Copy the unforgeable properties from the unforgeable holder for
+    this interface to the instance object we have.
+    """
+    assert not descriptor.isGlobal();
+
+    if not descriptor.hasUnforgeableMembers:
+        return ""
+
+    copyCode = [
+        CGGeneric(dedent(
+            """
+            // Important: do unforgeable property setup after we have handed
+            // over ownership of the C++ object to obj as needed, so that if
+            // we fail and it ends up GCed it won't have problems in the
+            // finalizer trying to drop its ownership of the C++ object.
+            """))
+    ]
+
+    # For proxies, we want to define on the expando object, not directly on the
+    # reflector, so we can make sure we don't get confused by named getters.
+    if descriptor.proxy:
+        copyCode.append(CGGeneric(fill(
+            """
+            JS::Rooted<JSObject*> expando(aCx,
+              DOMProxyHandler::EnsureExpandoObject(aCx, aReflector));
+            if (!expando) {
+              $*{failureCode}
+            }
+            """,
+            failureCode=failureCode)))
+        obj = "expando"
+    else:
+        obj = "aReflector"
+
+    copyCode.append(CGGeneric(fill(
+        """
+        JS::Rooted<JSObject*> unforgeableHolder(aCx,
+          &js::GetReservedSlot(canonicalProto, DOM_INTERFACE_PROTO_SLOTS_BASE).toObject());
+        if (!JS_InitializePropertiesFromCompatibleNativeObject(aCx, ${obj}, unforgeableHolder)) {
+          $*{failureCode}
+        }
+        """,
+        obj=obj,
+        failureCode=failureCode)))
+
+    return CGWrapper(CGList(copyCode), pre="\n").define()
+
+
+def AssertInheritanceChain(descriptor):
+    asserts = ""
+    iface = descriptor.interface
+    while iface:
+        desc = descriptor.getDescriptor(iface.identifier.name)
+        asserts += (
+            "MOZ_ASSERT(static_cast<%s*>(aObject) == \n"
+            "           reinterpret_cast<%s*>(aObject),\n"
+            "           \"Multiple inheritance for %s is broken.\");\n" %
+            (desc.nativeType, desc.nativeType, desc.nativeType))
+        iface = iface.parent
+    asserts += "MOZ_ASSERT(ToSupportsIsCorrect(aObject));\n"
+    return asserts
+
+
+def InitMemberSlots(descriptor, failureCode):
+    """
+    Initialize member slots on our JS object if we're supposed to have some.
+
+    Note that this is called after the SetWrapper() call in the
+    wrapperCache case, since that can affect how our getters behave
+    and we plan to invoke them here.  So if we fail, we need to
+    ClearWrapper.
+    """
+    if not descriptor.interface.hasMembersInSlots():
+        return ""
+    return fill(
+        """
+        if (!UpdateMemberSlots(aCx, aReflector, aObject)) {
+          $*{failureCode}
+        }
+        """,
+        failureCode=failureCode)
+
+
+def SetImmutablePrototype(descriptor, failureCode):
+    if not descriptor.hasNonOrdinaryGetPrototypeOf():
+        return ""
+
+    return fill(
+        """
+        bool succeeded;
+        if (!JS_SetImmutablePrototype(aCx, aReflector, &succeeded)) {
+          ${failureCode}
+        }
+        MOZ_ASSERT(succeeded,
+                   "Making a fresh reflector instance have an immutable "
+                   "prototype can internally fail, but it should never be "
+                   "unsuccessful");
+        """,
+        failureCode=failureCode)
+
+
+def DeclareProto():
+    """
+    Declare the canonicalProto and proto we have for our wrapping operation.
+    """
+    return dedent(
+        """
+        JS::Handle<JSObject*> canonicalProto = GetProtoObjectHandle(aCx);
+        if (!canonicalProto) {
+          return false;
+        }
+        JS::Rooted<JSObject*> proto(aCx);
+        if (aGivenProto) {
+          proto = aGivenProto;
+          // Unfortunately, while aGivenProto was in the compartment of aCx
+          // coming in, we changed compartments to that of "parent" so may need
+          // to wrap the proto here.
+          if (js::GetContextCompartment(aCx) != js::GetObjectCompartment(proto)) {
+            if (!JS_WrapObject(aCx, &proto)) {
+              return false;
+            }
+          }
+        } else {
+          proto = canonicalProto;
+        }
+        """)
+
+
+class CGWrapWithCacheMethod(CGAbstractMethod):
+    """
+    Create a wrapper JSObject for a given native that implements nsWrapperCache.
+
+    properties should be a PropertyArrays instance.
+    """
+    def __init__(self, descriptor, properties):
+        assert descriptor.interface.hasInterfacePrototypeObject()
+        args = [Argument('JSContext*', 'aCx'),
+                Argument(descriptor.nativeType + '*', 'aObject'),
+                Argument('nsWrapperCache*', 'aCache'),
+                Argument('JS::Handle<JSObject*>', 'aGivenProto'),
+                Argument('JS::MutableHandle<JSObject*>', 'aReflector')]
+        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'bool', args)
+        self.properties = properties
+
+    def definition_body(self):
+        if self.descriptor.proxy:
+            preserveWrapper = dedent(
+                """
+                // For DOM proxies, the only reliable way to preserve the wrapper
+                // is to force creation of the expando object.
+                JS::Rooted<JSObject*> unused(aCx,
+                  DOMProxyHandler::EnsureExpandoObject(aCx, aReflector));
+                """)
+        else:
+            preserveWrapper = "PreserveWrapper(aObject);\n"
+
+        failureCode = dedent(
+            """
+            aCache->ReleaseWrapper(aObject);
+            aCache->ClearWrapper();
+            return false;
+            """)
+
+        return fill(
+            """
+            $*{assertInheritance}
+            MOZ_ASSERT(!aCache->GetWrapper(),
+                       "You should probably not be using Wrap() directly; use "
+                       "GetOrCreateDOMReflector instead");
+
+            MOZ_ASSERT(ToSupportsIsOnPrimaryInheritanceChain(aObject, aCache),
+                       "nsISupports must be on our primary inheritance chain");
+
+            JS::Rooted<JSObject*> global(aCx, FindAssociatedGlobal(aCx, aObject->GetParentObject()));
+            if (!global) {
+              return false;
+            }
+            MOZ_ASSERT(JS_IsGlobalObject(global));
+            MOZ_ASSERT(!JS::ObjectIsMarkedGray(global));
+
+            // That might have ended up wrapping us already, due to the wonders
+            // of XBL.  Check for that, and bail out as needed.
+            aReflector.set(aCache->GetWrapper());
+            if (aReflector) {
+            #ifdef DEBUG
+              binding_detail::AssertReflectorHasGivenProto(aCx, aReflector, aGivenProto);
+            #endif // DEBUG
+              return true;
+            }
+
+            JSAutoCompartment ac(aCx, global);
+            $*{declareProto}
+
+            $*{createObject}
+
+            aCache->SetWrapper(aReflector);
+            $*{unforgeable}
+            $*{slots}
+            $*{setImmutablePrototype}
+            creator.InitializationSucceeded();
+
+            MOZ_ASSERT(aCache->GetWrapperPreserveColor() &&
+                       aCache->GetWrapperPreserveColor() == aReflector);
+            // If proto != canonicalProto, we have to preserve our wrapper;
+            // otherwise we won't be able to properly recreate it later, since
+            // we won't know what proto to use.  Note that we don't check
+            // aGivenProto here, since it's entirely possible (and even
+            // somewhat common) to have a non-null aGivenProto which is the
+            // same as canonicalProto.
+            if (proto != canonicalProto) {
+              $*{preserveWrapper}
+            }
+
+            return true;
+            """,
+            assertInheritance=AssertInheritanceChain(self.descriptor),
+            declareProto=DeclareProto(),
+            createObject=CreateBindingJSObject(self.descriptor, self.properties),
+            unforgeable=CopyUnforgeablePropertiesToInstance(self.descriptor,
+                                                            failureCode),
+            slots=InitMemberSlots(self.descriptor, failureCode),
+            setImmutablePrototype=SetImmutablePrototype(self.descriptor,
+                                                        failureCode),
+            preserveWrapper=preserveWrapper)
+
+
+class CGWrapMethod(CGAbstractMethod):
+    def __init__(self, descriptor):
+        # XXX can we wrap if we don't have an interface prototype object?
+        assert descriptor.interface.hasInterfacePrototypeObject()
+        args = [Argument('JSContext*', 'aCx'),
+                Argument('T*', 'aObject'),
+                Argument('JS::Handle<JSObject*>', 'aGivenProto')]
+        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'JSObject*', args,
+                                  inline=True, templateArgs=["class T"])
+
+    def definition_body(self):
+        return dedent("""
+            JS::Rooted<JSObject*> reflector(aCx);
+            return Wrap(aCx, aObject, aObject, aGivenProto, &reflector) ? reflector.get() : nullptr;
+            """)
+
+
+class CGWrapNonWrapperCacheMethod(CGAbstractMethod):
+    """
+    Create a wrapper JSObject for a given native that does not implement
+    nsWrapperCache.
+
+    properties should be a PropertyArrays instance.
+    """
+    def __init__(self, descriptor, properties):
+        # XXX can we wrap if we don't have an interface prototype object?
+        assert descriptor.interface.hasInterfacePrototypeObject()
+        args = [Argument('JSContext*', 'aCx'),
+                Argument(descriptor.nativeType + '*', 'aObject'),
+                Argument('JS::Handle<JSObject*>', 'aGivenProto'),
+                Argument('JS::MutableHandle<JSObject*>', 'aReflector')]
+        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'bool', args)
+        self.properties = properties
+
+    def definition_body(self):
+        failureCode = "return false;\n"
+
+        return fill(
+            """
+            $*{assertions}
+
+            JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
+            $*{declareProto}
+
+            $*{createObject}
+
+            $*{unforgeable}
+
+            $*{slots}
+
+            $*{setImmutablePrototype}
+            creator.InitializationSucceeded();
+            return true;
+            """,
+            assertions=AssertInheritanceChain(self.descriptor),
+            declareProto=DeclareProto(),
+            createObject=CreateBindingJSObject(self.descriptor, self.properties),
+            unforgeable=CopyUnforgeablePropertiesToInstance(self.descriptor,
+                                                            failureCode),
+            slots=InitMemberSlots(self.descriptor, failureCode),
+            setImmutablePrototype=SetImmutablePrototype(self.descriptor,
+                                                        failureCode))
+
+
+class CGWrapGlobalMethod(CGAbstractMethod):
+    """
+    Create a wrapper JSObject for a global.  The global must implement
+    nsWrapperCache.
+
+    properties should be a PropertyArrays instance.
+    """
+    def __init__(self, descriptor, properties):
+        assert descriptor.interface.hasInterfacePrototypeObject()
+        args = [Argument('JSContext*', 'aCx'),
+                Argument(descriptor.nativeType + '*', 'aObject'),
+                Argument('nsWrapperCache*', 'aCache'),
+                Argument('JS::CompartmentOptions&', 'aOptions'),
+                Argument('JSPrincipals*', 'aPrincipal'),
+                Argument('bool', 'aInitStandardClasses'),
+                Argument('JS::MutableHandle<JSObject*>', 'aReflector')]
+        CGAbstractMethod.__init__(self, descriptor, 'Wrap', 'bool', args)
+        self.descriptor = descriptor
+        self.properties = properties
+
+    def definition_body(self):
+        if self.properties.hasNonChromeOnly():
+            properties = "sNativeProperties.Upcast()"
+        else:
+            properties = "nullptr"
+        if self.properties.hasChromeOnly():
+            chromeProperties = "nsContentUtils::ThreadsafeIsCallerChrome() ? sChromeOnlyNativeProperties.Upcast() : nullptr"
+        else:
+            chromeProperties = "nullptr"
+
+        failureCode = dedent(
+            """
+            aCache->ReleaseWrapper(aObject);
+            aCache->ClearWrapper();
+            return false;
+            """);
+
+        if self.descriptor.hasUnforgeableMembers:
+            unforgeable = InitUnforgeablePropertiesOnHolder(
+                self.descriptor, self.properties, failureCode,
+                "aReflector").define();
+        else:
+            unforgeable = ""
+
+        return fill(
+            """
+            $*{assertions}
+            MOZ_ASSERT(ToSupportsIsOnPrimaryInheritanceChain(aObject, aCache),
+                       "nsISupports must be on our primary inheritance chain");
+
+            if (!CreateGlobal<${nativeType}, GetProtoObjectHandle>(aCx,
+                                             aObject,
+                                             aCache,
+                                             sClass.ToJSClass(),
+                                             aOptions,
+                                             aPrincipal,
+                                             aInitStandardClasses,
+                                             aReflector)) {
+              $*{failureCode}
+            }
+
+            // aReflector is a new global, so has a new compartment.  Enter it
+            // before doing anything with it.
+            JSAutoCompartment ac(aCx, aReflector);
+
+            if (!DefineProperties(aCx, aReflector, ${properties}, ${chromeProperties})) {
+              $*{failureCode}
+            }
+            $*{unforgeable}
+
+            $*{slots}
+
+            return true;
+            """,
+            assertions=AssertInheritanceChain(self.descriptor),
+            nativeType=self.descriptor.nativeType,
+            properties=properties,
+            chromeProperties=chromeProperties,
+            failureCode=failureCode,
+            unforgeable=unforgeable,
+            slots=InitMemberSlots(self.descriptor, failureCode))
+
+
+class CGUpdateMemberSlotsMethod(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'aCx'),
+                Argument('JS::Handle<JSObject*>', 'aWrapper'),
+                Argument(descriptor.nativeType + '*', 'aObject')]
+        CGAbstractStaticMethod.__init__(self, descriptor, 'UpdateMemberSlots', 'bool', args)
+
+    def definition_body(self):
+        body = ("JS::Rooted<JS::Value> temp(aCx);\n"
+                "JSJitGetterCallArgs args(&temp);\n")
+        for m in self.descriptor.interface.members:
+            if m.isAttr() and m.getExtendedAttribute("StoreInSlot"):
+                # Skip doing this for the "window" and "self" attributes on the
+                # Window interface, because those can't be gotten safely until
+                # we have hooked it up correctly to the outer window.  The
+                # window code handles doing the get itself.
+                if (self.descriptor.interface.identifier.name == "Window" and
+                    (m.identifier.name == "window" or m.identifier.name == "self")):
+                    continue
+                body += fill(
+                    """
+
+                    if (!get_${member}(aCx, aWrapper, aObject, args)) {
+                      return false;
+                    }
+                    // Getter handled setting our reserved slots
+                    """,
+                    member=m.identifier.name)
+
+        body += "\nreturn true;\n"
+        return body
+
+
+class CGClearCachedValueMethod(CGAbstractMethod):
+    def __init__(self, descriptor, member):
+        self.member = member
+        # If we're StoreInSlot, we'll need to call the getter
+        if member.getExtendedAttribute("StoreInSlot"):
+            args = [Argument('JSContext*', 'aCx')]
+            returnType = 'bool'
+        else:
+            args = []
+            returnType = 'void'
+        args.append(Argument(descriptor.nativeType + '*', 'aObject'))
+        name = MakeClearCachedValueNativeName(member)
+        CGAbstractMethod.__init__(self, descriptor, name, returnType, args)
+
+    def definition_body(self):
+        slotIndex = memberReservedSlot(self.member, self.descriptor)
+        if self.member.getExtendedAttribute("StoreInSlot"):
+            # We have to root things and save the old value in case
+            # regetting fails, so we can restore it.
+            declObj = "JS::Rooted<JSObject*> obj(aCx);\n"
+            noopRetval = " true"
+            saveMember = (
+                "JS::Rooted<JS::Value> oldValue(aCx, js::GetReservedSlot(obj, %s));\n" %
+                slotIndex)
+            regetMember = fill(
+                """
+                JS::Rooted<JS::Value> temp(aCx);
+                JSJitGetterCallArgs args(&temp);
+                JSAutoCompartment ac(aCx, obj);
+                if (!get_${name}(aCx, obj, aObject, args)) {
+                  js::SetReservedSlot(obj, ${slotIndex}, oldValue);
+                  return false;
+                }
+                return true;
+                """,
+                name=self.member.identifier.name,
+                slotIndex=slotIndex)
+        else:
+            declObj = "JSObject* obj;\n"
+            noopRetval = ""
+            saveMember = ""
+            regetMember = ""
+
+        if self.descriptor.wantsXrays:
+            clearXrayExpandoSlots = fill(
+                """
+                xpc::ClearXrayExpandoSlots(obj, ${xraySlotIndex});
+                """,
+                xraySlotIndex=memberXrayExpandoReservedSlot(self.member,
+                                                            self.descriptor))
+        else :
+            clearXrayExpandoSlots = ""
+
+        return fill(
+            """
+            $*{declObj}
+            obj = aObject->GetWrapper();
+            if (!obj) {
+              return${noopRetval};
+            }
+            $*{saveMember}
+            js::SetReservedSlot(obj, ${slotIndex}, JS::UndefinedValue());
+            $*{clearXrayExpandoSlots}
+            $*{regetMember}
+            """,
+            declObj=declObj,
+            noopRetval=noopRetval,
+            saveMember=saveMember,
+            slotIndex=slotIndex,
+            clearXrayExpandoSlots=clearXrayExpandoSlots,
+            regetMember=regetMember)
+
+
+class CGIsPermittedMethod(CGAbstractMethod):
+    """
+    crossOriginGetters/Setters/Methods are sets of names of the relevant members.
+    """
+    def __init__(self, descriptor, crossOriginGetters, crossOriginSetters,
+                 crossOriginMethods):
+        self.crossOriginGetters = crossOriginGetters
+        self.crossOriginSetters = crossOriginSetters
+        self.crossOriginMethods = crossOriginMethods
+        args = [Argument("JSFlatString*", "prop"),
+                Argument("char16_t", "propFirstChar"),
+                Argument("bool", "set")]
+        CGAbstractMethod.__init__(self, descriptor, "IsPermitted", "bool", args,
+                                  inline=True)
+
+    def definition_body(self):
+        allNames = self.crossOriginGetters | self.crossOriginSetters | self.crossOriginMethods
+        readwrite = self.crossOriginGetters & self.crossOriginSetters
+        readonly = (self.crossOriginGetters - self.crossOriginSetters) | self.crossOriginMethods
+        writeonly = self.crossOriginSetters - self.crossOriginGetters
+        cases = {}
+        for name in sorted(allNames):
+            cond = 'JS_FlatStringEqualsAscii(prop, "%s")' % name
+            if name in readonly:
+                cond = "!set && %s" % cond
+            elif name in writeonly:
+                cond = "set && %s" % cond
+            else:
+                assert name in readwrite
+            firstLetter = name[0]
+            case = cases.get(firstLetter, CGList([]))
+            case.append(CGGeneric("if (%s) {\n"
+                                  "  return true;\n"
+                                  "}\n" % cond))
+            cases[firstLetter] = case
+        caseList = []
+        for firstLetter in sorted(cases.keys()):
+            caseList.append(CGCase("'%s'" % firstLetter, cases[firstLetter]))
+        switch = CGSwitch("propFirstChar", caseList)
+        return switch.define() + "\nreturn false;\n"
+
+
+class CGCycleCollectionTraverseForOwningUnionMethod(CGAbstractMethod):
+    """
+    ImplCycleCollectionUnlink for owning union type.
+    """
+    def __init__(self, type):
+        self.type = type
+        args = [Argument("nsCycleCollectionTraversalCallback&", "aCallback"),
+                Argument("%s&" % CGUnionStruct.unionTypeName(type, True), "aUnion"),
+                Argument("const char*", "aName"),
+                Argument("uint32_t", "aFlags", "0")]
+        CGAbstractMethod.__init__(self, None, "ImplCycleCollectionTraverse", "void", args)
+
+    def deps(self):
+        return self.type.getDeps()
+
+    def definition_body(self):
+        memberNames = [getUnionMemberName(t)
+                       for t in self.type.flatMemberTypes
+                       if idlTypeNeedsCycleCollection(t)]
+        assert memberNames
+
+        conditionTemplate = 'aUnion.Is%s()'
+        functionCallTemplate = 'ImplCycleCollectionTraverse(aCallback, aUnion.GetAs%s(), "m%s", aFlags);\n'
+
+        ifStaments = (CGIfWrapper(CGGeneric(functionCallTemplate % (m, m)),
+                                  conditionTemplate % m)
+                      for m in memberNames)
+
+        return CGElseChain(ifStaments).define()
+
+
+class CGCycleCollectionUnlinkForOwningUnionMethod(CGAbstractMethod):
+    """
+    ImplCycleCollectionUnlink for owning union type.
+    """
+    def __init__(self, type):
+        self.type = type
+        args = [Argument("%s&" % CGUnionStruct.unionTypeName(type, True), "aUnion")]
+        CGAbstractMethod.__init__(self, None, "ImplCycleCollectionUnlink", "void", args)
+
+    def deps(self):
+        return self.type.getDeps()
+
+    def definition_body(self):
+        return "aUnion.Uninit();\n"
+
+
+builtinNames = {
+    IDLType.Tags.bool: 'bool',
+    IDLType.Tags.int8: 'int8_t',
+    IDLType.Tags.int16: 'int16_t',
+    IDLType.Tags.int32: 'int32_t',
+    IDLType.Tags.int64: 'int64_t',
+    IDLType.Tags.uint8: 'uint8_t',
+    IDLType.Tags.uint16: 'uint16_t',
+    IDLType.Tags.uint32: 'uint32_t',
+    IDLType.Tags.uint64: 'uint64_t',
+    IDLType.Tags.unrestricted_float: 'float',
+    IDLType.Tags.float: 'float',
+    IDLType.Tags.unrestricted_double: 'double',
+    IDLType.Tags.double: 'double'
+}
+
+numericSuffixes = {
+    IDLType.Tags.int8: '',
+    IDLType.Tags.uint8: '',
+    IDLType.Tags.int16: '',
+    IDLType.Tags.uint16: '',
+    IDLType.Tags.int32: '',
+    IDLType.Tags.uint32: 'U',
+    IDLType.Tags.int64: 'LL',
+    IDLType.Tags.uint64: 'ULL',
+    IDLType.Tags.unrestricted_float: 'F',
+    IDLType.Tags.float: 'F',
+    IDLType.Tags.unrestricted_double: '',
+    IDLType.Tags.double: ''
+}
+
+
+def numericValue(t, v):
+    if (t == IDLType.Tags.unrestricted_double or
+        t == IDLType.Tags.unrestricted_float):
+        typeName = builtinNames[t]
+        if v == float("inf"):
+            return "mozilla::PositiveInfinity<%s>()" % typeName
+        if v == float("-inf"):
+            return "mozilla::NegativeInfinity<%s>()" % typeName
+        if math.isnan(v):
+            return "mozilla::UnspecifiedNaN<%s>()" % typeName
+    return "%s%s" % (v, numericSuffixes[t])
+
+
+class CastableObjectUnwrapper():
+    """
+    A class for unwrapping an object stored in a JS Value (or
+    MutableHandle<Value> or Handle<Value>) named by the "source" and
+    "mutableSource" arguments based on the passed-in descriptor and storing it
+    in a variable called by the name in the "target" argument.  The "source"
+    argument should be able to produce a Value or Handle<Value>; the
+    "mutableSource" argument should be able to produce a MutableHandle<Value>
+
+    codeOnFailure is the code to run if unwrapping fails.
+
+    If isCallbackReturnValue is "JSImpl" and our descriptor is also
+    JS-implemented, fall back to just creating the right object if what we
+    have isn't one already.
+
+    If allowCrossOriginObj is True, then we'll first do an
+    UncheckedUnwrap and then operate on the result.
+    """
+    def __init__(self, descriptor, source, mutableSource, target, codeOnFailure,
+                 exceptionCode=None, isCallbackReturnValue=False,
+                 allowCrossOriginObj=False):
+        self.substitution = {
+            "type": descriptor.nativeType,
+            "protoID": "prototypes::id::" + descriptor.name,
+            "target": target,
+            "codeOnFailure": codeOnFailure,
+        }
+        # Supporting both the "cross origin object" case and the "has
+        # XPConnect impls" case at the same time is a pain, so let's
+        # not do that.  That allows us to assume that our source is
+        # always a Handle or MutableHandle.
+        if allowCrossOriginObj and descriptor.hasXPConnectImpls:
+            raise TypeError("Interface %s both allows a cross-origin 'this' "
+                            "and has XPConnect impls.  We don't support that" %
+                            descriptor.name)
+        if allowCrossOriginObj:
+            self.substitution["uncheckedObjDecl"] = fill(
+                """
+                JS::Rooted<JSObject*> maybeUncheckedObj(cx, &${source}.toObject());
+                """,
+                source=source)
+            self.substitution["uncheckedObjGet"] = fill(
+                """
+                if (xpc::WrapperFactory::IsXrayWrapper(maybeUncheckedObj)) {
+                  maybeUncheckedObj = js::UncheckedUnwrap(maybeUncheckedObj);
+                } else {
+                  maybeUncheckedObj = js::CheckedUnwrap(maybeUncheckedObj);
+                  if (!maybeUncheckedObj) {
+                    $*{codeOnFailure}
+                  }
+                }
+                """,
+                codeOnFailure=(codeOnFailure % { 'securityError': 'true'}))
+            self.substitution["source"] = "maybeUncheckedObj"
+            self.substitution["mutableSource"] = "&maybeUncheckedObj"
+            # No need to set up xpconnectUnwrap, since it won't be
+            # used in the allowCrossOriginObj case.
+        else:
+            self.substitution["uncheckedObjDecl"] = ""
+            self.substitution["uncheckedObjGet"] = ""
+            self.substitution["source"] = source
+            self.substitution["mutableSource"] = mutableSource
+            xpconnectUnwrap = (
+                "nsresult rv = UnwrapXPConnect<${type}>(cx, ${mutableSource}, getter_AddRefs(objPtr));\n")
+
+        if descriptor.hasXPConnectImpls:
+            self.substitution["codeOnFailure"] = string.Template(
+                "RefPtr<${type}> objPtr;\n" +
+                xpconnectUnwrap +
+                "if (NS_FAILED(rv)) {\n"
+                "${indentedCodeOnFailure}"
+                "}\n"
+                "// We should have an object\n"
+                "MOZ_ASSERT(objPtr);\n"
+                "${target} = objPtr;\n"
+            ).substitute(self.substitution,
+                         indentedCodeOnFailure=indent(codeOnFailure))
+        elif (isCallbackReturnValue == "JSImpl" and
+              descriptor.interface.isJSImplemented()):
+            exceptionCode = exceptionCode or codeOnFailure
+            self.substitution["codeOnFailure"] = fill(
+                """
+                // Be careful to not wrap random DOM objects here, even if
+                // they're wrapped in opaque security wrappers for some reason.
+                // XXXbz Wish we could check for a JS-implemented object
+                // that already has a content reflection...
+                if (!IsDOMObject(js::UncheckedUnwrap(&${source}.toObject()))) {
+                  nsCOMPtr<nsIGlobalObject> contentGlobal;
+                  if (!GetContentGlobalForJSImplementedObject(cx, Callback(), getter_AddRefs(contentGlobal))) {
+                    $*{exceptionCode}
+                  }
+                  JS::Rooted<JSObject*> jsImplSourceObj(cx, &${source}.toObject());
+                  ${target} = new ${type}(jsImplSourceObj, contentGlobal);
+                } else {
+                  $*{codeOnFailure}
+                }
+                """,
+                exceptionCode=exceptionCode,
+                **self.substitution)
+        else:
+            self.substitution["codeOnFailure"] = codeOnFailure
+
+    def __str__(self):
+        substitution = self.substitution.copy()
+        substitution["codeOnFailure"] %= {
+            'securityError': 'rv == NS_ERROR_XPC_SECURITY_MANAGER_VETO'
+        }
+        return fill(
+            """
+            $*{uncheckedObjDecl}
+            {
+              $*{uncheckedObjGet}
+              nsresult rv = UnwrapObject<${protoID}, ${type}>(${mutableSource}, ${target});
+              if (NS_FAILED(rv)) {
+                $*{codeOnFailure}
+              }
+            }
+            """,
+            **substitution)
+
+
+class FailureFatalCastableObjectUnwrapper(CastableObjectUnwrapper):
+    """
+    As CastableObjectUnwrapper, but defaulting to throwing if unwrapping fails
+    """
+    def __init__(self, descriptor, source, mutableSource, target, exceptionCode,
+                 isCallbackReturnValue, sourceDescription):
+        CastableObjectUnwrapper.__init__(
+            self, descriptor, source, mutableSource, target,
+            'ThrowErrorMessage(cx, MSG_DOES_NOT_IMPLEMENT_INTERFACE, "%s", "%s");\n'
+            '%s' % (sourceDescription, descriptor.interface.identifier.name,
+                    exceptionCode),
+            exceptionCode,
+            isCallbackReturnValue)
+
+
+class CGCallbackTempRoot(CGGeneric):
+    def __init__(self, name):
+        define = dedent("""
+            { // Scope for tempRoot
+              JS::Rooted<JSObject*> tempRoot(cx, &${val}.toObject());
+              ${declName} = new %s(cx, tempRoot, mozilla::dom::GetIncumbentGlobal());
+            }
+            """) % name
+        CGGeneric.__init__(self, define=define)
+
+
+def getCallbackConversionInfo(type, idlObject, isMember, isCallbackReturnValue,
+                              isOptional):
+    """
+    Returns a tuple containing the declType, declArgs, and basic
+    conversion for the given callback type, with the given callback
+    idl object in the given context (isMember/isCallbackReturnValue/isOptional).
+    """
+    name = idlObject.identifier.name
+
+    # We can't use fast callbacks if isOptional because then we get an
+    # Optional<RootedCallback> thing, which is not transparent to consumers.
+    useFastCallback = (not isMember and not isCallbackReturnValue and
+                       not isOptional)
+    if useFastCallback:
+        name = "binding_detail::Fast%s" % name
+
+    if type.nullable() or isCallbackReturnValue:
+        declType = CGGeneric("RefPtr<%s>" % name)
+    else:
+        declType = CGGeneric("OwningNonNull<%s>" % name)
+
+    if useFastCallback:
+        declType = CGTemplatedType("RootedCallback", declType)
+        declArgs = "cx"
+    else:
+        declArgs = None
+
+    conversion = indent(CGCallbackTempRoot(name).define())
+    return (declType, declArgs, conversion)
+
+
+class JSToNativeConversionInfo():
+    """
+    An object representing information about a JS-to-native conversion.
+    """
+    def __init__(self, template, declType=None, holderType=None,
+                 dealWithOptional=False, declArgs=None,
+                 holderArgs=None):
+        """
+        template: A string representing the conversion code.  This will have
+                  template substitution performed on it as follows:
+
+          ${val} is a handle to the JS::Value in question
+          ${maybeMutableVal} May be a mutable handle to the JS::Value in
+                             question. This is only OK to use if ${val} is
+                             known to not be undefined.
+          ${holderName} replaced by the holder's name, if any
+          ${declName} replaced by the declaration's name
+          ${haveValue} replaced by an expression that evaluates to a boolean
+                       for whether we have a JS::Value.  Only used when
+                       defaultValue is not None or when True is passed for
+                       checkForValue to instantiateJSToNativeConversion.
+          ${passedToJSImpl} replaced by an expression that evaluates to a boolean
+                            for whether this value is being passed to a JS-
+                            implemented interface.
+
+        declType: A CGThing representing the native C++ type we're converting
+                  to.  This is allowed to be None if the conversion code is
+                  supposed to be used as-is.
+
+        holderType: A CGThing representing the type of a "holder" which will
+                    hold a possible reference to the C++ thing whose type we
+                    returned in declType, or  None if no such holder is needed.
+
+        dealWithOptional: A boolean indicating whether the caller has to do
+                          optional-argument handling.  This should only be set
+                          to true if the JS-to-native conversion is being done
+                          for an optional argument or dictionary member with no
+                          default value and if the returned template expects
+                          both declType and holderType to be wrapped in
+                          Optional<>, with ${declName} and ${holderName}
+                          adjusted to point to the Value() of the Optional, and
+                          Construct() calls to be made on the Optional<>s as
+                          needed.
+
+        declArgs: If not None, the arguments to pass to the ${declName}
+                  constructor.  These will have template substitution performed
+                  on them so you can use things like ${val}.  This is a
+                  single string, not a list of strings.
+
+        holderArgs: If not None, the arguments to pass to the ${holderName}
+                    constructor.  These will have template substitution
+                    performed on them so you can use things like ${val}.
+                    This is a single string, not a list of strings.
+
+        ${declName} must be in scope before the code from 'template' is entered.
+
+        If holderType is not None then ${holderName} must be in scope before
+        the code from 'template' is entered.
+        """
+        assert isinstance(template, str)
+        assert declType is None or isinstance(declType, CGThing)
+        assert holderType is None or isinstance(holderType, CGThing)
+        self.template = template
+        self.declType = declType
+        self.holderType = holderType
+        self.dealWithOptional = dealWithOptional
+        self.declArgs = declArgs
+        self.holderArgs = holderArgs
+
+
+def getHandleDefault(defaultValue):
+    tag = defaultValue.type.tag()
+    if tag in numericSuffixes:
+        # Some numeric literals require a suffix to compile without warnings
+        return numericValue(tag, defaultValue.value)
+    assert tag == IDLType.Tags.bool
+    return toStringBool(defaultValue.value)
+
+
+def handleDefaultStringValue(defaultValue, method):
+    """
+    Returns a string which ends up calling 'method' with a (char_t*, length)
+    pair that sets this string default value.  This string is suitable for
+    passing as the second argument of handleDefault; in particular it does not
+    end with a ';'
+    """
+    assert defaultValue.type.isDOMString() or defaultValue.type.isByteString()
+    return ("static const %(char_t)s data[] = { %(data)s };\n"
+            "%(method)s(data, ArrayLength(data) - 1)") % {
+                'char_t': "char" if defaultValue.type.isByteString() else "char16_t",
+                'method': method,
+                'data': ", ".join(["'" + char + "'" for char in
+                                   defaultValue.value] + ["0"])
+            }
+
+
+# If this function is modified, modify CGNativeMember.getArg and
+# CGNativeMember.getRetvalInfo accordingly.  The latter cares about the decltype
+# and holdertype we end up using, because it needs to be able to return the code
+# that will convert those to the actual return value of the callback function.
+def getJSToNativeConversionInfo(type, descriptorProvider, failureCode=None,
+                                isDefinitelyObject=False,
+                                isMember=False,
+                                isOptional=False,
+                                invalidEnumValueFatal=True,
+                                defaultValue=None,
+                                treatNullAs="Default",
+                                isEnforceRange=False,
+                                isClamp=False,
+                                isNullOrUndefined=False,
+                                exceptionCode=None,
+                                lenientFloatCode=None,
+                                allowTreatNonCallableAsNull=False,
+                                isCallbackReturnValue=False,
+                                sourceDescription="value",
+                                nestingLevel=""):
+    """
+    Get a template for converting a JS value to a native object based on the
+    given type and descriptor.  If failureCode is given, then we're actually
+    testing whether we can convert the argument to the desired type.  That
+    means that failures to convert due to the JS value being the wrong type of
+    value need to use failureCode instead of throwing exceptions.  Failures to
+    convert that are due to JS exceptions (from toString or valueOf methods) or
+    out of memory conditions need to throw exceptions no matter what
+    failureCode is.  However what actually happens when throwing an exception
+    can be controlled by exceptionCode.  The only requirement on that is that
+    exceptionCode must end up doing a return, and every return from this
+    function must happen via exceptionCode if exceptionCode is not None.
+
+    If isDefinitelyObject is True, that means we know the value
+    isObject() and we have no need to recheck that.
+
+    if isMember is not False, we're being converted from a property of some JS
+    object, not from an actual method argument, so we can't rely on our jsval
+    being rooted or outliving us in any way.  Callers can pass "Dictionary",
+    "Variadic", "Sequence", or "OwningUnion" to indicate that the conversion is
+    for something that is a dictionary member, a variadic argument, a sequence,
+    or an owning union respectively.
+
+    If isOptional is true, then we are doing conversion of an optional
+    argument with no default value.
+
+    invalidEnumValueFatal controls whether an invalid enum value conversion
+    attempt will throw (if true) or simply return without doing anything (if
+    false).
+
+    If defaultValue is not None, it's the IDL default value for this conversion
+
+    If isEnforceRange is true, we're converting an integer and throwing if the
+    value is out of range.
+
+    If isClamp is true, we're converting an integer and clamping if the
+    value is out of range.
+
+    If lenientFloatCode is not None, it should be used in cases when
+    we're a non-finite float that's not unrestricted.
+
+    If allowTreatNonCallableAsNull is true, then [TreatNonCallableAsNull] and
+    [TreatNonObjectAsNull] extended attributes on nullable callback functions
+    will be honored.
+
+    If isCallbackReturnValue is "JSImpl" or "Callback", then the declType may be
+    adjusted to make it easier to return from a callback.  Since that type is
+    never directly observable by any consumers of the callback code, this is OK.
+    Furthermore, if isCallbackReturnValue is "JSImpl", that affects the behavior
+    of the FailureFatalCastableObjectUnwrapper conversion; this is used for
+    implementing auto-wrapping of JS-implemented return values from a
+    JS-implemented interface.
+
+    sourceDescription is a description of what this JS value represents, to be
+    used in error reporting.  Callers should assume that it might get placed in
+    the middle of a sentence.  If it ends up at the beginning of a sentence, its
+    first character will be automatically uppercased.
+
+    The return value from this function is a JSToNativeConversionInfo.
+    """
+    # If we have a defaultValue then we're not actually optional for
+    # purposes of what we need to be declared as.
+    assert defaultValue is None or not isOptional
+
+    # Also, we should not have a defaultValue if we know we're an object
+    assert not isDefinitelyObject or defaultValue is None
+
+    # And we can't both be an object and be null or undefined
+    assert not isDefinitelyObject or not isNullOrUndefined
+
+    # If exceptionCode is not set, we'll just rethrow the exception we got.
+    # Note that we can't just set failureCode to exceptionCode, because setting
+    # failureCode will prevent pending exceptions from being set in cases when
+    # they really should be!
+    if exceptionCode is None:
+        exceptionCode = "return false;\n"
+
+    # Unfortunately, .capitalize() on a string will lowercase things inside the
+    # string, which we do not want.
+    def firstCap(string):
+        return string[0].upper() + string[1:]
+
+    # Helper functions for dealing with failures due to the JS value being the
+    # wrong type of value
+    def onFailureNotAnObject(failureCode):
+        return CGGeneric(
+            failureCode or
+            ('ThrowErrorMessage(cx, MSG_NOT_OBJECT, "%s");\n'
+             '%s' % (firstCap(sourceDescription), exceptionCode)))
+
+    def onFailureBadType(failureCode, typeName):
+        return CGGeneric(
+            failureCode or
+            ('ThrowErrorMessage(cx, MSG_DOES_NOT_IMPLEMENT_INTERFACE, "%s", "%s");\n'
+             '%s' % (firstCap(sourceDescription), typeName, exceptionCode)))
+
+    def onFailureNotCallable(failureCode):
+        return CGGeneric(
+            failureCode or
+            ('ThrowErrorMessage(cx, MSG_NOT_CALLABLE, "%s");\n'
+             '%s' % (firstCap(sourceDescription), exceptionCode)))
+
+    # A helper function for handling default values.  Takes a template
+    # body and the C++ code to set the default value and wraps the
+    # given template body in handling for the default value.
+    def handleDefault(template, setDefault):
+        if defaultValue is None:
+            return template
+        return (
+            "if (${haveValue}) {\n" +
+            indent(template) +
+            "} else {\n" +
+            indent(setDefault) +
+            "}\n")
+
+    # A helper function for wrapping up the template body for
+    # possibly-nullable objecty stuff
+    def wrapObjectTemplate(templateBody, type, codeToSetNull, failureCode=None):
+        if isNullOrUndefined and type.nullable():
+            # Just ignore templateBody and set ourselves to null.
+            # Note that we don't have to worry about default values
+            # here either, since we already examined this value.
+            return codeToSetNull
+
+        if not isDefinitelyObject:
+            # Handle the non-object cases by wrapping up the whole
+            # thing in an if cascade.
+            if type.nullable():
+                elifLine = "} else if (${val}.isNullOrUndefined()) {\n"
+                elifBody = codeToSetNull
+            else:
+                elifLine = ""
+                elifBody = ""
+
+            # Note that $${val} below expands to ${val}. This string is
+            # used as a template later, and val will be filled in then.
+            templateBody = fill(
+                """
+                if ($${val}.isObject()) {
+                  $*{templateBody}
+                $*{elifLine}
+                  $*{elifBody}
+                } else {
+                  $*{failureBody}
+                }
+                """,
+                templateBody=templateBody,
+                elifLine=elifLine,
+                elifBody=elifBody,
+                failureBody=onFailureNotAnObject(failureCode).define())
+
+            if isinstance(defaultValue, IDLNullValue):
+                assert type.nullable()  # Parser should enforce this
+                templateBody = handleDefault(templateBody, codeToSetNull)
+            elif isinstance(defaultValue, IDLEmptySequenceValue):
+                # Our caller will handle it
+                pass
+            else:
+                assert defaultValue is None
+
+        return templateBody
+
+    # A helper function for converting things that look like a JSObject*.
+    def handleJSObjectType(type, isMember, failureCode, exceptionCode, sourceDescription):
+        if not isMember:
+            if isOptional:
+                # We have a specialization of Optional that will use a
+                # Rooted for the storage here.
+                declType = CGGeneric("JS::Handle<JSObject*>")
+            else:
+                declType = CGGeneric("JS::Rooted<JSObject*>")
+            declArgs = "cx"
+        else:
+            assert (isMember in
+                    ("Sequence", "Variadic", "Dictionary", "OwningUnion", "MozMap"))
+            # We'll get traced by the sequence or dictionary or union tracer
+            declType = CGGeneric("JSObject*")
+            declArgs = None
+        templateBody = "${declName} = &${val}.toObject();\n"
+
+        # For JS-implemented APIs, we refuse to allow passing objects that the
+        # API consumer does not subsume. The extra parens around
+        # ($${passedToJSImpl}) suppress unreachable code warnings when
+        # $${passedToJSImpl} is the literal `false`.
+        if not isinstance(descriptorProvider, Descriptor) or descriptorProvider.interface.isJSImplemented():
+            templateBody = fill(
+                """
+                if (($${passedToJSImpl}) && !CallerSubsumes($${val})) {
+                  ThrowErrorMessage(cx, MSG_PERMISSION_DENIED_TO_PASS_ARG, "${sourceDescription}");
+                  $*{exceptionCode}
+                }
+                """,
+                sourceDescription=sourceDescription,
+                exceptionCode=exceptionCode) + templateBody
+
+        setToNullCode = "${declName} = nullptr;\n"
+        template = wrapObjectTemplate(templateBody, type, setToNullCode,
+                                      failureCode)
+        return JSToNativeConversionInfo(template, declType=declType,
+                                        dealWithOptional=isOptional,
+                                        declArgs=declArgs)
+
+    def incrementNestingLevel():
+        if nestingLevel is "":
+            return 1
+        return nestingLevel + 1
+
+    assert not (isEnforceRange and isClamp)  # These are mutually exclusive
+
+    if type.isSequence():
+        assert not isEnforceRange and not isClamp
+
+        if failureCode is None:
+            notSequence = ('ThrowErrorMessage(cx, MSG_NOT_SEQUENCE, "%s");\n'
+                           "%s" % (firstCap(sourceDescription), exceptionCode))
+        else:
+            notSequence = failureCode
+
+        nullable = type.nullable()
+        # Be very careful not to change "type": we need it later
+        if nullable:
+            elementType = type.inner.inner
+        else:
+            elementType = type.inner
+
+        # We want to use auto arrays if we can, but we have to be careful with
+        # reallocation behavior for arrays.  In particular, if we use auto
+        # arrays for sequences and have a sequence of elements which are
+        # themselves sequences or have sequences as members, we have a problem.
+        # In that case, resizing the outermost AutoTArray to the right size
+        # will memmove its elements, but AutoTArrays are not memmovable and
+        # hence will end up with pointers to bogus memory, which is bad.  To
+        # deal with this, we typically map WebIDL sequences to our Sequence
+        # type, which is in fact memmovable.  The one exception is when we're
+        # passing in a sequence directly as an argument without any sort of
+        # optional or nullable complexity going on.  In that situation, we can
+        # use an AutoSequence instead.  We have to keep using Sequence in the
+        # nullable and optional cases because we don't want to leak the
+        # AutoSequence type to consumers, which would be unavoidable with
+        # Nullable<AutoSequence> or Optional<AutoSequence>.
+        if isMember or isOptional or nullable or isCallbackReturnValue:
+            sequenceClass = "Sequence"
+        else:
+            sequenceClass = "binding_detail::AutoSequence"
+
+        # XXXbz we can't include the index in the sourceDescription, because
+        # we don't really have a way to pass one in dynamically at runtime...
+        elementInfo = getJSToNativeConversionInfo(
+            elementType, descriptorProvider, isMember="Sequence",
+            exceptionCode=exceptionCode, lenientFloatCode=lenientFloatCode,
+            isCallbackReturnValue=isCallbackReturnValue,
+            sourceDescription="element of %s" % sourceDescription,
+            nestingLevel=incrementNestingLevel())
+        if elementInfo.dealWithOptional:
+            raise TypeError("Shouldn't have optional things in sequences")
+        if elementInfo.holderType is not None:
+            raise TypeError("Shouldn't need holders for sequences")
+
+        typeName = CGTemplatedType(sequenceClass, elementInfo.declType)
+        sequenceType = typeName.define()
+        if nullable:
+            typeName = CGTemplatedType("Nullable", typeName)
+            arrayRef = "${declName}.SetValue()"
+        else:
+            arrayRef = "${declName}"
+
+        elementConversion = string.Template(elementInfo.template).substitute({
+            "val": "temp" + str(nestingLevel),
+            "maybeMutableVal": "&temp" + str(nestingLevel),
+            "declName": "slot" + str(nestingLevel),
+            # We only need holderName here to handle isExternal()
+            # interfaces, which use an internal holder for the
+            # conversion even when forceOwningType ends up true.
+            "holderName": "tempHolder" + str(nestingLevel),
+            "passedToJSImpl": "${passedToJSImpl}"
+        })
+
+        # NOTE: Keep this in sync with variadic conversions as needed
+        templateBody = fill(
+            """
+            JS::ForOfIterator iter${nestingLevel}(cx);
+            if (!iter${nestingLevel}.init($${val}, JS::ForOfIterator::AllowNonIterable)) {
+              $*{exceptionCode}
+            }
+            if (!iter${nestingLevel}.valueIsIterable()) {
+              $*{notSequence}
+            }
+            ${sequenceType} &arr${nestingLevel} = ${arrayRef};
+            JS::Rooted<JS::Value> temp${nestingLevel}(cx);
+            while (true) {
+              bool done${nestingLevel};
+              if (!iter${nestingLevel}.next(&temp${nestingLevel}, &done${nestingLevel})) {
+                $*{exceptionCode}
+              }
+              if (done${nestingLevel}) {
+                break;
+              }
+              ${elementType}* slotPtr${nestingLevel} = arr${nestingLevel}.AppendElement(mozilla::fallible);
+              if (!slotPtr${nestingLevel}) {
+                JS_ReportOutOfMemory(cx);
+                $*{exceptionCode}
+              }
+              ${elementType}& slot${nestingLevel} = *slotPtr${nestingLevel};
+              $*{elementConversion}
+            }
+            """,
+            exceptionCode=exceptionCode,
+            notSequence=notSequence,
+            sequenceType=sequenceType,
+            arrayRef=arrayRef,
+            elementType=elementInfo.declType.define(),
+            elementConversion=elementConversion,
+            nestingLevel=str(nestingLevel))
+
+        templateBody = wrapObjectTemplate(templateBody, type,
+                                          "${declName}.SetNull();\n", notSequence)
+        if isinstance(defaultValue, IDLEmptySequenceValue):
+            if type.nullable():
+                codeToSetEmpty = "${declName}.SetValue();\n"
+            else:
+                codeToSetEmpty = "/* Array is already empty; nothing to do */\n"
+            templateBody = handleDefault(templateBody, codeToSetEmpty)
+
+        # Sequence arguments that might contain traceable things need
+        # to get traced
+        if not isMember and typeNeedsRooting(elementType):
+            holderType = CGTemplatedType("SequenceRooter", elementInfo.declType)
+            # If our sequence is nullable, this will set the Nullable to be
+            # not-null, but that's ok because we make an explicit SetNull() call
+            # on it as needed if our JS value is actually null.
+            holderArgs = "cx, &%s" % arrayRef
+        else:
+            holderType = None
+            holderArgs = None
+
+        return JSToNativeConversionInfo(templateBody, declType=typeName,
+                                        holderType=holderType,
+                                        dealWithOptional=isOptional,
+                                        holderArgs=holderArgs)
+
+    if type.isMozMap():
+        assert not isEnforceRange and not isClamp
+        if failureCode is None:
+            notMozMap = ('ThrowErrorMessage(cx, MSG_NOT_OBJECT, "%s");\n'
+                         "%s" % (firstCap(sourceDescription), exceptionCode))
+        else:
+            notMozMap = failureCode
+
+        nullable = type.nullable()
+        # Be very careful not to change "type": we need it later
+        if nullable:
+            valueType = type.inner.inner
+        else:
+            valueType = type.inner
+
+        valueInfo = getJSToNativeConversionInfo(
+            valueType, descriptorProvider, isMember="MozMap",
+            exceptionCode=exceptionCode, lenientFloatCode=lenientFloatCode,
+            isCallbackReturnValue=isCallbackReturnValue,
+            sourceDescription="value in %s" % sourceDescription,
+            nestingLevel=incrementNestingLevel())
+        if valueInfo.dealWithOptional:
+            raise TypeError("Shouldn't have optional things in MozMap")
+        if valueInfo.holderType is not None:
+            raise TypeError("Shouldn't need holders for MozMap")
+
+        typeName = CGTemplatedType("MozMap", valueInfo.declType)
+        mozMapType = typeName.define()
+        if nullable:
+            typeName = CGTemplatedType("Nullable", typeName)
+            mozMapRef = "${declName}.SetValue()"
+        else:
+            mozMapRef = "${declName}"
+
+        valueConversion = string.Template(valueInfo.template).substitute({
+            "val": "temp",
+            "maybeMutableVal": "&temp",
+            "declName": "slot",
+            # We only need holderName here to handle isExternal()
+            # interfaces, which use an internal holder for the
+            # conversion even when forceOwningType ends up true.
+            "holderName": "tempHolder",
+            "passedToJSImpl": "${passedToJSImpl}"
+        })
+
+        templateBody = fill(
+            """
+            ${mozMapType} &mozMap = ${mozMapRef};
+
+            JS::Rooted<JSObject*> mozMapObj(cx, &$${val}.toObject());
+            JS::Rooted<JS::IdVector> ids(cx, JS::IdVector(cx));
+            if (!JS_Enumerate(cx, mozMapObj, &ids)) {
+              $*{exceptionCode}
+            }
+            JS::Rooted<JS::Value> propNameValue(cx);
+            JS::Rooted<JS::Value> temp(cx);
+            JS::Rooted<jsid> curId(cx);
+            for (size_t i = 0; i < ids.length(); ++i) {
+              // Make sure we get the value before converting the name, since
+              // getting the value can trigger GC but our name is a dependent
+              // string.
+              curId = ids[i];
+              binding_detail::FakeString propName;
+              bool isSymbol;
+              if (!ConvertIdToString(cx, curId, propName, isSymbol) ||
+                  (!isSymbol && !JS_GetPropertyById(cx, mozMapObj, curId, &temp))) {
+                $*{exceptionCode}
+              }
+              if (isSymbol) {
+                continue;
+              }
+
+              ${valueType}* slotPtr = mozMap.AddEntry(propName);
+              if (!slotPtr) {
+                JS_ReportOutOfMemory(cx);
+                $*{exceptionCode}
+              }
+              ${valueType}& slot = *slotPtr;
+              $*{valueConversion}
+            }
+            """,
+            exceptionCode=exceptionCode,
+            mozMapType=mozMapType,
+            mozMapRef=mozMapRef,
+            valueType=valueInfo.declType.define(),
+            valueConversion=valueConversion)
+
+        templateBody = wrapObjectTemplate(templateBody, type,
+                                          "${declName}.SetNull();\n",
+                                          notMozMap)
+
+        declType = typeName
+        declArgs = None
+        holderType = None
+        holderArgs = None
+        # MozMap arguments that might contain traceable things need
+        # to get traced
+        if not isMember and isCallbackReturnValue:
+            # Go ahead and just convert directly into our actual return value
+            declType = CGWrapper(declType, post="&")
+            declArgs = "aRetVal"
+        elif not isMember and typeNeedsRooting(valueType):
+            holderType = CGTemplatedType("MozMapRooter", valueInfo.declType)
+            # If our MozMap is nullable, this will set the Nullable to be
+            # not-null, but that's ok because we make an explicit SetNull() call
+            # on it as needed if our JS value is actually null.
+            holderArgs = "cx, &%s" % mozMapRef
+
+        return JSToNativeConversionInfo(templateBody, declType=declType,
+                                        declArgs=declArgs,
+                                        holderType=holderType,
+                                        dealWithOptional=isOptional,
+                                        holderArgs=holderArgs)
+
+    if type.isUnion():
+        nullable = type.nullable()
+        if nullable:
+            type = type.inner
+
+        isOwningUnion = isMember or isCallbackReturnValue
+        unionArgumentObj = "${declName}" if isOwningUnion else "${holderName}"
+        if nullable:
+            # If we're owning, we're a Nullable, which hasn't been told it has
+            # a value.  Otherwise we're an already-constructed Maybe.
+            unionArgumentObj += ".SetValue()" if isOwningUnion else ".ref()"
+
+        memberTypes = type.flatMemberTypes
+        names = []
+
+        interfaceMemberTypes = filter(lambda t: t.isNonCallbackInterface(), memberTypes)
+        if len(interfaceMemberTypes) > 0:
+            interfaceObject = []
+            for memberType in interfaceMemberTypes:
+                name = getUnionMemberName(memberType)
+                interfaceObject.append(
+                    CGGeneric("(failed = !%s.TrySetTo%s(cx, ${val}, tryNext, ${passedToJSImpl})) || !tryNext" %
+                              (unionArgumentObj, name)))
+                names.append(name)
+            interfaceObject = CGWrapper(CGList(interfaceObject, " ||\n"),
+                                        pre="done = ", post=";\n\n", reindent=True)
+        else:
+            interfaceObject = None
+
+        sequenceObjectMemberTypes = filter(lambda t: t.isSequence(), memberTypes)
+        if len(sequenceObjectMemberTypes) > 0:
+            assert len(sequenceObjectMemberTypes) == 1
+            name = getUnionMemberName(sequenceObjectMemberTypes[0])
+            sequenceObject = CGGeneric(
+                "done = (failed = !%s.TrySetTo%s(cx, ${val}, tryNext, ${passedToJSImpl})) || !tryNext;\n" %
+                (unionArgumentObj, name))
+            names.append(name)
+        else:
+            sequenceObject = None
+
+        dateObjectMemberTypes = filter(lambda t: t.isDate(), memberTypes)
+        if len(dateObjectMemberTypes) > 0:
+            assert len(dateObjectMemberTypes) == 1
+            memberType = dateObjectMemberTypes[0]
+            name = getUnionMemberName(memberType)
+            dateObject = CGGeneric("%s.SetTo%s(cx, ${val});\n"
+                                   "done = true;\n" % (unionArgumentObj, name))
+            dateObject = CGIfWrapper(dateObject, "JS_ObjectIsDate(cx, argObj)")
+            names.append(name)
+        else:
+            dateObject = None
+
+        callbackMemberTypes = filter(lambda t: t.isCallback() or t.isCallbackInterface(), memberTypes)
+        if len(callbackMemberTypes) > 0:
+            assert len(callbackMemberTypes) == 1
+            memberType = callbackMemberTypes[0]
+            name = getUnionMemberName(memberType)
+            callbackObject = CGGeneric(
+                "done = (failed = !%s.TrySetTo%s(cx, ${val}, tryNext, ${passedToJSImpl})) || !tryNext;\n" %
+                (unionArgumentObj, name))
+            names.append(name)
+        else:
+            callbackObject = None
+
+        dictionaryMemberTypes = filter(lambda t: t.isDictionary(), memberTypes)
+        if len(dictionaryMemberTypes) > 0:
+            assert len(dictionaryMemberTypes) == 1
+            name = getUnionMemberName(dictionaryMemberTypes[0])
+            setDictionary = CGGeneric(
+                "done = (failed = !%s.TrySetTo%s(cx, ${val}, tryNext, ${passedToJSImpl})) || !tryNext;\n" %
+                (unionArgumentObj, name))
+            names.append(name)
+        else:
+            setDictionary = None
+
+        mozMapMemberTypes = filter(lambda t: t.isMozMap(), memberTypes)
+        if len(mozMapMemberTypes) > 0:
+            assert len(mozMapMemberTypes) == 1
+            name = getUnionMemberName(mozMapMemberTypes[0])
+            mozMapObject = CGGeneric(
+                "done = (failed = !%s.TrySetTo%s(cx, ${val}, tryNext, ${passedToJSImpl})) || !tryNext;\n" %
+                (unionArgumentObj, name))
+            names.append(name)
+        else:
+            mozMapObject = None
+
+        objectMemberTypes = filter(lambda t: t.isObject(), memberTypes)
+        if len(objectMemberTypes) > 0:
+            assert len(objectMemberTypes) == 1
+            # Very important to NOT construct a temporary Rooted here, since the
+            # SetToObject call can call a Rooted constructor and we need to keep
+            # stack discipline for Rooted.
+            object = CGGeneric("if (!%s.SetToObject(cx, &${val}.toObject(), ${passedToJSImpl})) {\n"
+                               "%s"
+                               "}\n"
+                               "done = true;\n" % (unionArgumentObj, indent(exceptionCode)))
+            names.append(objectMemberTypes[0].name)
+        else:
+            object = None
+
+        hasObjectTypes = interfaceObject or sequenceObject or dateObject or callbackObject or object or mozMapObject
+        if hasObjectTypes:
+            # "object" is not distinguishable from other types
+            assert not object or not (interfaceObject or sequenceObject or dateObject or callbackObject or mozMapObject)
+            if sequenceObject or dateObject or callbackObject:
+                # An object can be both an sequence object and a callback or
+                # dictionary, but we shouldn't have both in the union's members
+                # because they are not distinguishable.
+                assert not (sequenceObject and callbackObject)
+                templateBody = CGElseChain([sequenceObject, dateObject, callbackObject])
+            else:
+                templateBody = None
+            if interfaceObject:
+                assert not object
+                if templateBody:
+                    templateBody = CGIfWrapper(templateBody, "!done")
+                templateBody = CGList([interfaceObject, templateBody])
+            else:
+                templateBody = CGList([templateBody, object])
+
+            if dateObject:
+                templateBody.prepend(CGGeneric("JS::Rooted<JSObject*> argObj(cx, &${val}.toObject());\n"))
+
+            if mozMapObject:
+                templateBody = CGList([templateBody,
+                                       CGIfWrapper(mozMapObject, "!done")])
+
+            templateBody = CGIfWrapper(templateBody, "${val}.isObject()")
+        else:
+            templateBody = CGGeneric()
+
+        if setDictionary:
+            assert not object
+            templateBody = CGList([templateBody,
+                                   CGIfWrapper(setDictionary, "!done")])
+
+        stringTypes = [t for t in memberTypes if t.isString() or t.isEnum()]
+        numericTypes = [t for t in memberTypes if t.isNumeric()]
+        booleanTypes = [t for t in memberTypes if t.isBoolean()]
+        if stringTypes or numericTypes or booleanTypes:
+            assert len(stringTypes) <= 1
+            assert len(numericTypes) <= 1
+            assert len(booleanTypes) <= 1
+
+            # We will wrap all this stuff in a do { } while (0); so we
+            # can use "break" for flow control.
+            def getStringOrPrimitiveConversion(memberType):
+                name = getUnionMemberName(memberType)
+                return CGGeneric("done = (failed = !%s.TrySetTo%s(cx, ${val}, tryNext)) || !tryNext;\n"
+                                 "break;\n" % (unionArgumentObj, name))
+            other = CGList([])
+            stringConversion = map(getStringOrPrimitiveConversion, stringTypes)
+            numericConversion = map(getStringOrPrimitiveConversion, numericTypes)
+            booleanConversion = map(getStringOrPrimitiveConversion, booleanTypes)
+            if stringConversion:
+                if booleanConversion:
+                    other.append(CGIfWrapper(booleanConversion[0],
+                                             "${val}.isBoolean()"))
+                if numericConversion:
+                    other.append(CGIfWrapper(numericConversion[0],
+                                             "${val}.isNumber()"))
+                other.append(stringConversion[0])
+            elif numericConversion:
+                if booleanConversion:
+                    other.append(CGIfWrapper(booleanConversion[0],
+                                             "${val}.isBoolean()"))
+                other.append(numericConversion[0])
+            else:
+                assert booleanConversion
+                other.append(booleanConversion[0])
+
+            other = CGWrapper(CGIndenter(other), pre="do {\n", post="} while (0);\n")
+            if hasObjectTypes or setDictionary:
+                other = CGWrapper(CGIndenter(other), "{\n", post="}\n")
+                if object:
+                    templateBody = CGElseChain([templateBody, other])
+                else:
+                    other = CGWrapper(other, pre="if (!done) ")
+                    templateBody = CGList([templateBody, other])
+            else:
+                assert templateBody.define() == ""
+                templateBody = other
+        else:
+            other = None
+
+        templateBody = CGWrapper(templateBody, pre="bool done = false, failed = false, tryNext;\n")
+        throw = CGGeneric(fill(
+            """
+            if (failed) {
+              $*{exceptionCode}
+            }
+            if (!done) {
+              ThrowErrorMessage(cx, MSG_NOT_IN_UNION, "${desc}", "${names}");
+              $*{exceptionCode}
+            }
+            """,
+            exceptionCode=exceptionCode,
+            desc=firstCap(sourceDescription),
+            names=", ".join(names)))
+
+        templateBody = CGWrapper(CGIndenter(CGList([templateBody, throw])), pre="{\n", post="}\n")
+
+        typeName = CGUnionStruct.unionTypeDecl(type, isOwningUnion)
+        argumentTypeName = typeName + "Argument"
+        if nullable:
+            typeName = "Nullable<" + typeName + " >"
+
+        def handleNull(templateBody, setToNullVar, extraConditionForNull=""):
+            nullTest = "%s${val}.isNullOrUndefined()" % extraConditionForNull
+            return CGIfElseWrapper(nullTest,
+                                   CGGeneric("%s.SetNull();\n" % setToNullVar),
+                                   templateBody)
+
+        if type.hasNullableType:
+            assert not nullable
+            # Make sure to handle a null default value here
+            if defaultValue and isinstance(defaultValue, IDLNullValue):
+                assert defaultValue.type == type
+                extraConditionForNull = "!(${haveValue}) || "
+            else:
+                extraConditionForNull = ""
+            templateBody = handleNull(templateBody, unionArgumentObj,
+                                      extraConditionForNull=extraConditionForNull)
+
+        declType = CGGeneric(typeName)
+        if isOwningUnion:
+            holderType = None
+        else:
+            holderType = CGGeneric(argumentTypeName)
+            if nullable:
+                holderType = CGTemplatedType("Maybe", holderType)
+
+        # If we're isOptional and not nullable the normal optional handling will
+        # handle lazy construction of our holder.  If we're nullable and not
+        # owning we do it all by hand because we do not want our holder
+        # constructed if we're null.  But if we're owning we don't have a
+        # holder anyway, so we can do the normal Optional codepath.
+        declLoc = "${declName}"
+        constructDecl = None
+        if nullable:
+            if isOptional and not isOwningUnion:
+                holderArgs = "${declName}.Value().SetValue()"
+                declType = CGTemplatedType("Optional", declType)
+                constructDecl = CGGeneric("${declName}.Construct();\n")
+                declLoc = "${declName}.Value()"
+            else:
+                holderArgs = "${declName}.SetValue()"
+            if holderType is not None:
+                constructHolder = CGGeneric("${holderName}.emplace(%s);\n" % holderArgs)
+            else:
+                constructHolder = None
+            # Don't need to pass those args when the holder is being constructed
+            holderArgs = None
+        else:
+            holderArgs = "${declName}"
+            constructHolder = None
+
+        if not isMember and isCallbackReturnValue:
+            declType = CGWrapper(declType, post="&")
+            declArgs = "aRetVal"
+        else:
+            declArgs = None
+
+        if defaultValue and not isinstance(defaultValue, IDLNullValue):
+            tag = defaultValue.type.tag()
+
+            if tag in numericSuffixes or tag is IDLType.Tags.bool:
+                defaultStr = getHandleDefault(defaultValue)
+                # Make sure we actually construct the thing inside the nullable.
+                value = declLoc + (".SetValue()" if nullable else "")
+                name = getUnionMemberName(defaultValue.type)
+                default = CGGeneric("%s.RawSetAs%s() = %s;\n" %
+                                    (value, name, defaultStr))
+            elif isinstance(defaultValue, IDLEmptySequenceValue):
+                name = getUnionMemberName(defaultValue.type)
+                # Make sure we actually construct the thing inside the nullable.
+                value = declLoc + (".SetValue()" if nullable else "")
+                # It's enough to set us to the right type; that will
+                # create an empty array, which is all we need here.
+                default = CGGeneric("%s.RawSetAs%s();\n" %
+                                    (value, name))
+            elif defaultValue.type.isEnum():
+                name = getUnionMemberName(defaultValue.type)
+                # Make sure we actually construct the thing inside the nullable.
+                value = declLoc + (".SetValue()" if nullable else "")
+                default = CGGeneric(
+                    "%s.RawSetAs%s() = %s::%s;\n" %
+                    (value, name,
+                     defaultValue.type.inner.identifier.name,
+                     getEnumValueName(defaultValue.value)))
+            else:
+                default = CGGeneric(
+                    handleDefaultStringValue(
+                        defaultValue, "%s.SetStringData" % unionArgumentObj) +
+                    ";\n")
+
+            templateBody = CGIfElseWrapper("!(${haveValue})", default, templateBody)
+
+        templateBody = CGList([constructHolder, templateBody])
+
+        if nullable:
+            if defaultValue:
+                if isinstance(defaultValue, IDLNullValue):
+                    extraConditionForNull = "!(${haveValue}) || "
+                else:
+                    extraConditionForNull = "${haveValue} && "
+            else:
+                extraConditionForNull = ""
+            templateBody = handleNull(templateBody, declLoc,
+                                      extraConditionForNull=extraConditionForNull)
+        elif (not type.hasNullableType and defaultValue and
+              isinstance(defaultValue, IDLNullValue)):
+            assert type.hasDictionaryType()
+            assert defaultValue.type.isDictionary()
+            if not isOwningUnion and typeNeedsRooting(defaultValue.type):
+                ctorArgs = "cx"
+            else:
+                ctorArgs = ""
+            initDictionaryWithNull = CGIfWrapper(
+                CGGeneric("return false;\n"),
+                ('!%s.RawSetAs%s(%s).Init(cx, JS::NullHandleValue, "Member of %s")'
+                 % (declLoc, getUnionMemberName(defaultValue.type),
+                    ctorArgs, type)))
+            templateBody = CGIfElseWrapper("!(${haveValue})",
+                                           initDictionaryWithNull,
+                                           templateBody)
+
+        templateBody = CGList([constructDecl, templateBody])
+
+        return JSToNativeConversionInfo(templateBody.define(),
+                                        declType=declType,
+                                        declArgs=declArgs,
+                                        holderType=holderType,
+                                        holderArgs=holderArgs,
+                                        dealWithOptional=isOptional and (not nullable or isOwningUnion))
+
+    if type.isGeckoInterface():
+        assert not isEnforceRange and not isClamp
+
+        descriptor = descriptorProvider.getDescriptor(
+            type.unroll().inner.identifier.name)
+
+        assert descriptor.nativeType != 'JSObject'
+
+        if descriptor.interface.isCallback():
+            (declType, declArgs,
+             conversion) = getCallbackConversionInfo(type, descriptor.interface,
+                                                     isMember,
+                                                     isCallbackReturnValue,
+                                                     isOptional)
+            template = wrapObjectTemplate(conversion, type,
+                                          "${declName} = nullptr;\n",
+                                          failureCode)
+            return JSToNativeConversionInfo(template, declType=declType,
+                                            declArgs=declArgs,
+                                            dealWithOptional=isOptional)
+
+        # This is an interface that we implement as a concrete class
+        # or an XPCOM interface.
+
+        # Allow null pointers for nullable types and old-binding classes, and
+        # use an RefPtr or raw pointer for callback return values to make
+        # them easier to return.
+        argIsPointer = (type.nullable() or type.unroll().inner.isExternal() or
+                        isCallbackReturnValue)
+
+        # Sequence and dictionary members, as well as owning unions (which can
+        # appear here as return values in JS-implemented interfaces) have to
+        # hold a strong ref to the thing being passed down.  Those all set
+        # isMember.
+        #
+        # Also, callback return values always end up addrefing anyway, so there
+        # is no point trying to avoid it here and it makes other things simpler
+        # since we can assume the return value is a strong ref.
+        #
+        # Finally, promises need to hold a strong ref because that's what
+        # Promise.resolve returns.
+        assert not descriptor.interface.isCallback()
+        isPromise = descriptor.interface.identifier.name == "Promise"
+        forceOwningType = isMember or isCallbackReturnValue or isPromise
+
+        typeName = descriptor.nativeType
+        typePtr = typeName + "*"
+
+        # Compute a few things:
+        #  - declType is the type we want to return as the first element of our
+        #    tuple.
+        #  - holderType is the type we want to return as the third element
+        #    of our tuple.
+
+        # Set up some sensible defaults for these things insofar as we can.
+        holderType = None
+        if argIsPointer:
+            if forceOwningType:
+                declType = "RefPtr<" + typeName + ">"
+            else:
+                declType = typePtr
+        else:
+            if forceOwningType:
+                declType = "OwningNonNull<" + typeName + ">"
+            else:
+                declType = "NonNull<" + typeName + ">"
+
+        templateBody = ""
+        if forceOwningType:
+            templateBody += 'static_assert(IsRefcounted<%s>::value, "We can only store refcounted classes.");' % typeName
+
+        if isPromise:
+            # Per spec, what we're supposed to do is take the original
+            # Promise.resolve and call it with the original Promise as this
+            # value to make a Promise out of whatever value we actually have
+            # here.  The question is which global we should use.  There are
+            # several cases to consider:
+            #
+            # 1) Normal call to API with a Promise argument.  This is a case the
+            #    spec covers, and we should be using the current Realm's
+            #    Promise.  That means the current compartment.
+            # 2) Call to API with a Promise argument over Xrays.  In practice,
+            #    this sort of thing seems to be used for giving an API
+            #    implementation a way to wait for conclusion of an asyc
+            #    operation, _not_ to expose the Promise to content code.  So we
+            #    probably want to allow callers to use such an API in a
+            #    "natural" way, by passing chrome-side promises; indeed, that
+            #    may be all that the caller has to represent their async
+            #    operation.  That means we really need to do the
+            #    Promise.resolve() in the caller (chrome) compartment: if we do
+            #    it in the content compartment, we will try to call .then() on
+            #    the chrome promise while in the content compartment, which will
+            #    throw and we'll just get a rejected Promise.  Note that this is
+            #    also the reason why a caller who has a chrome Promise
+            #    representing an async operation can't itself convert it to a
+            #    content-side Promise (at least not without some serious
+            #    gyrations).
+            # 3) Promise return value from a callback or callback interface.
+            #    This is in theory a case the spec covers but in practice it
+            #    really doesn't define behavior here because it doesn't define
+            #    what Realm we're in after the callback returns, which is when
+            #    the argument conversion happens.  We will use the current
+            #    compartment, which is the compartment of the callable (which
+            #    may itself be a cross-compartment wrapper itself), which makes
+            #    as much sense as anything else. In practice, such an API would
+            #    once again be providing a Promise to signal completion of an
+            #    operation, which would then not be exposed to anyone other than
+            #    our own implementation code.
+            # 4) Return value from a JS-implemented interface.  In this case we
+            #    have a problem.  Our current compartment is the compartment of
+            #    the JS implementation.  But if the JS implementation returned
+            #    a page-side Promise (which is a totally sane thing to do, and
+            #    in fact the right thing to do given that this return value is
+            #    going right to content script) then we don't want to
+            #    Promise.resolve with our current compartment Promise, because
+            #    that will wrap it up in a chrome-side Promise, which is
+            #    decidedly _not_ what's desired here.  So in that case we
+            #    should really unwrap the return value and use the global of
+            #    the result.  CheckedUnwrap should be good enough for that; if
+            #    it fails, then we're failing unwrap while in a
+            #    system-privileged compartment, so presumably we have a dead
+            #    object wrapper.  Just error out.  Do NOT fall back to using
+            #    the current compartment instead: that will return a
+            #    system-privileged rejected (because getting .then inside
+            #    resolve() failed) Promise to the caller, which they won't be
+            #    able to touch.  That's not helpful.  If we error out, on the
+            #    other hand, they will get a content-side rejected promise.
+            #    Same thing if the value returned is not even an object.
+            if isCallbackReturnValue == "JSImpl":
+                # Case 4 above.  Note that globalObj defaults to the current
+                # compartment global.  Note that we don't use $*{exceptionCode}
+                # here because that will try to aRv.Throw(NS_ERROR_UNEXPECTED)
+                # which we don't really want here.
+                assert exceptionCode == "aRv.Throw(NS_ERROR_UNEXPECTED);\nreturn nullptr;\n"
+                getPromiseGlobal = fill(
+                    """
+                    if (!$${val}.isObject()) {
+                      aRv.ThrowTypeError<MSG_NOT_OBJECT>(NS_LITERAL_STRING("${sourceDescription}"));
+                      return nullptr;
+                    }
+                    JSObject* unwrappedVal = js::CheckedUnwrap(&$${val}.toObject());
+                    if (!unwrappedVal) {
+                      // A slight lie, but not much of one, for a dead object wrapper.
+                      aRv.ThrowTypeError<MSG_NOT_OBJECT>(NS_LITERAL_STRING("${sourceDescription}"));
+                      return nullptr;
+                    }
+                    globalObj = js::GetGlobalForObjectCrossCompartment(unwrappedVal);
+                    """,
+                    sourceDescription=sourceDescription)
+            else:
+                getPromiseGlobal = ""
+
+            templateBody = fill(
+                """
+                { // Scope for our GlobalObject, FastErrorResult, JSAutoCompartment,
+                  // etc.
+
+                  JS::Rooted<JSObject*> globalObj(cx, JS::CurrentGlobalOrNull(cx));
+                  $*{getPromiseGlobal}
+                  JSAutoCompartment ac(cx, globalObj);
+                  GlobalObject promiseGlobal(cx, globalObj);
+                  if (promiseGlobal.Failed()) {
+                    $*{exceptionCode}
+                  }
+
+                  JS::Rooted<JS::Value> valueToResolve(cx, $${val});
+                  if (!JS_WrapValue(cx, &valueToResolve)) {
+                    $*{exceptionCode}
+                  }
+                  binding_detail::FastErrorResult promiseRv;
+                #ifdef SPIDERMONKEY_PROMISE
+                  nsCOMPtr<nsIGlobalObject> global =
+                    do_QueryInterface(promiseGlobal.GetAsSupports());
+                  if (!global) {
+                    promiseRv.Throw(NS_ERROR_UNEXPECTED);
+                    promiseRv.MaybeSetPendingException(cx);
+                    $*{exceptionCode}
+                  }
+                  $${declName} = Promise::Resolve(global, cx, valueToResolve,
+                                                  promiseRv);
+                  if (promiseRv.MaybeSetPendingException(cx)) {
+                    $*{exceptionCode}
+                  }
+                #else
+                  JS::Handle<JSObject*> promiseCtor =
+                    PromiseBinding::GetConstructorObjectHandle(cx);
+                  if (!promiseCtor) {
+                    $*{exceptionCode}
+                  }
+                  JS::Rooted<JS::Value> resolveThisv(cx, JS::ObjectValue(*promiseCtor));
+                  JS::Rooted<JS::Value> resolveResult(cx);
+                  Promise::Resolve(promiseGlobal, resolveThisv, valueToResolve,
+                                   &resolveResult, promiseRv);
+                  if (promiseRv.MaybeSetPendingException(cx)) {
+                    $*{exceptionCode}
+                  }
+                  nsresult unwrapRv = UNWRAP_OBJECT(Promise, &resolveResult.toObject(), $${declName});
+                  if (NS_FAILED(unwrapRv)) { // Quite odd
+                    promiseRv.Throw(unwrapRv);
+                    promiseRv.MaybeSetPendingException(cx);
+                    $*{exceptionCode}
+                  }
+                #endif // SPIDERMONKEY_PROMISE
+                }
+                """,
+                getPromiseGlobal=getPromiseGlobal,
+                exceptionCode=exceptionCode)
+        elif not descriptor.interface.isConsequential() and not descriptor.interface.isExternal():
+            if failureCode is not None:
+                templateBody += str(CastableObjectUnwrapper(
+                    descriptor,
+                    "${val}",
+                    "${maybeMutableVal}",
+                    "${declName}",
+                    failureCode))
+            else:
+                templateBody += str(FailureFatalCastableObjectUnwrapper(
+                    descriptor,
+                    "${val}",
+                    "${maybeMutableVal}",
+                    "${declName}",
+                    exceptionCode,
+                    isCallbackReturnValue,
+                    firstCap(sourceDescription)))
+        else:
+            # Either external, or new-binding non-castable.  We always have a
+            # holder for these, because we don't actually know whether we have
+            # to addref when unwrapping or not.  So we just pass an
+            # getter_AddRefs(RefPtr) to XPConnect and if we'll need a release
+            # it'll put a non-null pointer in there.
+            if forceOwningType:
+                # Don't return a holderType in this case; our declName
+                # will just own stuff.
+                templateBody += "RefPtr<" + typeName + "> ${holderName};\n"
+            else:
+                holderType = "RefPtr<" + typeName + ">"
+            templateBody += (
+                "JS::Rooted<JSObject*> source(cx, &${val}.toObject());\n" +
+                "if (NS_FAILED(UnwrapArg<" + typeName + ">(source, getter_AddRefs(${holderName})))) {\n")
+            templateBody += CGIndenter(onFailureBadType(failureCode,
+                                                        descriptor.interface.identifier.name)).define()
+            templateBody += ("}\n"
+                             "MOZ_ASSERT(${holderName});\n")
+
+            # And store our value in ${declName}
+            templateBody += "${declName} = ${holderName};\n"
+
+        if isPromise:
+            if type.nullable():
+                codeToSetNull = "${declName} = nullptr;\n"
+                templateBody = CGIfElseWrapper(
+                    "${val}.isNullOrUndefined()",
+                    CGGeneric(codeToSetNull),
+                    CGGeneric(templateBody)).define()
+                if isinstance(defaultValue, IDLNullValue):
+                    templateBody = handleDefault(templateBody, codeToSetNull)
+            else:
+                assert defaultValue is None
+        else:
+            # Just pass failureCode, not onFailureBadType, here, so we'll report
+            # the thing as not an object as opposed to not implementing whatever
+            # our interface is.
+            templateBody = wrapObjectTemplate(templateBody, type,
+                                              "${declName} = nullptr;\n",
+                                              failureCode)
+
+        declType = CGGeneric(declType)
+        if holderType is not None:
+            holderType = CGGeneric(holderType)
+        return JSToNativeConversionInfo(templateBody,
+                                        declType=declType,
+                                        holderType=holderType,
+                                        dealWithOptional=isOptional)
+
+    if type.isSpiderMonkeyInterface():
+        assert not isEnforceRange and not isClamp
+        name = type.unroll().name  # unroll() because it may be nullable
+        arrayType = CGGeneric(name)
+        declType = arrayType
+        if type.nullable():
+            declType = CGTemplatedType("Nullable", declType)
+            objRef = "${declName}.SetValue()"
+        else:
+            objRef = "${declName}"
+
+        # Again, this is a bit strange since we are actually building a
+        # template string here. ${objRef} and $*{badType} below are filled in
+        # right now; $${val} expands to ${val}, to be filled in later.
+        template = fill(
+            """
+            if (!${objRef}.Init(&$${val}.toObject())) {
+              $*{badType}
+            }
+            """,
+            objRef=objRef,
+            badType=onFailureBadType(failureCode, type.name).define())
+        template = wrapObjectTemplate(template, type, "${declName}.SetNull();\n",
+                                      failureCode)
+        if not isMember:
+            # This is a bit annoying.  In a union we don't want to have a
+            # holder, since unions don't support that.  But if we're optional we
+            # want to have a holder, so that the callee doesn't see
+            # Optional<RootedTypedArray<ArrayType> >.  So do a holder if we're
+            # optional and use a RootedTypedArray otherwise.
+            if isOptional:
+                holderType = CGTemplatedType("TypedArrayRooter", arrayType)
+                # If our typed array is nullable, this will set the Nullable to
+                # be not-null, but that's ok because we make an explicit
+                # SetNull() call on it as needed if our JS value is actually
+                # null.  XXXbz Because "Maybe" takes const refs for constructor
+                # arguments, we can't pass a reference here; have to pass a
+                # pointer.
+                holderArgs = "cx, &%s" % objRef
+                declArgs = None
+            else:
+                holderType = None
+                holderArgs = None
+                declType = CGTemplatedType("RootedTypedArray", declType)
+                declArgs = "cx"
+        else:
+            holderType = None
+            holderArgs = None
+            declArgs = None
+        return JSToNativeConversionInfo(template,
+                                        declType=declType,
+                                        holderType=holderType,
+                                        dealWithOptional=isOptional,
+                                        declArgs=declArgs,
+                                        holderArgs=holderArgs)
+
+    if type.isDOMString() or type.isUSVString():
+        assert not isEnforceRange and not isClamp
+
+        treatAs = {
+            "Default": "eStringify",
+            "EmptyString": "eEmpty",
+            "Null": "eNull",
+        }
+        if type.nullable():
+            # For nullable strings null becomes a null string.
+            treatNullAs = "Null"
+            # For nullable strings undefined also becomes a null string.
+            undefinedBehavior = "eNull"
+        else:
+            undefinedBehavior = "eStringify"
+        nullBehavior = treatAs[treatNullAs]
+
+        def getConversionCode(varName):
+            normalizeCode = ""
+            if type.isUSVString():
+                normalizeCode = "NormalizeUSVString(cx, %s);\n" % varName
+
+            conversionCode = fill("""
+                if (!ConvertJSValueToString(cx, $${val}, ${nullBehavior}, ${undefinedBehavior}, ${varName})) {
+                  $*{exceptionCode}
+                }
+                $*{normalizeCode}
+                """
+                ,
+                nullBehavior=nullBehavior,
+                undefinedBehavior=undefinedBehavior,
+                varName=varName,
+                exceptionCode=exceptionCode,
+                normalizeCode=normalizeCode)
+
+            if defaultValue is None:
+                return conversionCode
+
+            if isinstance(defaultValue, IDLNullValue):
+                assert(type.nullable())
+                defaultCode = "%s.SetIsVoid(true)" % varName
+            else:
+                defaultCode = handleDefaultStringValue(defaultValue,
+                                                       "%s.Rebind" % varName)
+            return handleDefault(conversionCode, defaultCode + ";\n")
+
+        if isMember:
+            # Convert directly into the nsString member we have.
+            declType = CGGeneric("nsString")
+            return JSToNativeConversionInfo(
+                getConversionCode("${declName}"),
+                declType=declType,
+                dealWithOptional=isOptional)
+
+        if isOptional:
+            declType = "Optional<nsAString>"
+            holderType = CGGeneric("binding_detail::FakeString")
+            conversionCode = ("%s"
+                              "${declName} = &${holderName};\n" %
+                              getConversionCode("${holderName}"))
+        else:
+            declType = "binding_detail::FakeString"
+            holderType = None
+            conversionCode = getConversionCode("${declName}")
+
+        # No need to deal with optional here; we handled it already
+        return JSToNativeConversionInfo(
+            conversionCode,
+            declType=CGGeneric(declType),
+            holderType=holderType)
+
+    if type.isByteString():
+        assert not isEnforceRange and not isClamp
+
+        nullable = toStringBool(type.nullable())
+
+        conversionCode = fill("""
+            if (!ConvertJSValueToByteString(cx, $${val}, ${nullable}, $${declName})) {
+              $*{exceptionCode}
+            }
+            """,
+            nullable=nullable,
+            exceptionCode=exceptionCode)
+
+        if defaultValue is not None:
+            if isinstance(defaultValue, IDLNullValue):
+                assert(type.nullable())
+                defaultCode = "${declName}.SetIsVoid(true)"
+            else:
+                defaultCode = handleDefaultStringValue(defaultValue,
+                                                       "${declName}.Rebind")
+            conversionCode = handleDefault(conversionCode, defaultCode + ";\n")
+
+        return JSToNativeConversionInfo(
+            conversionCode,
+            declType=CGGeneric("nsCString"),
+            dealWithOptional=isOptional)
+
+    if type.isEnum():
+        assert not isEnforceRange and not isClamp
+
+        enumName = type.unroll().inner.identifier.name
+        declType = CGGeneric(enumName)
+        if type.nullable():
+            declType = CGTemplatedType("Nullable", declType)
+            declType = declType.define()
+            enumLoc = "${declName}.SetValue()"
+        else:
+            enumLoc = "${declName}"
+            declType = declType.define()
+
+        if invalidEnumValueFatal:
+            handleInvalidEnumValueCode = "MOZ_ASSERT(index >= 0);\n"
+        else:
+            # invalidEnumValueFatal is false only for attributes.  So we won't
+            # have a non-default exceptionCode here unless attribute "arg
+            # conversion" code starts passing in an exceptionCode.  At which
+            # point we'll need to figure out what that even means.
+            assert exceptionCode == "return false;\n"
+            handleInvalidEnumValueCode = dedent("""
+                if (index < 0) {
+                  return true;
+                }
+                """)
+
+        template = fill(
+            """
+            {
+              int index;
+              if (!FindEnumStringIndex<${invalidEnumValueFatal}>(cx, $${val}, ${values}, "${enumtype}", "${sourceDescription}", &index)) {
+                $*{exceptionCode}
+              }
+              $*{handleInvalidEnumValueCode}
+              ${enumLoc} = static_cast<${enumtype}>(index);
+            }
+            """,
+            enumtype=enumName,
+            values=enumName + "Values::" + ENUM_ENTRY_VARIABLE_NAME,
+            invalidEnumValueFatal=toStringBool(invalidEnumValueFatal),
+            handleInvalidEnumValueCode=handleInvalidEnumValueCode,
+            exceptionCode=exceptionCode,
+            enumLoc=enumLoc,
+            sourceDescription=firstCap(sourceDescription))
+
+        setNull = "${declName}.SetNull();\n"
+
+        if type.nullable():
+            template = CGIfElseWrapper("${val}.isNullOrUndefined()",
+                                       CGGeneric(setNull),
+                                       CGGeneric(template)).define()
+
+        if defaultValue is not None:
+            if isinstance(defaultValue, IDLNullValue):
+                assert type.nullable()
+                template = handleDefault(template, setNull)
+            else:
+                assert(defaultValue.type.tag() == IDLType.Tags.domstring)
+                template = handleDefault(template,
+                                         ("%s = %s::%s;\n" %
+                                          (enumLoc, enumName,
+                                           getEnumValueName(defaultValue.value))))
+        return JSToNativeConversionInfo(template, declType=CGGeneric(declType),
+                                        dealWithOptional=isOptional)
+
+    if type.isCallback():
+        assert not isEnforceRange and not isClamp
+        assert not type.treatNonCallableAsNull() or type.nullable()
+        assert not type.treatNonObjectAsNull() or type.nullable()
+        assert not type.treatNonObjectAsNull() or not type.treatNonCallableAsNull()
+
+        callback = type.unroll().callback
+        name = callback.identifier.name
+        (declType, declArgs,
+         conversion) = getCallbackConversionInfo(type, callback, isMember,
+                                                 isCallbackReturnValue,
+                                                 isOptional)
+
+        if allowTreatNonCallableAsNull and type.treatNonCallableAsNull():
+            haveCallable = "JS::IsCallable(&${val}.toObject())"
+            if not isDefinitelyObject:
+                haveCallable = "${val}.isObject() && " + haveCallable
+            if defaultValue is not None:
+                assert(isinstance(defaultValue, IDLNullValue))
+                haveCallable = "${haveValue} && " + haveCallable
+            template = (
+                ("if (%s) {\n" % haveCallable) +
+                conversion +
+                "} else {\n"
+                "  ${declName} = nullptr;\n"
+                "}\n")
+        elif allowTreatNonCallableAsNull and type.treatNonObjectAsNull():
+            if not isDefinitelyObject:
+                haveObject = "${val}.isObject()"
+                if defaultValue is not None:
+                    assert(isinstance(defaultValue, IDLNullValue))
+                    haveObject = "${haveValue} && " + haveObject
+                template = CGIfElseWrapper(haveObject,
+                                           CGGeneric(conversion),
+                                           CGGeneric("${declName} = nullptr;\n")).define()
+            else:
+                template = conversion
+        else:
+            template = wrapObjectTemplate(
+                "if (JS::IsCallable(&${val}.toObject())) {\n" +
+                conversion +
+                "} else {\n" +
+                indent(onFailureNotCallable(failureCode).define()) +
+                "}\n",
+                type,
+                "${declName} = nullptr;\n",
+                failureCode)
+        return JSToNativeConversionInfo(template, declType=declType,
+                                        declArgs=declArgs,
+                                        dealWithOptional=isOptional)
+
+    if type.isAny():
+        assert not isEnforceRange and not isClamp
+
+        declArgs = None
+        if isMember in ("Variadic", "Sequence", "Dictionary", "MozMap"):
+            # Rooting is handled by the sequence and dictionary tracers.
+            declType = "JS::Value"
+        else:
+            assert not isMember
+            declType = "JS::Rooted<JS::Value>"
+            declArgs = "cx"
+
+        assert not isOptional
+        templateBody = "${declName} = ${val};\n"
+
+        # For JS-implemented APIs, we refuse to allow passing objects that the
+        # API consumer does not subsume. The extra parens around
+        # ($${passedToJSImpl}) suppress unreachable code warnings when
+        # $${passedToJSImpl} is the literal `false`.
+        if not isinstance(descriptorProvider, Descriptor) or descriptorProvider.interface.isJSImplemented():
+            templateBody = fill(
+                """
+                if (($${passedToJSImpl}) && !CallerSubsumes($${val})) {
+                  ThrowErrorMessage(cx, MSG_PERMISSION_DENIED_TO_PASS_ARG, "${sourceDescription}");
+                  $*{exceptionCode}
+                }
+                """,
+                sourceDescription=sourceDescription,
+                exceptionCode=exceptionCode) + templateBody
+
+        # We may not have a default value if we're being converted for
+        # a setter, say.
+        if defaultValue:
+            if isinstance(defaultValue, IDLNullValue):
+                defaultHandling = "${declName} = JS::NullValue();\n"
+            else:
+                assert isinstance(defaultValue, IDLUndefinedValue)
+                defaultHandling = "${declName} = JS::UndefinedValue();\n"
+            templateBody = handleDefault(templateBody, defaultHandling)
+        return JSToNativeConversionInfo(templateBody,
+                                        declType=CGGeneric(declType),
+                                        declArgs=declArgs)
+
+    if type.isObject():
+        assert not isEnforceRange and not isClamp
+        return handleJSObjectType(type, isMember, failureCode, exceptionCode, sourceDescription)
+
+    if type.isDictionary():
+        # There are no nullable dictionaries
+        assert not type.nullable() or isCallbackReturnValue
+        # All optional dictionaries always have default values, so we
+        # should be able to assume not isOptional here.
+        assert not isOptional
+        # In the callback return value case we never have to worry
+        # about a default value; we always have a value.
+        assert not isCallbackReturnValue or defaultValue is None
+
+        typeName = CGDictionary.makeDictionaryName(type.unroll().inner)
+        if not isMember and not isCallbackReturnValue:
+            # Since we're not a member and not nullable or optional, no one will
+            # see our real type, so we can do the fast version of the dictionary
+            # that doesn't pre-initialize members.
+            typeName = "binding_detail::Fast" + typeName
+
+        declType = CGGeneric(typeName)
+
+        # We do manual default value handling here, because we
+        # actually do want a jsval, and we only handle null anyway
+        # NOTE: if isNullOrUndefined or isDefinitelyObject are true,
+        # we know we have a value, so we don't have to worry about the
+        # default value.
+        if (not isNullOrUndefined and not isDefinitelyObject and
+            defaultValue is not None):
+            assert(isinstance(defaultValue, IDLNullValue))
+            val = "(${haveValue}) ? ${val} : JS::NullHandleValue"
+        else:
+            val = "${val}"
+
+        dictLoc = "${declName}"
+        if type.nullable():
+            dictLoc += ".SetValue()"
+
+        conversionCode = fill("""
+            if (!${dictLoc}.Init(cx, ${val},  "${desc}", $${passedToJSImpl})) {
+              $*{exceptionCode}
+            }
+            """,
+            dictLoc=dictLoc,
+            val=val,
+            desc=firstCap(sourceDescription),
+            exceptionCode=exceptionCode)
+
+        if failureCode is not None:
+            if isDefinitelyObject:
+                dictionaryTest = "IsObjectValueConvertibleToDictionary"
+            else:
+                dictionaryTest = "IsConvertibleToDictionary"
+
+            template = fill("""
+                { // scope for isConvertible
+                  bool isConvertible;
+                  if (!${testConvertible}(cx, ${val}, &isConvertible)) {
+                    $*{exceptionCode}
+                  }
+                  if (!isConvertible) {
+                    $*{failureCode}
+                  }
+
+                  $*{conversionCode}
+                }
+
+                """,
+                testConvertible=dictionaryTest,
+                val=val,
+                exceptionCode=exceptionCode,
+                failureCode=failureCode,
+                conversionCode=conversionCode)
+        else:
+            template = conversionCode
+
+        if type.nullable():
+            declType = CGTemplatedType("Nullable", declType)
+            template = CGIfElseWrapper("${val}.isNullOrUndefined()",
+                                       CGGeneric("${declName}.SetNull();\n"),
+                                       CGGeneric(template)).define()
+
+        # Dictionary arguments that might contain traceable things need to get
+        # traced
+        if not isMember and isCallbackReturnValue:
+            # Go ahead and just convert directly into our actual return value
+            declType = CGWrapper(declType, post="&")
+            declArgs = "aRetVal"
+        elif not isMember and typeNeedsRooting(type):
+            declType = CGTemplatedType("RootedDictionary", declType)
+            declArgs = "cx"
+        else:
+            declArgs = None
+
+        return JSToNativeConversionInfo(template, declType=declType,
+                                        declArgs=declArgs)
+
+    if type.isVoid():
+        assert not isOptional
+        # This one only happens for return values, and its easy: Just
+        # ignore the jsval.
+        return JSToNativeConversionInfo("")
+
+    if type.isDate():
+        assert not isEnforceRange and not isClamp
+
+        declType = CGGeneric("Date")
+        if type.nullable():
+            declType = CGTemplatedType("Nullable", declType)
+            dateVal = "${declName}.SetValue()"
+        else:
+            dateVal = "${declName}"
+
+        if failureCode is None:
+            notDate = ('ThrowErrorMessage(cx, MSG_NOT_DATE, "%s");\n'
+                       "%s" % (firstCap(sourceDescription), exceptionCode))
+        else:
+            notDate = failureCode
+
+        conversion = fill(
+            """
+            JS::Rooted<JSObject*> possibleDateObject(cx, &$${val}.toObject());
+            { // scope for isDate
+              bool isDate;
+              if (!JS_ObjectIsDate(cx, possibleDateObject, &isDate)) {
+                $*{exceptionCode}
+              }
+              if (!isDate) {
+                $*{notDate}
+              }
+              if (!${dateVal}.SetTimeStamp(cx, possibleDateObject)) {
+                $*{exceptionCode}
+              }
+            }
+            """,
+            exceptionCode=exceptionCode,
+            dateVal=dateVal,
+            notDate=notDate)
+
+        conversion = wrapObjectTemplate(conversion, type,
+                                        "${declName}.SetNull();\n", notDate)
+        return JSToNativeConversionInfo(conversion,
+                                        declType=declType,
+                                        dealWithOptional=isOptional)
+
+    if not type.isPrimitive():
+        raise TypeError("Need conversion for argument type '%s'" % str(type))
+
+    typeName = builtinNames[type.tag()]
+
+    conversionBehavior = "eDefault"
+    if isEnforceRange:
+        assert type.isInteger()
+        conversionBehavior = "eEnforceRange"
+    elif isClamp:
+        assert type.isInteger()
+        conversionBehavior = "eClamp"
+
+    if type.nullable():
+        declType = CGGeneric("Nullable<" + typeName + ">")
+        writeLoc = "${declName}.SetValue()"
+        readLoc = "${declName}.Value()"
+        nullCondition = "${val}.isNullOrUndefined()"
+        if defaultValue is not None and isinstance(defaultValue, IDLNullValue):
+            nullCondition = "!(${haveValue}) || " + nullCondition
+        template = fill("""
+            if (${nullCondition}) {
+              $${declName}.SetNull();
+            } else if (!ValueToPrimitive<${typeName}, ${conversionBehavior}>(cx, $${val}, &${writeLoc})) {
+              $*{exceptionCode}
+            }
+            """,
+            nullCondition=nullCondition,
+            typeName=typeName,
+            conversionBehavior=conversionBehavior,
+            writeLoc=writeLoc,
+            exceptionCode=exceptionCode)
+    else:
+        assert(defaultValue is None or
+               not isinstance(defaultValue, IDLNullValue))
+        writeLoc = "${declName}"
+        readLoc = writeLoc
+        template = fill("""
+            if (!ValueToPrimitive<${typeName}, ${conversionBehavior}>(cx, $${val}, &${writeLoc})) {
+              $*{exceptionCode}
+            }
+            """,
+            typeName=typeName,
+            conversionBehavior=conversionBehavior,
+            writeLoc=writeLoc,
+            exceptionCode=exceptionCode)
+        declType = CGGeneric(typeName)
+
+    if type.isFloat() and not type.isUnrestricted():
+        if lenientFloatCode is not None:
+            nonFiniteCode = lenientFloatCode
+        else:
+            nonFiniteCode = ('ThrowErrorMessage(cx, MSG_NOT_FINITE, "%s");\n'
+                             "%s" % (firstCap(sourceDescription), exceptionCode))
+
+        # We're appending to an if-block brace, so strip trailing whitespace
+        # and add an extra space before the else.
+        template = template.rstrip()
+        template += fill("""
+             else if (!mozilla::IsFinite(${readLoc})) {
+              $*{nonFiniteCode}
+            }
+            """,
+            readLoc=readLoc,
+            nonFiniteCode=nonFiniteCode)
+
+    if (defaultValue is not None and
+        # We already handled IDLNullValue, so just deal with the other ones
+        not isinstance(defaultValue, IDLNullValue)):
+        tag = defaultValue.type.tag()
+        defaultStr = getHandleDefault(defaultValue)
+        template = CGIfElseWrapper(
+            "${haveValue}",
+            CGGeneric(template),
+            CGGeneric("%s = %s;\n" % (writeLoc, defaultStr))).define()
+
+    return JSToNativeConversionInfo(template, declType=declType,
+                                    dealWithOptional=isOptional)
+
+
+def instantiateJSToNativeConversion(info, replacements, checkForValue=False):
+    """
+    Take a JSToNativeConversionInfo as returned by getJSToNativeConversionInfo
+    and a set of replacements as required by the strings in such an object, and
+    generate code to convert into stack C++ types.
+
+    If checkForValue is True, then the conversion will get wrapped in
+    a check for ${haveValue}.
+    """
+    templateBody, declType, holderType, dealWithOptional = (
+        info.template, info.declType, info.holderType, info.dealWithOptional)
+
+    if dealWithOptional and not checkForValue:
+        raise TypeError("Have to deal with optional things, but don't know how")
+    if checkForValue and declType is None:
+        raise TypeError("Need to predeclare optional things, so they will be "
+                        "outside the check for big enough arg count!")
+
+    # We can't precompute our holder constructor arguments, since
+    # those might depend on ${declName}, which we change below.  Just
+    # compute arguments at the point when we need them as we go.
+    def getArgsCGThing(args):
+        return CGGeneric(string.Template(args).substitute(replacements))
+
+    result = CGList([])
+    # Make a copy of "replacements" since we may be about to start modifying it
+    replacements = dict(replacements)
+    originalDeclName = replacements["declName"]
+    if declType is not None:
+        if dealWithOptional:
+            replacements["declName"] = "%s.Value()" % originalDeclName
+            declType = CGTemplatedType("Optional", declType)
+            declCtorArgs = None
+        elif info.declArgs is not None:
+            declCtorArgs = CGWrapper(getArgsCGThing(info.declArgs),
+                                     pre="(", post=")")
+        else:
+            declCtorArgs = None
+        result.append(
+            CGList([declType, CGGeneric(" "),
+                    CGGeneric(originalDeclName),
+                    declCtorArgs, CGGeneric(";\n")]))
+
+    originalHolderName = replacements["holderName"]
+    if holderType is not None:
+        if dealWithOptional:
+            replacements["holderName"] = "%s.ref()" % originalHolderName
+            holderType = CGTemplatedType("Maybe", holderType)
+            holderCtorArgs = None
+        elif info.holderArgs is not None:
+            holderCtorArgs = CGWrapper(getArgsCGThing(info.holderArgs),
+                                       pre="(", post=")")
+        else:
+            holderCtorArgs = None
+        result.append(
+            CGList([holderType, CGGeneric(" "),
+                    CGGeneric(originalHolderName),
+                    holderCtorArgs, CGGeneric(";\n")]))
+
+    if "maybeMutableVal" not in replacements:
+        replacements["maybeMutableVal"] = replacements["val"]
+
+    conversion = CGGeneric(
+        string.Template(templateBody).substitute(replacements))
+
+    if checkForValue:
+        if dealWithOptional:
+            declConstruct = CGIndenter(
+                CGGeneric("%s.Construct(%s);\n" %
+                          (originalDeclName,
+                           getArgsCGThing(info.declArgs).define() if
+                           info.declArgs else "")))
+            if holderType is not None:
+                holderConstruct = CGIndenter(
+                    CGGeneric("%s.emplace(%s);\n" %
+                              (originalHolderName,
+                               getArgsCGThing(info.holderArgs).define() if
+                               info.holderArgs else "")))
+            else:
+                holderConstruct = None
+        else:
+            declConstruct = None
+            holderConstruct = None
+
+        conversion = CGList([
+            CGGeneric(
+                string.Template("if (${haveValue}) {\n").substitute(replacements)),
+            declConstruct,
+            holderConstruct,
+            CGIndenter(conversion),
+            CGGeneric("}\n")
+        ])
+
+    result.append(conversion)
+    return result
+
+
+def convertConstIDLValueToJSVal(value):
+    if isinstance(value, IDLNullValue):
+        return "JS::NullValue()"
+    if isinstance(value, IDLUndefinedValue):
+        return "JS::UndefinedValue()"
+    tag = value.type.tag()
+    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
+               IDLType.Tags.uint16, IDLType.Tags.int32]:
+        return "JS::Int32Value(%s)" % (value.value)
+    if tag == IDLType.Tags.uint32:
+        return "JS::NumberValue(%sU)" % (value.value)
+    if tag in [IDLType.Tags.int64, IDLType.Tags.uint64]:
+        return "JS::CanonicalizedDoubleValue(%s)" % numericValue(tag, value.value)
+    if tag == IDLType.Tags.bool:
+        return "JS::BooleanValue(true)" if value.value else "JS::BooleanValue(false)"
+    if tag in [IDLType.Tags.float, IDLType.Tags.double]:
+        return "JS::CanonicalizedDoubleValue(%s)" % (value.value)
+    raise TypeError("Const value of unhandled type: %s" % value.type)
+
+
+class CGArgumentConverter(CGThing):
+    """
+    A class that takes an IDL argument object and its index in the
+    argument list and generates code to unwrap the argument to the
+    right native type.
+
+    argDescription is a description of the argument for error-reporting
+    purposes.  Callers should assume that it might get placed in the middle of a
+    sentence.  If it ends up at the beginning of a sentence, its first character
+    will be automatically uppercased.
+    """
+    def __init__(self, argument, index, descriptorProvider,
+                 argDescription, member,
+                 invalidEnumValueFatal=True, lenientFloatCode=None):
+        CGThing.__init__(self)
+        self.argument = argument
+        self.argDescription = argDescription
+        assert(not argument.defaultValue or argument.optional)
+
+        replacer = {
+            "index": index,
+            "argc": "args.length()"
+        }
+        self.replacementVariables = {
+            "declName": "arg%d" % index,
+            "holderName": ("arg%d" % index) + "_holder",
+            "obj": "obj",
+            "passedToJSImpl": toStringBool(isJSImplementedDescriptor(descriptorProvider))
+        }
+        # If we have a method generated by the maplike/setlike portion of an
+        # interface, arguments can possibly be undefined, but will need to be
+        # converted to the key/value type of the backing object. In this case,
+        # use .get() instead of direct access to the argument. This won't
+        # matter for iterable since generated functions for those interface
+        # don't take arguments.
+        if member.isMethod() and member.isMaplikeOrSetlikeOrIterableMethod():
+            self.replacementVariables["val"] = string.Template(
+                "args.get(${index})").substitute(replacer)
+            self.replacementVariables["maybeMutableVal"] = string.Template(
+                "args[${index}]").substitute(replacer)
+        else:
+            self.replacementVariables["val"] = string.Template(
+                "args[${index}]").substitute(replacer)
+        haveValueCheck = string.Template(
+            "args.hasDefined(${index})").substitute(replacer)
+        self.replacementVariables["haveValue"] = haveValueCheck
+        self.descriptorProvider = descriptorProvider
+        if self.argument.canHaveMissingValue():
+            self.argcAndIndex = replacer
+        else:
+            self.argcAndIndex = None
+        self.invalidEnumValueFatal = invalidEnumValueFatal
+        self.lenientFloatCode = lenientFloatCode
+
+    def define(self):
+        typeConversion = getJSToNativeConversionInfo(
+            self.argument.type,
+            self.descriptorProvider,
+            isOptional=(self.argcAndIndex is not None and
+                        not self.argument.variadic),
+            invalidEnumValueFatal=self.invalidEnumValueFatal,
+            defaultValue=self.argument.defaultValue,
+            treatNullAs=self.argument.treatNullAs,
+            isEnforceRange=self.argument.enforceRange,
+            isClamp=self.argument.clamp,
+            lenientFloatCode=self.lenientFloatCode,
+            isMember="Variadic" if self.argument.variadic else False,
+            allowTreatNonCallableAsNull=self.argument.allowTreatNonCallableAsNull(),
+            sourceDescription=self.argDescription)
+
+        if not self.argument.variadic:
+            return instantiateJSToNativeConversion(
+                typeConversion,
+                self.replacementVariables,
+                self.argcAndIndex is not None).define()
+
+        # Variadic arguments get turned into a sequence.
+        if typeConversion.dealWithOptional:
+            raise TypeError("Shouldn't have optional things in variadics")
+        if typeConversion.holderType is not None:
+            raise TypeError("Shouldn't need holders for variadics")
+
+        replacer = dict(self.argcAndIndex, **self.replacementVariables)
+        replacer["seqType"] = CGTemplatedType("binding_detail::AutoSequence",
+                                              typeConversion.declType).define()
+        if typeNeedsRooting(self.argument.type):
+            rooterDecl = ("SequenceRooter<%s> ${holderName}(cx, &${declName});\n" %
+                          typeConversion.declType.define())
+        else:
+            rooterDecl = ""
+        replacer["elemType"] = typeConversion.declType.define()
+
+        # NOTE: Keep this in sync with sequence conversions as needed
+        variadicConversion = string.Template(
+            "${seqType} ${declName};\n" +
+            rooterDecl +
+            dedent("""
+                if (${argc} > ${index}) {
+                  if (!${declName}.SetCapacity(${argc} - ${index}, mozilla::fallible)) {
+                    JS_ReportOutOfMemory(cx);
+                    return false;
+                  }
+                  for (uint32_t variadicArg = ${index}; variadicArg < ${argc}; ++variadicArg) {
+                    ${elemType}& slot = *${declName}.AppendElement(mozilla::fallible);
+                """)
+        ).substitute(replacer)
+
+        val = string.Template("args[variadicArg]").substitute(replacer)
+        variadicConversion += indent(
+            string.Template(typeConversion.template).substitute({
+                "val": val,
+                "maybeMutableVal": val,
+                "declName": "slot",
+                # We only need holderName here to handle isExternal()
+                # interfaces, which use an internal holder for the
+                # conversion even when forceOwningType ends up true.
+                "holderName": "tempHolder",
+                # Use the same ${obj} as for the variadic arg itself
+                "obj": replacer["obj"],
+                "passedToJSImpl": toStringBool(isJSImplementedDescriptor(self.descriptorProvider))
+            }), 4)
+
+        variadicConversion += ("  }\n"
+                               "}\n")
+        return variadicConversion
+
+
+def getMaybeWrapValueFuncForType(type):
+    # Callbacks might actually be DOM objects; nothing prevents a page from
+    # doing that.
+    if type.isCallback() or type.isCallbackInterface() or type.isObject():
+        if type.nullable():
+            return "MaybeWrapObjectOrNullValue"
+        return "MaybeWrapObjectValue"
+    # Spidermonkey interfaces are never DOM objects.  Neither are sequences or
+    # dictionaries, since those are always plain JS objects.
+    if type.isSpiderMonkeyInterface() or type.isDictionary() or type.isSequence():
+        if type.nullable():
+            return "MaybeWrapNonDOMObjectOrNullValue"
+        return "MaybeWrapNonDOMObjectValue"
+    if type.isAny():
+        return "MaybeWrapValue"
+
+    # For other types, just go ahead an fall back on MaybeWrapValue for now:
+    # it's always safe to do, and shouldn't be particularly slow for any of
+    # them
+    return "MaybeWrapValue"
+
+
+sequenceWrapLevel = 0
+mozMapWrapLevel = 0
+
+
+def getWrapTemplateForType(type, descriptorProvider, result, successCode,
+                           returnsNewObject, exceptionCode, typedArraysAreStructs,
+                           isConstructorRetval=False):
+    """
+    Reflect a C++ value stored in "result", of IDL type "type" into JS.  The
+    "successCode" is the code to run once we have successfully done the
+    conversion and must guarantee that execution of the conversion template
+    stops once the successCode has executed (e.g. by doing a 'return', or by
+    doing a 'break' if the entire conversion template is inside a block that
+    the 'break' will exit).
+
+    If typedArraysAreStructs is true, then if the type is a typed array,
+    "result" is one of the dom::TypedArray subclasses, not a JSObject*.
+
+    The resulting string should be used with string.Template.  It
+    needs the following keys when substituting:
+
+      jsvalHandle: something that can be passed to methods taking a
+                   JS::MutableHandle<JS::Value>.  This can be a
+                   JS::MutableHandle<JS::Value> or a JS::Rooted<JS::Value>*.
+      jsvalRef: something that can have .address() called on it to get a
+                JS::Value* and .set() called on it to set it to a JS::Value.
+                This can be a JS::MutableHandle<JS::Value> or a
+                JS::Rooted<JS::Value>.
+      obj: a JS::Handle<JSObject*>.
+
+    Returns (templateString, infallibility of conversion template)
+    """
+    if successCode is None:
+        successCode = "return true;\n"
+
+    def setUndefined():
+        return _setValue("", setter="setUndefined")
+
+    def setNull():
+        return _setValue("", setter="setNull")
+
+    def setInt32(value):
+        return _setValue(value, setter="setInt32")
+
+    def setString(value):
+        return _setValue(value, setter="setString")
+
+    def setObject(value, wrapAsType=None):
+        return _setValue(value, wrapAsType=wrapAsType, setter="setObject")
+
+    def setObjectOrNull(value, wrapAsType=None):
+        return _setValue(value, wrapAsType=wrapAsType, setter="setObjectOrNull")
+
+    def setUint32(value):
+        return _setValue(value, setter="setNumber")
+
+    def setDouble(value):
+        return _setValue("JS_NumberValue(%s)" % value)
+
+    def setBoolean(value):
+        return _setValue(value, setter="setBoolean")
+
+    def _setValue(value, wrapAsType=None, setter="set"):
+        """
+        Returns the code to set the jsval to value.
+
+        If wrapAsType is not None, then will wrap the resulting value using the
+        function that getMaybeWrapValueFuncForType(wrapAsType) returns.
+        Otherwise, no wrapping will be done.
+        """
+        if wrapAsType is None:
+            tail = successCode
+        else:
+            tail = fill(
+                """
+                if (!${maybeWrap}(cx, $${jsvalHandle})) {
+                  $*{exceptionCode}
+                }
+                $*{successCode}
+                """,
+                maybeWrap=getMaybeWrapValueFuncForType(wrapAsType),
+                exceptionCode=exceptionCode,
+                successCode=successCode)
+        return ("${jsvalRef}.%s(%s);\n" % (setter, value)) + tail
+
+    def wrapAndSetPtr(wrapCall, failureCode=None):
+        """
+        Returns the code to set the jsval by calling "wrapCall". "failureCode"
+        is the code to run if calling "wrapCall" fails
+        """
+        if failureCode is None:
+            failureCode = exceptionCode
+        return fill(
+            """
+            if (!${wrapCall}) {
+              $*{failureCode}
+            }
+            $*{successCode}
+            """,
+            wrapCall=wrapCall,
+            failureCode=failureCode,
+            successCode=successCode)
+
+    if type is None or type.isVoid():
+        return (setUndefined(), True)
+
+    if (type.isSequence() or type.isMozMap()) and type.nullable():
+        # These are both wrapped in Nullable<>
+        recTemplate, recInfall = getWrapTemplateForType(type.inner, descriptorProvider,
+                                                        "%s.Value()" % result, successCode,
+                                                        returnsNewObject, exceptionCode,
+                                                        typedArraysAreStructs)
+        code = fill(
+            """
+
+            if (${result}.IsNull()) {
+              $*{setNull}
+            }
+            $*{recTemplate}
+            """,
+            result=result,
+            setNull=setNull(),
+            recTemplate=recTemplate)
+        return code, recInfall
+
+    if type.isSequence():
+        # Now do non-nullable sequences.  Our success code is just to break to
+        # where we set the element in the array.  Note that we bump the
+        # sequenceWrapLevel around this call so that nested sequence conversions
+        # will use different iteration variables.
+        global sequenceWrapLevel
+        index = "sequenceIdx%d" % sequenceWrapLevel
+        sequenceWrapLevel += 1
+        innerTemplate = wrapForType(
+            type.inner, descriptorProvider,
+            {
+                'result': "%s[%s]" % (result, index),
+                'successCode': "break;\n",
+                'jsvalRef': "tmp",
+                'jsvalHandle': "&tmp",
+                'returnsNewObject': returnsNewObject,
+                'exceptionCode': exceptionCode,
+                'obj': "returnArray",
+                'typedArraysAreStructs': typedArraysAreStructs
+            })
+        sequenceWrapLevel -= 1
+        code = fill(
+            """
+
+            uint32_t length = ${result}.Length();
+            JS::Rooted<JSObject*> returnArray(cx, JS_NewArrayObject(cx, length));
+            if (!returnArray) {
+              $*{exceptionCode}
+            }
+            // Scope for 'tmp'
+            {
+              JS::Rooted<JS::Value> tmp(cx);
+              for (uint32_t ${index} = 0; ${index} < length; ++${index}) {
+                // Control block to let us common up the JS_DefineElement calls when there
+                // are different ways to succeed at wrapping the object.
+                do {
+                  $*{innerTemplate}
+                } while (0);
+                if (!JS_DefineElement(cx, returnArray, ${index}, tmp,
+                                      JSPROP_ENUMERATE)) {
+                  $*{exceptionCode}
+                }
+              }
+            }
+            $*{set}
+            """,
+            result=result,
+            exceptionCode=exceptionCode,
+            index=index,
+            innerTemplate=innerTemplate,
+            set=setObject("*returnArray"))
+
+        return (code, False)
+
+    if type.isMozMap():
+        # Now do non-nullable MozMap.  Our success code is just to break to
+        # where we define the property on the object.  Note that we bump the
+        # mozMapWrapLevel around this call so that nested MozMap conversions
+        # will use different temp value names.
+        global mozMapWrapLevel
+        valueName = "mozMapValue%d" % mozMapWrapLevel
+        mozMapWrapLevel += 1
+        innerTemplate = wrapForType(
+            type.inner, descriptorProvider,
+            {
+                'result': valueName,
+                'successCode': "break;\n",
+                'jsvalRef': "tmp",
+                'jsvalHandle': "&tmp",
+                'returnsNewObject': returnsNewObject,
+                'exceptionCode': exceptionCode,
+                'obj': "returnObj",
+                'typedArraysAreStructs': typedArraysAreStructs
+            })
+        mozMapWrapLevel -= 1
+        code = fill(
+            """
+
+            nsTArray<nsString> keys;
+            ${result}.GetKeys(keys);
+            JS::Rooted<JSObject*> returnObj(cx, JS_NewPlainObject(cx));
+            if (!returnObj) {
+              $*{exceptionCode}
+            }
+            // Scope for 'tmp'
+            {
+              JS::Rooted<JS::Value> tmp(cx);
+              for (size_t idx = 0; idx < keys.Length(); ++idx) {
+                auto& ${valueName} = ${result}.Get(keys[idx]);
+                // Control block to let us common up the JS_DefineUCProperty calls when there
+                // are different ways to succeed at wrapping the value.
+                do {
+                  $*{innerTemplate}
+                } while (0);
+                if (!JS_DefineUCProperty(cx, returnObj, keys[idx].get(),
+                                         keys[idx].Length(), tmp,
+                                         JSPROP_ENUMERATE)) {
+                  $*{exceptionCode}
+                }
+              }
+            }
+            $*{set}
+            """,
+            result=result,
+            exceptionCode=exceptionCode,
+            valueName=valueName,
+            innerTemplate=innerTemplate,
+            set=setObject("*returnObj"))
+
+        return (code, False)
+
+    if type.isGeckoInterface() and not type.isCallbackInterface():
+        descriptor = descriptorProvider.getDescriptor(type.unroll().inner.identifier.name)
+        if type.nullable():
+            wrappingCode = ("if (!%s) {\n" % (result) +
+                            indent(setNull()) +
+                            "}\n")
+        else:
+            wrappingCode = ""
+
+        if not descriptor.interface.isExternal():
+            if descriptor.wrapperCache:
+                wrapMethod = "GetOrCreateDOMReflector"
+                wrapArgs = "cx, %s, ${jsvalHandle}" % result
+            else:
+                # Hack: the "Promise" interface is OK to return from
+                # non-newobject things even when it's not wrappercached; that
+                # happens when using SpiderMonkey promises, and the WrapObject()
+                # method will just return the existing reflector, which is just
+                # not stored in a wrappercache.
+                if (not returnsNewObject and
+                    descriptor.interface.identifier.name != "Promise"):
+                    raise MethodNotNewObjectError(descriptor.interface.identifier.name)
+                wrapMethod = "WrapNewBindingNonWrapperCachedObject"
+                wrapArgs = "cx, ${obj}, %s, ${jsvalHandle}" % result
+            if isConstructorRetval:
+                wrapArgs += ", desiredProto"
+            wrap = "%s(%s)" % (wrapMethod, wrapArgs)
+            if not descriptor.hasXPConnectImpls:
+                # Can only fail to wrap as a new-binding object
+                # if they already threw an exception.
+                # XXX Assertion disabled for now, see bug 991271.
+                failed = ("MOZ_ASSERT(true || JS_IsExceptionPending(cx));\n" +
+                          exceptionCode)
+            else:
+                if descriptor.notflattened:
+                    raise TypeError("%s has XPConnect impls but not flattened; "
+                                    "fallback won't work correctly" %
+                                    descriptor.interface.identifier.name)
+                # Try old-style wrapping for bindings which might be XPConnect impls.
+                failed = wrapAndSetPtr("HandleNewBindingWrappingFailure(cx, ${obj}, %s, ${jsvalHandle})" % result)
+        else:
+            if descriptor.notflattened:
+                getIID = "&NS_GET_IID(%s), " % descriptor.nativeType
+            else:
+                getIID = ""
+            wrap = "WrapObject(cx, %s, %s${jsvalHandle})" % (result, getIID)
+            failed = None
+
+        wrappingCode += wrapAndSetPtr(wrap, failed)
+        return (wrappingCode, False)
+
+    if type.isDOMString() or type.isUSVString():
+        if type.nullable():
+            return (wrapAndSetPtr("xpc::StringToJsval(cx, %s, ${jsvalHandle})" % result), False)
+        else:
+            return (wrapAndSetPtr("xpc::NonVoidStringToJsval(cx, %s, ${jsvalHandle})" % result), False)
+
+    if type.isByteString():
+        if type.nullable():
+            return (wrapAndSetPtr("ByteStringToJsval(cx, %s, ${jsvalHandle})" % result), False)
+        else:
+            return (wrapAndSetPtr("NonVoidByteStringToJsval(cx, %s, ${jsvalHandle})" % result), False)
+
+    if type.isEnum():
+        if type.nullable():
+            resultLoc = "%s.Value()" % result
+        else:
+            resultLoc = result
+        conversion = fill(
+            """
+            if (!ToJSValue(cx, ${result}, $${jsvalHandle})) {
+              $*{exceptionCode}
+            }
+            $*{successCode}
+            """,
+            result=resultLoc,
+            exceptionCode=exceptionCode,
+            successCode=successCode)
+
+        if type.nullable():
+            conversion = CGIfElseWrapper(
+                "%s.IsNull()" % result,
+                CGGeneric(setNull()),
+                CGGeneric(conversion)).define()
+        return conversion, False
+
+    if type.isCallback() or type.isCallbackInterface():
+        wrapCode = setObject(
+            "*GetCallbackFromCallbackObject(%(result)s)",
+            wrapAsType=type)
+        if type.nullable():
+            wrapCode = (
+                "if (%(result)s) {\n" +
+                indent(wrapCode) +
+                "} else {\n" +
+                indent(setNull()) +
+                "}\n")
+        wrapCode = wrapCode % {"result": result}
+        return wrapCode, False
+
+    if type.isAny():
+        # See comments in GetOrCreateDOMReflector explaining why we need
+        # to wrap here.
+        # NB: _setValue(..., type-that-is-any) calls JS_WrapValue(), so is fallible
+        head = "JS::ExposeValueToActiveJS(%s);\n" % result
+        return (head + _setValue(result, wrapAsType=type), False)
+
+    if (type.isObject() or (type.isSpiderMonkeyInterface() and
+                            not typedArraysAreStructs)):
+        # See comments in GetOrCreateDOMReflector explaining why we need
+        # to wrap here.
+        if type.nullable():
+            toValue = "%s"
+            setter = setObjectOrNull
+            head = """if (%s) {
+              JS::ExposeObjectToActiveJS(%s);
+            }
+            """ % (result, result)
+        else:
+            toValue = "*%s"
+            setter = setObject
+            head = "JS::ExposeObjectToActiveJS(%s);\n" % result
+        # NB: setObject{,OrNull}(..., some-object-type) calls JS_WrapValue(), so is fallible
+        return (head + setter(toValue % result, wrapAsType=type), False)
+
+    if not (type.isUnion() or type.isPrimitive() or type.isDictionary() or
+            type.isDate() or
+            (type.isSpiderMonkeyInterface() and typedArraysAreStructs)):
+        raise TypeError("Need to learn to wrap %s" % type)
+
+    if type.nullable():
+        recTemplate, recInfal = getWrapTemplateForType(type.inner, descriptorProvider,
+                                                       "%s.Value()" % result, successCode,
+                                                       returnsNewObject, exceptionCode,
+                                                       typedArraysAreStructs)
+        return ("if (%s.IsNull()) {\n" % result +
+                indent(setNull()) +
+                "}\n" +
+                recTemplate, recInfal)
+
+    if type.isSpiderMonkeyInterface():
+        assert typedArraysAreStructs
+        # See comments in GetOrCreateDOMReflector explaining why we need
+        # to wrap here.
+        # NB: setObject(..., some-object-type) calls JS_WrapValue(), so is fallible
+        return (setObject("*%s.Obj()" % result,
+                          wrapAsType=type), False)
+
+    if type.isUnion():
+        return (wrapAndSetPtr("%s.ToJSVal(cx, ${obj}, ${jsvalHandle})" % result),
+                False)
+
+    if type.isDictionary():
+        return (wrapAndSetPtr("%s.ToObjectInternal(cx, ${jsvalHandle})" % result),
+                False)
+
+    if type.isDate():
+        return (wrapAndSetPtr("%s.ToDateObject(cx, ${jsvalHandle})" % result),
+                False)
+
+    tag = type.tag()
+
+    if tag in [IDLType.Tags.int8, IDLType.Tags.uint8, IDLType.Tags.int16,
+               IDLType.Tags.uint16, IDLType.Tags.int32]:
+        return (setInt32("int32_t(%s)" % result), True)
+
+    elif tag in [IDLType.Tags.int64, IDLType.Tags.uint64,
+                 IDLType.Tags.unrestricted_float, IDLType.Tags.float,
+                 IDLType.Tags.unrestricted_double, IDLType.Tags.double]:
+        # XXXbz will cast to double do the "even significand" thing that webidl
+        # calls for for 64-bit ints?  Do we care?
+        return (setDouble("double(%s)" % result), True)
+
+    elif tag == IDLType.Tags.uint32:
+        return (setUint32(result), True)
+
+    elif tag == IDLType.Tags.bool:
+        return (setBoolean(result), True)
+
+    else:
+        raise TypeError("Need to learn to wrap primitive: %s" % type)
+
+
+def wrapForType(type, descriptorProvider, templateValues):
+    """
+    Reflect a C++ value of IDL type "type" into JS.  TemplateValues is a dict
+    that should contain:
+
+      * 'jsvalRef': something that can have .address() called on it to get a
+                    JS::Value* and .set() called on it to set it to a JS::Value.
+                    This can be a JS::MutableHandle<JS::Value> or a
+                    JS::Rooted<JS::Value>.
+      * 'jsvalHandle': something that can be passed to methods taking a
+                       JS::MutableHandle<JS::Value>.  This can be a
+                       JS::MutableHandle<JS::Value> or a JS::Rooted<JS::Value>*.
+      * 'obj' (optional): the name of the variable that contains the JSObject to
+                          use as a scope when wrapping, if not supplied 'obj'
+                          will be used as the name
+      * 'result' (optional): the name of the variable in which the C++ value is
+                             stored, if not supplied 'result' will be used as
+                             the name
+      * 'successCode' (optional): the code to run once we have successfully
+                                  done the conversion, if not supplied 'return
+                                  true;' will be used as the code.  The
+                                  successCode must ensure that once it runs no
+                                  more of the conversion template will be
+                                  executed (e.g. by doing a 'return' or 'break'
+                                  as appropriate).
+      * 'returnsNewObject' (optional): If true, we're wrapping for the return
+                                       value of a [NewObject] method.  Assumed
+                                       false if not set.
+      * 'exceptionCode' (optional): Code to run when a JS exception is thrown.
+                                    The default is "return false;".  The code
+                                    passed here must return.
+      * 'isConstructorRetval' (optional): If true, we're wrapping a constructor
+                                          return value.
+    """
+    wrap = getWrapTemplateForType(
+        type, descriptorProvider,
+        templateValues.get('result', 'result'),
+        templateValues.get('successCode', None),
+        templateValues.get('returnsNewObject', False),
+        templateValues.get('exceptionCode', "return false;\n"),
+        templateValues.get('typedArraysAreStructs', False),
+        isConstructorRetval=templateValues.get('isConstructorRetval', False))[0]
+
+    defaultValues = {'obj': 'obj'}
+    return string.Template(wrap).substitute(defaultValues, **templateValues)
+
+
+def infallibleForMember(member, type, descriptorProvider):
+    """
+    Determine the fallibility of changing a C++ value of IDL type "type" into
+    JS for the given attribute. Apart from returnsNewObject, all the defaults
+    are used, since the fallbility does not change based on the boolean values,
+    and the template will be discarded.
+
+    CURRENT ASSUMPTIONS:
+        We assume that successCode for wrapping up return values cannot contain
+        failure conditions.
+    """
+    return getWrapTemplateForType(type, descriptorProvider, 'result', None,
+                                  memberReturnsNewObject(member), "return false;\n",
+                                  False)[1]
+
+
+def leafTypeNeedsCx(type, retVal):
+    return (type.isAny() or type.isObject() or
+            (retVal and type.isSpiderMonkeyInterface()))
+
+
+def leafTypeNeedsScopeObject(type, retVal):
+    return retVal and type.isSpiderMonkeyInterface()
+
+
+def leafTypeNeedsRooting(type):
+    return leafTypeNeedsCx(type, False) or type.isSpiderMonkeyInterface()
+
+
+def typeNeedsRooting(type):
+    return typeMatchesLambda(type,
+                             lambda t: leafTypeNeedsRooting(t))
+
+
+def typeNeedsCx(type, retVal=False):
+    return typeMatchesLambda(type,
+                             lambda t: leafTypeNeedsCx(t, retVal))
+
+
+def typeNeedsScopeObject(type, retVal=False):
+    return typeMatchesLambda(type,
+                             lambda t: leafTypeNeedsScopeObject(t, retVal))
+
+
+def typeMatchesLambda(type, func):
+    if type is None:
+        return False
+    if type.nullable():
+        return typeMatchesLambda(type.inner, func)
+    if type.isSequence() or type.isMozMap():
+        return typeMatchesLambda(type.inner, func)
+    if type.isUnion():
+        return any(typeMatchesLambda(t, func) for t in
+                   type.unroll().flatMemberTypes)
+    if type.isDictionary():
+        return dictionaryMatchesLambda(type.inner, func)
+    return func(type)
+
+
+def dictionaryMatchesLambda(dictionary, func):
+    return (any(typeMatchesLambda(m.type, func) for m in dictionary.members) or
+            (dictionary.parent and dictionaryMatchesLambda(dictionary.parent, func)))
+
+
+# Whenever this is modified, please update CGNativeMember.getRetvalInfo as
+# needed to keep the types compatible.
+def getRetvalDeclarationForType(returnType, descriptorProvider,
+                                isMember=False):
+    """
+    Returns a tuple containing five things:
+
+    1) A CGThing for the type of the return value, or None if there is no need
+       for a return value.
+
+    2) A value indicating the kind of ourparam to pass the value as.  Valid
+       options are None to not pass as an out param at all, "ref" (to pass a
+       reference as an out param), and "ptr" (to pass a pointer as an out
+       param).
+
+    3) A CGThing for a tracer for the return value, or None if no tracing is
+       needed.
+
+    4) An argument string to pass to the retval declaration
+       constructor or None if there are no arguments.
+
+    5) The name of a function that needs to be called with the return value
+       before using it, or None if no function needs to be called.
+    """
+    if returnType is None or returnType.isVoid():
+        # Nothing to declare
+        return None, None, None, None, None
+    if returnType.isPrimitive() and returnType.tag() in builtinNames:
+        result = CGGeneric(builtinNames[returnType.tag()])
+        if returnType.nullable():
+            result = CGTemplatedType("Nullable", result)
+        return result, None, None, None, None
+    if returnType.isDOMString() or returnType.isUSVString():
+        if isMember:
+            return CGGeneric("nsString"), "ref", None, None, None
+        return CGGeneric("DOMString"), "ref", None, None, None
+    if returnType.isByteString():
+        return CGGeneric("nsCString"), "ref", None, None, None
+    if returnType.isEnum():
+        result = CGGeneric(returnType.unroll().inner.identifier.name)
+        if returnType.nullable():
+            result = CGTemplatedType("Nullable", result)
+        return result, None, None, None, None
+    if returnType.isGeckoInterface():
+        result = CGGeneric(descriptorProvider.getDescriptor(
+            returnType.unroll().inner.identifier.name).nativeType)
+        conversion = None
+        if isMember:
+            result = CGGeneric("StrongPtrForMember<%s>::Type" % result.define())
+        else:
+            conversion = CGGeneric("StrongOrRawPtr<%s>" % result.define())
+            result = CGGeneric("auto")
+        return result, None, None, None, conversion
+    if returnType.isCallback():
+        name = returnType.unroll().callback.identifier.name
+        return CGGeneric("RefPtr<%s>" % name), None, None, None, None
+    if returnType.isAny():
+        if isMember:
+            return CGGeneric("JS::Value"), None, None, None, None
+        return CGGeneric("JS::Rooted<JS::Value>"), "ptr", None, "cx", None
+    if returnType.isObject() or returnType.isSpiderMonkeyInterface():
+        if isMember:
+            return CGGeneric("JSObject*"), None, None, None, None
+        return CGGeneric("JS::Rooted<JSObject*>"), "ptr", None, "cx", None
+    if returnType.isSequence():
+        nullable = returnType.nullable()
+        if nullable:
+            returnType = returnType.inner
+        result, _, _, _, _ = getRetvalDeclarationForType(returnType.inner,
+                                                         descriptorProvider,
+                                                         isMember="Sequence")
+        # While we have our inner type, set up our rooter, if needed
+        if not isMember and typeNeedsRooting(returnType):
+            rooter = CGGeneric("SequenceRooter<%s > resultRooter(cx, &result);\n" %
+                               result.define())
+        else:
+            rooter = None
+        result = CGTemplatedType("nsTArray", result)
+        if nullable:
+            result = CGTemplatedType("Nullable", result)
+        return result, "ref", rooter, None, None
+    if returnType.isMozMap():
+        nullable = returnType.nullable()
+        if nullable:
+            returnType = returnType.inner
+        result, _, _, _, _ = getRetvalDeclarationForType(returnType.inner,
+                                                         descriptorProvider,
+                                                         isMember="MozMap")
+        # While we have our inner type, set up our rooter, if needed
+        if not isMember and typeNeedsRooting(returnType):
+            rooter = CGGeneric("MozMapRooter<%s> resultRooter(cx, &result);\n" %
+                               result.define())
+        else:
+            rooter = None
+        result = CGTemplatedType("MozMap", result)
+        if nullable:
+            result = CGTemplatedType("Nullable", result)
+        return result, "ref", rooter, None, None
+    if returnType.isDictionary():
+        nullable = returnType.nullable()
+        dictName = CGDictionary.makeDictionaryName(returnType.unroll().inner)
+        result = CGGeneric(dictName)
+        if not isMember and typeNeedsRooting(returnType):
+            if nullable:
+                result = CGTemplatedType("NullableRootedDictionary", result)
+            else:
+                result = CGTemplatedType("RootedDictionary", result)
+            resultArgs = "cx"
+        else:
+            if nullable:
+                result = CGTemplatedType("Nullable", result)
+            resultArgs = None
+        return result, "ref", None, resultArgs, None
+    if returnType.isUnion():
+        result = CGGeneric(CGUnionStruct.unionTypeName(returnType.unroll(), True))
+        if not isMember and typeNeedsRooting(returnType):
+            if returnType.nullable():
+                result = CGTemplatedType("NullableRootedUnion", result)
+            else:
+                result = CGTemplatedType("RootedUnion", result)
+            resultArgs = "cx"
+        else:
+            if returnType.nullable():
+                result = CGTemplatedType("Nullable", result)
+            resultArgs = None
+        return result, "ref", None, resultArgs, None
+    if returnType.isDate():
+        result = CGGeneric("Date")
+        if returnType.nullable():
+            result = CGTemplatedType("Nullable", result)
+        return result, None, None, None, None
+    raise TypeError("Don't know how to declare return value for %s" %
+                    returnType)
+
+
+def needCx(returnType, arguments, extendedAttributes, considerTypes,
+           static=False):
+    return (not static and considerTypes and
+            (typeNeedsCx(returnType, True) or
+             any(typeNeedsCx(a.type) for a in arguments)) or
+            'implicitJSContext' in extendedAttributes)
+
+
+def needScopeObject(returnType, arguments, extendedAttributes,
+                    isWrapperCached, considerTypes, isMember):
+    """
+    isMember should be true if we're dealing with an attribute
+    annotated as [StoreInSlot].
+    """
+    return (considerTypes and not isWrapperCached and
+            ((not isMember and typeNeedsScopeObject(returnType, True)) or
+             any(typeNeedsScopeObject(a.type) for a in arguments)))
+
+
+class CGCallGenerator(CGThing):
+    """
+    A class to generate an actual call to a C++ object.  Assumes that the C++
+    object is stored in a variable whose name is given by the |object| argument.
+
+    needsSubjectPrincipal is a boolean indicating whether the call should
+    receive the subject nsIPrincipal as argument.
+
+    needsCallerType is a boolean indicating whether the call should receive
+    a PrincipalType for the caller.
+
+    isFallible is a boolean indicating whether the call should be fallible.
+
+    resultVar: If the returnType is not void, then the result of the call is
+    stored in a C++ variable named by resultVar. The caller is responsible for
+    declaring the result variable. If the caller doesn't care about the result
+    value, resultVar can be omitted.
+    """
+    def __init__(self, isFallible, needsSubjectPrincipal, needsCallerType,
+                 arguments, argsPre, returnType, extendedAttributes, descriptor,
+                 nativeMethodName, static, object="self", argsPost=[],
+                 resultVar=None):
+        CGThing.__init__(self)
+
+        result, resultOutParam, resultRooter, resultArgs, resultConversion = \
+            getRetvalDeclarationForType(returnType, descriptor)
+
+        args = CGList([CGGeneric(arg) for arg in argsPre], ", ")
+        for a, name in arguments:
+            arg = CGGeneric(name)
+
+            # Now constify the things that need it
+            def needsConst(a):
+                if a.type.isDictionary():
+                    return True
+                if a.type.isSequence():
+                    return True
+                if a.type.isMozMap():
+                    return True
+                # isObject() types are always a JS::Rooted, whether
+                # nullable or not, and it turns out a const JS::Rooted
+                # is not very helpful at all (in particular, it won't
+                # even convert to a JS::Handle).
+                # XXX bz Well, why not???
+                if a.type.nullable() and not a.type.isObject():
+                    return True
+                if a.type.isString():
+                    return True
+                if a.canHaveMissingValue():
+                    # This will need an Optional or it's a variadic;
+                    # in both cases it should be const.
+                    return True
+                if a.type.isUnion():
+                    return True
+                if a.type.isSpiderMonkeyInterface():
+                    return True
+                return False
+            if needsConst(a):
+                arg = CGWrapper(arg, pre="Constify(", post=")")
+            # And convert NonNull<T> to T&
+            if (((a.type.isGeckoInterface() or a.type.isCallback()) and not a.type.nullable()) or
+                a.type.isDOMString()):
+                arg = CGWrapper(arg, pre="NonNullHelper(", post=")")
+            args.append(arg)
+
+        needResultDecl = False
+
+        # Return values that go in outparams go here
+        if resultOutParam is not None:
+            if resultVar is None:
+                needResultDecl = True
+                resultVar = "result"
+            if resultOutParam == "ref":
+                args.append(CGGeneric(resultVar))
+            else:
+                assert resultOutParam == "ptr"
+                args.append(CGGeneric("&" + resultVar))
+
+        if needsSubjectPrincipal:
+            args.append(CGGeneric("subjectPrincipal"))
+
+        if needsCallerType:
+            args.append(CGGeneric("callerType"))
+
+        if isFallible:
+            args.append(CGGeneric("rv"))
+        args.extend(CGGeneric(arg) for arg in argsPost)
+
+        # Build up our actual call
+        self.cgRoot = CGList([])
+
+        call = CGGeneric(nativeMethodName)
+        if not static:
+            call = CGWrapper(call, pre="%s->" % object)
+        call = CGList([call, CGWrapper(args, pre="(", post=")")])
+        if resultConversion is not None:
+            call = CGList([resultConversion, CGWrapper(call, pre="(", post=")")])
+        if resultVar is None and result is not None:
+            needResultDecl = True
+            resultVar = "result"
+
+        if needResultDecl:
+            if resultRooter is not None:
+                self.cgRoot.prepend(resultRooter)
+            if resultArgs is not None:
+                resultArgsStr = "(%s)" % resultArgs
+            else:
+                resultArgsStr = ""
+            result = CGWrapper(result, post=(" %s%s" % (resultVar, resultArgsStr)))
+            if resultOutParam is None and resultArgs is None:
+                call = CGList([result, CGWrapper(call, pre="(", post=")")])
+            else:
+                self.cgRoot.prepend(CGWrapper(result, post=";\n"))
+                if resultOutParam is None:
+                    call = CGWrapper(call, pre=resultVar + " = ")
+        elif result is not None:
+            assert resultOutParam is None
+            call = CGWrapper(call, pre=resultVar + " = ")
+
+        call = CGWrapper(call, post=";\n")
+        self.cgRoot.append(call)
+
+        if needsSubjectPrincipal:
+            getPrincipal = dedent(
+                """
+                JSCompartment* compartment = js::GetContextCompartment(cx);
+                MOZ_ASSERT(compartment);
+                JSPrincipals* principals = JS_GetCompartmentPrincipals(compartment);
+                """)
+
+            if descriptor.interface.isExposedInAnyWorker():
+                self.cgRoot.prepend(CGGeneric(fill(
+                    """
+                    Maybe<nsIPrincipal*> subjectPrincipal;
+                    if (NS_IsMainThread()) {
+                      $*{getPrincipal}
+                      subjectPrincipal.emplace(nsJSPrincipals::get(principals));
+                    }
+                    """,
+                    getPrincipal=getPrincipal)))
+            else:
+                self.cgRoot.prepend(CGGeneric(fill(
+                    """
+                    $*{getPrincipal}
+                    // Initializing a nonnull is pretty darn annoying...
+                    NonNull<nsIPrincipal> subjectPrincipal;
+                    subjectPrincipal = static_cast<nsIPrincipal*>(nsJSPrincipals::get(principals));
+                    """,
+                    getPrincipal=getPrincipal)))
+
+        if needsCallerType:
+            # Note that we do not want to use
+            # IsCallerChrome/ThreadsafeIsCallerChrome directly because those
+            # will pull in the check for UniversalXPConnect, which we ideally
+            # don't want to have in the new thing we're doing here.  If not
+            # NS_IsMainThread(), though, we'll go ahead and call
+            # ThreasafeIsCallerChrome(), since that won't mess with
+            # UnivesalXPConnect and we don't want to worry about the right
+            # worker includes here.
+            callerCheck = CGGeneric("callerType = nsContentUtils::IsSystemPrincipal(nsContentUtils::SubjectPrincipal()) ? CallerType::System : CallerType::NonSystem;\n")
+            if descriptor.interface.isExposedInAnyWorker():
+                callerCheck = CGIfElseWrapper(
+                    "NS_IsMainThread()",
+                    callerCheck,
+                    CGGeneric("callerType = nsContentUtils::ThreadsafeIsCallerChrome() ? CallerType::System : CallerType::NonSystem;\n"));
+            self.cgRoot.prepend(callerCheck)
+            self.cgRoot.prepend(CGGeneric("CallerType callerType;\n"))
+
+        if isFallible:
+            self.cgRoot.prepend(CGGeneric("binding_detail::FastErrorResult rv;\n"))
+            self.cgRoot.append(CGGeneric(dedent(
+                """
+                if (MOZ_UNLIKELY(rv.MaybeSetPendingException(cx))) {
+                  return false;
+                }
+                """)))
+
+        self.cgRoot.append(CGGeneric("MOZ_ASSERT(!JS_IsExceptionPending(cx));\n"))
+
+    def define(self):
+        return self.cgRoot.define()
+
+
+def getUnionMemberName(type):
+    if type.isGeckoInterface():
+        return type.inner.identifier.name
+    if type.isEnum():
+        return type.inner.identifier.name
+    return type.name
+
+
+class MethodNotNewObjectError(Exception):
+    def __init__(self, typename):
+        self.typename = typename
+
+# A counter for making sure that when we're wrapping up things in
+# nested sequences we don't use the same variable name to iterate over
+# different sequences.
+sequenceWrapLevel = 0
+mapWrapLevel = 0
+
+
+def wrapTypeIntoCurrentCompartment(type, value, isMember=True):
+    """
+    Take the thing named by "value" and if it contains "any",
+    "object", or spidermonkey-interface types inside return a CGThing
+    that will wrap them into the current compartment.
+    """
+    if type.isAny():
+        assert not type.nullable()
+        if isMember:
+            value = "JS::MutableHandle<JS::Value>::fromMarkedLocation(&%s)" % value
+        else:
+            value = "&" + value
+        return CGGeneric("if (!JS_WrapValue(cx, %s)) {\n"
+                         "  return false;\n"
+                         "}\n" % value)
+
+    if type.isObject():
+        if isMember:
+            value = "JS::MutableHandle<JSObject*>::fromMarkedLocation(&%s)" % value
+        else:
+            value = "&" + value
+        return CGGeneric("if (!JS_WrapObject(cx, %s)) {\n"
+                         "  return false;\n"
+                         "}\n" % value)
+
+    if type.isSpiderMonkeyInterface():
+        origValue = value
+        if type.nullable():
+            value = "%s.Value()" % value
+        wrapCode = CGGeneric("if (!%s.WrapIntoNewCompartment(cx)) {\n"
+                             "  return false;\n"
+                             "}\n" % value)
+        if type.nullable():
+            wrapCode = CGIfWrapper(wrapCode, "!%s.IsNull()" % origValue)
+        return wrapCode
+
+    if type.isSequence():
+        origValue = value
+        origType = type
+        if type.nullable():
+            type = type.inner
+            value = "%s.Value()" % value
+        global sequenceWrapLevel
+        index = "indexName%d" % sequenceWrapLevel
+        sequenceWrapLevel += 1
+        wrapElement = wrapTypeIntoCurrentCompartment(type.inner,
+                                                     "%s[%s]" % (value, index))
+        sequenceWrapLevel -= 1
+        if not wrapElement:
+            return None
+        wrapCode = CGWrapper(CGIndenter(wrapElement),
+                             pre=("for (uint32_t %s = 0; %s < %s.Length(); ++%s) {\n" %
+                                  (index, index, value, index)),
+                             post="}\n")
+        if origType.nullable():
+            wrapCode = CGIfWrapper(wrapCode, "!%s.IsNull()" % origValue)
+        return wrapCode
+
+    if type.isMozMap():
+        origValue = value
+        origType = type
+        if type.nullable():
+            type = type.inner
+            value = "%s.Value()" % value
+        global mapWrapLevel
+        key = "mapName%d" % mapWrapLevel
+        mapWrapLevel += 1
+        wrapElement = wrapTypeIntoCurrentCompartment(type.inner,
+                                                     "%s.Get(%sKeys[%sIndex])" % (value, key, key))
+        mapWrapLevel -= 1
+        if not wrapElement:
+            return None
+        wrapCode = CGWrapper(CGIndenter(wrapElement),
+                             pre=("""
+                                  nsTArray<nsString> %sKeys;
+                                  %s.GetKeys(%sKeys);
+                                  for (uint32_t %sIndex = 0; %sIndex < %sKeys.Length(); ++%sIndex) {
+                                  """ % (key, value, key, key, key, key, key)),
+                             post="}\n")
+        if origType.nullable():
+            wrapCode = CGIfWrapper(wrapCode, "!%s.IsNull()" % origValue)
+        return wrapCode
+
+    if type.isDictionary():
+        assert not type.nullable()
+        myDict = type.inner
+        memberWraps = []
+        while myDict:
+            for member in myDict.members:
+                memberWrap = wrapArgIntoCurrentCompartment(
+                    member,
+                    "%s.%s" % (value, CGDictionary.makeMemberName(member.identifier.name)))
+                if memberWrap:
+                    memberWraps.append(memberWrap)
+            myDict = myDict.parent
+        return CGList(memberWraps) if len(memberWraps) != 0 else None
+
+    if type.isUnion():
+        memberWraps = []
+        if type.nullable():
+            type = type.inner
+            value = "%s.Value()" % value
+        for member in type.flatMemberTypes:
+            memberName = getUnionMemberName(member)
+            memberWrap = wrapTypeIntoCurrentCompartment(
+                member, "%s.GetAs%s()" % (value, memberName))
+            if memberWrap:
+                memberWrap = CGIfWrapper(
+                    memberWrap, "%s.Is%s()" % (value, memberName))
+                memberWraps.append(memberWrap)
+        return CGList(memberWraps, "else ") if len(memberWraps) != 0 else None
+
+    if (type.isString() or type.isPrimitive() or type.isEnum() or
+        type.isGeckoInterface() or type.isCallback() or type.isDate()):
+        # All of these don't need wrapping
+        return None
+
+    raise TypeError("Unknown type; we don't know how to wrap it in constructor "
+                    "arguments: %s" % type)
+
+
+def wrapArgIntoCurrentCompartment(arg, value, isMember=True):
+    """
+    As wrapTypeIntoCurrentCompartment but handles things being optional
+    """
+    origValue = value
+    isOptional = arg.canHaveMissingValue()
+    if isOptional:
+        value = value + ".Value()"
+    wrap = wrapTypeIntoCurrentCompartment(arg.type, value, isMember)
+    if wrap and isOptional:
+        wrap = CGIfWrapper(wrap, "%s.WasPassed()" % origValue)
+    return wrap
+
+
+def needsContainsHack(m):
+    return m.getExtendedAttribute("ReturnValueNeedsContainsHack")
+
+def needsCallerType(m):
+    return m.getExtendedAttribute("NeedsCallerType")
+
+class CGPerSignatureCall(CGThing):
+    """
+    This class handles the guts of generating code for a particular
+    call signature.  A call signature consists of four things:
+
+    1) A return type, which can be None to indicate that there is no
+       actual return value (e.g. this is an attribute setter) or an
+       IDLType if there's an IDL type involved (including |void|).
+    2) An argument list, which is allowed to be empty.
+    3) A name of a native method to call.
+    4) Whether or not this method is static. Note that this only controls how
+       the method is called (|self->nativeMethodName(...)| vs
+       |nativeMethodName(...)|).
+
+    We also need to know whether this is a method or a getter/setter
+    to do error reporting correctly.
+
+    The idlNode parameter can be either a method or an attr. We can query
+    |idlNode.identifier| in both cases, so we can be agnostic between the two.
+    """
+    # XXXbz For now each entry in the argument list is either an
+    # IDLArgument or a FakeArgument, but longer-term we may want to
+    # have ways of flagging things like JSContext* or optional_argc in
+    # there.
+
+    def __init__(self, returnType, arguments, nativeMethodName, static,
+                 descriptor, idlNode, argConversionStartsAt=0, getter=False,
+                 setter=False, isConstructor=False, useCounterName=None,
+                 resultVar=None):
+        assert idlNode.isMethod() == (not getter and not setter)
+        assert idlNode.isAttr() == (getter or setter)
+        # Constructors are always static
+        assert not isConstructor or static
+
+        CGThing.__init__(self)
+        self.returnType = returnType
+        self.descriptor = descriptor
+        self.idlNode = idlNode
+        self.extendedAttributes = descriptor.getExtendedAttributes(idlNode,
+                                                                   getter=getter,
+                                                                   setter=setter)
+        self.arguments = arguments
+        self.argCount = len(arguments)
+        self.isConstructor = isConstructor
+        cgThings = []
+
+        # Here, we check if the current getter, setter, method, interface or
+        # inherited interfaces have the UnsafeInPrerendering extended attribute
+        # and if so, we add a check to make sure it is safe.
+        if (idlNode.getExtendedAttribute("UnsafeInPrerendering") or
+            descriptor.interface.getExtendedAttribute("UnsafeInPrerendering") or
+            any(i.getExtendedAttribute("UnsafeInPrerendering")
+                for i in descriptor.interface.getInheritedInterfaces())):
+                cgThings.append(CGGeneric(dedent(
+                    """
+                    if (!mozilla::dom::EnforceNotInPrerendering(cx, obj)) {
+                        // Return false from the JSNative in order to trigger
+                        // an uncatchable exception.
+                        MOZ_ASSERT(!JS_IsExceptionPending(cx));
+                        return false;
+                    }
+                    """)))
+
+        deprecated = (idlNode.getExtendedAttribute("Deprecated") or
+                      (idlNode.isStatic() and descriptor.interface.getExtendedAttribute("Deprecated")))
+        if deprecated:
+            cgThings.append(CGGeneric(dedent(
+                """
+                DeprecationWarning(cx, obj, nsIDocument::e%s);
+                """ % deprecated[0])))
+
+        lenientFloatCode = None
+        if (idlNode.getExtendedAttribute('LenientFloat') is not None and
+            (setter or idlNode.isMethod())):
+            cgThings.append(CGGeneric(dedent(
+                """
+                bool foundNonFiniteFloat = false;
+                """)))
+            lenientFloatCode = "foundNonFiniteFloat = true;\n"
+
+        argsPre = []
+        if idlNode.isStatic():
+            # If we're a constructor, "obj" may not be a function, so calling
+            # XrayAwareCalleeGlobal() on it is not safe.  Of course in the
+            # constructor case either "obj" is an Xray or we're already in the
+            # content compartment, not the Xray compartment, so just
+            # constructing the GlobalObject from "obj" is fine.
+            if isConstructor:
+                objForGlobalObject = "obj"
+            else:
+                objForGlobalObject = "xpc::XrayAwareCalleeGlobal(obj)"
+            cgThings.append(CGGeneric(fill(
+                """
+                GlobalObject global(cx, ${obj});
+                if (global.Failed()) {
+                  return false;
+                }
+
+                """,
+                obj=objForGlobalObject)))
+            argsPre.append("global")
+
+        # For JS-implemented interfaces we do not want to base the
+        # needsCx decision on the types involved, just on our extended
+        # attributes. Also, JSContext is not needed for the static case
+        # since GlobalObject already contains the context.
+        needsCx = needCx(returnType, arguments, self.extendedAttributes,
+                         not descriptor.interface.isJSImplemented(), static)
+        if needsCx:
+            argsPre.append("cx")
+
+        # Hack for making Promise.prototype.then work well over Xrays.
+        if (not idlNode.isStatic() and
+            descriptor.name == "Promise" and
+            idlNode.isMethod() and
+            idlNode.identifier.name == "then"):
+            cgThings.append(CGGeneric(dedent(
+                """
+                JS::Rooted<JSObject*> calleeGlobal(cx, xpc::XrayAwareCalleeGlobal(&args.callee()));
+                """)))
+            argsPre.append("calleeGlobal")
+
+        needsUnwrap = False
+        argsPost = []
+        if isConstructor:
+            if descriptor.name == "Promise":
+                # Hack for Promise for now: pass in our desired proto so the
+                # implementation can create the reflector with the right proto.
+                argsPost.append("desiredProto")
+                # Also, we do not want to enter the content compartment when the
+                # Promise constructor is called via Xrays, because we want to
+                # create our callback functions that we will hand to our caller
+                # in the Xray compartment.  The reason we want to do that is the
+                # following situation, over Xrays:
+                #
+                #   contentWindow.Promise.race([Promise.resolve(5)])
+                #
+                # Ideally this would work.  Internally, race() does a
+                # contentWindow.Promise.resolve() on everything in the array.
+                # Per spec, to support subclassing,
+                # contentWindow.Promise.resolve has to do:
+                #
+                #   var resolve, reject;
+                #   var p = new contentWindow.Promise(function(a, b) {
+                #    resolve = a;
+                #    reject = b;
+                #  });
+                #  resolve(arg);
+                #  return p;
+                #
+                # where "arg" is, in this case, the chrome-side return value of
+                # Promise.resolve(5).  But if the "resolve" function in that
+                # case were created in the content compartment, then calling it
+                # would wrap "arg" in an opaque wrapper, and that function tries
+                # to get .then off the argument, which would throw.  So we need
+                # to create the "resolve" function in the chrome compartment,
+                # and hence want to be running the entire Promise constructor
+                # (which creates that function) in the chrome compartment in
+                # this case. So don't set needsUnwrap here.
+            else:
+                needsUnwrap = True
+                needsUnwrappedVar = False
+                unwrappedVar = "obj"
+        elif descriptor.interface.isJSImplemented():
+            if not idlNode.isStatic():
+                needsUnwrap = True
+                needsUnwrappedVar = True
+                argsPost.append("js::GetObjectCompartment(unwrappedObj ? *unwrappedObj : obj)")
+        elif needScopeObject(returnType, arguments, self.extendedAttributes,
+                             descriptor.wrapperCache, True,
+                             idlNode.getExtendedAttribute("StoreInSlot")):
+            needsUnwrap = True
+            needsUnwrappedVar = True
+            argsPre.append("unwrappedObj ? *unwrappedObj : obj")
+
+        if idlNode.isStatic() and not isConstructor and descriptor.name == "Promise":
+            # Hack for Promise for now: pass in the "this" value to
+            # Promise static methods.
+            argsPre.append("args.thisv()")
+
+        if needsUnwrap and needsUnwrappedVar:
+            # We cannot assign into obj because it's a Handle, not a
+            # MutableHandle, so we need a separate Rooted.
+            cgThings.append(CGGeneric("Maybe<JS::Rooted<JSObject*> > unwrappedObj;\n"))
+            unwrappedVar = "unwrappedObj.ref()"
+
+        if idlNode.isMethod() and idlNode.isLegacycaller():
+            # If we can have legacycaller with identifier, we can't
+            # just use the idlNode to determine whether we're
+            # generating code for the legacycaller or not.
+            assert idlNode.isIdentifierLess()
+            # Pass in our thisVal
+            argsPre.append("args.thisv()")
+
+        ourName = "%s.%s" % (descriptor.interface.identifier.name,
+                             idlNode.identifier.name)
+        if idlNode.isMethod():
+            argDescription = "argument %(index)d of " + ourName
+        elif setter:
+            argDescription = "value being assigned to %s" % ourName
+        else:
+            assert self.argCount == 0
+
+        if needsUnwrap:
+            # It's very important that we construct our unwrappedObj, if we need
+            # to do it, before we might start setting up Rooted things for our
+            # arguments, so that we don't violate the stack discipline Rooted
+            # depends on.
+            cgThings.append(CGGeneric(
+                "bool objIsXray = xpc::WrapperFactory::IsXrayWrapper(obj);\n"))
+            if needsUnwrappedVar:
+                cgThings.append(CGIfWrapper(
+                    CGGeneric("unwrappedObj.emplace(cx, obj);\n"),
+                    "objIsXray"))
+
+        for i in range(argConversionStartsAt, self.argCount):
+            cgThings.append(
+                CGArgumentConverter(arguments[i], i, self.descriptor,
+                                    argDescription % {"index": i + 1},
+                                    idlNode, invalidEnumValueFatal=not setter,
+                                    lenientFloatCode=lenientFloatCode))
+
+        # Now that argument processing is done, enforce the LenientFloat stuff
+        if lenientFloatCode:
+            if setter:
+                foundNonFiniteFloatBehavior = "return true;\n"
+            else:
+                assert idlNode.isMethod()
+                foundNonFiniteFloatBehavior = dedent(
+                    """
+                    args.rval().setUndefined();
+                    return true;
+                    """)
+            cgThings.append(CGGeneric(fill(
+                """
+                if (foundNonFiniteFloat) {
+                  $*{returnSteps}
+                }
+                """,
+                returnSteps=foundNonFiniteFloatBehavior)))
+
+        if needsUnwrap:
+            # Something depends on having the unwrapped object, so unwrap it now.
+            xraySteps = []
+            # XXXkhuey we should be able to MOZ_ASSERT that ${obj} is
+            # not null.
+            xraySteps.append(
+                CGGeneric(fill(
+                    """
+                    ${obj} = js::CheckedUnwrap(${obj});
+                    if (!${obj}) {
+                      return false;
+                    }
+                    """,
+                    obj=unwrappedVar)))
+            if isConstructor:
+                # If we're called via an xray, we need to enter the underlying
+                # object's compartment and then wrap up all of our arguments into
+                # that compartment as needed.  This is all happening after we've
+                # already done the conversions from JS values to WebIDL (C++)
+                # values, so we only need to worry about cases where there are 'any'
+                # or 'object' types, or other things that we represent as actual
+                # JSAPI types, present.  Effectively, we're emulating a
+                # CrossCompartmentWrapper, but working with the C++ types, not the
+                # original list of JS::Values.
+                cgThings.append(CGGeneric("Maybe<JSAutoCompartment> ac;\n"))
+                xraySteps.append(CGGeneric("ac.emplace(cx, obj);\n"))
+                xraySteps.append(CGGeneric(dedent(
+                    """
+                    if (!JS_WrapObject(cx, &desiredProto)) {
+                      return false;
+                    }
+                    """)))
+                xraySteps.extend(
+                    wrapArgIntoCurrentCompartment(arg, argname, isMember=False)
+                    for arg, argname in self.getArguments())
+
+            cgThings.append(
+                CGIfWrapper(CGList(xraySteps),
+                            "objIsXray"))
+
+        # If this is a method that was generated by a maplike/setlike
+        # interface, use the maplike/setlike generator to fill in the body.
+        # Otherwise, use CGCallGenerator to call the native method.
+        if idlNode.isMethod() and idlNode.isMaplikeOrSetlikeOrIterableMethod():
+            if (idlNode.maplikeOrSetlikeOrIterable.isMaplike() or
+                idlNode.maplikeOrSetlikeOrIterable.isSetlike()):
+                cgThings.append(CGMaplikeOrSetlikeMethodGenerator(descriptor,
+                                                                  idlNode.maplikeOrSetlikeOrIterable,
+                                                                  idlNode.identifier.name))
+            else:
+                cgThings.append(CGIterableMethodGenerator(descriptor,
+                                                          idlNode.maplikeOrSetlikeOrIterable,
+                                                          idlNode.identifier.name))
+        else:
+            cgThings.append(CGCallGenerator(
+                self.isFallible(),
+                idlNode.getExtendedAttribute('NeedsSubjectPrincipal'),
+                needsCallerType(idlNode),
+                self.getArguments(), argsPre, returnType,
+                self.extendedAttributes, descriptor,
+                nativeMethodName,
+                static, argsPost=argsPost, resultVar=resultVar))
+
+        if useCounterName:
+            # Generate a telemetry call for when [UseCounter] is used.
+            code = "SetDocumentAndPageUseCounter(cx, obj, eUseCounter_%s);\n" % useCounterName
+            cgThings.append(CGGeneric(code))
+
+        self.cgRoot = CGList(cgThings)
+
+    def getArguments(self):
+        return [(a, "arg" + str(i)) for i, a in enumerate(self.arguments)]
+
+    def isFallible(self):
+        return 'infallible' not in self.extendedAttributes
+
+    def wrap_return_value(self):
+        wrapCode = ""
+
+        returnsNewObject = memberReturnsNewObject(self.idlNode)
+        if (returnsNewObject and
+            self.returnType.isGeckoInterface()):
+            wrapCode += dedent(
+                """
+                static_assert(!IsPointer<decltype(result)>::value,
+                              "NewObject implies that we need to keep the object alive with a strong reference.");
+                """)
+
+        setSlot = self.idlNode.isAttr() and self.idlNode.slotIndices is not None
+        if setSlot:
+            # For attributes in slots, we want to do some
+            # post-processing once we've wrapped them.
+            successCode = "break;\n"
+        else:
+            successCode = None
+
+        resultTemplateValues = {
+            'jsvalRef': 'args.rval()',
+            'jsvalHandle': 'args.rval()',
+            'returnsNewObject': returnsNewObject,
+            'isConstructorRetval': self.isConstructor,
+            'successCode': successCode,
+            # 'obj' in this dictionary is the thing whose compartment we are
+            # trying to do the to-JS conversion in.  We're going to put that
+            # thing in a variable named "conversionScope" if setSlot is true.
+            # Otherwise, just use "obj" for lack of anything better.
+            'obj': "conversionScope" if setSlot else "obj"
+        }
+        try:
+            wrapCode += wrapForType(self.returnType, self.descriptor, resultTemplateValues)
+        except MethodNotNewObjectError, err:
+            assert not returnsNewObject
+            raise TypeError("%s being returned from non-NewObject method or property %s.%s" %
+                            (err.typename,
+                             self.descriptor.interface.identifier.name,
+                             self.idlNode.identifier.name))
+        if setSlot:
+            # When using a slot on the Xray expando, we need to make sure that
+            # our initial conversion to a JS::Value is done in the caller
+            # compartment.  When using a slot on our reflector, we want to do
+            # the conversion in the compartment of that reflector (that is,
+            # slotStorage).  In both cases we want to make sure that we finally
+            # set up args.rval() to be in the caller compartment.  We also need
+            # to make sure that the conversion steps happen inside a do/while
+            # that they can break out of on success.
+            #
+            # Of course we always have to wrap the value into the slotStorage
+            # compartment before we store it in slotStorage.
+
+            # postConversionSteps are the steps that run while we're still in
+            # the compartment we do our conversion in but after we've finished
+            # the initial conversion into args.rval().
+            postConversionSteps = ""
+            if needsContainsHack(self.idlNode):
+                # Define a .contains on the object that has the same value as
+                # .includes; needed for backwards compat in extensions as we
+                # migrate some DOMStringLists to FrozenArray.
+                postConversionSteps += dedent(
+                    """
+                    if (args.rval().isObject() && nsContentUtils::ThreadsafeIsCallerChrome()) {
+                      JS::Rooted<JSObject*> rvalObj(cx, &args.rval().toObject());
+                      JS::Rooted<JS::Value> includesVal(cx);
+                      if (!JS_GetProperty(cx, rvalObj, "includes", &includesVal) ||
+                          !JS_DefineProperty(cx, rvalObj, "contains", includesVal, JSPROP_ENUMERATE)) {
+                        return false;
+                      }
+                    }
+
+                    """)
+            if self.idlNode.getExtendedAttribute("Frozen"):
+                assert self.idlNode.type.isSequence() or self.idlNode.type.isDictionary()
+                freezeValue = CGGeneric(
+                    "JS::Rooted<JSObject*> rvalObj(cx, &args.rval().toObject());\n"
+                    "if (!JS_FreezeObject(cx, rvalObj)) {\n"
+                    "  return false;\n"
+                    "}\n")
+                if self.idlNode.type.nullable():
+                    freezeValue = CGIfWrapper(freezeValue,
+                                              "args.rval().isObject()")
+                postConversionSteps += freezeValue.define()
+
+            # slotStorageSteps are steps that run once we have entered the
+            # slotStorage compartment.
+            slotStorageSteps= fill(
+                """
+                // Make a copy so that we don't do unnecessary wrapping on args.rval().
+                JS::Rooted<JS::Value> storedVal(cx, args.rval());
+                if (!${maybeWrap}(cx, &storedVal)) {
+                  return false;
+                }
+                js::SetReservedSlot(slotStorage, slotIndex, storedVal);
+                """,
+                maybeWrap=getMaybeWrapValueFuncForType(self.idlNode.type))
+
+            checkForXray = mayUseXrayExpandoSlots(self.descriptor, self.idlNode)
+
+            # For the case of Cached attributes, go ahead and preserve our
+            # wrapper if needed.  We need to do this because otherwise the
+            # wrapper could get garbage-collected and the cached value would
+            # suddenly disappear, but the whole premise of cached values is that
+            # they never change without explicit action on someone's part.  We
+            # don't do this for StoreInSlot, since those get dealt with during
+            # wrapper setup, and failure would involve us trying to clear an
+            # already-preserved wrapper.
+            if (self.idlNode.getExtendedAttribute("Cached") and
+                self.descriptor.wrapperCache):
+                preserveWrapper = dedent(
+                    """
+                    PreserveWrapper(self);
+                    """)
+                if checkForXray:
+                    preserveWrapper = fill(
+                        """
+                        if (!isXray) {
+                          // In the Xray case we don't need to do this, because getting the
+                          // expando object already preserved our wrapper.
+                          $*{preserveWrapper}
+                        }
+                        """,
+                        preserveWrapper=preserveWrapper)
+                slotStorageSteps += preserveWrapper
+
+            if checkForXray:
+                conversionScope = "isXray ? obj : slotStorage"
+            else:
+                conversionScope = "slotStorage"
+
+            wrapCode = fill(
+                """
+                {
+                  JS::Rooted<JSObject*> conversionScope(cx, ${conversionScope});
+                  JSAutoCompartment ac(cx, conversionScope);
+                  do { // block we break out of when done wrapping
+                    $*{wrapCode}
+                  } while (0);
+                  $*{postConversionSteps}
+                }
+                { // And now store things in the compartment of our slotStorage.
+                  JSAutoCompartment ac(cx, slotStorage);
+                  $*{slotStorageSteps}
+                }
+                // And now make sure args.rval() is in the caller compartment
+                return ${maybeWrap}(cx, args.rval());
+                """,
+                conversionScope=conversionScope,
+                wrapCode=wrapCode,
+                postConversionSteps=postConversionSteps,
+                slotStorageSteps=slotStorageSteps,
+                maybeWrap=getMaybeWrapValueFuncForType(self.idlNode.type))
+        return wrapCode
+
+    def define(self):
+        return (self.cgRoot.define() + self.wrap_return_value())
+
+
+class CGSwitch(CGList):
+    """
+    A class to generate code for a switch statement.
+
+    Takes three constructor arguments: an expression, a list of cases,
+    and an optional default.
+
+    Each case is a CGCase.  The default is a CGThing for the body of
+    the default case, if any.
+    """
+    def __init__(self, expression, cases, default=None):
+        CGList.__init__(self, [CGIndenter(c) for c in cases])
+        self.prepend(CGGeneric("switch (" + expression + ") {\n"))
+        if default is not None:
+            self.append(
+                CGIndenter(
+                    CGWrapper(
+                        CGIndenter(default),
+                        pre="default: {\n",
+                        post="  break;\n}\n")))
+
+        self.append(CGGeneric("}\n"))
+
+
+class CGCase(CGList):
+    """
+    A class to generate code for a case statement.
+
+    Takes three constructor arguments: an expression, a CGThing for
+    the body (allowed to be None if there is no body), and an optional
+    argument (defaulting to False) for whether to fall through.
+    """
+    def __init__(self, expression, body, fallThrough=False):
+        CGList.__init__(self, [])
+        self.append(CGGeneric("case " + expression + ": {\n"))
+        bodyList = CGList([body])
+        if fallThrough:
+            bodyList.append(CGGeneric("MOZ_FALLTHROUGH;\n"))
+        else:
+            bodyList.append(CGGeneric("break;\n"))
+        self.append(CGIndenter(bodyList))
+        self.append(CGGeneric("}\n"))
+
+
+class CGMethodCall(CGThing):
+    """
+    A class to generate selection of a method signature from a set of
+    signatures and generation of a call to that signature.
+    """
+    def __init__(self, nativeMethodName, static, descriptor, method,
+                 isConstructor=False, constructorName=None):
+        CGThing.__init__(self)
+
+        if isConstructor:
+            assert constructorName is not None
+            methodName = constructorName
+        else:
+            methodName = "%s.%s" % (descriptor.interface.identifier.name, method.identifier.name)
+        argDesc = "argument %d of " + methodName
+
+        if method.getExtendedAttribute("UseCounter"):
+            useCounterName = methodName.replace(".", "_")
+        else:
+            useCounterName = None
+
+        if method.isStatic():
+            nativeType = descriptor.nativeType
+            staticTypeOverride = PropertyDefiner.getStringAttr(method, "StaticClassOverride")
+            if (staticTypeOverride):
+                nativeType = staticTypeOverride
+            nativeMethodName = "%s::%s" % (nativeType, nativeMethodName)
+
+        def requiredArgCount(signature):
+            arguments = signature[1]
+            if len(arguments) == 0:
+                return 0
+            requiredArgs = len(arguments)
+            while requiredArgs and arguments[requiredArgs-1].optional:
+                requiredArgs -= 1
+            return requiredArgs
+
+        def getPerSignatureCall(signature, argConversionStartsAt=0):
+            return CGPerSignatureCall(signature[0], signature[1],
+                                      nativeMethodName, static, descriptor,
+                                      method,
+                                      argConversionStartsAt=argConversionStartsAt,
+                                      isConstructor=isConstructor,
+                                      useCounterName=useCounterName)
+
+        signatures = method.signatures()
+        if len(signatures) == 1:
+            # Special case: we can just do a per-signature method call
+            # here for our one signature and not worry about switching
+            # on anything.
+            signature = signatures[0]
+            self.cgRoot = CGList([getPerSignatureCall(signature)])
+            requiredArgs = requiredArgCount(signature)
+
+            # Skip required arguments check for maplike/setlike interfaces, as
+            # they can have arguments which are not passed, and are treated as
+            # if undefined had been explicitly passed.
+            if requiredArgs > 0 and not method.isMaplikeOrSetlikeOrIterableMethod():
+                code = fill(
+                    """
+                    if (MOZ_UNLIKELY(args.length() < ${requiredArgs})) {
+                      return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, "${methodName}");
+                    }
+                    """,
+                    requiredArgs=requiredArgs,
+                    methodName=methodName)
+                self.cgRoot.prepend(CGGeneric(code))
+            return
+
+        # Need to find the right overload
+        maxArgCount = method.maxArgCount
+        allowedArgCounts = method.allowedArgCounts
+
+        argCountCases = []
+        for argCountIdx, argCount in enumerate(allowedArgCounts):
+            possibleSignatures = method.signaturesForArgCount(argCount)
+
+            # Try to optimize away cases when the next argCount in the list
+            # will have the same code as us; if it does, we can fall through to
+            # that case.
+            if argCountIdx+1 < len(allowedArgCounts):
+                nextPossibleSignatures = method.signaturesForArgCount(allowedArgCounts[argCountIdx+1])
+            else:
+                nextPossibleSignatures = None
+            if possibleSignatures == nextPossibleSignatures:
+                # Same set of signatures means we better have the same
+                # distinguishing index.  So we can in fact just fall through to
+                # the next case here.
+                assert (len(possibleSignatures) == 1 or
+                        (method.distinguishingIndexForArgCount(argCount) ==
+                         method.distinguishingIndexForArgCount(allowedArgCounts[argCountIdx+1])))
+                argCountCases.append(CGCase(str(argCount), None, True))
+                continue
+
+            if len(possibleSignatures) == 1:
+                # easy case!
+                signature = possibleSignatures[0]
+                argCountCases.append(
+                    CGCase(str(argCount), getPerSignatureCall(signature)))
+                continue
+
+            distinguishingIndex = method.distinguishingIndexForArgCount(argCount)
+
+            def distinguishingArgument(signature):
+                args = signature[1]
+                if distinguishingIndex < len(args):
+                    return args[distinguishingIndex]
+                assert args[-1].variadic
+                return args[-1]
+
+            def distinguishingType(signature):
+                return distinguishingArgument(signature).type
+
+            for sig in possibleSignatures:
+                # We should not have "any" args at distinguishingIndex,
+                # since we have multiple possible signatures remaining,
+                # but "any" is never distinguishable from anything else.
+                assert not distinguishingType(sig).isAny()
+                # We can't handle unions at the distinguishing index.
+                if distinguishingType(sig).isUnion():
+                    raise TypeError("No support for unions as distinguishing "
+                                    "arguments yet: %s" %
+                                    distinguishingArgument(sig).location)
+                # We don't support variadics as the distinguishingArgument yet.
+                # If you want to add support, consider this case:
+                #
+                #   void(long... foo);
+                #   void(long bar, Int32Array baz);
+                #
+                # in which we have to convert argument 0 to long before picking
+                # an overload... but all the variadic stuff needs to go into a
+                # single array in case we pick that overload, so we have to have
+                # machinery for converting argument 0 to long and then either
+                # placing it in the variadic bit or not.  Or something.  We may
+                # be able to loosen this restriction if the variadic arg is in
+                # fact at distinguishingIndex, perhaps.  Would need to
+                # double-check.
+                if distinguishingArgument(sig).variadic:
+                    raise TypeError("No support for variadics as distinguishing "
+                                    "arguments yet: %s" %
+                                    distinguishingArgument(sig).location)
+
+            # Convert all our arguments up to the distinguishing index.
+            # Doesn't matter which of the possible signatures we use, since
+            # they all have the same types up to that point; just use
+            # possibleSignatures[0]
+            caseBody = [CGArgumentConverter(possibleSignatures[0][1][i],
+                                            i, descriptor,
+                                            argDesc % (i + 1), method)
+                        for i in range(0, distinguishingIndex)]
+
+            # Select the right overload from our set.
+            distinguishingArg = "args[%d]" % distinguishingIndex
+
+            def tryCall(signature, indent, isDefinitelyObject=False,
+                        isNullOrUndefined=False):
+                assert not isDefinitelyObject or not isNullOrUndefined
+                assert isDefinitelyObject or isNullOrUndefined
+                if isDefinitelyObject:
+                    failureCode = "break;\n"
+                else:
+                    failureCode = None
+                type = distinguishingType(signature)
+                # The argument at index distinguishingIndex can't possibly be
+                # unset here, because we've already checked that argc is large
+                # enough that we can examine this argument.  But note that we
+                # still want to claim that optional arguments are optional, in
+                # case undefined was passed in.
+                argIsOptional = distinguishingArgument(signature).canHaveMissingValue()
+                testCode = instantiateJSToNativeConversion(
+                    getJSToNativeConversionInfo(type, descriptor,
+                                                failureCode=failureCode,
+                                                isDefinitelyObject=isDefinitelyObject,
+                                                isNullOrUndefined=isNullOrUndefined,
+                                                isOptional=argIsOptional,
+                                                sourceDescription=(argDesc % (distinguishingIndex + 1))),
+                    {
+                        "declName": "arg%d" % distinguishingIndex,
+                        "holderName": ("arg%d" % distinguishingIndex) + "_holder",
+                        "val": distinguishingArg,
+                        "obj": "obj",
+                        "haveValue": "args.hasDefined(%d)" % distinguishingIndex,
+                        "passedToJSImpl": toStringBool(isJSImplementedDescriptor(descriptor))
+                    },
+                    checkForValue=argIsOptional)
+                caseBody.append(CGIndenter(testCode, indent))
+
+                # If we got this far, we know we unwrapped to the right
+                # C++ type, so just do the call.  Start conversion with
+                # distinguishingIndex + 1, since we already converted
+                # distinguishingIndex.
+                caseBody.append(CGIndenter(
+                    getPerSignatureCall(signature, distinguishingIndex + 1),
+                    indent))
+
+            def hasConditionalConversion(type):
+                """
+                Return whether the argument conversion for this type will be
+                conditional on the type of incoming JS value.  For example, for
+                interface types the conversion is conditional on the incoming
+                value being isObject().
+
+                For the types for which this returns false, we do not have to
+                output extra isUndefined() or isNullOrUndefined() cases, because
+                null/undefined values will just fall through into our
+                unconditional conversion.
+                """
+                if type.isString() or type.isEnum():
+                    return False
+                if type.isBoolean():
+                    distinguishingTypes = (distinguishingType(s) for s in
+                                           possibleSignatures)
+                    return any(t.isString() or t.isEnum() or t.isNumeric()
+                               for t in distinguishingTypes)
+                if type.isNumeric():
+                    distinguishingTypes = (distinguishingType(s) for s in
+                                           possibleSignatures)
+                    return any(t.isString() or t.isEnum()
+                               for t in distinguishingTypes)
+                return True
+
+            def needsNullOrUndefinedCase(type):
+                """
+                Return true if the type needs a special isNullOrUndefined() case
+                """
+                return ((type.nullable() and
+                        hasConditionalConversion(type)) or
+                        type.isDictionary())
+
+            # First check for undefined and optional distinguishing arguments
+            # and output a special branch for that case.  Note that we don't
+            # use distinguishingArgument here because we actualy want to
+            # exclude variadic arguments.  Also note that we skip this check if
+            # we plan to output a isNullOrUndefined() special case for this
+            # argument anyway, since that will subsume our isUndefined() check.
+            # This is safe, because there can be at most one nullable
+            # distinguishing argument, so if we're it we'll definitely get
+            # picked up by the nullable handling.  Also, we can skip this check
+            # if the argument has an unconditional conversion later on.
+            undefSigs = [s for s in possibleSignatures if
+                         distinguishingIndex < len(s[1]) and
+                         s[1][distinguishingIndex].optional and
+                         hasConditionalConversion(s[1][distinguishingIndex].type) and
+                         not needsNullOrUndefinedCase(s[1][distinguishingIndex].type)]
+            # Can't have multiple signatures with an optional argument at the
+            # same index.
+            assert len(undefSigs) < 2
+            if len(undefSigs) > 0:
+                caseBody.append(CGGeneric("if (%s.isUndefined()) {\n" %
+                                          distinguishingArg))
+                tryCall(undefSigs[0], 2, isNullOrUndefined=True)
+                caseBody.append(CGGeneric("}\n"))
+
+            # Next, check for null or undefined.  That means looking for
+            # nullable arguments at the distinguishing index and outputting a
+            # separate branch for them.  But if the nullable argument has an
+            # unconditional conversion, we don't need to do that.  The reason
+            # for that is that at most one argument at the distinguishing index
+            # is nullable (since two nullable arguments are not
+            # distinguishable), and null/undefined values will always fall
+            # through to the unconditional conversion we have, if any, since
+            # they will fail whatever the conditions on the input value are for
+            # our other conversions.
+            nullOrUndefSigs = [s for s in possibleSignatures
+                               if needsNullOrUndefinedCase(distinguishingType(s))]
+            # Can't have multiple nullable types here
+            assert len(nullOrUndefSigs) < 2
+            if len(nullOrUndefSigs) > 0:
+                caseBody.append(CGGeneric("if (%s.isNullOrUndefined()) {\n" %
+                                          distinguishingArg))
+                tryCall(nullOrUndefSigs[0], 2, isNullOrUndefined=True)
+                caseBody.append(CGGeneric("}\n"))
+
+            # Now check for distinguishingArg being various kinds of objects.
+            # The spec says to check for the following things in order:
+            # 1)  A platform object that's not a platform array object, being
+            #     passed to an interface or "object" arg.
+            # 2)  A Date object being passed to a Date or "object" arg.
+            # 3)  A RegExp object being passed to a RegExp or "object" arg.
+            # 4)  A callable object being passed to a callback or "object" arg.
+            # 5)  An iterable object being passed to a sequence arg.
+            # 6)  Any non-Date and non-RegExp object being passed to a
+            #     array or callback interface or dictionary or
+            #     "object" arg.
+
+            # First grab all the overloads that have a non-callback interface
+            # (which includes typed arrays and arraybuffers) at the
+            # distinguishing index.  We can also include the ones that have an
+            # "object" here, since if those are present no other object-typed
+            # argument will be.
+            objectSigs = [
+                s for s in possibleSignatures
+                if (distinguishingType(s).isObject() or
+                    distinguishingType(s).isNonCallbackInterface())]
+
+            # And all the overloads that take Date
+            objectSigs.extend(s for s in possibleSignatures
+                              if distinguishingType(s).isDate())
+
+            # And all the overloads that take callbacks
+            objectSigs.extend(s for s in possibleSignatures
+                              if distinguishingType(s).isCallback())
+
+            # And all the overloads that take sequences
+            objectSigs.extend(s for s in possibleSignatures
+                              if distinguishingType(s).isSequence())
+
+            # Now append all the overloads that take a dictionary or callback
+            # interface or MozMap.  There should be only one of these!
+            genericObjectSigs = [
+                s for s in possibleSignatures
+                if (distinguishingType(s).isDictionary() or
+                    distinguishingType(s).isMozMap() or
+                    distinguishingType(s).isCallbackInterface())]
+            assert len(genericObjectSigs) <= 1
+            objectSigs.extend(genericObjectSigs)
+
+            # There might be more than one thing in objectSigs; we need to check
+            # which ones we unwrap to.
+            if len(objectSigs) > 0:
+                # Here it's enough to guard on our argument being an object. The
+                # code for unwrapping non-callback interfaces, typed arrays,
+                # sequences, and Dates will just bail out and move on to
+                # the next overload if the object fails to unwrap correctly,
+                # while "object" accepts any object anyway.  We could even not
+                # do the isObject() check up front here, but in cases where we
+                # have multiple object overloads it makes sense to do it only
+                # once instead of for each overload.  That will also allow the
+                # unwrapping test to skip having to do codegen for the
+                # null-or-undefined case, which we already handled above.
+                caseBody.append(CGGeneric("if (%s.isObject()) {\n" %
+                                          distinguishingArg))
+                for sig in objectSigs:
+                    caseBody.append(CGIndenter(CGGeneric("do {\n")))
+                    # Indent by 4, since we need to indent further
+                    # than our "do" statement
+                    tryCall(sig, 4, isDefinitelyObject=True)
+                    caseBody.append(CGIndenter(CGGeneric("} while (0);\n")))
+
+                caseBody.append(CGGeneric("}\n"))
+
+            # Now we only have to consider booleans, numerics, and strings.  If
+            # we only have one of them, then we can just output it.  But if not,
+            # then we need to output some of the cases conditionally: if we have
+            # a string overload, then boolean and numeric are conditional, and
+            # if not then boolean is conditional if we have a numeric overload.
+            def findUniqueSignature(filterLambda):
+                sigs = filter(filterLambda, possibleSignatures)
+                assert len(sigs) < 2
+                if len(sigs) > 0:
+                    return sigs[0]
+                return None
+
+            stringSignature = findUniqueSignature(
+                lambda s: (distinguishingType(s).isString() or
+                           distinguishingType(s).isEnum()))
+            numericSignature = findUniqueSignature(
+                lambda s: distinguishingType(s).isNumeric())
+            booleanSignature = findUniqueSignature(
+                lambda s: distinguishingType(s).isBoolean())
+
+            if stringSignature or numericSignature:
+                booleanCondition = "%s.isBoolean()"
+            else:
+                booleanCondition = None
+
+            if stringSignature:
+                numericCondition = "%s.isNumber()"
+            else:
+                numericCondition = None
+
+            def addCase(sig, condition):
+                sigCode = getPerSignatureCall(sig, distinguishingIndex)
+                if condition:
+                    sigCode = CGIfWrapper(sigCode,
+                                          condition % distinguishingArg)
+                caseBody.append(sigCode)
+
+            if booleanSignature:
+                addCase(booleanSignature, booleanCondition)
+            if numericSignature:
+                addCase(numericSignature, numericCondition)
+            if stringSignature:
+                addCase(stringSignature, None)
+
+            if (not booleanSignature and not numericSignature and
+                not stringSignature):
+                # Just throw; we have no idea what we're supposed to
+                # do with this.
+                caseBody.append(CGGeneric(
+                    'return ThrowErrorMessage(cx, MSG_OVERLOAD_RESOLUTION_FAILED, "%d", "%d", "%s");\n' %
+                    (distinguishingIndex + 1, argCount, methodName)))
+
+            argCountCases.append(CGCase(str(argCount), CGList(caseBody)))
+
+        overloadCGThings = []
+        overloadCGThings.append(
+            CGGeneric("unsigned argcount = std::min(args.length(), %du);\n" %
+                      maxArgCount))
+        overloadCGThings.append(
+            CGSwitch("argcount",
+                     argCountCases,
+                     CGGeneric('return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, "%s");\n' %
+                               methodName)))
+        overloadCGThings.append(
+            CGGeneric('MOZ_CRASH("We have an always-returning default case");\n'
+                      'return false;\n'))
+        self.cgRoot = CGList(overloadCGThings)
+
+    def define(self):
+        return self.cgRoot.define()
+
+
+class CGGetterCall(CGPerSignatureCall):
+    """
+    A class to generate a native object getter call for a particular IDL
+    getter.
+    """
+    def __init__(self, returnType, nativeMethodName, descriptor, attr):
+        if attr.getExtendedAttribute("UseCounter"):
+            useCounterName = "%s_%s_getter" % (descriptor.interface.identifier.name,
+                                               attr.identifier.name)
+        else:
+            useCounterName = None
+        if attr.isStatic():
+            nativeMethodName = "%s::%s" % (descriptor.nativeType, nativeMethodName)
+        CGPerSignatureCall.__init__(self, returnType, [], nativeMethodName,
+                                    attr.isStatic(), descriptor, attr,
+                                    getter=True, useCounterName=useCounterName)
+
+
+class CGNavigatorGetterCall(CGPerSignatureCall):
+    """
+    A class to generate a native object getter call for an IDL getter for a
+    property generated by NavigatorProperty.
+    """
+    def __init__(self, returnType, _, descriptor, attr):
+        nativeMethodName = "%s::ConstructNavigatorObject" % (toBindingNamespace(returnType.inner.identifier.name))
+        CGPerSignatureCall.__init__(self, returnType, [], nativeMethodName,
+                                    True, descriptor, attr, getter=True)
+
+    def getArguments(self):
+        # The navigator object should be associated with the global of
+        # the navigator it's coming from, which will be the global of
+        # the object whose slot it gets cached in.  That's stored in
+        # "slotStorage".
+        return [(FakeArgument(BuiltinTypes[IDLBuiltinType.Types.object],
+                              self.idlNode),
+                 "slotStorage")]
+
+
+class FakeIdentifier():
+    def __init__(self, name):
+        self.name = name
+
+
+class FakeArgument():
+    """
+    A class that quacks like an IDLArgument.  This is used to make
+    setters look like method calls or for special operations.
+    """
+    def __init__(self, type, interfaceMember, name="arg", allowTreatNonCallableAsNull=False):
+        self.type = type
+        self.optional = False
+        self.variadic = False
+        self.defaultValue = None
+        self._allowTreatNonCallableAsNull = allowTreatNonCallableAsNull
+        # For FakeArguments generated by maplike/setlike convenience functions,
+        # we won't have an interfaceMember to pass in.
+        if interfaceMember:
+            self.treatNullAs = interfaceMember.treatNullAs
+        else:
+            self.treatNullAs = "Default"
+        if isinstance(interfaceMember, IDLAttribute):
+            self.enforceRange = interfaceMember.enforceRange
+            self.clamp = interfaceMember.clamp
+        else:
+            self.enforceRange = False
+            self.clamp = False
+
+        self.identifier = FakeIdentifier(name)
+
+    def allowTreatNonCallableAsNull(self):
+        return self._allowTreatNonCallableAsNull
+
+    def canHaveMissingValue(self):
+        return False
+
+
+class CGSetterCall(CGPerSignatureCall):
+    """
+    A class to generate a native object setter call for a particular IDL
+    setter.
+    """
+    def __init__(self, argType, nativeMethodName, descriptor, attr):
+        if attr.getExtendedAttribute("UseCounter"):
+            useCounterName = "%s_%s_setter" % (descriptor.interface.identifier.name,
+                                               attr.identifier.name)
+        else:
+            useCounterName = None
+        if attr.isStatic():
+            nativeMethodName = "%s::%s" % (descriptor.nativeType, nativeMethodName)
+        CGPerSignatureCall.__init__(self, None,
+                                    [FakeArgument(argType, attr, allowTreatNonCallableAsNull=True)],
+                                    nativeMethodName, attr.isStatic(),
+                                    descriptor, attr, setter=True, useCounterName=useCounterName)
+
+    def wrap_return_value(self):
+        attr = self.idlNode
+        if self.descriptor.wrapperCache and attr.slotIndices is not None:
+            if attr.getExtendedAttribute("StoreInSlot"):
+                args = "cx, self"
+            else:
+                args = "self"
+            clearSlot = ("%s(%s);\n" %
+                         (MakeClearCachedValueNativeName(self.idlNode), args))
+        else:
+            clearSlot = ""
+
+        # We have no return value
+        return ("\n"
+                "%s"
+                "return true;\n" % clearSlot)
+
+
+class CGAbstractBindingMethod(CGAbstractStaticMethod):
+    """
+    Common class to generate the JSNatives for all our methods, getters, and
+    setters.  This will generate the function declaration and unwrap the
+    |this| object.  Subclasses are expected to override the generate_code
+    function to do the rest of the work.  This function should return a
+    CGThing which is already properly indented.
+
+    getThisObj should be code for getting a JSObject* for the binding
+    object.  If this is None, we will auto-generate code based on
+    descriptor to do the right thing.  "" can be passed in if the
+    binding object is already stored in 'obj'.
+
+    callArgs should be code for getting a JS::CallArgs into a variable
+    called 'args'.  This can be "" if there is already such a variable
+    around.
+
+    If allowCrossOriginThis is true, then this-unwrapping will first do an
+    UncheckedUnwrap and after that operate on the result.
+    """
+    def __init__(self, descriptor, name, args, unwrapFailureCode=None,
+                 getThisObj=None,
+                 callArgs="JS::CallArgs args = JS::CallArgsFromVp(argc, vp);\n",
+                 allowCrossOriginThis=False):
+        CGAbstractStaticMethod.__init__(self, descriptor, name, "bool", args)
+
+        if unwrapFailureCode is None:
+            self.unwrapFailureCode = 'return ThrowErrorMessage(cx, MSG_THIS_DOES_NOT_IMPLEMENT_INTERFACE, "Value", "%s");\n' % descriptor.interface.identifier.name
+        else:
+            self.unwrapFailureCode = unwrapFailureCode
+
+        if getThisObj == "":
+            self.getThisObj = None
+        else:
+            if getThisObj is None:
+                if descriptor.interface.isOnGlobalProtoChain():
+                    ensureCondition = "!args.thisv().isNullOrUndefined() && !args.thisv().isObject()"
+                    getThisObj = "args.thisv().isObject() ? &args.thisv().toObject() : js::GetGlobalForObjectCrossCompartment(&args.callee())"
+                else:
+                    ensureCondition = "!args.thisv().isObject()"
+                    getThisObj = "&args.thisv().toObject()"
+                unwrapFailureCode = self.unwrapFailureCode % {'securityError': 'false'}
+                ensureThisObj = CGIfWrapper(CGGeneric(unwrapFailureCode),
+                                            ensureCondition)
+            else:
+                ensureThisObj = None
+            self.getThisObj = CGList(
+                [ensureThisObj,
+                 CGGeneric("JS::Rooted<JSObject*> obj(cx, %s);\n" %
+                           getThisObj)])
+        self.callArgs = callArgs
+        self.allowCrossOriginThis = allowCrossOriginThis
+
+    def definition_body(self):
+        body = self.callArgs
+        if self.getThisObj is not None:
+            body += self.getThisObj.define() + "\n"
+        body += "%s* self;\n" % self.descriptor.nativeType
+        body += dedent(
+            """
+            JS::Rooted<JS::Value> rootSelf(cx, JS::ObjectValue(*obj));
+            """)
+
+        # Our descriptor might claim that we're not castable, simply because
+        # we're someone's consequential interface.  But for this-unwrapping, we
+        # know that we're the real deal.  So fake a descriptor here for
+        # consumption by CastableObjectUnwrapper.
+        body += str(CastableObjectUnwrapper(
+            self.descriptor,
+            "rootSelf",
+            "&rootSelf",
+            "self",
+            self.unwrapFailureCode,
+            allowCrossOriginObj=self.allowCrossOriginThis))
+
+        return body + self.generate_code().define()
+
+    def generate_code(self):
+        assert False  # Override me
+
+
+class CGAbstractStaticBindingMethod(CGAbstractStaticMethod):
+    """
+    Common class to generate the JSNatives for all our static methods, getters
+    and setters.  This will generate the function declaration and unwrap the
+    global object.  Subclasses are expected to override the generate_code
+    function to do the rest of the work.  This function should return a
+    CGThing which is already properly indented.
+    """
+    def __init__(self, descriptor, name):
+        CGAbstractStaticMethod.__init__(self, descriptor, name, "bool",
+                                        JSNativeArguments())
+
+    def definition_body(self):
+        # Make sure that "obj" is in the same compartment as "cx", since we'll
+        # later use it to wrap return values.
+        unwrap = dedent("""
+            JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+            JS::Rooted<JSObject*> obj(cx, &args.callee());
+
+            """)
+        return unwrap + self.generate_code().define()
+
+    def generate_code(self):
+        assert False  # Override me
+
+
+def MakeNativeName(name):
+    return name[0].upper() + IDLToCIdentifier(name[1:])
+
+
+class CGGenericMethod(CGAbstractBindingMethod):
+    """
+    A class for generating the C++ code for an IDL method.
+
+    If allowCrossOriginThis is true, then this-unwrapping will first do an
+    UncheckedUnwrap and after that operate on the result.
+    """
+    def __init__(self, descriptor, allowCrossOriginThis=False):
+        unwrapFailureCode = (
+            'return ThrowInvalidThis(cx, args, %%(securityError)s, "%s");\n' %
+            descriptor.interface.identifier.name)
+        name = "genericCrossOriginMethod" if allowCrossOriginThis else "genericMethod"
+        CGAbstractBindingMethod.__init__(self, descriptor, name,
+                                         JSNativeArguments(),
+                                         unwrapFailureCode=unwrapFailureCode,
+                                         allowCrossOriginThis=allowCrossOriginThis)
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+            MOZ_ASSERT(info->type() == JSJitInfo::Method);
+            JSJitMethodOp method = info->method;
+            bool ok = method(cx, obj, self, JSJitMethodCallArgs(args));
+            #ifdef DEBUG
+            if (ok) {
+              AssertReturnTypeMatchesJitinfo(info, args.rval());
+            }
+            #endif
+            return ok;
+            """))
+
+
+class CGGenericPromiseReturningMethod(CGAbstractBindingMethod):
+    """
+    A class for generating the C++ code for an IDL method that returns a Promise.
+
+    Does not handle cross-origin this.
+    """
+    def __init__(self, descriptor):
+        unwrapFailureCode = dedent("""
+            ThrowInvalidThis(cx, args, %%(securityError)s, "%s");\n
+            return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                             args.rval());\n""" %
+                                   descriptor.interface.identifier.name)
+
+        name = "genericPromiseReturningMethod"
+        customCallArgs = dedent("""
+            JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+            // Make sure to save the callee before someone maybe messes with rval().
+            JS::Rooted<JSObject*> callee(cx, &args.callee());
+        """)
+
+        CGAbstractBindingMethod.__init__(self, descriptor, name,
+                                         JSNativeArguments(),
+                                         callArgs=customCallArgs,
+                                         unwrapFailureCode=unwrapFailureCode)
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+            MOZ_ASSERT(info->type() == JSJitInfo::Method);
+            JSJitMethodOp method = info->method;
+            bool ok = method(cx, obj, self, JSJitMethodCallArgs(args));
+            if (ok) {
+            #ifdef DEBUG
+              AssertReturnTypeMatchesJitinfo(info, args.rval());
+            #endif
+              return true;
+            }
+
+            MOZ_ASSERT(info->returnType() == JSVAL_TYPE_OBJECT);
+            return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                             args.rval());
+            """))
+
+
+class CGSpecializedMethod(CGAbstractStaticMethod):
+    """
+    A class for generating the C++ code for a specialized method that the JIT
+    can call with lower overhead.
+    """
+    def __init__(self, descriptor, method):
+        self.method = method
+        name = CppKeywords.checkMethodName(IDLToCIdentifier(method.identifier.name))
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('%s*' % descriptor.nativeType, 'self'),
+                Argument('const JSJitMethodCallArgs&', 'args')]
+        CGAbstractStaticMethod.__init__(self, descriptor, name, 'bool', args)
+
+    def definition_body(self):
+        nativeName = CGSpecializedMethod.makeNativeName(self.descriptor,
+                                                        self.method)
+        return CGMethodCall(nativeName, self.method.isStatic(), self.descriptor,
+                            self.method).define()
+
+    @staticmethod
+    def makeNativeName(descriptor, method):
+        name = method.identifier.name
+        return MakeNativeName(descriptor.binaryNameFor(name))
+
+
+class CGMethodPromiseWrapper(CGAbstractStaticMethod):
+    """
+    A class for generating a wrapper around another method that will
+    convert exceptions to promises.
+    """
+    def __init__(self, descriptor, methodToWrap):
+        self.method = methodToWrap
+        name = self.makeName(methodToWrap.name)
+        args = list(methodToWrap.args)
+        CGAbstractStaticMethod.__init__(self, descriptor, name, 'bool', args)
+
+    def definition_body(self):
+        return fill(
+            """
+            // Make sure to save the callee before someone maybe messes
+            // with rval().
+            JS::Rooted<JSObject*> callee(cx, &args.callee());
+            bool ok = ${methodName}(${args});
+            if (ok) {
+              return true;
+            }
+            return ConvertExceptionToPromise(cx, xpc::XrayAwareCalleeGlobal(callee),
+                                             args.rval());
+            """,
+            methodName=self.method.name,
+            args=", ".join(arg.name for arg in self.args))
+
+    @staticmethod
+    def makeName(methodName):
+        return methodName + "_promiseWrapper"
+
+
+class CGJsonifierMethod(CGSpecializedMethod):
+    def __init__(self, descriptor, method):
+        assert method.isJsonifier()
+        CGSpecializedMethod.__init__(self, descriptor, method)
+
+    def definition_body(self):
+        ret = dedent("""
+            JS::Rooted<JSObject*> result(cx, JS_NewPlainObject(cx));
+            if (!result) {
+              return false;
+            }
+            """)
+
+        jsonDescriptors = [self.descriptor]
+        interface = self.descriptor.interface.parent
+        while interface:
+            descriptor = self.descriptor.getDescriptor(interface.identifier.name)
+            if descriptor.operations['Jsonifier']:
+                jsonDescriptors.append(descriptor)
+            interface = interface.parent
+
+        # Iterate the array in reverse: oldest ancestor first
+        for descriptor in jsonDescriptors[::-1]:
+            ret += fill(
+                """
+                if (!${parentclass}::JsonifyAttributes(cx, obj, self, result)) {
+                  return false;
+                }
+                """,
+                parentclass=toBindingNamespace(descriptor.name)
+                )
+        ret += ('args.rval().setObject(*result);\n'
+                'return true;\n')
+        return ret
+
+
+class CGLegacyCallHook(CGAbstractBindingMethod):
+    """
+    Call hook for our object
+    """
+    def __init__(self, descriptor):
+        self._legacycaller = descriptor.operations["LegacyCaller"]
+        # Our "self" is actually the callee in this case, not the thisval.
+        CGAbstractBindingMethod.__init__(
+            self, descriptor, LEGACYCALLER_HOOK_NAME,
+            JSNativeArguments(), getThisObj="&args.callee()")
+
+    def define(self):
+        if not self._legacycaller:
+            return ""
+        return CGAbstractBindingMethod.define(self)
+
+    def generate_code(self):
+        name = self._legacycaller.identifier.name
+        nativeName = MakeNativeName(self.descriptor.binaryNameFor(name))
+        return CGMethodCall(nativeName, False, self.descriptor,
+                            self._legacycaller)
+
+
+class CGResolveHook(CGAbstractClassHook):
+    """
+    Resolve hook for objects that have the NeedResolve extended attribute.
+    """
+    def __init__(self, descriptor):
+        assert descriptor.interface.getExtendedAttribute("NeedResolve")
+
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('bool*', 'resolvedp')]
+        CGAbstractClassHook.__init__(self, descriptor, RESOLVE_HOOK_NAME,
+                                     "bool", args)
+
+    def generate_code(self):
+        return dedent("""
+            JS::Rooted<JS::PropertyDescriptor> desc(cx);
+            if (!self->DoResolve(cx, obj, id, &desc)) {
+              return false;
+            }
+            if (!desc.object()) {
+              return true;
+            }
+            // If desc.value() is undefined, then the DoResolve call
+            // has already defined it on the object.  Don't try to also
+            // define it.
+            if (!desc.value().isUndefined()) {
+              desc.attributesRef() |= JSPROP_RESOLVING;
+              if (!JS_DefinePropertyById(cx, obj, id, desc)) {
+                return false;
+              }
+            }
+            *resolvedp = true;
+            return true;
+            """)
+
+    def definition_body(self):
+        if self.descriptor.isGlobal():
+            # Resolve standard classes
+            prefix = dedent("""
+                if (!ResolveGlobal(cx, obj, id, resolvedp)) {
+                  return false;
+                }
+                if (*resolvedp) {
+                  return true;
+                }
+
+                """)
+        else:
+            prefix = ""
+        return prefix + CGAbstractClassHook.definition_body(self)
+
+
+class CGMayResolveHook(CGAbstractStaticMethod):
+    """
+    Resolve hook for objects that have the NeedResolve extended attribute.
+    """
+    def __init__(self, descriptor):
+        assert descriptor.interface.getExtendedAttribute("NeedResolve")
+
+        args = [Argument('const JSAtomState&', 'names'),
+                Argument('jsid', 'id'),
+                Argument('JSObject*', 'maybeObj')]
+        CGAbstractStaticMethod.__init__(self, descriptor, MAY_RESOLVE_HOOK_NAME,
+                                        "bool", args)
+
+    def definition_body(self):
+        if self.descriptor.isGlobal():
+            # Check whether this would resolve as a standard class.
+            prefix = dedent("""
+                if (MayResolveGlobal(names, id, maybeObj)) {
+                  return true;
+                }
+
+                """)
+        else:
+            prefix = ""
+        return (prefix +
+                "return %s::MayResolve(id);\n" % self.descriptor.nativeType)
+
+
+class CGEnumerateHook(CGAbstractBindingMethod):
+    """
+    Enumerate hook for objects with custom hooks.
+    """
+    def __init__(self, descriptor):
+        assert descriptor.interface.getExtendedAttribute("NeedResolve")
+
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj')]
+        # Our "self" is actually the "obj" argument in this case, not the thisval.
+        CGAbstractBindingMethod.__init__(
+            self, descriptor, ENUMERATE_HOOK_NAME,
+            args, getThisObj="", callArgs="")
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            AutoTArray<nsString, 8> names;
+            binding_detail::FastErrorResult rv;
+            self->GetOwnPropertyNames(cx, names, rv);
+            if (rv.MaybeSetPendingException(cx)) {
+              return false;
+            }
+            bool dummy;
+            for (uint32_t i = 0; i < names.Length(); ++i) {
+              if (!JS_HasUCProperty(cx, obj, names[i].get(), names[i].Length(), &dummy)) {
+                return false;
+              }
+            }
+            return true;
+            """))
+
+    def definition_body(self):
+        if self.descriptor.isGlobal():
+            # Enumerate standard classes
+            prefix = dedent("""
+                if (!EnumerateGlobal(cx, obj)) {
+                  return false;
+                }
+
+                """)
+        else:
+            prefix = ""
+        return prefix + CGAbstractBindingMethod.definition_body(self)
+
+
+class CppKeywords():
+    """
+    A class for checking if method names declared in webidl
+    are not in conflict with C++ keywords.
+    """
+    keywords = frozenset([
+        'alignas', 'alignof', 'and', 'and_eq', 'asm', 'assert', 'auto', 'bitand', 'bitor', 'bool',
+        'break', 'case', 'catch', 'char', 'char16_t', 'char32_t', 'class', 'compl', 'const',
+        'constexpr', 'const_cast', 'continue', 'decltype', 'default', 'delete', 'do', 'double',
+        'dynamic_cast', 'else', 'enum', 'explicit', 'export', 'extern', 'false', 'final', 'float',
+        'for', 'friend', 'goto', 'if', 'inline', 'int', 'long', 'mutable', 'namespace', 'new',
+        'noexcept', 'not', 'not_eq', 'nullptr', 'operator', 'or', 'or_eq', 'override', 'private',
+        'protected', 'public', 'register', 'reinterpret_cast', 'return', 'short', 'signed',
+        'sizeof', 'static', 'static_assert', 'static_cast', 'struct', 'switch', 'template', 'this',
+        'thread_local', 'throw', 'true', 'try', 'typedef', 'typeid', 'typename', 'union',
+        'unsigned', 'using', 'virtual', 'void', 'volatile', 'wchar_t', 'while', 'xor', 'xor_eq'])
+
+    @staticmethod
+    def checkMethodName(name):
+        # Double '_' because 'assert' and '_assert' cannot be used in MS2013 compiler.
+        # Bug 964892 and bug 963560.
+        if name in CppKeywords.keywords:
+            name = '_' + name + '_'
+        return name
+
+
+class CGStaticMethod(CGAbstractStaticBindingMethod):
+    """
+    A class for generating the C++ code for an IDL static method.
+    """
+    def __init__(self, descriptor, method):
+        self.method = method
+        name = CppKeywords.checkMethodName(IDLToCIdentifier(method.identifier.name))
+        CGAbstractStaticBindingMethod.__init__(self, descriptor, name)
+
+    def generate_code(self):
+        nativeName = CGSpecializedMethod.makeNativeName(self.descriptor,
+                                                        self.method)
+        return CGMethodCall(nativeName, True, self.descriptor, self.method)
+
+
+class CGGenericGetter(CGAbstractBindingMethod):
+    """
+    A class for generating the C++ code for an IDL attribute getter.
+    """
+    def __init__(self, descriptor, lenientThis=False, allowCrossOriginThis=False):
+        if lenientThis:
+            name = "genericLenientGetter"
+            unwrapFailureCode = dedent("""
+                MOZ_ASSERT(!JS_IsExceptionPending(cx));
+                if (!ReportLenientThisUnwrappingFailure(cx, &args.callee())) {
+                  return false;
+                }
+                args.rval().set(JS::UndefinedValue());
+                return true;
+                """)
+        else:
+            if allowCrossOriginThis:
+                name = "genericCrossOriginGetter"
+            else:
+                name = "genericGetter"
+            unwrapFailureCode = (
+                'return ThrowInvalidThis(cx, args, %%(securityError)s, "%s");\n' %
+                descriptor.interface.identifier.name)
+        CGAbstractBindingMethod.__init__(self, descriptor, name, JSNativeArguments(),
+                                         unwrapFailureCode,
+                                         allowCrossOriginThis=allowCrossOriginThis)
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+            MOZ_ASSERT(info->type() == JSJitInfo::Getter);
+            JSJitGetterOp getter = info->getter;
+            bool ok = getter(cx, obj, self, JSJitGetterCallArgs(args));
+            #ifdef DEBUG
+            if (ok) {
+              AssertReturnTypeMatchesJitinfo(info, args.rval());
+            }
+            #endif
+            return ok;
+            """))
+
+
+class CGSpecializedGetter(CGAbstractStaticMethod):
+    """
+    A class for generating the code for a specialized attribute getter
+    that the JIT can call with lower overhead.
+    """
+    def __init__(self, descriptor, attr):
+        self.attr = attr
+        name = 'get_' + IDLToCIdentifier(attr.identifier.name)
+        args = [
+            Argument('JSContext*', 'cx'),
+            Argument('JS::Handle<JSObject*>', 'obj'),
+            Argument('%s*' % descriptor.nativeType, 'self'),
+            Argument('JSJitGetterCallArgs', 'args')
+        ]
+        CGAbstractStaticMethod.__init__(self, descriptor, name, "bool", args)
+
+    def definition_body(self):
+        if self.attr.isMaplikeOrSetlikeAttr():
+            # If the interface is maplike/setlike, there will be one getter
+            # method for the size property of the backing object. Due to having
+            # to unpack the backing object from the slot, this requires its own
+            # generator.
+            return getMaplikeOrSetlikeSizeGetterBody(self.descriptor, self.attr)
+        nativeName = CGSpecializedGetter.makeNativeName(self.descriptor,
+                                                        self.attr)
+        if self.attr.slotIndices is not None:
+            if self.descriptor.hasXPConnectImpls:
+                raise TypeError("Interface '%s' has XPConnect impls, so we "
+                                "can't use our slot for property '%s'!" %
+                                (self.descriptor.interface.identifier.name,
+                                 self.attr.identifier.name))
+
+            # We're going to store this return value in a slot on some object,
+            # to cache it.  The question is, which object?  For dictionary and
+            # sequence return values, we want to use a slot on the Xray expando
+            # if we're called via Xrays, and a slot on our reflector otherwise.
+            # On the other hand, when dealing with some interfacce types
+            # (navigator properties, window.document) we want to avoid calling
+            # the getter more than once.  In the case of navigator properties
+            # that's because the getter actually creates a new object each time.
+            # In the case of window.document, it's because the getter can start
+            # returning null, which would get hidden in he non-Xray case by the
+            # fact that it's [StoreOnSlot], so the cached version is always
+            # around.
+            #
+            # The upshot is that we use the reflector slot for any getter whose
+            # type is a gecko interface, whether we're called via Xrays or not.
+            # Since [Cached] and [StoreInSlot] cannot be used with "NewObject",
+            # we know that in the interface type case the returned object is
+            # wrappercached.  So creating Xrays to it is reasonable.
+            if mayUseXrayExpandoSlots(self.descriptor, self.attr):
+                prefix = fill(
+                    """
+                    // Have to either root across the getter call or reget after.
+                    bool isXray;
+                    JS::Rooted<JSObject*> slotStorage(cx, GetCachedSlotStorageObject(cx, obj, &isXray));
+                    if (!slotStorage) {
+                      return false;
+                    }
+                    const size_t slotIndex = isXray ? ${xraySlotIndex} : ${slotIndex};
+                    """,
+                    xraySlotIndex=memberXrayExpandoReservedSlot(self.attr,
+                                                                self.descriptor),
+                    slotIndex=memberReservedSlot(self.attr, self.descriptor))
+            else:
+                prefix = fill(
+                    """
+                    // Have to either root across the getter call or reget after.
+                    JS::Rooted<JSObject*> slotStorage(cx, js::UncheckedUnwrap(obj, /* stopAtWindowProxy = */ false));
+                    MOZ_ASSERT(IsDOMObject(slotStorage));
+                    const size_t slotIndex = ${slotIndex};
+                    """,
+                    slotIndex=memberReservedSlot(self.attr, self.descriptor))
+
+            prefix += fill(
+                """
+                MOZ_ASSERT(JSCLASS_RESERVED_SLOTS(js::GetObjectClass(slotStorage)) > slotIndex);
+                {
+                  // Scope for cachedVal
+                  JS::Value cachedVal = js::GetReservedSlot(slotStorage, slotIndex);
+                  if (!cachedVal.isUndefined()) {
+                    args.rval().set(cachedVal);
+                    // The cached value is in the compartment of slotStorage,
+                    // so wrap into the caller compartment as needed.
+                    return ${maybeWrap}(cx, args.rval());
+                  }
+                }
+
+                """,
+                maybeWrap=getMaybeWrapValueFuncForType(self.attr.type))
+        else:
+            prefix = ""
+
+        if self.attr.navigatorObjectGetter:
+            cgGetterCall = CGNavigatorGetterCall
+        else:
+            cgGetterCall = CGGetterCall
+        return (prefix +
+                cgGetterCall(self.attr.type, nativeName,
+                             self.descriptor, self.attr).define())
+
+    @staticmethod
+    def makeNativeName(descriptor, attr):
+        name = attr.identifier.name
+        nativeName = MakeNativeName(descriptor.binaryNameFor(name))
+        _, resultOutParam, _, _, _ = getRetvalDeclarationForType(attr.type,
+                                                                 descriptor)
+        infallible = ('infallible' in
+                      descriptor.getExtendedAttributes(attr, getter=True))
+        if resultOutParam or attr.type.nullable() or not infallible:
+            nativeName = "Get" + nativeName
+        return nativeName
+
+
+class CGStaticGetter(CGAbstractStaticBindingMethod):
+    """
+    A class for generating the C++ code for an IDL static attribute getter.
+    """
+    def __init__(self, descriptor, attr):
+        self.attr = attr
+        name = 'get_' + IDLToCIdentifier(attr.identifier.name)
+        CGAbstractStaticBindingMethod.__init__(self, descriptor, name)
+
+    def generate_code(self):
+        nativeName = CGSpecializedGetter.makeNativeName(self.descriptor,
+                                                        self.attr)
+        return CGGetterCall(self.attr.type, nativeName, self.descriptor,
+                            self.attr)
+
+
+class CGGenericSetter(CGAbstractBindingMethod):
+    """
+    A class for generating the C++ code for an IDL attribute setter.
+    """
+    def __init__(self, descriptor, lenientThis=False, allowCrossOriginThis=False):
+        if lenientThis:
+            name = "genericLenientSetter"
+            unwrapFailureCode = dedent("""
+                MOZ_ASSERT(!JS_IsExceptionPending(cx));
+                if (!ReportLenientThisUnwrappingFailure(cx, &args.callee())) {
+                  return false;
+                }
+                args.rval().set(JS::UndefinedValue());
+                return true;
+                """)
+        else:
+            if allowCrossOriginThis:
+                name = "genericCrossOriginSetter"
+            else:
+                name = "genericSetter"
+            unwrapFailureCode = (
+                'return ThrowInvalidThis(cx, args, %%(securityError)s, "%s");\n' %
+                descriptor.interface.identifier.name)
+
+        CGAbstractBindingMethod.__init__(self, descriptor, name, JSNativeArguments(),
+                                         unwrapFailureCode,
+                                         allowCrossOriginThis=allowCrossOriginThis)
+
+    def generate_code(self):
+        return CGGeneric(fill(
+            """
+            if (args.length() == 0) {
+              return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, "${name} attribute setter");
+            }
+            const JSJitInfo *info = FUNCTION_VALUE_TO_JITINFO(args.calleev());
+            MOZ_ASSERT(info->type() == JSJitInfo::Setter);
+            JSJitSetterOp setter = info->setter;
+            if (!setter(cx, obj, self, JSJitSetterCallArgs(args))) {
+              return false;
+            }
+            args.rval().setUndefined();
+            #ifdef DEBUG
+            AssertReturnTypeMatchesJitinfo(info, args.rval());
+            #endif
+            return true;
+            """,
+            name=self.descriptor.interface.identifier.name))
+
+
+class CGSpecializedSetter(CGAbstractStaticMethod):
+    """
+    A class for generating the code for a specialized attribute setter
+    that the JIT can call with lower overhead.
+    """
+    def __init__(self, descriptor, attr):
+        self.attr = attr
+        name = 'set_' + IDLToCIdentifier(attr.identifier.name)
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('%s*' % descriptor.nativeType, 'self'),
+                Argument('JSJitSetterCallArgs', 'args')]
+        CGAbstractStaticMethod.__init__(self, descriptor, name, "bool", args)
+
+    def definition_body(self):
+        nativeName = CGSpecializedSetter.makeNativeName(self.descriptor,
+                                                        self.attr)
+        return CGSetterCall(self.attr.type, nativeName, self.descriptor,
+                            self.attr).define()
+
+    @staticmethod
+    def makeNativeName(descriptor, attr):
+        name = attr.identifier.name
+        return "Set" + MakeNativeName(descriptor.binaryNameFor(name))
+
+
+class CGStaticSetter(CGAbstractStaticBindingMethod):
+    """
+    A class for generating the C++ code for an IDL static attribute setter.
+    """
+    def __init__(self, descriptor, attr):
+        self.attr = attr
+        name = 'set_' + IDLToCIdentifier(attr.identifier.name)
+        CGAbstractStaticBindingMethod.__init__(self, descriptor, name)
+
+    def generate_code(self):
+        nativeName = CGSpecializedSetter.makeNativeName(self.descriptor,
+                                                        self.attr)
+        checkForArg = CGGeneric(fill(
+            """
+            if (args.length() == 0) {
+              return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, "${name} setter");
+            }
+            """,
+            name=self.attr.identifier.name))
+        call = CGSetterCall(self.attr.type, nativeName, self.descriptor,
+                            self.attr)
+        return CGList([checkForArg, call])
+
+
+class CGSpecializedForwardingSetter(CGSpecializedSetter):
+    """
+    A class for generating the code for a specialized attribute setter with
+    PutForwards that the JIT can call with lower overhead.
+    """
+    def __init__(self, descriptor, attr):
+        CGSpecializedSetter.__init__(self, descriptor, attr)
+
+    def definition_body(self):
+        attrName = self.attr.identifier.name
+        forwardToAttrName = self.attr.getExtendedAttribute("PutForwards")[0]
+        # JS_GetProperty and JS_SetProperty can only deal with ASCII
+        assert all(ord(c) < 128 for c in attrName)
+        assert all(ord(c) < 128 for c in forwardToAttrName)
+        return fill(
+            """
+            JS::Rooted<JS::Value> v(cx);
+            if (!JS_GetProperty(cx, obj, "${attr}", &v)) {
+              return false;
+            }
+
+            if (!v.isObject()) {
+              return ThrowErrorMessage(cx, MSG_NOT_OBJECT, "${interface}.${attr}");
+            }
+
+            JS::Rooted<JSObject*> targetObj(cx, &v.toObject());
+            return JS_SetProperty(cx, targetObj, "${forwardToAttrName}", args[0]);
+            """,
+            attr=attrName,
+            interface=self.descriptor.interface.identifier.name,
+            forwardToAttrName=forwardToAttrName)
+
+
+class CGSpecializedReplaceableSetter(CGSpecializedSetter):
+    """
+    A class for generating the code for a specialized attribute setter with
+    Replaceable that the JIT can call with lower overhead.
+    """
+    def __init__(self, descriptor, attr):
+        CGSpecializedSetter.__init__(self, descriptor, attr)
+
+    def definition_body(self):
+        attrName = self.attr.identifier.name
+        # JS_DefineProperty can only deal with ASCII
+        assert all(ord(c) < 128 for c in attrName)
+        return ('return JS_DefineProperty(cx, obj, "%s", args[0], JSPROP_ENUMERATE);\n' %
+                attrName)
+
+
+class CGSpecializedLenientSetter(CGSpecializedSetter):
+    """
+    A class for generating the code for a specialized attribute setter with
+    LenientSetter that the JIT can call with lower overhead.
+    """
+    def __init__(self, descriptor, attr):
+        CGSpecializedSetter.__init__(self, descriptor, attr)
+
+    def definition_body(self):
+        attrName = self.attr.identifier.name
+        # JS_DefineProperty can only deal with ASCII
+        assert all(ord(c) < 128 for c in attrName)
+        return dedent("""
+            DeprecationWarning(cx, obj, nsIDocument::eLenientSetter);
+            return true;
+            """)
+
+
+def memberReturnsNewObject(member):
+    return member.getExtendedAttribute("NewObject") is not None
+
+
+class CGMemberJITInfo(CGThing):
+    """
+    A class for generating the JITInfo for a property that points to
+    our specialized getter and setter.
+    """
+    def __init__(self, descriptor, member):
+        self.member = member
+        self.descriptor = descriptor
+
+    def declare(self):
+        return ""
+
+    def defineJitInfo(self, infoName, opName, opType, infallible, movable,
+                      eliminatable, aliasSet, alwaysInSlot, lazilyInSlot,
+                      slotIndex, returnTypes, args):
+        """
+        aliasSet is a JSJitInfo::AliasSet value, without the "JSJitInfo::" bit.
+
+        args is None if we don't want to output argTypes for some
+        reason (e.g. we have overloads or we're not a method) and
+        otherwise an iterable of the arguments for this method.
+        """
+        assert(not movable or aliasSet != "AliasEverything")  # Can't move write-aliasing things
+        assert(not alwaysInSlot or movable)  # Things always in slots had better be movable
+        assert(not eliminatable or aliasSet != "AliasEverything")  # Can't eliminate write-aliasing things
+        assert(not alwaysInSlot or eliminatable)  # Things always in slots had better be eliminatable
+
+        def jitInfoInitializer(isTypedMethod):
+            initializer = fill(
+                """
+                {
+                  { ${opName} },
+                  { prototypes::id::${name} },
+                  { PrototypeTraits<prototypes::id::${name}>::Depth },
+                  JSJitInfo::${opType},
+                  JSJitInfo::${aliasSet}, /* aliasSet.  Not relevant for setters. */
+                  ${returnType},  /* returnType.  Not relevant for setters. */
+                  ${isInfallible},  /* isInfallible. False in setters. */
+                  ${isMovable},  /* isMovable.  Not relevant for setters. */
+                  ${isEliminatable}, /* isEliminatable.  Not relevant for setters. */
+                  ${isAlwaysInSlot}, /* isAlwaysInSlot.  Only relevant for getters. */
+                  ${isLazilyCachedInSlot}, /* isLazilyCachedInSlot.  Only relevant for getters. */
+                  ${isTypedMethod},  /* isTypedMethod.  Only relevant for methods. */
+                  ${slotIndex}   /* Reserved slot index, if we're stored in a slot, else 0. */
+                }
+                """,
+                opName=opName,
+                name=self.descriptor.name,
+                opType=opType,
+                aliasSet=aliasSet,
+                returnType=reduce(CGMemberJITInfo.getSingleReturnType, returnTypes,
+                                  ""),
+                isInfallible=toStringBool(infallible),
+                isMovable=toStringBool(movable),
+                isEliminatable=toStringBool(eliminatable),
+                isAlwaysInSlot=toStringBool(alwaysInSlot),
+                isLazilyCachedInSlot=toStringBool(lazilyInSlot),
+                isTypedMethod=toStringBool(isTypedMethod),
+                slotIndex=slotIndex)
+            return initializer.rstrip()
+
+        slotAssert = fill(
+            """
+            static_assert(${slotIndex} <= JSJitInfo::maxSlotIndex, "We won't fit");
+            static_assert(${slotIndex} < ${classReservedSlots}, "There is no slot for us");
+            """,
+            slotIndex=slotIndex,
+            classReservedSlots=INSTANCE_RESERVED_SLOTS + self.descriptor.interface.totalMembersInSlots)
+        if args is not None:
+            argTypes = "%s_argTypes" % infoName
+            args = [CGMemberJITInfo.getJSArgType(arg.type) for arg in args]
+            args.append("JSJitInfo::ArgTypeListEnd")
+            argTypesDecl = (
+                "static const JSJitInfo::ArgType %s[] = { %s };\n" %
+                (argTypes, ", ".join(args)))
+            return fill(
+                """
+                $*{argTypesDecl}
+                static const JSTypedMethodJitInfo ${infoName} = {
+                ${jitInfo},
+                  ${argTypes}
+                };
+                $*{slotAssert}
+                """,
+                argTypesDecl=argTypesDecl,
+                infoName=infoName,
+                jitInfo=indent(jitInfoInitializer(True)),
+                argTypes=argTypes,
+                slotAssert=slotAssert)
+
+        return fill(
+            """
+            static const JSJitInfo ${infoName} = ${jitInfo};
+            $*{slotAssert}
+            """,
+            infoName=infoName,
+            jitInfo=jitInfoInitializer(False),
+            slotAssert=slotAssert)
+
+    def define(self):
+        if self.member.isAttr():
+            getterinfo = ("%s_getterinfo" %
+                          IDLToCIdentifier(self.member.identifier.name))
+            # We need the cast here because JSJitGetterOp has a "void* self"
+            # while we have the right type.
+            getter = ("(JSJitGetterOp)get_%s" %
+                      IDLToCIdentifier(self.member.identifier.name))
+            getterinfal = "infallible" in self.descriptor.getExtendedAttributes(self.member, getter=True)
+
+            movable = self.mayBeMovable() and getterinfal
+            eliminatable = self.mayBeEliminatable() and getterinfal
+            aliasSet = self.aliasSet()
+
+            getterinfal = getterinfal and infallibleForMember(self.member, self.member.type, self.descriptor)
+            isAlwaysInSlot = self.member.getExtendedAttribute("StoreInSlot")
+            if self.member.slotIndices is not None:
+                assert isAlwaysInSlot or self.member.getExtendedAttribute("Cached")
+                isLazilyCachedInSlot = not isAlwaysInSlot
+                slotIndex = memberReservedSlot(self.member, self.descriptor)
+                # We'll statically assert that this is not too big in
+                # CGUpdateMemberSlotsMethod, in the case when
+                # isAlwaysInSlot is true.
+            else:
+                isLazilyCachedInSlot = False
+                slotIndex = "0"
+
+            result = self.defineJitInfo(getterinfo, getter, "Getter",
+                                        getterinfal, movable, eliminatable,
+                                        aliasSet, isAlwaysInSlot,
+                                        isLazilyCachedInSlot, slotIndex,
+                                        [self.member.type], None)
+            if (not self.member.readonly or
+                self.member.getExtendedAttribute("PutForwards") is not None or
+                self.member.getExtendedAttribute("Replaceable") is not None or
+                self.member.getExtendedAttribute("LenientSetter") is not None):
+                setterinfo = ("%s_setterinfo" %
+                              IDLToCIdentifier(self.member.identifier.name))
+                # Actually a JSJitSetterOp, but JSJitGetterOp is first in the
+                # union.
+                setter = ("(JSJitGetterOp)set_%s" %
+                          IDLToCIdentifier(self.member.identifier.name))
+                # Setters are always fallible, since they have to do a typed unwrap.
+                result += self.defineJitInfo(setterinfo, setter, "Setter",
+                                             False, False, False, "AliasEverything",
+                                             False, False, "0",
+                                             [BuiltinTypes[IDLBuiltinType.Types.void]],
+                                             None)
+            return result
+        if self.member.isMethod():
+            methodinfo = ("%s_methodinfo" %
+                          IDLToCIdentifier(self.member.identifier.name))
+            name = CppKeywords.checkMethodName(
+                IDLToCIdentifier(self.member.identifier.name))
+            if self.member.returnsPromise():
+                name = CGMethodPromiseWrapper.makeName(name)
+            # Actually a JSJitMethodOp, but JSJitGetterOp is first in the union.
+            method = ("(JSJitGetterOp)%s" % name)
+
+            # Methods are infallible if they are infallible, have no arguments
+            # to unwrap, and have a return type that's infallible to wrap up for
+            # return.
+            sigs = self.member.signatures()
+            if len(sigs) != 1:
+                # Don't handle overloading.  If there's more than one signature,
+                # one of them must take arguments.
+                methodInfal = False
+                args = None
+                movable = False
+                eliminatable = False
+            else:
+                sig = sigs[0]
+                # For methods that affect nothing, it's OK to set movable to our
+                # notion of infallible on the C++ side, without considering
+                # argument conversions, since argument conversions that can
+                # reliably throw would be effectful anyway and the jit doesn't
+                # move effectful things.
+                hasInfallibleImpl = "infallible" in self.descriptor.getExtendedAttributes(self.member)
+                movable = self.mayBeMovable() and hasInfallibleImpl
+                eliminatable = self.mayBeEliminatable() and hasInfallibleImpl
+                # XXXbz can we move the smarts about fallibility due to arg
+                # conversions into the JIT, using our new args stuff?
+                if (len(sig[1]) != 0 or
+                    not infallibleForMember(self.member, sig[0], self.descriptor)):
+                    # We have arguments or our return-value boxing can fail
+                    methodInfal = False
+                else:
+                    methodInfal = hasInfallibleImpl
+                # For now, only bother to output args if we're side-effect-free.
+                if self.member.affects == "Nothing":
+                    args = sig[1]
+                else:
+                    args = None
+
+            aliasSet = self.aliasSet()
+            result = self.defineJitInfo(methodinfo, method, "Method",
+                                        methodInfal, movable, eliminatable,
+                                        aliasSet, False, False, "0",
+                                        [s[0] for s in sigs], args)
+            return result
+        raise TypeError("Illegal member type to CGPropertyJITInfo")
+
+    def mayBeMovable(self):
+        """
+        Returns whether this attribute or method may be movable, just
+        based on Affects/DependsOn annotations.
+        """
+        affects = self.member.affects
+        dependsOn = self.member.dependsOn
+        assert affects in IDLInterfaceMember.AffectsValues
+        assert dependsOn in IDLInterfaceMember.DependsOnValues
+        # Things that are DependsOn=DeviceState are not movable, because we
+        # don't want them coalesced with each other or loop-hoisted, since
+        # their return value can change even if nothing is going on from our
+        # point of view.
+        return (affects == "Nothing" and
+                (dependsOn != "Everything" and dependsOn != "DeviceState"))
+
+    def mayBeEliminatable(self):
+        """
+        Returns whether this attribute or method may be eliminatable, just
+        based on Affects/DependsOn annotations.
+        """
+        # dependsOn shouldn't affect this decision at all, except in jitinfo we
+        # have no way to express "Depends on everything, affects nothing",
+        # because we only have three alias set values: AliasNone ("depends on
+        # nothing, affects nothing"), AliasDOMSets ("depends on DOM sets,
+        # affects nothing"), AliasEverything ("depends on everything, affects
+        # everything").  So the [Affects=Nothing, DependsOn=Everything] case
+        # gets encoded as AliasEverything and defineJitInfo asserts that if our
+        # alias state is AliasEverything then we're not eliminatable (because it
+        # thinks we might have side-effects at that point).  Bug 1155796 is
+        # tracking possible solutions for this.
+        affects = self.member.affects
+        dependsOn = self.member.dependsOn
+        assert affects in IDLInterfaceMember.AffectsValues
+        assert dependsOn in IDLInterfaceMember.DependsOnValues
+        return affects == "Nothing" and dependsOn != "Everything"
+
+    def aliasSet(self):
+        """
+        Returns the alias set to store in the jitinfo.  This may not be the
+        effective alias set the JIT uses, depending on whether we have enough
+        information about our args to allow the JIT to prove that effectful
+        argument conversions won't happen.
+        """
+        dependsOn = self.member.dependsOn
+        assert dependsOn in IDLInterfaceMember.DependsOnValues
+
+        if dependsOn == "Nothing" or dependsOn == "DeviceState":
+            assert self.member.affects == "Nothing"
+            return "AliasNone"
+
+        if dependsOn == "DOMState":
+            assert self.member.affects == "Nothing"
+            return "AliasDOMSets"
+
+        return "AliasEverything"
+
+    @staticmethod
+    def getJSReturnTypeTag(t):
+        if t.nullable():
+            # Sometimes it might return null, sometimes not
+            return "JSVAL_TYPE_UNKNOWN"
+        if t.isVoid():
+            # No return, every time
+            return "JSVAL_TYPE_UNDEFINED"
+        if t.isSequence():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isMozMap():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isGeckoInterface():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isString():
+            return "JSVAL_TYPE_STRING"
+        if t.isEnum():
+            return "JSVAL_TYPE_STRING"
+        if t.isCallback():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isAny():
+            # The whole point is to return various stuff
+            return "JSVAL_TYPE_UNKNOWN"
+        if t.isObject():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isSpiderMonkeyInterface():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isUnion():
+            u = t.unroll()
+            if u.hasNullableType:
+                # Might be null or not
+                return "JSVAL_TYPE_UNKNOWN"
+            return reduce(CGMemberJITInfo.getSingleReturnType,
+                          u.flatMemberTypes, "")
+        if t.isDictionary():
+            return "JSVAL_TYPE_OBJECT"
+        if t.isDate():
+            return "JSVAL_TYPE_OBJECT"
+        if not t.isPrimitive():
+            raise TypeError("No idea what type " + str(t) + " is.")
+        tag = t.tag()
+        if tag == IDLType.Tags.bool:
+            return "JSVAL_TYPE_BOOLEAN"
+        if tag in [IDLType.Tags.int8, IDLType.Tags.uint8,
+                   IDLType.Tags.int16, IDLType.Tags.uint16,
+                   IDLType.Tags.int32]:
+            return "JSVAL_TYPE_INT32"
+        if tag in [IDLType.Tags.int64, IDLType.Tags.uint64,
+                   IDLType.Tags.unrestricted_float, IDLType.Tags.float,
+                   IDLType.Tags.unrestricted_double, IDLType.Tags.double]:
+            # These all use JS_NumberValue, which can return int or double.
+            # But TI treats "double" as meaning "int or double", so we're
+            # good to return JSVAL_TYPE_DOUBLE here.
+            return "JSVAL_TYPE_DOUBLE"
+        if tag != IDLType.Tags.uint32:
+            raise TypeError("No idea what type " + str(t) + " is.")
+        # uint32 is sometimes int and sometimes double.
+        return "JSVAL_TYPE_DOUBLE"
+
+    @staticmethod
+    def getSingleReturnType(existingType, t):
+        type = CGMemberJITInfo.getJSReturnTypeTag(t)
+        if existingType == "":
+            # First element of the list; just return its type
+            return type
+
+        if type == existingType:
+            return existingType
+        if ((type == "JSVAL_TYPE_DOUBLE" and
+             existingType == "JSVAL_TYPE_INT32") or
+            (existingType == "JSVAL_TYPE_DOUBLE" and
+             type == "JSVAL_TYPE_INT32")):
+            # Promote INT32 to DOUBLE as needed
+            return "JSVAL_TYPE_DOUBLE"
+        # Different types
+        return "JSVAL_TYPE_UNKNOWN"
+
+    @staticmethod
+    def getJSArgType(t):
+        assert not t.isVoid()
+        if t.nullable():
+            # Sometimes it might return null, sometimes not
+            return "JSJitInfo::ArgType(JSJitInfo::Null | %s)" % CGMemberJITInfo.getJSArgType(t.inner)
+        if t.isSequence():
+            return "JSJitInfo::Object"
+        if t.isGeckoInterface():
+            return "JSJitInfo::Object"
+        if t.isString():
+            return "JSJitInfo::String"
+        if t.isEnum():
+            return "JSJitInfo::String"
+        if t.isCallback():
+            return "JSJitInfo::Object"
+        if t.isAny():
+            # The whole point is to return various stuff
+            return "JSJitInfo::Any"
+        if t.isObject():
+            return "JSJitInfo::Object"
+        if t.isSpiderMonkeyInterface():
+            return "JSJitInfo::Object"
+        if t.isUnion():
+            u = t.unroll()
+            type = "JSJitInfo::Null" if u.hasNullableType else ""
+            return ("JSJitInfo::ArgType(%s)" %
+                    reduce(CGMemberJITInfo.getSingleArgType,
+                           u.flatMemberTypes, type))
+        if t.isDictionary():
+            return "JSJitInfo::Object"
+        if t.isDate():
+            return "JSJitInfo::Object"
+        if not t.isPrimitive():
+            raise TypeError("No idea what type " + str(t) + " is.")
+        tag = t.tag()
+        if tag == IDLType.Tags.bool:
+            return "JSJitInfo::Boolean"
+        if tag in [IDLType.Tags.int8, IDLType.Tags.uint8,
+                   IDLType.Tags.int16, IDLType.Tags.uint16,
+                   IDLType.Tags.int32]:
+            return "JSJitInfo::Integer"
+        if tag in [IDLType.Tags.int64, IDLType.Tags.uint64,
+                   IDLType.Tags.unrestricted_float, IDLType.Tags.float,
+                   IDLType.Tags.unrestricted_double, IDLType.Tags.double]:
+            # These all use JS_NumberValue, which can return int or double.
+            # But TI treats "double" as meaning "int or double", so we're
+            # good to return JSVAL_TYPE_DOUBLE here.
+            return "JSJitInfo::Double"
+        if tag != IDLType.Tags.uint32:
+            raise TypeError("No idea what type " + str(t) + " is.")
+        # uint32 is sometimes int and sometimes double.
+        return "JSJitInfo::Double"
+
+    @staticmethod
+    def getSingleArgType(existingType, t):
+        type = CGMemberJITInfo.getJSArgType(t)
+        if existingType == "":
+            # First element of the list; just return its type
+            return type
+
+        if type == existingType:
+            return existingType
+        return "%s | %s" % (existingType, type)
+
+
+class CGStaticMethodJitinfo(CGGeneric):
+    """
+    A class for generating the JITInfo for a promise-returning static method.
+    """
+    def __init__(self, method):
+        CGGeneric.__init__(
+            self,
+            "\n"
+            "static const JSJitInfo %s_methodinfo = {\n"
+            "  { (JSJitGetterOp)%s },\n"
+            "  { prototypes::id::_ID_Count }, { 0 }, JSJitInfo::StaticMethod,\n"
+            "  JSJitInfo::AliasEverything, JSVAL_TYPE_MISSING, false, false,\n"
+            "  false, false, 0\n"
+            "};\n" %
+            (IDLToCIdentifier(method.identifier.name),
+             CppKeywords.checkMethodName(
+                 IDLToCIdentifier(method.identifier.name))))
+
+
+def getEnumValueName(value):
+    # Some enum values can be empty strings.  Others might have weird
+    # characters in them.  Deal with the former by returning "_empty",
+    # deal with possible name collisions from that by throwing if the
+    # enum value is actually "_empty", and throw on any value
+    # containing non-ASCII chars for now. Replace all chars other than
+    # [0-9A-Za-z_] with '_'.
+    if re.match("[^\x20-\x7E]", value):
+        raise SyntaxError('Enum value "' + value + '" contains non-ASCII characters')
+    if re.match("^[0-9]", value):
+        return '_' + value
+    value = re.sub(r'[^0-9A-Za-z_]', '_', value)
+    if re.match("^_[A-Z]|__", value):
+        raise SyntaxError('Enum value "' + value + '" is reserved by the C++ spec')
+    if value == "_empty":
+        raise SyntaxError('"_empty" is not an IDL enum value we support yet')
+    if value == "":
+        return "_empty"
+    nativeName = MakeNativeName(value)
+    if nativeName == "EndGuard_":
+        raise SyntaxError('Enum value "' + value + '" cannot be used because it'
+                          ' collides with our internal EndGuard_ value.  Please'
+                          ' rename our internal EndGuard_ to something else')
+    return nativeName
+
+class CGEnumToJSValue(CGAbstractMethod):
+    def __init__(self, enum):
+        enumType = enum.identifier.name
+        self.stringsArray = enumType + "Values::" + ENUM_ENTRY_VARIABLE_NAME
+        CGAbstractMethod.__init__(self, None, "ToJSValue", "bool",
+                                  [Argument("JSContext*", "aCx"),
+                                   Argument(enumType, "aArgument"),
+                                   Argument("JS::MutableHandle<JS::Value>",
+                                            "aValue")])
+
+    def definition_body(self):
+        return fill(
+            """
+            MOZ_ASSERT(uint32_t(aArgument) < ArrayLength(${strings}));
+            JSString* resultStr =
+              JS_NewStringCopyN(aCx, ${strings}[uint32_t(aArgument)].value,
+                                ${strings}[uint32_t(aArgument)].length);
+            if (!resultStr) {
+              return false;
+            }
+            aValue.setString(resultStr);
+            return true;
+            """,
+            strings=self.stringsArray)
+
+
+class CGEnum(CGThing):
+    def __init__(self, enum):
+        CGThing.__init__(self)
+        self.enum = enum
+        strings = CGNamespace(
+            self.stringsNamespace(),
+            CGGeneric(declare=("extern const EnumEntry %s[%d];\n" %
+                               (ENUM_ENTRY_VARIABLE_NAME, self.nEnumStrings())),
+                      define=fill(
+                          """
+                          extern const EnumEntry ${name}[${count}] = {
+                            $*{entries}
+                            { nullptr, 0 }
+                          };
+                          """,
+                          name=ENUM_ENTRY_VARIABLE_NAME,
+                          count=self.nEnumStrings(),
+                          entries=''.join('{"%s", %d},\n' % (val, len(val))
+                                          for val in self.enum.values()))))
+        toJSValue = CGEnumToJSValue(enum)
+        self.cgThings = CGList([strings, toJSValue], "\n")
+
+    def stringsNamespace(self):
+        return self.enum.identifier.name + "Values"
+
+    def nEnumStrings(self):
+        return len(self.enum.values()) + 1
+
+    def declare(self):
+        decl = fill(
+            """
+            enum class ${name} : uint32_t {
+              $*{enums}
+              EndGuard_
+            };
+            """,
+            name=self.enum.identifier.name,
+            enums=",\n".join(map(getEnumValueName, self.enum.values())) + ",\n")
+        strings = CGNamespace(self.stringsNamespace(),
+                              CGGeneric(declare="extern const EnumEntry %s[%d];\n"
+                                        % (ENUM_ENTRY_VARIABLE_NAME, self.nEnumStrings())))
+        return decl + "\n" + self.cgThings.declare()
+
+    def define(self):
+        return self.cgThings.define()
+
+    def deps(self):
+        return self.enum.getDeps()
+
+
+def getUnionAccessorSignatureType(type, descriptorProvider):
+    """
+    Returns the types that are used in the getter and setter signatures for
+    union types
+    """
+    # Flat member types have already unwrapped nullables.
+    assert not type.nullable()
+
+    if type.isSequence() or type.isMozMap():
+        if type.isSequence():
+            wrapperType = "Sequence"
+        else:
+            wrapperType = "MozMap"
+        # We don't use the returned template here, so it's OK to just pass no
+        # sourceDescription.
+        elementInfo = getJSToNativeConversionInfo(type.inner,
+                                                  descriptorProvider,
+                                                  isMember=wrapperType)
+        return CGTemplatedType(wrapperType, elementInfo.declType,
+                               isConst=True, isReference=True)
+
+    # Nested unions are unwrapped automatically into our flatMemberTypes.
+    assert not type.isUnion()
+
+    if type.isGeckoInterface():
+        descriptor = descriptorProvider.getDescriptor(
+            type.unroll().inner.identifier.name)
+        typeName = CGGeneric(descriptor.nativeType)
+        # Allow null pointers for old-binding classes.
+        if type.unroll().inner.isExternal():
+            typeName = CGWrapper(typeName, post="*")
+        else:
+            typeName = CGWrapper(typeName, post="&")
+        return typeName
+
+    if type.isSpiderMonkeyInterface():
+        typeName = CGGeneric(type.name)
+        return CGWrapper(typeName, post=" const &")
+
+    if type.isDOMString() or type.isUSVString():
+        return CGGeneric("const nsAString&")
+
+    if type.isByteString():
+        return CGGeneric("const nsCString&")
+
+    if type.isEnum():
+        return CGGeneric(type.inner.identifier.name)
+
+    if type.isCallback():
+        return CGGeneric("%s&" % type.unroll().callback.identifier.name)
+
+    if type.isAny():
+        return CGGeneric("JS::Value")
+
+    if type.isObject():
+        return CGGeneric("JSObject*")
+
+    if type.isDictionary():
+        return CGGeneric("const %s&" % type.inner.identifier.name)
+
+    if not type.isPrimitive():
+        raise TypeError("Need native type for argument type '%s'" % str(type))
+
+    return CGGeneric(builtinNames[type.tag()])
+
+
+def getUnionTypeTemplateVars(unionType, type, descriptorProvider,
+                             ownsMembers=False):
+    name = getUnionMemberName(type)
+    holderName = "m" + name + "Holder"
+
+    # By the time tryNextCode is invoked, we're guaranteed the union has been
+    # constructed as some type, since we've been trying to convert into the
+    # corresponding member.
+    prefix = "" if ownsMembers else "mUnion."
+    tryNextCode = ("$*{destroyHolder}\n"
+                   "%sDestroy%s();\n"
+                   "tryNext = true;\n"
+                   "return true;\n" % (prefix, name))
+
+    conversionInfo = getJSToNativeConversionInfo(
+        type, descriptorProvider, failureCode=tryNextCode,
+        isDefinitelyObject=not type.isDictionary(),
+        isMember=("OwningUnion" if ownsMembers else None),
+        sourceDescription="member of %s" % unionType)
+
+    if conversionInfo.holderType is not None:
+        assert not ownsMembers
+        destroyHolder = "%s.reset();\n" % holderName
+    else:
+        destroyHolder = ""
+
+    ctorNeedsCx = conversionInfo.declArgs == "cx"
+    ctorArgs = "cx" if ctorNeedsCx else ""
+
+    structType = conversionInfo.declType.define()
+    externalType = getUnionAccessorSignatureType(type, descriptorProvider).define()
+
+    if type.isObject():
+        if ownsMembers:
+            body = dedent("""
+                MOZ_ASSERT(mType == eUninitialized);
+                mValue.mObject.SetValue(obj);
+                mType = eObject;
+                """)
+        else:
+            body = dedent("""
+                MOZ_ASSERT(mUnion.mType == mUnion.eUninitialized);
+                mUnion.mValue.mObject.SetValue(cx, obj);
+                mUnion.mType = mUnion.eObject;
+                """)
+
+        # It's a bit sketchy to do the security check after setting the value,
+        # but it keeps the code cleaner and lets us avoid rooting |obj| over the
+        # call to CallerSubsumes().
+        body = body + dedent("""
+            if (passedToJSImpl && !CallerSubsumes(obj)) {
+              ThrowErrorMessage(cx, MSG_PERMISSION_DENIED_TO_PASS_ARG, "%s");
+              return false;
+            }
+            return true;
+            """)
+
+        setter = ClassMethod("SetToObject", "bool",
+                             [Argument("JSContext*", "cx"),
+                              Argument("JSObject*", "obj"),
+                              Argument("bool", "passedToJSImpl", default="false")],
+                             inline=True, bodyInHeader=True,
+                             body=body)
+
+    else:
+        # Important: we need to not have our declName involve
+        # maybe-GCing operations.
+        if conversionInfo.holderType is not None:
+            holderArgs = conversionInfo.holderArgs
+            if holderArgs is None:
+                holderArgs = ""
+            initHolder = "%s.emplace(%s);\n" % (holderName, holderArgs)
+        else:
+            initHolder = ""
+
+        jsConversion = fill(
+            initHolder + conversionInfo.template,
+            val="value",
+            maybeMutableVal="value",
+            declName="memberSlot",
+            holderName=(holderName if ownsMembers else "%s.ref()" % holderName),
+            destroyHolder=destroyHolder,
+            passedToJSImpl="passedToJSImpl")
+
+        jsConversion = fill(
+            """
+            tryNext = false;
+            { // scope for memberSlot
+              ${structType}& memberSlot = RawSetAs${name}(${ctorArgs});
+              $*{jsConversion}
+            }
+            return true;
+            """,
+            structType=structType,
+            name=name,
+            ctorArgs=ctorArgs,
+            jsConversion=jsConversion)
+
+        if ownsMembers:
+            handleType = "JS::Handle<JS::Value>"
+        else:
+            handleType = "JS::MutableHandle<JS::Value>"
+
+        setter = ClassMethod("TrySetTo" + name, "bool",
+                             [Argument("JSContext*", "cx"),
+                              Argument(handleType, "value"),
+                              Argument("bool&", "tryNext"),
+                              Argument("bool", "passedToJSImpl", default="false")],
+                             inline=not ownsMembers,
+                             bodyInHeader=not ownsMembers,
+                             body=jsConversion)
+
+    return {
+        "name": name,
+        "structType": structType,
+        "externalType": externalType,
+        "setter": setter,
+        "holderType": conversionInfo.holderType.define() if conversionInfo.holderType else None,
+        "ctorArgs": ctorArgs,
+        "ctorArgList": [Argument("JSContext*", "cx")] if ctorNeedsCx else []
+    }
+
+
+class CGUnionStruct(CGThing):
+    def __init__(self, type, descriptorProvider, ownsMembers=False):
+        CGThing.__init__(self)
+        self.type = type.unroll()
+        self.descriptorProvider = descriptorProvider
+        self.ownsMembers = ownsMembers
+        self.struct = self.getStruct()
+
+    def declare(self):
+        return self.struct.declare()
+
+    def define(self):
+        return self.struct.define()
+
+    def deps(self):
+        return self.type.getDeps()
+
+    def getStruct(self):
+
+        members = [ClassMember("mType", "Type", body="eUninitialized"),
+                   ClassMember("mValue", "Value")]
+        ctor = ClassConstructor([], bodyInHeader=True, visibility="public",
+                                explicit=True)
+
+        methods = []
+        enumValues = ["eUninitialized"]
+        toJSValCases = [CGCase("eUninitialized", CGGeneric("return false;\n"))]
+        destructorCases = [CGCase("eUninitialized", None)]
+        assignmentCases = [
+            CGCase("eUninitialized",
+                   CGGeneric('MOZ_ASSERT(mType == eUninitialized,\n'
+                             '           "We need to destroy ourselves?");\n'))]
+        traceCases = []
+        unionValues = []
+        if self.type.hasNullableType:
+            enumValues.append("eNull")
+            methods.append(ClassMethod("IsNull", "bool", [], const=True, inline=True,
+                                       body="return mType == eNull;\n",
+                                       bodyInHeader=True))
+            methods.append(ClassMethod("SetNull", "void", [], inline=True,
+                                       body=("Uninit();\n"
+                                             "mType = eNull;\n"),
+                                       bodyInHeader=True))
+            destructorCases.append(CGCase("eNull", None))
+            assignmentCases.append(CGCase("eNull",
+                                          CGGeneric("MOZ_ASSERT(mType == eUninitialized);\n"
+                                                    "mType = eNull;\n")))
+            toJSValCases.append(CGCase("eNull", CGGeneric("rval.setNull();\n"
+                                                          "return true;\n")))
+
+        hasObjectType = any(t.isObject() for t in self.type.flatMemberTypes)
+        for t in self.type.flatMemberTypes:
+            vars = getUnionTypeTemplateVars(self.type,
+                                            t, self.descriptorProvider,
+                                            ownsMembers=self.ownsMembers)
+            if vars["name"] != "Object" or self.ownsMembers:
+                body = fill(
+                    """
+                    if (mType == e${name}) {
+                      return mValue.m${name}.Value();
+                    }
+                    %s
+                    mType = e${name};
+                    return mValue.m${name}.SetValue(${ctorArgs});
+                    """,
+                    **vars)
+
+                # bodyInHeader must be false for return values because they own
+                # their union members and we don't want include headers in
+                # UnionTypes.h just to call Addref/Release
+                methods.append(ClassMethod(
+                    "RawSetAs" + vars["name"],
+                    vars["structType"] + "&",
+                    vars["ctorArgList"],
+                    bodyInHeader=not self.ownsMembers,
+                    body=body % "MOZ_ASSERT(mType == eUninitialized);"))
+                uninit = "Uninit();"
+                if hasObjectType and not self.ownsMembers:
+                    uninit = 'MOZ_ASSERT(mType != eObject, "This will not play well with Rooted");\n' + uninit
+                methods.append(ClassMethod(
+                    "SetAs" + vars["name"],
+                    vars["structType"] + "&",
+                    vars["ctorArgList"],
+                    bodyInHeader=not self.ownsMembers,
+                    body=body % uninit))
+                if self.ownsMembers:
+                    methods.append(vars["setter"])
+                    # Provide a SetStringData() method to support string defaults.
+                    if t.isByteString():
+                        methods.append(
+                            ClassMethod("SetStringData", "void",
+                                        [Argument("const nsCString::char_type*", "aData"),
+                                         Argument("nsCString::size_type", "aLength")],
+                                        inline=True, bodyInHeader=True,
+                                        body="RawSetAs%s().Assign(aData, aLength);\n" % t.name))
+                    elif t.isString():
+                        methods.append(
+                            ClassMethod("SetStringData", "void",
+                                        [Argument("const nsString::char_type*", "aData"),
+                                         Argument("nsString::size_type", "aLength")],
+                                        inline=True, bodyInHeader=True,
+                                        body="RawSetAs%s().Assign(aData, aLength);\n" % t.name))
+
+            body = fill(
+                """
+                MOZ_ASSERT(Is${name}(), "Wrong type!");
+                mValue.m${name}.Destroy();
+                mType = eUninitialized;
+                """,
+                **vars)
+            methods.append(ClassMethod("Destroy" + vars["name"],
+                                       "void",
+                                       [],
+                                       visibility="private",
+                                       bodyInHeader=not self.ownsMembers,
+                                       body=body))
+
+            body = fill("return mType == e${name};\n", **vars)
+            methods.append(ClassMethod("Is" + vars["name"],
+                                       "bool",
+                                       [],
+                                       const=True,
+                                       bodyInHeader=True,
+                                       body=body))
+
+            body = fill(
+                """
+                MOZ_ASSERT(Is${name}(), "Wrong type!");
+                return mValue.m${name}.Value();
+                """,
+                **vars)
+            # The non-const version of GetAs* returns our internal type
+            getterReturnType = "%s&" % vars["structType"]
+            methods.append(ClassMethod("GetAs" + vars["name"],
+                                       getterReturnType,
+                                       [],
+                                       bodyInHeader=True,
+                                       body=body))
+            # The const version of GetAs* returns our internal type
+            # for owning unions, but our external type for non-owning
+            # ones.
+            if self.ownsMembers:
+                getterReturnType = "%s const &" % vars["structType"]
+            else:
+                getterReturnType = vars["externalType"]
+            methods.append(ClassMethod("GetAs" + vars["name"],
+                                       getterReturnType,
+                                       [],
+                                       const=True,
+                                       bodyInHeader=True,
+                                       body=body))
+
+            unionValues.append(
+                fill("UnionMember<${structType} > m${name}", **vars))
+            enumValues.append("e" + vars["name"])
+
+            skipToJSVal = False
+            try:
+                toJSValCases.append(
+                    CGCase("e" + vars["name"],
+                           self.getConversionToJS(vars, t)))
+            except MethodNotNewObjectError:
+                # If we can't have a ToJSVal() because one of our members can
+                # only be returned from [NewObject] methods, then just skip
+                # generating ToJSVal.
+                skipToJSVal = True
+            destructorCases.append(
+                CGCase("e" + vars["name"],
+                       CGGeneric("Destroy%s();\n" % vars["name"])))
+            assignmentCases.append(
+                CGCase("e" + vars["name"],
+                       CGGeneric("SetAs%s() = aOther.GetAs%s();\n" %
+                                 (vars["name"], vars["name"]))))
+            if self.ownsMembers and typeNeedsRooting(t):
+                if t.isObject():
+                    traceCases.append(
+                        CGCase("e" + vars["name"],
+                               CGGeneric('JS::UnsafeTraceRoot(trc, %s, "%s");\n' %
+                                         ("&mValue.m" + vars["name"] + ".Value()",
+                                          "mValue.m" + vars["name"]))))
+                elif t.isDictionary():
+                    traceCases.append(
+                        CGCase("e" + vars["name"],
+                               CGGeneric("mValue.m%s.Value().TraceDictionary(trc);\n" %
+                                         vars["name"])))
+                elif t.isSequence():
+                    traceCases.append(
+                        CGCase("e" + vars["name"],
+                               CGGeneric("DoTraceSequence(trc, mValue.m%s.Value());\n" %
+                                         vars["name"])))
+                elif t.isMozMap():
+                    traceCases.append(
+                        CGCase("e" + vars["name"],
+                               CGGeneric("TraceMozMap(trc, mValue.m%s.Value());\n" %
+                                         vars["name"])))
+                else:
+                    assert t.isSpiderMonkeyInterface()
+                    traceCases.append(
+                        CGCase("e" + vars["name"],
+                               CGGeneric("mValue.m%s.Value().TraceSelf(trc);\n" %
+                                         vars["name"])))
+
+        dtor = CGSwitch("mType", destructorCases).define()
+
+        methods.append(ClassMethod("Uninit", "void", [],
+                                   visibility="public", body=dtor,
+                                   bodyInHeader=not self.ownsMembers,
+                                   inline=not self.ownsMembers))
+
+        if not skipToJSVal:
+            methods.append(
+                ClassMethod(
+                    "ToJSVal",
+                    "bool",
+                    [
+                        Argument("JSContext*", "cx"),
+                        Argument("JS::Handle<JSObject*>", "scopeObj"),
+                        Argument("JS::MutableHandle<JS::Value>", "rval")
+                    ],
+                    body=CGSwitch("mType", toJSValCases,
+                                  default=CGGeneric("return false;\n")).define() + "\nreturn false;\n",
+                    const=True))
+
+        constructors = [ctor]
+        selfName = CGUnionStruct.unionTypeName(self.type, self.ownsMembers)
+        if self.ownsMembers:
+            if traceCases:
+                traceBody = CGSwitch("mType", traceCases,
+                                     default=CGGeneric("")).define()
+            else:
+                traceBody = ""
+            methods.append(ClassMethod("TraceUnion", "void",
+                                       [Argument("JSTracer*", "trc")],
+                                       body=traceBody))
+            if CGUnionStruct.isUnionCopyConstructible(self.type):
+                constructors.append(
+                    ClassConstructor(
+                        [Argument("const %s&" % selfName, "aOther")],
+                        bodyInHeader=True,
+                        visibility="public",
+                        explicit=True,
+                        body="*this = aOther;\n"))
+                methods.append(ClassMethod(
+                    "operator=", "void",
+                    [Argument("const %s&" % selfName, "aOther")],
+                    body=CGSwitch("aOther.mType", assignmentCases).define()))
+                disallowCopyConstruction = False
+            else:
+                disallowCopyConstruction = True
+        else:
+            disallowCopyConstruction = True
+
+        if self.ownsMembers:
+            friend = "  friend void ImplCycleCollectionUnlink(%s& aUnion);\n" % CGUnionStruct.unionTypeName(self.type, True)
+        else:
+            friend = "  friend class %sArgument;\n" % str(self.type)
+
+        bases = [ClassBase("AllOwningUnionBase")] if self.ownsMembers else []
+        return CGClass(selfName,
+                       bases=bases,
+                       members=members,
+                       constructors=constructors,
+                       methods=methods,
+                       disallowCopyConstruction=disallowCopyConstruction,
+                       extradeclarations=friend,
+                       destructor=ClassDestructor(visibility="public",
+                                                  body="Uninit();\n",
+                                                  bodyInHeader=True),
+                       enums=[ClassEnum("Type", enumValues, visibility="private")],
+                       unions=[ClassUnion("Value", unionValues, visibility="private")])
+
+    def getConversionToJS(self, templateVars, type):
+        assert not type.nullable()  # flatMemberTypes never has nullable types
+        val = "mValue.m%(name)s.Value()" % templateVars
+        wrapCode = wrapForType(
+            type, self.descriptorProvider,
+            {
+                "jsvalRef": "rval",
+                "jsvalHandle": "rval",
+                "obj": "scopeObj",
+                "result": val,
+                "typedArraysAreStructs": True
+            })
+        return CGGeneric(wrapCode)
+
+    @staticmethod
+    def isUnionCopyConstructible(type):
+        return all(isTypeCopyConstructible(t) for t in type.flatMemberTypes)
+
+    @staticmethod
+    def unionTypeName(type, ownsMembers):
+        """
+        Returns a string name for this known union type.
+        """
+        assert type.isUnion() and not type.nullable()
+        return ("Owning" if ownsMembers else "") + type.name
+
+    @staticmethod
+    def unionTypeDecl(type, ownsMembers):
+        """
+        Returns a string for declaring this possibly-nullable union type.
+        """
+        assert type.isUnion()
+        nullable = type.nullable()
+        if nullable:
+            type = type.inner
+        decl = CGGeneric(CGUnionStruct.unionTypeName(type, ownsMembers))
+        if nullable:
+            decl = CGTemplatedType("Nullable", decl)
+        return decl.define()
+
+
+class CGUnionConversionStruct(CGThing):
+    def __init__(self, type, descriptorProvider):
+        CGThing.__init__(self)
+        self.type = type.unroll()
+        self.descriptorProvider = descriptorProvider
+
+    def declare(self):
+
+        structName = str(self.type)
+        members = [ClassMember("mUnion", structName + "&",
+                               body="const_cast<%s&>(aUnion)" % structName)]
+        # Argument needs to be a const ref because that's all Maybe<> allows
+        ctor = ClassConstructor([Argument("const %s&" % structName, "aUnion")],
+                                bodyInHeader=True,
+                                visibility="public",
+                                explicit=True)
+        methods = []
+
+        if self.type.hasNullableType:
+            methods.append(ClassMethod("SetNull", "bool", [],
+                                       body=("MOZ_ASSERT(mUnion.mType == mUnion.eUninitialized);\n"
+                                             "mUnion.mType = mUnion.eNull;\n"
+                                             "return true;\n"),
+                                       inline=True, bodyInHeader=True))
+
+        for t in self.type.flatMemberTypes:
+            vars = getUnionTypeTemplateVars(self.type,
+                                            t, self.descriptorProvider)
+            methods.append(vars["setter"])
+            if vars["name"] != "Object":
+                body = fill(
+                    """
+                    MOZ_ASSERT(mUnion.mType == mUnion.eUninitialized);
+                    mUnion.mType = mUnion.e${name};
+                    return mUnion.mValue.m${name}.SetValue(${ctorArgs});
+                    """,
+                    **vars)
+                methods.append(ClassMethod("RawSetAs" + vars["name"],
+                                           vars["structType"] + "&",
+                                           vars["ctorArgList"],
+                                           bodyInHeader=True,
+                                           body=body,
+                                           visibility="private"))
+                # Provide a SetStringData() method to support string defaults.
+                if t.isByteString():
+                    methods.append(
+                        ClassMethod("SetStringData", "void",
+                                    [Argument("const nsDependentCString::char_type*", "aData"),
+                                     Argument("nsDependentCString::size_type", "aLength")],
+                                    inline=True, bodyInHeader=True,
+                                    body="RawSetAs%s().Rebind(aData, aLength);\n" % t.name))
+                elif t.isString():
+                    methods.append(
+                        ClassMethod("SetStringData", "void",
+                                    [Argument("const nsDependentString::char_type*", "aData"),
+                                     Argument("nsDependentString::size_type", "aLength")],
+                                    inline=True, bodyInHeader=True,
+                                    body="RawSetAs%s().Rebind(aData, aLength);\n" % t.name))
+
+            if vars["holderType"] is not None:
+                holderType = CGTemplatedType("Maybe",
+                                             CGGeneric(vars["holderType"])).define()
+                members.append(ClassMember("m%sHolder" % vars["name"],
+                                           holderType))
+
+        return CGClass(structName + "Argument",
+                       members=members,
+                       constructors=[ctor],
+                       methods=methods,
+                       disallowCopyConstruction=True).declare()
+
+    def define(self):
+        return ""
+
+    def deps(self):
+        return set()
+
+
+class ClassItem:
+    """ Use with CGClass """
+    def __init__(self, name, visibility):
+        self.name = name
+        self.visibility = visibility
+
+    def declare(self, cgClass):
+        assert False
+
+    def define(self, cgClass):
+        assert False
+
+
+class ClassBase(ClassItem):
+    def __init__(self, name, visibility='public'):
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        return '%s %s' % (self.visibility, self.name)
+
+    def define(self, cgClass):
+        # Only in the header
+        return ''
+
+
+class ClassMethod(ClassItem):
+    def __init__(self, name, returnType, args, inline=False, static=False,
+                 virtual=False, const=False, bodyInHeader=False,
+                 templateArgs=None, visibility='public', body=None,
+                 breakAfterReturnDecl="\n",
+                 breakAfterSelf="\n", override=False):
+        """
+        override indicates whether to flag the method as override
+        """
+        assert not override or virtual
+        assert not (override and static)
+        self.returnType = returnType
+        self.args = args
+        self.inline = inline or bodyInHeader
+        self.static = static
+        self.virtual = virtual
+        self.const = const
+        self.bodyInHeader = bodyInHeader
+        self.templateArgs = templateArgs
+        self.body = body
+        self.breakAfterReturnDecl = breakAfterReturnDecl
+        self.breakAfterSelf = breakAfterSelf
+        self.override = override
+        ClassItem.__init__(self, name, visibility)
+
+    def getDecorators(self, declaring):
+        decorators = []
+        if self.inline:
+            decorators.append('inline')
+        if declaring:
+            if self.static:
+                decorators.append('static')
+            if self.virtual:
+                decorators.append('virtual')
+        if decorators:
+            return ' '.join(decorators) + ' '
+        return ''
+
+    def getBody(self):
+        # Override me or pass a string to constructor
+        assert self.body is not None
+        return self.body
+
+    def declare(self, cgClass):
+        templateClause = ('template <%s>\n' % ', '.join(self.templateArgs)
+                          if self.bodyInHeader and self.templateArgs else '')
+        args = ', '.join([a.declare() for a in self.args])
+        if self.bodyInHeader:
+            body = indent(self.getBody())
+            body = '\n{\n' + body + '}\n'
+        else:
+            body = ';\n'
+
+        return fill(
+            "${templateClause}${decorators}${returnType}${breakAfterReturnDecl}"
+            "${name}(${args})${const}${override}${body}"
+            "${breakAfterSelf}",
+            templateClause=templateClause,
+            decorators=self.getDecorators(True),
+            returnType=self.returnType,
+            breakAfterReturnDecl=self.breakAfterReturnDecl,
+            name=self.name,
+            args=args,
+            const=' const' if self.const else '',
+            override=' override' if self.override else '',
+            body=body,
+            breakAfterSelf=self.breakAfterSelf)
+
+    def define(self, cgClass):
+        if self.bodyInHeader:
+            return ''
+
+        templateArgs = cgClass.templateArgs
+        if templateArgs:
+            if cgClass.templateSpecialization:
+                templateArgs = \
+                    templateArgs[len(cgClass.templateSpecialization):]
+
+        if templateArgs:
+            templateClause = \
+                'template <%s>\n' % ', '.join([str(a) for a in templateArgs])
+        else:
+            templateClause = ''
+
+        return fill(
+            """
+            ${templateClause}${decorators}${returnType}
+            ${className}::${name}(${args})${const}
+            {
+              $*{body}
+            }
+            """,
+            templateClause=templateClause,
+            decorators=self.getDecorators(False),
+            returnType=self.returnType,
+            className=cgClass.getNameString(),
+            name=self.name,
+            args=', '.join([a.define() for a in self.args]),
+            const=' const' if self.const else '',
+            body=self.getBody())
+
+
+class ClassUsingDeclaration(ClassItem):
+    """
+    Used for importing a name from a base class into a CGClass
+
+    baseClass is the name of the base class to import the name from
+
+    name is the name to import
+
+    visibility determines the visibility of the name (public,
+    protected, private), defaults to public.
+    """
+    def __init__(self, baseClass, name, visibility='public'):
+        self.baseClass = baseClass
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        return "using %s::%s;\n\n" % (self.baseClass, self.name)
+
+    def define(self, cgClass):
+        return ''
+
+
+class ClassConstructor(ClassItem):
+    """
+    Used for adding a constructor to a CGClass.
+
+    args is a list of Argument objects that are the arguments taken by the
+    constructor.
+
+    inline should be True if the constructor should be marked inline.
+
+    bodyInHeader should be True if the body should be placed in the class
+    declaration in the header.
+
+    visibility determines the visibility of the constructor (public,
+    protected, private), defaults to private.
+
+    explicit should be True if the constructor should be marked explicit.
+
+    baseConstructors is a list of strings containing calls to base constructors,
+    defaults to None.
+
+    body contains a string with the code for the constructor, defaults to empty.
+    """
+    def __init__(self, args, inline=False, bodyInHeader=False,
+                 visibility="private", explicit=False, constexpr=False, baseConstructors=None,
+                 body=""):
+        assert not (inline and constexpr)
+        assert not (bodyInHeader and constexpr)
+        self.args = args
+        self.inline = inline or bodyInHeader
+        self.bodyInHeader = bodyInHeader or constexpr
+        self.explicit = explicit
+        self.constexpr = constexpr
+        self.baseConstructors = baseConstructors or []
+        self.body = body
+        ClassItem.__init__(self, None, visibility)
+
+    def getDecorators(self, declaring):
+        decorators = []
+        if self.explicit:
+            decorators.append('explicit')
+        if self.inline and declaring:
+            decorators.append('inline')
+        if self.constexpr and declaring:
+            decorators.append('constexpr')
+        if decorators:
+            return ' '.join(decorators) + ' '
+        return ''
+
+    def getInitializationList(self, cgClass):
+        items = [str(c) for c in self.baseConstructors]
+        for m in cgClass.members:
+            if not m.static:
+                initialize = m.body
+                if initialize:
+                    items.append(m.name + "(" + initialize + ")")
+
+        if len(items) > 0:
+            return '\n  : ' + ',\n    '.join(items)
+        return ''
+
+    def getBody(self):
+        return self.body
+
+    def declare(self, cgClass):
+        args = ', '.join([a.declare() for a in self.args])
+        if self.bodyInHeader:
+            body = self.getInitializationList(cgClass) + '\n{\n' + indent(self.getBody()) + '}\n'
+        else:
+            body = ';\n'
+
+        return fill(
+            "${decorators}${className}(${args})${body}\n",
+            decorators=self.getDecorators(True),
+            className=cgClass.getNameString(),
+            args=args,
+            body=body)
+
+    def define(self, cgClass):
+        if self.bodyInHeader:
+            return ''
+
+        return fill(
+            """
+            ${decorators}
+            ${className}::${className}(${args})${initializationList}
+            {
+              $*{body}
+            }
+            """,
+            decorators=self.getDecorators(False),
+            className=cgClass.getNameString(),
+            args=', '.join([a.define() for a in self.args]),
+            initializationList=self.getInitializationList(cgClass),
+            body=self.getBody())
+
+
+class ClassDestructor(ClassItem):
+    """
+    Used for adding a destructor to a CGClass.
+
+    inline should be True if the destructor should be marked inline.
+
+    bodyInHeader should be True if the body should be placed in the class
+    declaration in the header.
+
+    visibility determines the visibility of the destructor (public,
+    protected, private), defaults to private.
+
+    body contains a string with the code for the destructor, defaults to empty.
+
+    virtual determines whether the destructor is virtual, defaults to False.
+    """
+    def __init__(self, inline=False, bodyInHeader=False,
+                 visibility="private", body='', virtual=False):
+        self.inline = inline or bodyInHeader
+        self.bodyInHeader = bodyInHeader
+        self.body = body
+        self.virtual = virtual
+        ClassItem.__init__(self, None, visibility)
+
+    def getDecorators(self, declaring):
+        decorators = []
+        if self.virtual and declaring:
+            decorators.append('virtual')
+        if self.inline and declaring:
+            decorators.append('inline')
+        if decorators:
+            return ' '.join(decorators) + ' '
+        return ''
+
+    def getBody(self):
+        return self.body
+
+    def declare(self, cgClass):
+        if self.bodyInHeader:
+            body = '\n{\n' + indent(self.getBody()) + '}\n'
+        else:
+            body = ';\n'
+
+        return fill(
+            "${decorators}~${className}()${body}\n",
+            decorators=self.getDecorators(True),
+            className=cgClass.getNameString(),
+            body=body)
+
+    def define(self, cgClass):
+        if self.bodyInHeader:
+            return ''
+        return fill(
+            """
+            ${decorators}
+            ${className}::~${className}()
+            {
+              $*{body}
+            }
+            """,
+            decorators=self.getDecorators(False),
+            className=cgClass.getNameString(),
+            body=self.getBody())
+
+
+class ClassMember(ClassItem):
+    def __init__(self, name, type, visibility="private", static=False,
+                 body=None, hasIgnoreInitCheckFlag=False):
+        self.type = type
+        self.static = static
+        self.body = body
+        self.hasIgnoreInitCheckFlag = hasIgnoreInitCheckFlag;
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        return '%s%s%s %s;\n' % ('static ' if self.static else '',
+                                 'MOZ_INIT_OUTSIDE_CTOR '
+                                 if self.hasIgnoreInitCheckFlag else '',
+                                 self.type, self.name)
+
+    def define(self, cgClass):
+        if not self.static:
+            return ''
+        if self.body:
+            body = " = " + self.body
+        else:
+            body = ""
+        return '%s %s::%s%s;\n' % (self.type, cgClass.getNameString(),
+                                   self.name, body)
+
+
+class ClassTypedef(ClassItem):
+    def __init__(self, name, type, visibility="public"):
+        self.type = type
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        return 'typedef %s %s;\n' % (self.type, self.name)
+
+    def define(self, cgClass):
+        # Only goes in the header
+        return ''
+
+
+class ClassEnum(ClassItem):
+    def __init__(self, name, entries, values=None, visibility="public"):
+        self.entries = entries
+        self.values = values
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        entries = []
+        for i in range(0, len(self.entries)):
+            if not self.values or i >= len(self.values):
+                entry = '%s' % self.entries[i]
+            else:
+                entry = '%s = %s' % (self.entries[i], self.values[i])
+            entries.append(entry)
+        name = '' if not self.name else ' ' + self.name
+        return 'enum%s\n{\n%s\n};\n' % (name, indent(',\n'.join(entries)))
+
+    def define(self, cgClass):
+        # Only goes in the header
+        return ''
+
+
+class ClassUnion(ClassItem):
+    def __init__(self, name, entries, visibility="public"):
+        self.entries = [entry + ";\n" for entry in entries]
+        ClassItem.__init__(self, name, visibility)
+
+    def declare(self, cgClass):
+        return "union %s\n{\n%s\n};\n" % (self.name, indent(''.join(self.entries)))
+
+    def define(self, cgClass):
+        # Only goes in the header
+        return ''
+
+
+class CGClass(CGThing):
+    def __init__(self, name, bases=[], members=[], constructors=[],
+                 destructor=None, methods=[],
+                 typedefs=[], enums=[], unions=[], templateArgs=[],
+                 templateSpecialization=[], isStruct=False,
+                 disallowCopyConstruction=False, indent='',
+                 decorators='',
+                 extradeclarations='',
+                 extradefinitions=''):
+        CGThing.__init__(self)
+        self.name = name
+        self.bases = bases
+        self.members = members
+        self.constructors = constructors
+        # We store our single destructor in a list, since all of our
+        # code wants lists of members.
+        self.destructors = [destructor] if destructor else []
+        self.methods = methods
+        self.typedefs = typedefs
+        self.enums = enums
+        self.unions = unions
+        self.templateArgs = templateArgs
+        self.templateSpecialization = templateSpecialization
+        self.isStruct = isStruct
+        self.disallowCopyConstruction = disallowCopyConstruction
+        self.indent = indent
+        self.defaultVisibility = 'public' if isStruct else 'private'
+        self.decorators = decorators
+        self.extradeclarations = extradeclarations
+        self.extradefinitions = extradefinitions
+
+    def getNameString(self):
+        className = self.name
+        if self.templateSpecialization:
+            className += '<%s>' % ', '.join([str(a)
+                                             for a in self.templateSpecialization])
+        return className
+
+    def declare(self):
+        result = ''
+        if self.templateArgs:
+            templateArgs = [a.declare() for a in self.templateArgs]
+            templateArgs = templateArgs[len(self.templateSpecialization):]
+            result += ('template <%s>\n' %
+                       ','.join([str(a) for a in templateArgs]))
+
+        type = 'struct' if self.isStruct else 'class'
+
+        if self.templateSpecialization:
+            specialization = \
+                '<%s>' % ', '.join([str(a) for a in self.templateSpecialization])
+        else:
+            specialization = ''
+
+        myself = '%s %s%s' % (type, self.name, specialization)
+        if self.decorators != '':
+            myself += " " + self.decorators
+        result += myself
+
+        if self.bases:
+            inherit = ' : '
+            result += inherit
+            # Grab our first base
+            baseItems = [CGGeneric(b.declare(self)) for b in self.bases]
+            bases = baseItems[:1]
+            # Indent the rest
+            bases.extend(CGIndenter(b, len(myself) + len(inherit))
+                         for b in baseItems[1:])
+            result += ",\n".join(b.define() for b in bases)
+
+        result += '\n{\n'
+
+        result += self.extradeclarations
+
+        def declareMembers(cgClass, memberList, defaultVisibility):
+            members = {'private': [], 'protected': [], 'public': []}
+
+            for member in memberList:
+                members[member.visibility].append(member)
+
+            if defaultVisibility == 'public':
+                order = ['public', 'protected', 'private']
+            else:
+                order = ['private', 'protected', 'public']
+
+            result = ''
+
+            lastVisibility = defaultVisibility
+            for visibility in order:
+                list = members[visibility]
+                if list:
+                    if visibility != lastVisibility:
+                        result += visibility + ':\n'
+                    for member in list:
+                        result += indent(member.declare(cgClass))
+                    lastVisibility = visibility
+            return (result, lastVisibility)
+
+        if self.disallowCopyConstruction:
+            class DisallowedCopyConstructor(object):
+                def __init__(self):
+                    self.visibility = "private"
+
+                def declare(self, cgClass):
+                    name = cgClass.getNameString()
+                    return ("%s(const %s&) = delete;\n"
+                            "void operator=(const %s&) = delete;\n" % (name, name, name))
+
+            disallowedCopyConstructors = [DisallowedCopyConstructor()]
+        else:
+            disallowedCopyConstructors = []
+
+        order = [self.enums, self.unions,
+                 self.typedefs, self.members,
+                 self.constructors + disallowedCopyConstructors,
+                 self.destructors, self.methods]
+
+        lastVisibility = self.defaultVisibility
+        pieces = []
+        for memberList in order:
+            code, lastVisibility = declareMembers(self, memberList, lastVisibility)
+
+            if code:
+                code = code.rstrip() + "\n"  # remove extra blank lines at the end
+                pieces.append(code)
+
+        result += '\n'.join(pieces)
+        result += '};\n'
+        result = indent(result, len(self.indent))
+        return result
+
+    def define(self):
+        def defineMembers(cgClass, memberList, itemCount, separator=''):
+            result = ''
+            for member in memberList:
+                if itemCount != 0:
+                    result = result + separator
+                definition = member.define(cgClass)
+                if definition:
+                    # Member variables would only produce empty lines here.
+                    result += definition
+                    itemCount += 1
+            return (result, itemCount)
+
+        order = [(self.members, ''), (self.constructors, '\n'),
+                 (self.destructors, '\n'), (self.methods, '\n')]
+
+        result = self.extradefinitions
+        itemCount = 0
+        for memberList, separator in order:
+            memberString, itemCount = defineMembers(self, memberList,
+                                                    itemCount, separator)
+            result = result + memberString
+        return result
+
+
+class CGResolveOwnProperty(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'wrapper'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::MutableHandle<JS::PropertyDescriptor>', 'desc'),
+                ]
+        CGAbstractStaticMethod.__init__(self, descriptor, "ResolveOwnProperty",
+                                        "bool", args)
+
+    def definition_body(self):
+        return "return js::GetProxyHandler(obj)->getOwnPropertyDescriptor(cx, wrapper, id, desc);\n"
+
+
+class CGResolveOwnPropertyViaResolve(CGAbstractBindingMethod):
+    """
+    An implementation of Xray ResolveOwnProperty stuff for things that have a
+    resolve hook.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'wrapper'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::MutableHandle<JS::PropertyDescriptor>', 'desc')]
+        CGAbstractBindingMethod.__init__(self, descriptor,
+                                         "ResolveOwnPropertyViaResolve",
+                                         args, getThisObj="",
+                                         callArgs="")
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            {
+              // Since we're dealing with an Xray, do the resolve on the
+              // underlying object first.  That gives it a chance to
+              // define properties on the actual object as needed, and
+              // then use the fact that it created the objects as a flag
+              // to avoid re-resolving the properties if someone deletes
+              // them.
+              JSAutoCompartment ac(cx, obj);
+              JS::Rooted<JS::PropertyDescriptor> objDesc(cx);
+              if (!self->DoResolve(cx, obj, id, &objDesc)) {
+                return false;
+              }
+              // If desc.value() is undefined, then the DoResolve call
+              // has already defined the property on the object.  Don't
+              // try to also define it.
+              if (objDesc.object() &&
+                  !objDesc.value().isUndefined() &&
+                  !JS_DefinePropertyById(cx, obj, id, objDesc)) {
+                return false;
+              }
+            }
+            return self->DoResolve(cx, wrapper, id, desc);
+            """))
+
+
+class CGEnumerateOwnProperties(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'wrapper'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::AutoIdVector&', 'props')]
+        CGAbstractStaticMethod.__init__(self, descriptor,
+                                        "EnumerateOwnProperties", "bool", args)
+
+    def definition_body(self):
+        return "return js::GetProxyHandler(obj)->ownPropertyKeys(cx, wrapper, props);\n"
+
+
+class CGEnumerateOwnPropertiesViaGetOwnPropertyNames(CGAbstractBindingMethod):
+    """
+    An implementation of Xray EnumerateOwnProperties stuff for things
+    that have a resolve hook.
+    """
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'wrapper'),
+                Argument('JS::Handle<JSObject*>', 'obj'),
+                Argument('JS::AutoIdVector&', 'props')]
+        CGAbstractBindingMethod.__init__(self, descriptor,
+                                         "EnumerateOwnPropertiesViaGetOwnPropertyNames",
+                                         args, getThisObj="",
+                                         callArgs="")
+
+    def generate_code(self):
+        return CGGeneric(dedent("""
+            AutoTArray<nsString, 8> names;
+            binding_detail::FastErrorResult rv;
+            self->GetOwnPropertyNames(cx, names, rv);
+            if (rv.MaybeSetPendingException(cx)) {
+              return false;
+            }
+            // OK to pass null as "proxy" because it's ignored if
+            // shadowPrototypeProperties is true
+            return AppendNamedPropertyIds(cx, nullptr, names, true, props);
+            """))
+
+
+class CGPrototypeTraitsClass(CGClass):
+    def __init__(self, descriptor, indent=''):
+        templateArgs = [Argument('prototypes::ID', 'PrototypeID')]
+        templateSpecialization = ['prototypes::id::' + descriptor.name]
+        enums = [ClassEnum('', ['Depth'],
+                           [descriptor.interface.inheritanceDepth()])]
+        CGClass.__init__(self, 'PrototypeTraits', indent=indent,
+                         templateArgs=templateArgs,
+                         templateSpecialization=templateSpecialization,
+                         enums=enums, isStruct=True)
+
+    def deps(self):
+        return set()
+
+
+class CGClassForwardDeclare(CGThing):
+    def __init__(self, name, isStruct=False):
+        CGThing.__init__(self)
+        self.name = name
+        self.isStruct = isStruct
+
+    def declare(self):
+        type = 'struct' if self.isStruct else 'class'
+        return '%s %s;\n' % (type, self.name)
+
+    def define(self):
+        # Header only
+        return ''
+
+    def deps(self):
+        return set()
+
+
+class CGProxySpecialOperation(CGPerSignatureCall):
+    """
+    Base class for classes for calling an indexed or named special operation
+    (don't use this directly, use the derived classes below).
+
+    If checkFound is False, will just assert that the prop is found instead of
+    checking that it is before wrapping the value.
+
+    resultVar: See the docstring for CGCallGenerator.
+
+    foundVar: For getters and deleters, the generated code can also set a bool
+    variable, declared by the caller, if the given indexed or named property
+    already existed. If the caller wants this, it should pass the name of the
+    bool variable as the foundVar keyword argument to the constructor. The
+    caller is responsible for declaring the variable and initializing it to
+    false.
+    """
+    def __init__(self, descriptor, operation, checkFound=True,
+                 argumentHandleValue=None, resultVar=None, foundVar=None):
+        self.checkFound = checkFound
+        self.foundVar = foundVar or "found"
+
+        nativeName = MakeNativeName(descriptor.binaryNameFor(operation))
+        operation = descriptor.operations[operation]
+        assert len(operation.signatures()) == 1
+        signature = operation.signatures()[0]
+
+        returnType, arguments = signature
+
+        # We pass len(arguments) as the final argument so that the
+        # CGPerSignatureCall won't do any argument conversion of its own.
+        CGPerSignatureCall.__init__(self, returnType, arguments, nativeName,
+                                    False, descriptor, operation,
+                                    len(arguments), resultVar=resultVar)
+
+        if operation.isSetter() or operation.isCreator():
+            # arguments[0] is the index or name of the item that we're setting.
+            argument = arguments[1]
+            info = getJSToNativeConversionInfo(
+                argument.type, descriptor,
+                treatNullAs=argument.treatNullAs,
+                sourceDescription=("value being assigned to %s setter" %
+                                   descriptor.interface.identifier.name))
+            if argumentHandleValue is None:
+                argumentHandleValue = "desc.value()"
+            rootedValue = fill(
+                """
+                JS::Rooted<JS::Value> rootedValue(cx, ${argumentHandleValue});
+                """,
+                argumentHandleValue = argumentHandleValue)
+            templateValues = {
+                "declName": argument.identifier.name,
+                "holderName": argument.identifier.name + "_holder",
+                "val": argumentHandleValue,
+                "maybeMutableVal": "&rootedValue",
+                "obj": "obj",
+                "passedToJSImpl": "false"
+            }
+            self.cgRoot.prepend(instantiateJSToNativeConversion(info, templateValues))
+            # rootedValue needs to come before the conversion, so we
+            # need to prepend it last.
+            self.cgRoot.prepend(CGGeneric(rootedValue))
+        elif operation.isGetter() or operation.isDeleter():
+            if foundVar is None:
+                self.cgRoot.prepend(CGGeneric("bool found = false;\n"))
+
+    def getArguments(self):
+        args = [(a, a.identifier.name) for a in self.arguments]
+        if self.idlNode.isGetter() or self.idlNode.isDeleter():
+            args.append((FakeArgument(BuiltinTypes[IDLBuiltinType.Types.boolean],
+                                      self.idlNode),
+                         self.foundVar))
+        return args
+
+    def wrap_return_value(self):
+        if not self.idlNode.isGetter() or self.templateValues is None:
+            return ""
+
+        wrap = CGGeneric(wrapForType(self.returnType, self.descriptor, self.templateValues))
+        if self.checkFound:
+            wrap = CGIfWrapper(wrap, self.foundVar)
+        else:
+            wrap = CGList([CGGeneric("MOZ_ASSERT(" + self.foundVar + ");\n"), wrap])
+        return "\n" + wrap.define()
+
+
+class CGProxyIndexedOperation(CGProxySpecialOperation):
+    """
+    Class to generate a call to an indexed operation.
+
+    If doUnwrap is False, the caller is responsible for making sure a variable
+    named 'self' holds the C++ object somewhere where the code we generate
+    will see it.
+
+    If checkFound is False, will just assert that the prop is found instead of
+    checking that it is before wrapping the value.
+
+    resultVar: See the docstring for CGCallGenerator.
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, name, doUnwrap=True, checkFound=True,
+                 argumentHandleValue=None, resultVar=None, foundVar=None):
+        self.doUnwrap = doUnwrap
+        CGProxySpecialOperation.__init__(self, descriptor, name, checkFound,
+                                         argumentHandleValue=argumentHandleValue,
+                                         resultVar=resultVar,
+                                         foundVar=foundVar)
+
+    def define(self):
+        # Our first argument is the id we're getting.
+        argName = self.arguments[0].identifier.name
+        if argName == "index":
+            # We already have our index in a variable with that name
+            setIndex = ""
+        else:
+            setIndex = "uint32_t %s = index;\n" % argName
+        if self.doUnwrap:
+            unwrap = "%s* self = UnwrapProxy(proxy);\n" % self.descriptor.nativeType
+        else:
+            unwrap = ""
+        return (setIndex + unwrap +
+                CGProxySpecialOperation.define(self))
+
+
+class CGProxyIndexedGetter(CGProxyIndexedOperation):
+    """
+    Class to generate a call to an indexed getter. If templateValues is not None
+    the returned value will be wrapped with wrapForType using templateValues.
+
+    If doUnwrap is False, the caller is responsible for making sure a variable
+    named 'self' holds the C++ object somewhere where the code we generate
+    will see it.
+
+    If checkFound is False, will just assert that the prop is found instead of
+    checking that it is before wrapping the value.
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, templateValues=None, doUnwrap=True,
+                 checkFound=True, foundVar=None):
+        self.templateValues = templateValues
+        CGProxyIndexedOperation.__init__(self, descriptor, 'IndexedGetter',
+                                         doUnwrap, checkFound, foundVar=foundVar)
+
+
+class CGProxyIndexedPresenceChecker(CGProxyIndexedGetter):
+    """
+    Class to generate a call that checks whether an indexed property exists.
+
+    For now, we just delegate to CGProxyIndexedGetter
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, foundVar):
+        CGProxyIndexedGetter.__init__(self, descriptor, foundVar=foundVar)
+        self.cgRoot.append(CGGeneric("(void)result;\n"))
+
+
+class CGProxyIndexedSetter(CGProxyIndexedOperation):
+    """
+    Class to generate a call to an indexed setter.
+    """
+    def __init__(self, descriptor, argumentHandleValue=None):
+        CGProxyIndexedOperation.__init__(self, descriptor, 'IndexedSetter',
+                                         argumentHandleValue=argumentHandleValue)
+
+
+class CGProxyNamedOperation(CGProxySpecialOperation):
+    """
+    Class to generate a call to a named operation.
+
+    'value' is the jsval to use for the name; None indicates that it should be
+    gotten from the property id.
+
+    resultVar: See the docstring for CGCallGenerator.
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, name, value=None, argumentHandleValue=None,
+                 resultVar=None, foundVar=None):
+        CGProxySpecialOperation.__init__(self, descriptor, name,
+                                         argumentHandleValue=argumentHandleValue,
+                                         resultVar=resultVar,
+                                         foundVar=foundVar)
+        self.value = value
+
+    def define(self):
+        # Our first argument is the id we're getting.
+        argName = self.arguments[0].identifier.name
+        if argName == "id":
+            # deal with the name collision
+            decls = "JS::Rooted<jsid> id_(cx, id);\n"
+            idName = "id_"
+        else:
+            decls = ""
+            idName = "id"
+
+        decls += "binding_detail::FakeString %s;\n" % argName
+
+        main = fill(
+            """
+            ${nativeType}* self = UnwrapProxy(proxy);
+            $*{op}
+            """,
+            nativeType=self.descriptor.nativeType,
+            op=CGProxySpecialOperation.define(self))
+
+        if self.value is None:
+            return fill(
+                """
+                $*{decls}
+                bool isSymbol;
+                if (!ConvertIdToString(cx, ${idName}, ${argName}, isSymbol)) {
+                  return false;
+                }
+                if (!isSymbol) {
+                  $*{main}
+                }
+                """,
+                decls=decls,
+                idName=idName,
+                argName=argName,
+                main=main)
+
+        # Sadly, we have to set up nameVal even if we have an atom id,
+        # because we don't know for sure, and we can end up needing it
+        # so it needs to be higher up the stack.  Using a Maybe here
+        # seems like probable overkill.
+        return fill(
+            """
+            $*{decls}
+            JS::Rooted<JS::Value> nameVal(cx, ${value});
+            if (!nameVal.isSymbol()) {
+              if (!ConvertJSValueToString(cx, nameVal, eStringify, eStringify,
+                                          ${argName})) {
+                return false;
+              }
+              $*{main}
+            }
+            """,
+            decls=decls,
+            value=self.value,
+            argName=argName,
+            main=main)
+
+
+class CGProxyNamedGetter(CGProxyNamedOperation):
+    """
+    Class to generate a call to an named getter. If templateValues is not None
+    the returned value will be wrapped with wrapForType using templateValues.
+    'value' is the jsval to use for the name; None indicates that it should be
+    gotten from the property id.
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, templateValues=None, value=None,
+                 foundVar=None):
+        self.templateValues = templateValues
+        CGProxyNamedOperation.__init__(self, descriptor, 'NamedGetter', value,
+                                       foundVar=foundVar)
+
+
+class CGProxyNamedPresenceChecker(CGProxyNamedGetter):
+    """
+    Class to generate a call that checks whether a named property exists.
+
+    For now, we just delegate to CGProxyNamedGetter
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, foundVar=None):
+        CGProxyNamedGetter.__init__(self, descriptor, foundVar=foundVar)
+        self.cgRoot.append(CGGeneric("(void)result;\n"))
+
+
+class CGProxyNamedSetter(CGProxyNamedOperation):
+    """
+    Class to generate a call to a named setter.
+    """
+    def __init__(self, descriptor, argumentHandleValue=None):
+        CGProxyNamedOperation.__init__(self, descriptor, 'NamedSetter',
+                                       argumentHandleValue=argumentHandleValue)
+
+
+class CGProxyNamedDeleter(CGProxyNamedOperation):
+    """
+    Class to generate a call to a named deleter.
+
+    resultVar: See the docstring for CGCallGenerator.
+
+    foundVar: See the docstring for CGProxySpecialOperation.
+    """
+    def __init__(self, descriptor, resultVar=None, foundVar=None):
+        CGProxyNamedOperation.__init__(self, descriptor, 'NamedDeleter',
+                                       resultVar=resultVar,
+                                       foundVar=foundVar)
+
+
+class CGProxyIsProxy(CGAbstractMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSObject*', 'obj')]
+        CGAbstractMethod.__init__(self, descriptor, "IsProxy", "bool", args, alwaysInline=True)
+
+    def declare(self):
+        return ""
+
+    def definition_body(self):
+        return "return js::IsProxy(obj) && js::GetProxyHandler(obj) == DOMProxyHandler::getInstance();\n"
+
+
+class CGProxyUnwrap(CGAbstractMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSObject*', 'obj')]
+        CGAbstractMethod.__init__(self, descriptor, "UnwrapProxy", descriptor.nativeType + '*', args, alwaysInline=True)
+
+    def declare(self):
+        return ""
+
+    def definition_body(self):
+        return fill(
+            """
+            MOZ_ASSERT(js::IsProxy(obj));
+            if (js::GetProxyHandler(obj) != DOMProxyHandler::getInstance()) {
+              MOZ_ASSERT(xpc::WrapperFactory::IsXrayWrapper(obj));
+              obj = js::UncheckedUnwrap(obj);
+            }
+            MOZ_ASSERT(IsProxy(obj));
+            return static_cast<${type}*>(js::GetProxyPrivate(obj).toPrivate());
+            """,
+            type=self.descriptor.nativeType)
+
+
+class CGDOMJSProxyHandler_getOwnPropDescriptor(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('bool', 'ignoreNamedProps'),
+                Argument('JS::MutableHandle<JS::PropertyDescriptor>', 'desc')]
+        ClassMethod.__init__(self, "getOwnPropDescriptor", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        indexedGetter = self.descriptor.operations['IndexedGetter']
+        indexedSetter = self.descriptor.operations['IndexedSetter']
+
+        if self.descriptor.supportsIndexedProperties():
+            readonly = toStringBool(indexedSetter is None)
+            fillDescriptor = "FillPropertyDescriptor(desc, proxy, %s);\nreturn true;\n" % readonly
+            templateValues = {
+                'jsvalRef': 'desc.value()',
+                'jsvalHandle': 'desc.value()',
+                'obj': 'proxy',
+                'successCode': fillDescriptor
+            }
+            getIndexed = fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  $*{callGetter}
+                }
+
+                """,
+                callGetter=CGProxyIndexedGetter(self.descriptor, templateValues).define())
+        else:
+            getIndexed = ""
+
+        if self.descriptor.supportsNamedProperties():
+            operations = self.descriptor.operations
+            readonly = toStringBool(operations['NamedSetter'] is None)
+            fillDescriptor = (
+                "FillPropertyDescriptor(desc, proxy, %s, %s);\n"
+                "return true;\n" %
+                (readonly,
+                 toStringBool(self.descriptor.namedPropertiesEnumerable)))
+            templateValues = {'jsvalRef': 'desc.value()', 'jsvalHandle': 'desc.value()',
+                              'obj': 'proxy', 'successCode': fillDescriptor}
+
+            computeCondition = dedent("""
+                bool hasOnProto;
+                if (!HasPropertyOnPrototype(cx, proxy, id, &hasOnProto)) {
+                  return false;
+                }
+                callNamedGetter = !hasOnProto;
+                """)
+            if self.descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+                computeCondition = fill(
+                    """
+                    if (!isXray) {
+                      callNamedGetter = true;
+                    } else {
+                      $*{hasOnProto}
+                    }
+                    """,
+                    hasOnProto=computeCondition)
+
+            outerCondition = "!ignoreNamedProps"
+            if self.descriptor.supportsIndexedProperties():
+                outerCondition = "!IsArrayIndex(index) && " + outerCondition
+
+            namedGetCode = CGProxyNamedGetter(self.descriptor,
+                                              templateValues).define()
+            namedGet = fill("""
+                bool callNamedGetter = false;
+                if (${outerCondition}) {
+                  $*{computeCondition}
+                }
+                if (callNamedGetter) {
+                  $*{namedGetCode}
+                }
+                """,
+                            outerCondition=outerCondition,
+                            computeCondition=computeCondition,
+                            namedGetCode=namedGetCode)
+            namedGet += "\n"
+        else:
+            namedGet = ""
+
+        return fill(
+            """
+            bool isXray = xpc::WrapperFactory::IsXrayWrapper(proxy);
+            $*{getIndexed}
+            JS::Rooted<JSObject*> expando(cx);
+            if (!isXray && (expando = GetExpandoObject(proxy))) {
+              if (!JS_GetOwnPropertyDescriptorById(cx, expando, id, desc)) {
+                return false;
+              }
+              if (desc.object()) {
+                // Pretend the property lives on the wrapper.
+                desc.object().set(proxy);
+                return true;
+              }
+            }
+
+            $*{namedGet}
+            desc.object().set(nullptr);
+            return true;
+            """,
+            getIndexed=getIndexed,
+            namedGet=namedGet)
+
+
+class CGDOMJSProxyHandler_defineProperty(ClassMethod):
+    def __init__(self, descriptor):
+        # The usual convention is to name the ObjectOpResult out-parameter
+        # `result`, but that name is a bit overloaded around here.
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::Handle<JS::PropertyDescriptor>', 'desc'),
+                Argument('JS::ObjectOpResult&', 'opresult'),
+                Argument('bool*', 'defined')]
+        ClassMethod.__init__(self, "defineProperty", "bool", args, virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        set = ""
+
+        indexedSetter = self.descriptor.operations['IndexedSetter']
+        if indexedSetter:
+            if self.descriptor.operations['IndexedCreator'] is not indexedSetter:
+                raise TypeError("Can't handle creator that's different from the setter")
+            set += fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  *defined = true;
+                  $*{callSetter}
+                  return opresult.succeed();
+                }
+                """,
+                callSetter=CGProxyIndexedSetter(self.descriptor).define())
+        elif self.descriptor.supportsIndexedProperties():
+            # We allow untrusted content to prevent Xrays from setting a
+            # property if that property is an indexed property and we have no
+            # indexed setter.  That's how the object would normally behave if
+            # you tried to set the property on it.  That means we don't need to
+            # do anything special for Xrays here.
+            set += dedent(
+                """
+                if (IsArrayIndex(GetArrayIndexFromId(cx, id))) {
+                  *defined = true;
+                  return opresult.failNoIndexedSetter();
+                }
+                """)
+
+        namedSetter = self.descriptor.operations['NamedSetter']
+        if namedSetter:
+            if self.descriptor.hasUnforgeableMembers:
+                raise TypeError("Can't handle a named setter on an interface "
+                                "that has unforgeables.  Figure out how that "
+                                "should work!")
+            if self.descriptor.operations['NamedCreator'] is not namedSetter:
+                raise TypeError("Can't handle creator that's different from the setter")
+            # If we support indexed properties, we won't get down here for
+            # indices, so we can just do our setter unconditionally here.
+            set += fill(
+                """
+                *defined = true;
+                $*{callSetter}
+
+                return opresult.succeed();
+                """,
+                callSetter=CGProxyNamedSetter(self.descriptor).define())
+        else:
+            # We allow untrusted content to prevent Xrays from setting a
+            # property if that property is already a named property on the
+            # object and we have no named setter.  That's how the object would
+            # normally behave if you tried to set the property on it.  That
+            # means we don't need to do anything special for Xrays here.
+            if self.descriptor.supportsNamedProperties():
+                set += fill(
+                    """
+                    bool found = false;
+                    $*{presenceChecker}
+
+                    if (found) {
+                      *defined = true;
+                      return opresult.failNoNamedSetter();
+                    }
+                    """,
+                    presenceChecker=CGProxyNamedPresenceChecker(self.descriptor, foundVar="found").define())
+            set += ("return mozilla::dom::DOMProxyHandler::defineProperty(%s);\n" %
+                    ", ".join(a.name for a in self.args))
+        return set
+
+
+def getDeleterBody(descriptor, type, foundVar=None):
+    """
+    type should be "Named" or "Indexed"
+
+    The possible outcomes:
+    - an error happened                       (the emitted code returns false)
+    - own property not found                  (foundVar=false, deleteSucceeded=true)
+    - own property found and deleted          (foundVar=true,  deleteSucceeded=true)
+    - own property found but can't be deleted (foundVar=true,  deleteSucceeded=false)
+    """
+    assert type in ("Named", "Indexed")
+    deleter = descriptor.operations[type + 'Deleter']
+    if deleter:
+        assert type == "Named"
+        assert foundVar is not None
+        if descriptor.hasUnforgeableMembers:
+            raise TypeError("Can't handle a deleter on an interface "
+                            "that has unforgeables.  Figure out how "
+                            "that should work!")
+        # See if the deleter method is fallible.
+        t = deleter.signatures()[0][0]
+        if t.isPrimitive() and not t.nullable() and t.tag() == IDLType.Tags.bool:
+            # The deleter method has a boolean return value. When a
+            # property is found, the return value indicates whether it
+            # was successfully deleted.
+            setDS = fill(
+                """
+                if (!${foundVar}) {
+                  deleteSucceeded = true;
+                }
+                """,
+                foundVar=foundVar)
+        else:
+            # No boolean return value: if a property is found,
+            # deleting it always succeeds.
+            setDS = "deleteSucceeded = true;\n"
+
+        body = (CGProxyNamedDeleter(descriptor,
+                                    resultVar="deleteSucceeded",
+                                    foundVar=foundVar).define() +
+                setDS)
+    elif getattr(descriptor, "supports%sProperties" % type)():
+        presenceCheckerClass = globals()["CGProxy%sPresenceChecker" % type]
+        foundDecl = ""
+        if foundVar is None:
+            foundVar = "found"
+            foundDecl = "bool found = false;\n"
+        body = fill(
+            """
+            $*{foundDecl}
+            $*{presenceChecker}
+            deleteSucceeded = !${foundVar};
+            """,
+            foundDecl=foundDecl,
+            presenceChecker=presenceCheckerClass(descriptor, foundVar=foundVar).define(),
+            foundVar=foundVar)
+    else:
+        body = None
+    return body
+
+
+class CGDeleteNamedProperty(CGAbstractStaticMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'xray'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::ObjectOpResult&', 'opresult')]
+        CGAbstractStaticMethod.__init__(self, descriptor, "DeleteNamedProperty",
+                                        "bool", args)
+
+    def definition_body(self):
+        return fill(
+            """
+            MOZ_ASSERT(xpc::WrapperFactory::IsXrayWrapper(xray));
+            MOZ_ASSERT(js::IsProxy(proxy));
+            MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy));
+            JSAutoCompartment ac(cx, proxy);
+            bool deleteSucceeded;
+            bool found = false;
+            $*{namedBody}
+            if (!found || deleteSucceeded) {
+              return opresult.succeed();
+            }
+            return opresult.failCantDelete();
+            """,
+            namedBody=getDeleterBody(self.descriptor, "Named", foundVar="found"))
+
+
+class CGDOMJSProxyHandler_delete(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::ObjectOpResult&', 'opresult')]
+        ClassMethod.__init__(self, "delete_", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        delete = dedent("""
+            MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
+                      "Should not have a XrayWrapper here");
+
+            """)
+
+        indexedBody = getDeleterBody(self.descriptor, "Indexed")
+        if indexedBody is not None:
+            delete += fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  bool deleteSucceeded;
+                  $*{indexedBody}
+                  return deleteSucceeded ? opresult.succeed() : opresult.failCantDelete();
+                }
+                """,
+                indexedBody=indexedBody)
+
+        namedBody = getDeleterBody(self.descriptor, "Named", foundVar="found")
+        if namedBody is not None:
+            delete += dedent(
+                """
+                // Try named delete only if the named property visibility
+                // algorithm says the property is visible.
+                bool tryNamedDelete = true;
+                { // Scope for expando
+                  JS::Rooted<JSObject*> expando(cx, DOMProxyHandler::GetExpandoObject(proxy));
+                  if (expando) {
+                    bool hasProp;
+                    if (!JS_HasPropertyById(cx, expando, id, &hasProp)) {
+                      return false;
+                    }
+                    tryNamedDelete = !hasProp;
+                  }
+                }
+                """)
+
+            if not self.descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+                delete += dedent(
+                    """
+                    if (tryNamedDelete) {
+                      bool hasOnProto;
+                      if (!HasPropertyOnPrototype(cx, proxy, id, &hasOnProto)) {
+                        return false;
+                      }
+                      tryNamedDelete = !hasOnProto;
+                    }
+                    """)
+
+            # We always return above for an index id in the case when we support
+            # indexed properties, so we can just treat the id as a name
+            # unconditionally here.
+            delete += fill(
+                """
+                if (tryNamedDelete) {
+                  bool found = false;
+                  bool deleteSucceeded;
+                  $*{namedBody}
+                  if (found) {
+                    return deleteSucceeded ? opresult.succeed() : opresult.failCantDelete();
+                  }
+                }
+                """,
+                namedBody=namedBody)
+
+        delete += dedent("""
+
+            return dom::DOMProxyHandler::delete_(cx, proxy, id, opresult);
+            """)
+
+        return delete
+
+
+class CGDOMJSProxyHandler_ownPropNames(ClassMethod):
+    def __init__(self, descriptor, ):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('unsigned', 'flags'),
+                Argument('JS::AutoIdVector&', 'props')]
+        ClassMethod.__init__(self, "ownPropNames", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        # Per spec, we do indices, then named props, then everything else
+        if self.descriptor.supportsIndexedProperties():
+            addIndices = dedent("""
+
+                uint32_t length = UnwrapProxy(proxy)->Length();
+                MOZ_ASSERT(int32_t(length) >= 0);
+                for (int32_t i = 0; i < int32_t(length); ++i) {
+                  if (!props.append(INT_TO_JSID(i))) {
+                    return false;
+                  }
+                }
+                """)
+        else:
+            addIndices = ""
+
+        if self.descriptor.supportsNamedProperties():
+            if self.descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+                shadow = "!isXray"
+            else:
+                shadow = "false"
+            addNames = fill(
+                """
+                nsTArray<nsString> names;
+                UnwrapProxy(proxy)->GetSupportedNames(names);
+                if (!AppendNamedPropertyIds(cx, proxy, names, ${shadow}, props)) {
+                  return false;
+                }
+                """,
+                shadow=shadow)
+            if not self.descriptor.namedPropertiesEnumerable:
+                addNames = CGIfWrapper(CGGeneric(addNames),
+                                       "flags & JSITER_HIDDEN").define()
+            addNames = "\n" + addNames
+        else:
+            addNames = ""
+
+        return fill(
+            """
+            bool isXray = xpc::WrapperFactory::IsXrayWrapper(proxy);
+            $*{addIndices}
+            $*{addNames}
+
+            JS::Rooted<JSObject*> expando(cx);
+            if (!isXray && (expando = DOMProxyHandler::GetExpandoObject(proxy)) &&
+                !js::GetPropertyKeys(cx, expando, flags, &props)) {
+              return false;
+            }
+
+            return true;
+            """,
+            addIndices=addIndices,
+            addNames=addNames)
+
+
+class CGDOMJSProxyHandler_hasOwn(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('bool*', 'bp')]
+        ClassMethod.__init__(self, "hasOwn", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        if self.descriptor.supportsIndexedProperties():
+            indexed = fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  bool found = false;
+                  $*{presenceChecker}
+
+                  *bp = found;
+                  return true;
+                }
+
+                """,
+                presenceChecker=CGProxyIndexedPresenceChecker(self.descriptor, foundVar="found").define())
+        else:
+            indexed = ""
+
+        if self.descriptor.supportsNamedProperties():
+            # If we support indexed properties we always return above for index
+            # property names, so no need to check for those here.
+            named = fill(
+                """
+                bool found = false;
+                $*{presenceChecker}
+
+                *bp = found;
+                """,
+                presenceChecker=CGProxyNamedPresenceChecker(self.descriptor, foundVar="found").define())
+            if not self.descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+                named = fill(
+                    """
+                    bool hasOnProto;
+                    if (!HasPropertyOnPrototype(cx, proxy, id, &hasOnProto)) {
+                      return false;
+                    }
+                    if (!hasOnProto) {
+                      $*{protoLacksProperty}
+                      return true;
+                    }
+                    """,
+                    protoLacksProperty=named)
+                named += "*bp = false;\n"
+            else:
+                named += "\n"
+        else:
+            named = "*bp = false;\n"
+
+        return fill(
+            """
+            MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
+                      "Should not have a XrayWrapper here");
+
+            $*{indexed}
+
+            JS::Rooted<JSObject*> expando(cx, GetExpandoObject(proxy));
+            if (expando) {
+              bool b = true;
+              bool ok = JS_HasPropertyById(cx, expando, id, &b);
+              *bp = !!b;
+              if (!ok || *bp) {
+                return ok;
+              }
+            }
+
+            $*{named}
+            return true;
+            """,
+            indexed=indexed,
+            named=named)
+
+
+class CGDOMJSProxyHandler_get(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<JS::Value>', 'receiver'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::MutableHandle<JS::Value>', 'vp')]
+        ClassMethod.__init__(self, "get", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        getUnforgeableOrExpando = dedent("""
+            { // Scope for expando
+              JS::Rooted<JSObject*> expando(cx, DOMProxyHandler::GetExpandoObject(proxy));
+              if (expando) {
+                bool hasProp;
+                if (!JS_HasPropertyById(cx, expando, id, &hasProp)) {
+                  return false;
+                }
+
+                if (hasProp) {
+                  // Forward the get to the expando object, but our receiver is whatever our
+                  // receiver is.
+                  return JS_ForwardGetPropertyTo(cx, expando, id, receiver, vp);
+                }
+              }
+            }
+            """)
+
+        templateValues = {'jsvalRef': 'vp', 'jsvalHandle': 'vp', 'obj': 'proxy'}
+
+        if self.descriptor.supportsIndexedProperties():
+            getIndexedOrExpando = fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  $*{callGetter}
+                  // Even if we don't have this index, we don't forward the
+                  // get on to our expando object.
+                } else {
+                  $*{getUnforgeableOrExpando}
+                }
+                """,
+                callGetter=CGProxyIndexedGetter(self.descriptor, templateValues).define(),
+                getUnforgeableOrExpando=getUnforgeableOrExpando)
+        else:
+            getIndexedOrExpando = getUnforgeableOrExpando
+
+        if self.descriptor.supportsNamedProperties():
+            getNamed = CGProxyNamedGetter(self.descriptor, templateValues)
+            if self.descriptor.supportsIndexedProperties():
+                getNamed = CGIfWrapper(getNamed, "!IsArrayIndex(index)")
+            getNamed = getNamed.define() + "\n"
+        else:
+            getNamed = ""
+
+        getOnPrototype = dedent("""
+            bool foundOnPrototype;
+            if (!GetPropertyOnPrototype(cx, proxy, receiver, id, &foundOnPrototype, vp)) {
+              return false;
+            }
+
+            if (foundOnPrototype) {
+              return true;
+            }
+
+            """)
+        if self.descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+            getNamed = getNamed + getOnPrototype
+        else:
+            getNamed = getOnPrototype + getNamed
+
+        return fill(
+            """
+            MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
+                        "Should not have a XrayWrapper here");
+
+            $*{indexedOrExpando}
+
+            $*{named}
+            vp.setUndefined();
+            return true;
+            """,
+            indexedOrExpando=getIndexedOrExpando,
+            named=getNamed)
+
+
+class CGDOMJSProxyHandler_setCustom(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('JS::Handle<jsid>', 'id'),
+                Argument('JS::Handle<JS::Value>', 'v'),
+                Argument('bool*', 'done')]
+        ClassMethod.__init__(self, "setCustom", "bool", args, virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        assertion = ("MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),\n"
+                     '           "Should not have a XrayWrapper here");\n')
+
+        # Correctness first. If we have a NamedSetter and [OverrideBuiltins],
+        # always call the NamedSetter and never do anything else.
+        namedSetter = self.descriptor.operations['NamedSetter']
+        if (namedSetter is not None and
+            self.descriptor.interface.getExtendedAttribute('OverrideBuiltins')):
+            # Check assumptions.
+            if self.descriptor.supportsIndexedProperties():
+                raise ValueError("In interface " + self.descriptor.name + ": " +
+                                 "Can't cope with [OverrideBuiltins] and an indexed getter")
+            if self.descriptor.operations['NamedCreator'] is not namedSetter:
+                raise ValueError("In interface " + self.descriptor.name + ": " +
+                                 "Can't cope with named setter that is not also a named creator")
+            if self.descriptor.hasUnforgeableMembers:
+                raise ValueError("In interface " + self.descriptor.name + ": " +
+                                 "Can't cope with [OverrideBuiltins] and unforgeable members")
+
+            callSetter = CGProxyNamedSetter(self.descriptor, argumentHandleValue="v")
+            return (assertion +
+                    callSetter.define() +
+                    "*done = true;\n"
+                    "return true;\n")
+
+        # As an optimization, if we are going to call an IndexedSetter, go
+        # ahead and call it and have done.
+        indexedSetter = self.descriptor.operations['IndexedSetter']
+        if indexedSetter is not None:
+            if self.descriptor.operations['IndexedCreator'] is not indexedSetter:
+                raise ValueError("In interface " + self.descriptor.name + ": " +
+                                 "Can't cope with indexed setter that is not " +
+                                 "also an indexed creator")
+            setIndexed = fill(
+                """
+                uint32_t index = GetArrayIndexFromId(cx, id);
+                if (IsArrayIndex(index)) {
+                  $*{callSetter}
+                  *done = true;
+                  return true;
+                }
+
+                """,
+                callSetter=CGProxyIndexedSetter(self.descriptor,
+                                                argumentHandleValue="v").define())
+        else:
+            setIndexed = ""
+
+        return (assertion +
+                setIndexed +
+                "*done = false;\n"
+                "return true;\n")
+
+
+class CGDOMJSProxyHandler_className(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy')]
+        ClassMethod.__init__(self, "className", "const char*", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        return 'return "%s";\n' % self.descriptor.name
+
+
+class CGDOMJSProxyHandler_finalizeInBackground(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('const JS::Value&', 'priv')]
+        ClassMethod.__init__(self, "finalizeInBackground", "bool", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        return "return false;\n"
+
+
+class CGDOMJSProxyHandler_finalize(ClassMethod):
+    def __init__(self, descriptor):
+        args = [Argument('JSFreeOp*', 'fop'), Argument('JSObject*', 'proxy')]
+        ClassMethod.__init__(self, "finalize", "void", args,
+                             virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        return (("%s* self = UnwrapPossiblyNotInitializedDOMObject<%s>(proxy);\n" %
+                 (self.descriptor.nativeType, self.descriptor.nativeType)) +
+                finalizeHook(self.descriptor, FINALIZE_HOOK_NAME, self.args[0].name).define())
+
+
+class CGDOMJSProxyHandler_getElements(ClassMethod):
+    def __init__(self, descriptor):
+        assert descriptor.supportsIndexedProperties()
+
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('uint32_t', 'begin'),
+                Argument('uint32_t', 'end'),
+                Argument('js::ElementAdder*', 'adder')]
+        ClassMethod.__init__(self, "getElements", "bool", args, virtual=True, override=True, const=True)
+        self.descriptor = descriptor
+
+    def getBody(self):
+        # Just like ownPropertyKeys we'll assume that we have no holes, so
+        # we have all properties from 0 to length.  If that ever changes
+        # (unlikely), we'll need to do something a bit more clever with how we
+        # forward on to our ancestor.
+
+        templateValues = {
+            'jsvalRef': 'temp',
+            'jsvalHandle': '&temp',
+            'obj': 'proxy',
+            'successCode': ("if (!adder->append(cx, temp)) return false;\n"
+                            "continue;\n")
+        }
+        get = CGProxyIndexedGetter(self.descriptor, templateValues, False, False).define()
+
+        return fill(
+            """
+            JS::Rooted<JS::Value> temp(cx);
+            MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
+                       "Should not have a XrayWrapper here");
+
+            ${nativeType}* self = UnwrapProxy(proxy);
+            uint32_t length = self->Length();
+            // Compute the end of the indices we'll get ourselves
+            uint32_t ourEnd = std::max(begin, std::min(end, length));
+
+            for (uint32_t index = begin; index < ourEnd; ++index) {
+              $*{get}
+            }
+
+            if (end > ourEnd) {
+              JS::Rooted<JSObject*> proto(cx);
+              if (!js::GetObjectProto(cx, proxy, &proto)) {
+                return false;
+              }
+              return js::GetElementsWithAdder(cx, proto, proxy, ourEnd, end, adder);
+            }
+
+            return true;
+            """,
+            nativeType=self.descriptor.nativeType,
+            get=get)
+
+
+class CGDOMJSProxyHandler_getInstance(ClassMethod):
+    def __init__(self):
+        ClassMethod.__init__(self, "getInstance", "const DOMProxyHandler*", [], static=True)
+
+    def getBody(self):
+        return dedent("""
+            static const DOMProxyHandler instance;
+            return &instance;
+            """)
+
+
+class CGDOMJSProxyHandler_getPrototypeIfOrdinary(ClassMethod):
+    def __init__(self):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('bool*', 'isOrdinary'),
+                Argument('JS::MutableHandle<JSObject*>', 'proto')]
+
+        ClassMethod.__init__(self, "getPrototypeIfOrdinary", "bool", args,
+                             virtual=True, override=True, const=True)
+
+    def getBody(self):
+        return dedent("""
+            *isOrdinary = false;
+            return true;
+            """)
+
+
+class CGDOMJSProxyHandler_call(ClassMethod):
+    def __init__(self):
+        args = [Argument('JSContext*', 'cx'),
+                Argument('JS::Handle<JSObject*>', 'proxy'),
+                Argument('const JS::CallArgs&', 'args')]
+
+        ClassMethod.__init__(self, "call", "bool", args, virtual=True, override=True, const=True)
+
+    def getBody(self):
+        return fill(
+            """
+            return js::ForwardToNative(cx, ${legacyCaller}, args);
+            """,
+            legacyCaller=LEGACYCALLER_HOOK_NAME)
+
+
+class CGDOMJSProxyHandler_isCallable(ClassMethod):
+    def __init__(self):
+        ClassMethod.__init__(self, "isCallable", "bool",
+                             [Argument('JSObject*', 'obj')],
+                             virtual=True, override=True, const=True)
+
+    def getBody(self):
+        return dedent("""
+            return true;
+        """)
+
+
+class CGDOMJSProxyHandler(CGClass):
+    def __init__(self, descriptor):
+        assert (descriptor.supportsIndexedProperties() or
+                descriptor.supportsNamedProperties() or
+                descriptor.hasNonOrdinaryGetPrototypeOf())
+        methods = [CGDOMJSProxyHandler_getOwnPropDescriptor(descriptor),
+                   CGDOMJSProxyHandler_defineProperty(descriptor),
+                   ClassUsingDeclaration("mozilla::dom::DOMProxyHandler",
+                                         "defineProperty"),
+                   CGDOMJSProxyHandler_ownPropNames(descriptor),
+                   CGDOMJSProxyHandler_hasOwn(descriptor),
+                   CGDOMJSProxyHandler_get(descriptor),
+                   CGDOMJSProxyHandler_className(descriptor),
+                   CGDOMJSProxyHandler_finalizeInBackground(descriptor),
+                   CGDOMJSProxyHandler_finalize(descriptor),
+                   CGDOMJSProxyHandler_getInstance(),
+                   CGDOMJSProxyHandler_delete(descriptor)]
+        constructors = [
+            ClassConstructor(
+                [],
+                constexpr=True,
+                visibility="public",
+                explicit=True)
+        ]
+
+        if descriptor.supportsIndexedProperties():
+            methods.append(CGDOMJSProxyHandler_getElements(descriptor))
+        if (descriptor.operations['IndexedSetter'] is not None or
+            (descriptor.operations['NamedSetter'] is not None and
+             descriptor.interface.getExtendedAttribute('OverrideBuiltins'))):
+            methods.append(CGDOMJSProxyHandler_setCustom(descriptor))
+        if descriptor.hasNonOrdinaryGetPrototypeOf():
+            methods.append(CGDOMJSProxyHandler_getPrototypeIfOrdinary())
+        if descriptor.operations['LegacyCaller']:
+            methods.append(CGDOMJSProxyHandler_call())
+            methods.append(CGDOMJSProxyHandler_isCallable())
+
+        if descriptor.interface.getExtendedAttribute('OverrideBuiltins'):
+            parentClass = 'ShadowingDOMProxyHandler'
+        else:
+            parentClass = 'mozilla::dom::DOMProxyHandler'
+
+        CGClass.__init__(self, 'DOMProxyHandler',
+                         bases=[ClassBase(parentClass)],
+                         constructors=constructors,
+                         methods=methods)
+
+
+class CGDOMJSProxyHandlerDeclarer(CGThing):
+    """
+    A class for declaring a DOMProxyHandler.
+    """
+    def __init__(self, handlerThing):
+        self.handlerThing = handlerThing
+
+    def declare(self):
+        # Our class declaration should happen when we're defining
+        return ""
+
+    def define(self):
+        return self.handlerThing.declare()
+
+
+class CGDOMJSProxyHandlerDefiner(CGThing):
+    """
+    A class for defining a DOMProxyHandler.
+    """
+    def __init__(self, handlerThing):
+        self.handlerThing = handlerThing
+
+    def declare(self):
+        return ""
+
+    def define(self):
+        return self.handlerThing.define()
+
+
+def stripTrailingWhitespace(text):
+    tail = '\n' if text.endswith('\n') else ''
+    lines = text.splitlines()
+    return '\n'.join(line.rstrip() for line in lines) + tail
+
+
+class MemberProperties:
+    def __init__(self):
+        self.isGenericMethod = False
+        self.isCrossOriginMethod = False
+        self.isPromiseReturningMethod = False
+        self.isGenericGetter = False
+        self.isLenientGetter = False
+        self.isCrossOriginGetter = False
+        self.isGenericSetter = False
+        self.isLenientSetter = False
+        self.isCrossOriginSetter = False
+        self.isJsonifier = False
+
+
+def memberProperties(m, descriptor):
+    props = MemberProperties()
+    if m.isMethod():
+        if m == descriptor.operations['Jsonifier']:
+            props.isGenericMethod = descriptor.needsSpecialGenericOps()
+            props.isJsonifier = True
+        elif (not m.isIdentifierLess() or m == descriptor.operations['Stringifier']):
+            if not m.isStatic() and descriptor.interface.hasInterfacePrototypeObject():
+                if descriptor.needsSpecialGenericOps():
+                    if m.returnsPromise():
+                        props.isPromiseReturningMethod = True
+                    else:
+                        props.isGenericMethod = True
+                if m.getExtendedAttribute("CrossOriginCallable"):
+                    props.isCrossOriginMethod = True
+    elif m.isAttr():
+        if not m.isStatic() and descriptor.interface.hasInterfacePrototypeObject():
+            if m.hasLenientThis():
+                props.isLenientGetter = True
+            elif m.getExtendedAttribute("CrossOriginReadable"):
+                props.isCrossOriginGetter = True
+            elif descriptor.needsSpecialGenericOps():
+                props.isGenericGetter = True
+        if not m.readonly:
+            if not m.isStatic() and descriptor.interface.hasInterfacePrototypeObject():
+                if m.hasLenientThis():
+                    props.isLenientSetter = True
+                elif IsCrossOriginWritable(m, descriptor):
+                    props.isCrossOriginSetter = True
+                elif descriptor.needsSpecialGenericOps():
+                    props.isGenericSetter = True
+        elif m.getExtendedAttribute("PutForwards"):
+            if IsCrossOriginWritable(m, descriptor):
+                props.isCrossOriginSetter = True
+            elif descriptor.needsSpecialGenericOps():
+                props.isGenericSetter = True
+        elif (m.getExtendedAttribute("Replaceable") or
+              m.getExtendedAttribute("LenientSetter")):
+            if descriptor.needsSpecialGenericOps():
+                props.isGenericSetter = True
+
+    return props
+
+
+class CGDescriptor(CGThing):
+    def __init__(self, descriptor):
+        CGThing.__init__(self)
+
+        assert not descriptor.concrete or descriptor.interface.hasInterfacePrototypeObject()
+
+        self._deps = descriptor.interface.getDeps()
+
+        cgThings = []
+        cgThings.append(CGGeneric(declare="typedef %s NativeType;\n" %
+                                  descriptor.nativeType))
+        parent = descriptor.interface.parent
+        if parent:
+            cgThings.append(CGGeneric("static_assert(IsRefcounted<NativeType>::value == IsRefcounted<%s::NativeType>::value,\n"
+                                      "              \"Can't inherit from an interface with a different ownership model.\");\n" %
+                                      toBindingNamespace(descriptor.parentPrototypeName)))
+
+        # These are set to true if at least one non-static
+        # method/getter/setter or jsonifier exist on the interface.
+        (hasMethod, hasGetter, hasLenientGetter, hasSetter, hasLenientSetter,
+            hasPromiseReturningMethod) = False, False, False, False, False, False
+        jsonifierMethod = None
+        crossOriginMethods, crossOriginGetters, crossOriginSetters = set(), set(), set()
+        unscopableNames = list()
+        for n in descriptor.interface.namedConstructors:
+            cgThings.append(CGClassConstructor(descriptor, n,
+                                               NamedConstructorName(n)))
+        for m in descriptor.interface.members:
+            if m.isMethod() and m.identifier.name == 'queryInterface':
+                continue
+
+            props = memberProperties(m, descriptor)
+
+            if m.isMethod():
+                if m.getExtendedAttribute("Unscopable"):
+                    assert not m.isStatic()
+                    unscopableNames.append(m.identifier.name)
+                if props.isJsonifier:
+                    jsonifierMethod = m
+                elif not m.isIdentifierLess() or m == descriptor.operations['Stringifier']:
+                    if m.isStatic():
+                        assert descriptor.interface.hasInterfaceObject()
+                        cgThings.append(CGStaticMethod(descriptor, m))
+                        if m.returnsPromise():
+                            cgThings.append(CGStaticMethodJitinfo(m))
+                    elif descriptor.interface.hasInterfacePrototypeObject():
+                        specializedMethod = CGSpecializedMethod(descriptor, m)
+                        cgThings.append(specializedMethod)
+                        if m.returnsPromise():
+                            cgThings.append(CGMethodPromiseWrapper(descriptor, specializedMethod))
+                        cgThings.append(CGMemberJITInfo(descriptor, m))
+                        if props.isCrossOriginMethod:
+                            crossOriginMethods.add(m.identifier.name)
+            # If we've hit the maplike/setlike member itself, go ahead and
+            # generate its convenience functions.
+            elif m.isMaplikeOrSetlike():
+                cgThings.append(CGMaplikeOrSetlikeHelperGenerator(descriptor, m))
+            elif m.isAttr():
+                if m.stringifier:
+                    raise TypeError("Stringifier attributes not supported yet. "
+                                    "See bug 824857.\n"
+                                    "%s" % m.location)
+                if m.getExtendedAttribute("Unscopable"):
+                    assert not m.isStatic()
+                    unscopableNames.append(m.identifier.name)
+                if m.isStatic():
+                    assert descriptor.interface.hasInterfaceObject()
+                    cgThings.append(CGStaticGetter(descriptor, m))
+                elif descriptor.interface.hasInterfacePrototypeObject():
+                    if isNonExposedNavigatorObjectGetter(m, descriptor):
+                        continue
+                    cgThings.append(CGSpecializedGetter(descriptor, m))
+                    if props.isCrossOriginGetter:
+                        crossOriginGetters.add(m.identifier.name)
+                if not m.readonly:
+                    if m.isStatic():
+                        assert descriptor.interface.hasInterfaceObject()
+                        cgThings.append(CGStaticSetter(descriptor, m))
+                    elif descriptor.interface.hasInterfacePrototypeObject():
+                        cgThings.append(CGSpecializedSetter(descriptor, m))
+                        if props.isCrossOriginSetter:
+                            crossOriginSetters.add(m.identifier.name)
+                elif m.getExtendedAttribute("PutForwards"):
+                    cgThings.append(CGSpecializedForwardingSetter(descriptor, m))
+                    if props.isCrossOriginSetter:
+                        crossOriginSetters.add(m.identifier.name)
+                elif m.getExtendedAttribute("Replaceable"):
+                    cgThings.append(CGSpecializedReplaceableSetter(descriptor, m))
+                elif m.getExtendedAttribute("LenientSetter"):
+                    cgThings.append(CGSpecializedLenientSetter(descriptor, m))
+                if (not m.isStatic() and
+                    descriptor.interface.hasInterfacePrototypeObject()):
+                    cgThings.append(CGMemberJITInfo(descriptor, m))
+
+            hasMethod = hasMethod or props.isGenericMethod
+            hasPromiseReturningMethod = (hasPromiseReturningMethod or
+                                         props.isPromiseReturningMethod)
+            hasGetter = hasGetter or props.isGenericGetter
+            hasLenientGetter = hasLenientGetter or props.isLenientGetter
+            hasSetter = hasSetter or props.isGenericSetter
+            hasLenientSetter = hasLenientSetter or props.isLenientSetter
+
+        if jsonifierMethod:
+            cgThings.append(CGJsonifyAttributesMethod(descriptor))
+            cgThings.append(CGJsonifierMethod(descriptor, jsonifierMethod))
+            cgThings.append(CGMemberJITInfo(descriptor, jsonifierMethod))
+        if hasMethod:
+            cgThings.append(CGGenericMethod(descriptor))
+        if hasPromiseReturningMethod:
+            cgThings.append(CGGenericPromiseReturningMethod(descriptor))
+        if len(crossOriginMethods):
+            cgThings.append(CGGenericMethod(descriptor,
+                                            allowCrossOriginThis=True))
+        if hasGetter:
+            cgThings.append(CGGenericGetter(descriptor))
+        if hasLenientGetter:
+            cgThings.append(CGGenericGetter(descriptor, lenientThis=True))
+        if len(crossOriginGetters):
+            cgThings.append(CGGenericGetter(descriptor,
+                                            allowCrossOriginThis=True))
+        if hasSetter:
+            cgThings.append(CGGenericSetter(descriptor))
+        if hasLenientSetter:
+            cgThings.append(CGGenericSetter(descriptor, lenientThis=True))
+        if len(crossOriginSetters):
+            cgThings.append(CGGenericSetter(descriptor,
+                                            allowCrossOriginThis=True))
+
+        if descriptor.interface.isNavigatorProperty():
+            cgThings.append(CGConstructNavigatorObject(descriptor))
+
+        if descriptor.concrete and not descriptor.proxy:
+            if wantsAddProperty(descriptor):
+                cgThings.append(CGAddPropertyHook(descriptor))
+
+            # Always have a finalize hook, regardless of whether the class
+            # wants a custom hook.
+            cgThings.append(CGClassFinalizeHook(descriptor))
+
+        if descriptor.concrete and descriptor.wrapperCache:
+            cgThings.append(CGClassObjectMovedHook(descriptor))
+
+        # Generate the _ClearCachedFooValue methods before the property arrays that use them.
+        if descriptor.interface.isJSImplemented():
+            for m in clearableCachedAttrs(descriptor):
+                cgThings.append(CGJSImplClearCachedValueMethod(descriptor, m))
+
+        # Need to output our generated hasinstance bits before
+        # PropertyArrays tries to use them.
+        if (descriptor.interface.hasInterfaceObject() and
+            NeedsGeneratedHasInstance(descriptor)):
+            cgThings.append(CGHasInstanceHook(descriptor))
+
+        properties = PropertyArrays(descriptor)
+        cgThings.append(CGGeneric(define=str(properties)))
+        cgThings.append(CGNativeProperties(descriptor, properties))
+
+        if descriptor.interface.hasInterfaceObject():
+            cgThings.append(CGClassConstructor(descriptor,
+                                               descriptor.interface.ctor()))
+            cgThings.append(CGInterfaceObjectJSClass(descriptor, properties))
+            cgThings.append(CGNamedConstructors(descriptor))
+
+        cgThings.append(CGLegacyCallHook(descriptor))
+        if descriptor.interface.getExtendedAttribute("NeedResolve"):
+            cgThings.append(CGResolveHook(descriptor))
+            cgThings.append(CGMayResolveHook(descriptor))
+            cgThings.append(CGEnumerateHook(descriptor))
+
+        if descriptor.hasNamedPropertiesObject:
+            cgThings.append(CGGetNamedPropertiesObjectMethod(descriptor))
+
+        if descriptor.interface.hasInterfacePrototypeObject():
+            cgThings.append(CGPrototypeJSClass(descriptor, properties))
+
+        if ((descriptor.interface.hasInterfaceObject() or descriptor.interface.isNavigatorProperty()) and
+            not descriptor.interface.isExternal() and
+            descriptor.isExposedConditionally()):
+            cgThings.append(CGConstructorEnabled(descriptor))
+
+        if descriptor.registersGlobalNamesOnWindow:
+            cgThings.append(CGDefineDOMInterfaceMethod(descriptor))
+
+        if (descriptor.interface.hasMembersInSlots() and
+            descriptor.interface.hasChildInterfaces()):
+            raise TypeError("We don't support members in slots on "
+                            "non-leaf interfaces like %s" %
+                            descriptor.interface.identifier.name)
+
+        if descriptor.concrete:
+            if descriptor.proxy:
+                if descriptor.interface.totalMembersInSlots != 0:
+                    raise TypeError("We can't have extra reserved slots for "
+                                    "proxy interface %s" %
+                                    descriptor.interface.identifier.name)
+                cgThings.append(CGGeneric(fill(
+                    """
+                    static_assert(IsBaseOf<nsISupports, ${nativeType} >::value,
+                                      "We don't support non-nsISupports native classes for "
+                                      "proxy-based bindings yet");
+
+                    """,
+                    nativeType=descriptor.nativeType)))
+                if not descriptor.wrapperCache:
+                    raise TypeError("We need a wrappercache to support expandos for proxy-based "
+                                    "bindings (" + descriptor.name + ")")
+                handlerThing = CGDOMJSProxyHandler(descriptor)
+                cgThings.append(CGDOMJSProxyHandlerDeclarer(handlerThing))
+                cgThings.append(CGProxyIsProxy(descriptor))
+                cgThings.append(CGProxyUnwrap(descriptor))
+                cgThings.append(CGDOMJSProxyHandlerDefiner(handlerThing))
+                cgThings.append(CGDOMProxyJSClass(descriptor))
+            else:
+                cgThings.append(CGDOMJSClass(descriptor))
+                cgThings.append(CGGetJSClassMethod(descriptor))
+                if descriptor.interface.hasMembersInSlots():
+                    cgThings.append(CGUpdateMemberSlotsMethod(descriptor))
+
+            if descriptor.isGlobal():
+                assert descriptor.wrapperCache
+                cgThings.append(CGWrapGlobalMethod(descriptor, properties))
+            elif descriptor.wrapperCache:
+                cgThings.append(CGWrapWithCacheMethod(descriptor, properties))
+                cgThings.append(CGWrapMethod(descriptor))
+            else:
+                cgThings.append(CGWrapNonWrapperCacheMethod(descriptor,
+                                                            properties))
+
+        # Set up our Xray callbacks as needed.  This needs to come
+        # after we have our DOMProxyHandler defined.
+        if descriptor.wantsXrays:
+            if descriptor.concrete and descriptor.proxy:
+                cgThings.append(CGResolveOwnProperty(descriptor))
+                cgThings.append(CGEnumerateOwnProperties(descriptor))
+                if descriptor.needsXrayNamedDeleterHook():
+                    cgThings.append(CGDeleteNamedProperty(descriptor))
+            elif descriptor.needsXrayResolveHooks():
+                cgThings.append(CGResolveOwnPropertyViaResolve(descriptor))
+                cgThings.append(CGEnumerateOwnPropertiesViaGetOwnPropertyNames(descriptor))
+            if descriptor.wantsXrayExpandoClass:
+                cgThings.append(CGXrayExpandoJSClass(descriptor))
+
+        # Now that we have our ResolveOwnProperty/EnumerateOwnProperties stuff
+        # done, set up our NativePropertyHooks.
+        cgThings.append(CGNativePropertyHooks(descriptor, properties))
+
+        # If we're not wrappercached, we don't know how to clear our
+        # cached values, since we can't get at the JSObject.
+        if descriptor.wrapperCache:
+            cgThings.extend(CGClearCachedValueMethod(descriptor, m) for
+                            m in clearableCachedAttrs(descriptor))
+
+        haveUnscopables = (len(unscopableNames) != 0 and
+                           descriptor.interface.hasInterfacePrototypeObject())
+        if haveUnscopables:
+            cgThings.append(
+                CGList([CGGeneric("static const char* const unscopableNames[] = {"),
+                        CGIndenter(CGList([CGGeneric('"%s"' % name) for
+                                           name in unscopableNames] +
+                                          [CGGeneric("nullptr")], ",\n")),
+                        CGGeneric("};\n")], "\n"))
+
+        # CGCreateInterfaceObjectsMethod needs to come after our
+        # CGDOMJSClass and unscopables, if any.
+        cgThings.append(CGCreateInterfaceObjectsMethod(descriptor, properties,
+                                                       haveUnscopables))
+
+        # CGGetProtoObjectMethod and CGGetConstructorObjectMethod need
+        # to come after CGCreateInterfaceObjectsMethod.
+        if descriptor.interface.hasInterfacePrototypeObject():
+            cgThings.append(CGGetProtoObjectHandleMethod(descriptor))
+            if descriptor.interface.hasChildInterfaces():
+                cgThings.append(CGGetProtoObjectMethod(descriptor))
+        if descriptor.interface.hasInterfaceObject():
+            cgThings.append(CGGetConstructorObjectHandleMethod(descriptor))
+            cgThings.append(CGGetConstructorObjectMethod(descriptor))
+
+        # See whether we need we need to generate an IsPermitted method
+        if crossOriginGetters or crossOriginSetters or crossOriginMethods:
+            cgThings.append(CGIsPermittedMethod(descriptor,
+                                                crossOriginGetters,
+                                                crossOriginSetters,
+                                                crossOriginMethods))
+
+        cgThings = CGList((CGIndenter(t, declareOnly=True) for t in cgThings), "\n")
+        cgThings = CGWrapper(cgThings, pre='\n', post='\n')
+        self.cgRoot = CGWrapper(CGNamespace(toBindingNamespace(descriptor.name),
+                                            cgThings),
+                                post='\n')
+
+    def declare(self):
+        return self.cgRoot.declare()
+
+    def define(self):
+        return self.cgRoot.define()
+
+    def deps(self):
+        return self._deps
+
+
+class CGNamespacedEnum(CGThing):
+    def __init__(self, namespace, enumName, names, values, comment=""):
+
+        if not values:
+            values = []
+
+        # Account for explicit enum values.
+        entries = []
+        for i in range(0, len(names)):
+            if len(values) > i and values[i] is not None:
+                entry = "%s = %s" % (names[i], values[i])
+            else:
+                entry = names[i]
+            entries.append(entry)
+
+        # Append a Count.
+        entries.append('_' + enumName + '_Count')
+
+        # Indent.
+        entries = ['  ' + e for e in entries]
+
+        # Build the enum body.
+        enumstr = comment + 'enum %s : uint16_t\n{\n%s\n};\n' % (enumName, ',\n'.join(entries))
+        curr = CGGeneric(declare=enumstr)
+
+        # Add some whitespace padding.
+        curr = CGWrapper(curr, pre='\n', post='\n')
+
+        # Add the namespace.
+        curr = CGNamespace(namespace, curr)
+
+        # Add the typedef
+        typedef = '\ntypedef %s::%s %s;\n\n' % (namespace, enumName, enumName)
+        curr = CGList([curr, CGGeneric(declare=typedef)])
+
+        # Save the result.
+        self.node = curr
+
+    def declare(self):
+        return self.node.declare()
+
+    def define(self):
+        return ""
+
+
+def initIdsClassMethod(identifiers, atomCacheName):
+    idinit = ['!atomsCache->%s.init(cx, "%s")' %
+              (CGDictionary.makeIdName(id),
+               id)
+              for id in identifiers]
+    idinit.reverse()
+    body = fill(
+        """
+        MOZ_ASSERT(!*reinterpret_cast<jsid**>(atomsCache));
+
+        // Initialize these in reverse order so that any failure leaves the first one
+        // uninitialized.
+        if (${idinit}) {
+          return false;
+        }
+        return true;
+        """,
+        idinit=" ||\n    ".join(idinit))
+    return ClassMethod("InitIds", "bool", [
+        Argument("JSContext*", "cx"),
+        Argument("%s*" % atomCacheName, "atomsCache")
+    ], static=True, body=body, visibility="private")
+
+
+class CGDictionary(CGThing):
+    def __init__(self, dictionary, descriptorProvider):
+        self.dictionary = dictionary
+        self.descriptorProvider = descriptorProvider
+        self.needToInitIds = len(dictionary.members) > 0
+        self.memberInfo = [
+            (member,
+             getJSToNativeConversionInfo(
+                 member.type,
+                 descriptorProvider,
+                 isEnforceRange=member.enforceRange,
+                 isClamp=member.clamp,
+                 isMember="Dictionary",
+                 isOptional=member.canHaveMissingValue(),
+                 defaultValue=member.defaultValue,
+                 sourceDescription=self.getMemberSourceDescription(member)))
+            for member in dictionary.members]
+
+        # If we have a union member containing something in the same
+        # file as us, bail: the C++ includes won't work out.
+        for member in dictionary.members:
+            type = member.type.unroll()
+            if type.isUnion():
+                for t in type.flatMemberTypes:
+                    if (t.isDictionary() and
+                        CGHeaders.getDeclarationFilename(t.inner) ==
+                        CGHeaders.getDeclarationFilename(dictionary)):
+                        raise TypeError(
+                            "Dictionary contains a union that contains a "
+                            "dictionary in the same WebIDL file.  This won't "
+                            "compile.  Move the inner dictionary to a "
+                            "different file.\n%s\n%s" %
+                            (t.location, t.inner.location))
+        self.structs = self.getStructs()
+
+    def declare(self):
+        return self.structs.declare()
+
+    def define(self):
+        return self.structs.define()
+
+    def base(self):
+        if self.dictionary.parent:
+            return self.makeClassName(self.dictionary.parent)
+        return "DictionaryBase"
+
+    def initMethod(self):
+        """
+        This function outputs the body of the Init() method for the dictionary.
+
+        For the most part, this is some bookkeeping for our atoms so
+        we can avoid atomizing strings all the time, then we just spit
+        out the getMemberConversion() output for each member,
+        separated by newlines.
+
+        """
+        body = dedent("""
+            // Passing a null JSContext is OK only if we're initing from null,
+            // Since in that case we will not have to do any property gets
+            MOZ_ASSERT_IF(!cx, val.isNull());
+            """)
+
+        if self.needToInitIds:
+            body += fill(
+                """
+                ${dictName}Atoms* atomsCache = nullptr;
+                if (cx) {
+                  atomsCache = GetAtomCache<${dictName}Atoms>(cx);
+                  if (!*reinterpret_cast<jsid**>(atomsCache) && !InitIds(cx, atomsCache)) {
+                    return false;
+                  }
+                }
+
+                """,
+                dictName=self.makeClassName(self.dictionary))
+
+        if self.dictionary.parent:
+            body += fill(
+                """
+                // Per spec, we init the parent's members first
+                if (!${dictName}::Init(cx, val)) {
+                  return false;
+                }
+
+                """,
+                dictName=self.makeClassName(self.dictionary.parent))
+        else:
+            body += dedent(
+                """
+                { // scope for isConvertible
+                  bool isConvertible;
+                  if (!IsConvertibleToDictionary(cx, val, &isConvertible)) {
+                    return false;
+                  }
+                  if (!isConvertible) {
+                    return ThrowErrorMessage(cx, MSG_NOT_DICTIONARY, sourceDescription);
+                  }
+                }
+
+                """)
+
+        memberInits = [self.getMemberConversion(m).define()
+                       for m in self.memberInfo]
+        if memberInits:
+            body += fill(
+                """
+                bool isNull = val.isNullOrUndefined();
+                // We only need these if !isNull, in which case we have |cx|.
+                Maybe<JS::Rooted<JSObject *> > object;
+                Maybe<JS::Rooted<JS::Value> > temp;
+                if (!isNull) {
+                  MOZ_ASSERT(cx);
+                  object.emplace(cx, &val.toObject());
+                  temp.emplace(cx);
+                }
+                $*{memberInits}
+                """,
+                memberInits="\n".join(memberInits))
+
+        body += "return true;\n"
+
+        return ClassMethod("Init", "bool", [
+            Argument('JSContext*', 'cx'),
+            Argument('JS::Handle<JS::Value>', 'val'),
+            Argument('const char*', 'sourceDescription', default='"Value"'),
+            Argument('bool', 'passedToJSImpl', default='false')
+        ], body=body)
+
+    def initFromJSONMethod(self):
+        return ClassMethod(
+            "Init", "bool",
+            [Argument('const nsAString&', 'aJSON')],
+            body=dedent("""
+                AutoJSAPI jsapi;
+                JSObject* cleanGlobal = SimpleGlobalObject::Create(SimpleGlobalObject::GlobalType::BindingDetail);
+                if (!cleanGlobal) {
+                  return false;
+                }
+                if (!jsapi.Init(cleanGlobal)) {
+                  return false;
+                }
+                JSContext* cx = jsapi.cx();
+                JS::Rooted<JS::Value> json(cx);
+                bool ok = ParseJSON(cx, aJSON, &json);
+                NS_ENSURE_TRUE(ok, false);
+                return Init(cx, json);
+                """))
+
+    def toJSONMethod(self):
+        return ClassMethod(
+            "ToJSON", "bool",
+            [Argument('nsAString&', 'aJSON')],
+            body=dedent("""
+                AutoJSAPI jsapi;
+                jsapi.Init();
+                JSContext *cx = jsapi.cx();
+                // It's safe to use UnprivilegedJunkScopeOrWorkerGlobal here
+                // because we'll only be creating objects, in ways that have no
+                // side-effects, followed by a call to JS::ToJSONMaybeSafely,
+                // which likewise guarantees no side-effects for the sorts of
+                // things we will pass it.
+                JSAutoCompartment ac(cx, binding_detail::UnprivilegedJunkScopeOrWorkerGlobal());
+                JS::Rooted<JS::Value> val(cx);
+                if (!ToObjectInternal(cx, &val)) {
+                  return false;
+                }
+                JS::Rooted<JSObject*> obj(cx, &val.toObject());
+                return StringifyToJSON(cx, obj, aJSON);
+            """), const=True)
+
+    def toObjectInternalMethod(self):
+        body = ""
+        if self.needToInitIds:
+            body += fill(
+                """
+                ${dictName}Atoms* atomsCache = GetAtomCache<${dictName}Atoms>(cx);
+                if (!*reinterpret_cast<jsid**>(atomsCache) && !InitIds(cx, atomsCache)) {
+                  return false;
+                }
+
+                """,
+                dictName=self.makeClassName(self.dictionary))
+
+        if self.dictionary.parent:
+            body += fill(
+                """
+                // Per spec, we define the parent's members first
+                if (!${dictName}::ToObjectInternal(cx, rval)) {
+                  return false;
+                }
+                JS::Rooted<JSObject*> obj(cx, &rval.toObject());
+
+                """,
+                dictName=self.makeClassName(self.dictionary.parent))
+        else:
+            body += dedent(
+                """
+                JS::Rooted<JSObject*> obj(cx, JS_NewPlainObject(cx));
+                if (!obj) {
+                  return false;
+                }
+                rval.set(JS::ObjectValue(*obj));
+
+                """)
+
+        if self.memberInfo:
+            body += "\n".join(self.getMemberDefinition(m).define()
+                              for m in self.memberInfo)
+        body += "\nreturn true;\n"
+
+        return ClassMethod("ToObjectInternal", "bool", [
+            Argument('JSContext*', 'cx'),
+            Argument('JS::MutableHandle<JS::Value>', 'rval'),
+        ], const=True, body=body)
+
+    def initIdsMethod(self):
+        assert self.needToInitIds
+        return initIdsClassMethod([m.identifier.name for m in self.dictionary.members],
+                                  "%sAtoms" % self.makeClassName(self.dictionary))
+
+    def traceDictionaryMethod(self):
+        body = ""
+        if self.dictionary.parent:
+            cls = self.makeClassName(self.dictionary.parent)
+            body += "%s::TraceDictionary(trc);\n" % cls
+
+        memberTraces = [self.getMemberTrace(m)
+                        for m in self.dictionary.members
+                        if typeNeedsRooting(m.type)]
+
+        if memberTraces:
+            body += "\n".join(memberTraces)
+
+        return ClassMethod("TraceDictionary", "void", [
+            Argument("JSTracer*", "trc"),
+        ], body=body)
+
+    def assignmentOperator(self):
+        body = CGList([])
+        if self.dictionary.parent:
+            body.append(CGGeneric(
+                "%s::operator=(aOther);\n" %
+                self.makeClassName(self.dictionary.parent)))
+        for m, _ in self.memberInfo:
+            memberName = self.makeMemberName(m.identifier.name)
+            if m.canHaveMissingValue():
+                memberAssign = CGGeneric(fill(
+                    """
+                    ${name}.Reset();
+                    if (aOther.${name}.WasPassed()) {
+                      ${name}.Construct(aOther.${name}.Value());
+                    }
+                    """,
+                    name=memberName))
+            else:
+                memberAssign = CGGeneric(
+                    "%s = aOther.%s;\n" % (memberName, memberName))
+            body.append(memberAssign)
+        return ClassMethod(
+            "operator=", "void",
+            [Argument("const %s&" % self.makeClassName(self.dictionary),
+                      "aOther")],
+            body=body.define())
+
+    def getStructs(self):
+        d = self.dictionary
+        selfName = self.makeClassName(d)
+        members = [ClassMember(self.makeMemberName(m[0].identifier.name),
+                               self.getMemberType(m),
+                               visibility="public",
+                               body=self.getMemberInitializer(m),
+                               hasIgnoreInitCheckFlag=True)
+                   for m in self.memberInfo]
+        if d.parent:
+            # We always want to init our parent with our non-initializing
+            # constructor arg, because either we're about to init ourselves (and
+            # hence our parent) or we don't want any init happening.
+            baseConstructors = [
+                "%s(%s)" % (self.makeClassName(d.parent),
+                            self.getNonInitializingCtorArg())
+            ]
+        else:
+            baseConstructors = None
+        ctors = [
+            ClassConstructor(
+                [],
+                visibility="public",
+                baseConstructors=baseConstructors,
+                body=(
+                    "// Safe to pass a null context if we pass a null value\n"
+                    "Init(nullptr, JS::NullHandleValue);\n")),
+            ClassConstructor(
+                [Argument("const FastDictionaryInitializer&", "")],
+                visibility="public",
+                baseConstructors=baseConstructors,
+                explicit=True,
+                bodyInHeader=True,
+                body='// Do nothing here; this is used by our "Fast" subclass\n')
+        ]
+        methods = []
+
+        if self.needToInitIds:
+            methods.append(self.initIdsMethod())
+
+        methods.append(self.initMethod())
+        canBeRepresentedAsJSON = self.dictionarySafeToJSONify(self.dictionary)
+        if canBeRepresentedAsJSON:
+            methods.append(self.initFromJSONMethod())
+        try:
+            methods.append(self.toObjectInternalMethod())
+            if canBeRepresentedAsJSON:
+                methods.append(self.toJSONMethod())
+        except MethodNotNewObjectError:
+            # If we can't have a ToObjectInternal() because one of our members
+            # can only be returned from [NewObject] methods, then just skip
+            # generating ToObjectInternal() and ToJSON (since the latter depens
+            # on the former).
+            pass
+        methods.append(self.traceDictionaryMethod())
+
+        if CGDictionary.isDictionaryCopyConstructible(d):
+            disallowCopyConstruction = False
+            # Note: no base constructors because our operator= will
+            # deal with that.
+            ctors.append(ClassConstructor([Argument("const %s&" % selfName,
+                                                    "aOther")],
+                                          bodyInHeader=True,
+                                          visibility="public",
+                                          explicit=True,
+                                          body="*this = aOther;\n"))
+            methods.append(self.assignmentOperator())
+        else:
+            disallowCopyConstruction = True
+
+        struct = CGClass(selfName,
+                         bases=[ClassBase(self.base())],
+                         members=members,
+                         constructors=ctors,
+                         methods=methods,
+                         isStruct=True,
+                         disallowCopyConstruction=disallowCopyConstruction)
+
+        fastDictionaryCtor = ClassConstructor(
+            [],
+            visibility="public",
+            bodyInHeader=True,
+            baseConstructors=["%s(%s)" %
+                              (selfName,
+                               self.getNonInitializingCtorArg())],
+            body="// Doesn't matter what int we pass to the parent constructor\n")
+
+        fastStruct = CGClass("Fast" + selfName,
+                             bases=[ClassBase(selfName)],
+                             constructors=[fastDictionaryCtor],
+                             isStruct=True)
+
+        return CGList([struct,
+                       CGNamespace('binding_detail', fastStruct)],
+                      "\n")
+
+    def deps(self):
+        return self.dictionary.getDeps()
+
+    @staticmethod
+    def makeDictionaryName(dictionary):
+        return dictionary.identifier.name
+
+    def makeClassName(self, dictionary):
+        return self.makeDictionaryName(dictionary)
+
+    @staticmethod
+    def makeMemberName(name):
+        return "m" + name[0].upper() + IDLToCIdentifier(name[1:])
+
+    def getMemberType(self, memberInfo):
+        _, conversionInfo = memberInfo
+        # We can't handle having a holderType here
+        assert conversionInfo.holderType is None
+        declType = conversionInfo.declType
+        if conversionInfo.dealWithOptional:
+            declType = CGTemplatedType("Optional", declType)
+        return declType.define()
+
+    def getMemberConversion(self, memberInfo):
+        """
+        A function that outputs the initialization of a single dictionary
+        member from the given dictionary value.
+
+        We start with our conversionInfo, which tells us how to
+        convert a JS::Value to whatever type this member is.  We
+        substiture the template from the conversionInfo with values
+        that point to our "temp" JS::Value and our member (which is
+        the C++ value we want to produce).  The output is a string of
+        code to do the conversion.  We store this string in
+        conversionReplacements["convert"].
+
+        Now we have three different ways we might use (or skip) this
+        string of code, depending on whether the value is required,
+        optional with default value, or optional without default
+        value.  We set up a template in the 'conversion' variable for
+        exactly how to do this, then substitute into it from the
+        conversionReplacements dictionary.
+        """
+        member, conversionInfo = memberInfo
+        replacements = {
+            "val": "temp.ref()",
+            "maybeMutableVal": "temp.ptr()",
+            "declName": self.makeMemberName(member.identifier.name),
+            # We need a holder name for external interfaces, but
+            # it's scoped down to the conversion so we can just use
+            # anything we want.
+            "holderName": "holder",
+            "passedToJSImpl": "passedToJSImpl"
+        }
+        # We can't handle having a holderType here
+        assert conversionInfo.holderType is None
+        if conversionInfo.dealWithOptional:
+            replacements["declName"] = "(" + replacements["declName"] + ".Value())"
+        if member.defaultValue:
+            replacements["haveValue"] = "!isNull && !temp->isUndefined()"
+
+        propId = self.makeIdName(member.identifier.name)
+        propGet = ("JS_GetPropertyById(cx, *object, atomsCache->%s, temp.ptr())" %
+                   propId)
+
+        conversionReplacements = {
+            "prop": self.makeMemberName(member.identifier.name),
+            "convert": string.Template(conversionInfo.template).substitute(replacements),
+            "propGet": propGet
+        }
+        # The conversion code will only run where a default value or a value passed
+        # by the author needs to get converted, so we can remember if we have any
+        # members present here.
+        conversionReplacements["convert"] += "mIsAnyMemberPresent = true;\n"
+        setTempValue = CGGeneric(dedent(
+            """
+            if (!${propGet}) {
+              return false;
+            }
+            """))
+        conditions = getConditionList(member, "cx", "*object")
+        if len(conditions) != 0:
+            setTempValue = CGIfElseWrapper(conditions.define(),
+                                           setTempValue,
+                                           CGGeneric("temp->setUndefined();\n"))
+        setTempValue = CGIfWrapper(setTempValue, "!isNull")
+        conversion = setTempValue.define()
+        if member.defaultValue:
+            if (member.type.isUnion() and
+                (not member.type.nullable() or
+                 not isinstance(member.defaultValue, IDLNullValue))):
+                # Since this has a default value, it might have been initialized
+                # already.  Go ahead and uninit it before we try to init it
+                # again.
+                memberName = self.makeMemberName(member.identifier.name)
+                if member.type.nullable():
+                    conversion += fill(
+                        """
+                        if (!${memberName}.IsNull()) {
+                          ${memberName}.Value().Uninit();
+                        }
+                        """,
+                        memberName=memberName)
+                else:
+                    conversion += "%s.Uninit();\n" % memberName
+            conversion += "${convert}"
+        elif not conversionInfo.dealWithOptional:
+            # We're required, but have no default value.  Make sure
+            # that we throw if we have no value provided.
+            conversion += dedent(
+                """
+                if (!isNull && !temp->isUndefined()) {
+                ${convert}
+                } else if (cx) {
+                  // Don't error out if we have no cx.  In that
+                  // situation the caller is default-constructing us and we'll
+                  // just assume they know what they're doing.
+                  return ThrowErrorMessage(cx, MSG_MISSING_REQUIRED_DICTIONARY_MEMBER,
+                                           "%s");
+                }
+                """ % self.getMemberSourceDescription(member))
+            conversionReplacements["convert"] = indent(conversionReplacements["convert"]).rstrip()
+        else:
+            conversion += (
+                "if (!isNull && !temp->isUndefined()) {\n"
+                "  ${prop}.Construct();\n"
+                "${convert}"
+                "}\n")
+            conversionReplacements["convert"] = indent(conversionReplacements["convert"])
+
+        return CGGeneric(
+            string.Template(conversion).substitute(conversionReplacements))
+
+    def getMemberDefinition(self, memberInfo):
+        member = memberInfo[0]
+        declType = memberInfo[1].declType
+        memberLoc = self.makeMemberName(member.identifier.name)
+        if not member.canHaveMissingValue():
+            memberData = memberLoc
+        else:
+            # The data is inside the Optional<>
+            memberData = "%s.InternalValue()" % memberLoc
+
+        # If you have to change this list (which you shouldn't!), make sure it
+        # continues to match the list in test_Object.prototype_props.html
+        if (member.identifier.name in
+            ["constructor", "toSource", "toString", "toLocaleString", "valueOf",
+             "watch", "unwatch", "hasOwnProperty", "isPrototypeOf",
+             "propertyIsEnumerable", "__defineGetter__", "__defineSetter__",
+             "__lookupGetter__", "__lookupSetter__", "__proto__"]):
+            raise TypeError("'%s' member of %s dictionary shadows "
+                            "a property of Object.prototype, and Xrays to "
+                            "Object can't handle that.\n"
+                            "%s" %
+                            (member.identifier.name,
+                             self.dictionary.identifier.name,
+                             member.location))
+
+        propDef = (
+            'JS_DefinePropertyById(cx, obj, atomsCache->%s, temp, JSPROP_ENUMERATE)' %
+            self.makeIdName(member.identifier.name))
+
+        innerTemplate = wrapForType(
+            member.type, self.descriptorProvider,
+            {
+                'result': "currentValue",
+                'successCode': ("if (!%s) {\n"
+                                "  return false;\n"
+                                "}\n"
+                                "break;\n" % propDef),
+                'jsvalRef': "temp",
+                'jsvalHandle': "&temp",
+                'returnsNewObject': False,
+                # 'obj' can just be allowed to be the string "obj", since that
+                # will be our dictionary object, which is presumably itself in
+                # the right scope.
+                'typedArraysAreStructs': True
+            })
+        conversion = CGGeneric(innerTemplate)
+        conversion = CGWrapper(conversion,
+                               pre=("JS::Rooted<JS::Value> temp(cx);\n"
+                                    "%s const & currentValue = %s;\n" %
+                                    (declType.define(), memberData)
+                                    ))
+
+        # Now make sure that our successCode can actually break out of the
+        # conversion.  This incidentally gives us a scope for 'temp' and
+        # 'currentValue'.
+        conversion = CGWrapper(
+            CGIndenter(conversion),
+            pre=("do {\n"
+                 "  // block for our 'break' successCode and scope for 'temp' and 'currentValue'\n"),
+            post="} while(0);\n")
+        if member.canHaveMissingValue():
+            # Only do the conversion if we have a value
+            conversion = CGIfWrapper(conversion, "%s.WasPassed()" % memberLoc)
+        conditions = getConditionList(member, "cx", "obj")
+        if len(conditions) != 0:
+            conversion = CGIfWrapper(conversion, conditions.define())
+        return conversion
+
+    def getMemberTrace(self, member):
+        type = member.type
+        assert typeNeedsRooting(type)
+        memberLoc = self.makeMemberName(member.identifier.name)
+        if not member.canHaveMissingValue():
+            memberData = memberLoc
+        else:
+            # The data is inside the Optional<>
+            memberData = "%s.Value()" % memberLoc
+
+        memberName = "%s.%s" % (self.makeClassName(self.dictionary),
+                                memberLoc)
+
+        if type.isObject():
+            trace = CGGeneric('JS::UnsafeTraceRoot(trc, %s, "%s");\n' %
+                              ("&"+memberData, memberName))
+            if type.nullable():
+                trace = CGIfWrapper(trace, memberData)
+        elif type.isAny():
+            trace = CGGeneric('JS::UnsafeTraceRoot(trc, %s, "%s");\n' %
+                              ("&"+memberData, memberName))
+        elif (type.isSequence() or type.isDictionary() or
+              type.isSpiderMonkeyInterface() or type.isUnion()):
+            if type.nullable():
+                memberNullable = memberData
+                memberData = "%s.Value()" % memberData
+            if type.isSequence():
+                trace = CGGeneric('DoTraceSequence(trc, %s);\n' % memberData)
+            elif type.isDictionary():
+                trace = CGGeneric('%s.TraceDictionary(trc);\n' % memberData)
+            elif type.isUnion():
+                trace = CGGeneric('%s.TraceUnion(trc);\n' % memberData)
+            else:
+                assert type.isSpiderMonkeyInterface()
+                trace = CGGeneric('%s.TraceSelf(trc);\n' % memberData)
+            if type.nullable():
+                trace = CGIfWrapper(trace, "!%s.IsNull()" % memberNullable)
+        elif type.isMozMap():
+            # If you implement this, add a MozMap<object> to
+            # TestInterfaceJSDictionary and test it in test_bug1036214.html
+            # to make sure we end up with the correct security properties.
+            assert False
+        else:
+            assert False  # unknown type
+
+        if member.canHaveMissingValue():
+            trace = CGIfWrapper(trace, "%s.WasPassed()" % memberLoc)
+
+        return trace.define()
+
+    def getMemberInitializer(self, memberInfo):
+        """
+        Get the right initializer for the member.  Most members don't need one,
+        but we need to pre-initialize 'any' and 'object' that have a default
+        value, so they're safe to trace at all times.
+        """
+        member, _ = memberInfo
+        if member.canHaveMissingValue():
+            # Allowed missing value means no need to set it up front, since it's
+            # inside an Optional and won't get traced until it's actually set
+            # up.
+            return None
+        type = member.type
+        if type.isAny():
+            return "JS::UndefinedValue()"
+        if type.isObject():
+            return "nullptr"
+        if type.isDictionary():
+            # When we construct ourselves, we don't want to init our member
+            # dictionaries.  Either we're being constructed-but-not-initialized
+            # ourselves (and then we don't want to init them) or we're about to
+            # init ourselves and then we'll init them anyway.
+            return CGDictionary.getNonInitializingCtorArg()
+        return None
+
+    def getMemberSourceDescription(self, member):
+        return ("'%s' member of %s" %
+                (member.identifier.name, self.dictionary.identifier.name))
+
+    @staticmethod
+    def makeIdName(name):
+        return IDLToCIdentifier(name) + "_id"
+
+    @staticmethod
+    def getNonInitializingCtorArg():
+        return "FastDictionaryInitializer()"
+
+    @staticmethod
+    def isDictionaryCopyConstructible(dictionary):
+        if (dictionary.parent and
+            not CGDictionary.isDictionaryCopyConstructible(dictionary.parent)):
+            return False
+        return all(isTypeCopyConstructible(m.type) for m in dictionary.members)
+
+    @staticmethod
+    def typeSafeToJSONify(type):
+        """
+        Determine whether the given type is safe to convert to JSON.  The
+        restriction is that this needs to be safe while in a global controlled
+        by an adversary, and "safe" means no side-effects when the JS
+        representation of this type is converted to JSON.  That means that we
+        have to be pretty restrictive about what things we can allow.  For
+        example, "object" is out, because it may have accessor properties on it.
+        """
+        if type.nullable():
+            # Converting null to JSON is always OK.
+            return CGDictionary.typeSafeToJSONify(type.inner)
+
+        if type.isSequence():
+            # Sequences are arrays we create ourselves, with no holes.  They
+            # should be safe if their contents are safe, as long as we suppress
+            # invocation of .toJSON on objects.
+            return CGDictionary.typeSafeToJSONify(type.inner)
+
+        if type.isUnion():
+            # OK if everything in it is ok.
+            return all(CGDictionary.typeSafeToJSONify(t)
+                       for t in type.flatMemberTypes)
+
+        if type.isDictionary():
+            # OK if the dictionary is OK
+            return CGDictionary.dictionarySafeToJSONify(type.inner)
+
+        if type.isString() or type.isEnum():
+            # Strings are always OK.
+            return True
+
+        if type.isPrimitive():
+            # Primitives (numbers and booleans) are ok, as long as
+            # they're not unrestricted float/double.
+            return not type.isFloat() or not type.isUnrestricted()
+
+        return False
+
+    @staticmethod
+    def dictionarySafeToJSONify(dictionary):
+        # The dictionary itself is OK, so we're good if all our types are.
+        return all(CGDictionary.typeSafeToJSONify(m.type)
+                   for m in dictionary.members)
+
+
+class CGRegisterWorkerBindings(CGAbstractMethod):
+    def __init__(self, config):
+        CGAbstractMethod.__init__(self, None, 'RegisterWorkerBindings', 'bool',
+                                  [Argument('JSContext*', 'aCx'),
+                                   Argument('JS::Handle<JSObject*>', 'aObj')])
+        self.config = config
+
+    def definition_body(self):
+        descriptors = self.config.getDescriptors(hasInterfaceObject=True,
+                                                 isExposedInAnyWorker=True,
+                                                 register=True)
+        conditions = []
+        for desc in descriptors:
+            bindingNS = toBindingNamespace(desc.name)
+            condition = "!%s::GetConstructorObject(aCx)" % bindingNS
+            if desc.isExposedConditionally():
+                condition = (
+                    "%s::ConstructorEnabled(aCx, aObj) && " % bindingNS
+                    + condition)
+            conditions.append(condition)
+        lines = [CGIfWrapper(CGGeneric("return false;\n"), condition) for
+                 condition in conditions]
+        lines.append(CGGeneric("return true;\n"))
+        return CGList(lines, "\n").define()
+
+class CGRegisterWorkerDebuggerBindings(CGAbstractMethod):
+    def __init__(self, config):
+        CGAbstractMethod.__init__(self, None, 'RegisterWorkerDebuggerBindings', 'bool',
+                                  [Argument('JSContext*', 'aCx'),
+                                   Argument('JS::Handle<JSObject*>', 'aObj')])
+        self.config = config
+
+    def definition_body(self):
+        descriptors = self.config.getDescriptors(hasInterfaceObject=True,
+                                                 isExposedInWorkerDebugger=True,
+                                                 register=True)
+        conditions = []
+        for desc in descriptors:
+            bindingNS = toBindingNamespace(desc.name)
+            condition = "!%s::GetConstructorObject(aCx)" % bindingNS
+            if desc.isExposedConditionally():
+                condition = (
+                    "%s::ConstructorEnabled(aCx, aObj) && " % bindingNS
+                    + condition)
+            conditions.append(condition)
+        lines = [CGIfWrapper(CGGeneric("return false;\n"), condition) for
+                 condition in conditions]
+        lines.append(CGGeneric("return true;\n"))
+        return CGList(lines, "\n").define()
+
+class CGRegisterWorkletBindings(CGAbstractMethod):
+    def __init__(self, config):
+        CGAbstractMethod.__init__(self, None, 'RegisterWorkletBindings', 'bool',
+                                  [Argument('JSContext*', 'aCx'),
+                                   Argument('JS::Handle<JSObject*>', 'aObj')])
+        self.config = config
+
+    def definition_body(self):
+        descriptors = self.config.getDescriptors(hasInterfaceObject=True,
+                                                 isExposedInAnyWorklet=True,
+                                                 register=True)
+        conditions = []
+        for desc in descriptors:
+            bindingNS = toBindingNamespace(desc.name)
+            condition = "!%s::GetConstructorObject(aCx)" % bindingNS
+            if desc.isExposedConditionally():
+                condition = (
+                    "%s::ConstructorEnabled(aCx, aObj) && " % bindingNS
+                    + condition)
+            conditions.append(condition)
+        lines = [CGIfWrapper(CGGeneric("return false;\n"), condition) for
+                 condition in conditions]
+        lines.append(CGGeneric("return true;\n"))
+        return CGList(lines, "\n").define()
+
+class CGResolveSystemBinding(CGAbstractMethod):
+    def __init__(self, config):
+        CGAbstractMethod.__init__(self, None, 'ResolveSystemBinding', 'bool',
+                                  [Argument('JSContext*', 'aCx'),
+                                   Argument('JS::Handle<JSObject*>', 'aObj'),
+                                   Argument('JS::Handle<jsid>', 'aId'),
+                                   Argument('bool*', 'aResolvedp')])
+        self.config = config
+
+    def definition_body(self):
+        descriptors = self.config.getDescriptors(hasInterfaceObject=True,
+                                                 isExposedInSystemGlobals=True,
+                                                 register=True)
+
+        def descNameToId(name):
+            return "s%s_id" % name
+        jsidNames = [descNameToId(desc.name) for desc in descriptors]
+        jsidDecls = CGList(CGGeneric("static jsid %s;\n" % name)
+                           for name in jsidNames)
+
+        jsidInits = CGList(
+            (CGIfWrapper(
+                CGGeneric("return false;\n"),
+                '!AtomizeAndPinJSString(aCx, %s, "%s")' %
+                (descNameToId(desc.name), desc.interface.identifier.name))
+             for desc in descriptors),
+            "\n")
+        jsidInits.append(CGGeneric("idsInited = true;\n"))
+        jsidInits = CGIfWrapper(jsidInits, "!idsInited")
+        jsidInits = CGList([CGGeneric("static bool idsInited = false;\n"),
+                            jsidInits])
+
+        definitions = CGList([], "\n")
+        for desc in descriptors:
+            bindingNS = toBindingNamespace(desc.name)
+            defineCode = "!%s::GetConstructorObject(aCx)" % bindingNS
+            defineCode = CGIfWrapper(CGGeneric("return false;\n"), defineCode)
+            defineCode = CGList([defineCode,
+                                 CGGeneric("*aResolvedp = true;\n")])
+
+            condition = "JSID_IS_VOID(aId) || aId == %s" % descNameToId(desc.name)
+            if desc.isExposedConditionally():
+                condition = "(%s) && %s::ConstructorEnabled(aCx, aObj)" % (condition, bindingNS)
+
+            definitions.append(CGIfWrapper(defineCode, condition))
+
+        return CGList([CGGeneric("MOZ_ASSERT(NS_IsMainThread());\n"),
+                       jsidDecls,
+                       jsidInits,
+                       definitions,
+                       CGGeneric("return true;\n")],
+                      "\n").define()
+
+
+def getGlobalNames(config):
+    names = []
+    for desc in config.getDescriptors(registersGlobalNamesOnWindow=True):
+        names.append((desc.name, desc))
+        names.extend((n.identifier.name, desc) for n in desc.interface.namedConstructors)
+    return names
+
+class CGGlobalNamesString(CGGeneric):
+    def __init__(self, config):
+        globalNames = getGlobalNames(config)
+        currentOffset = 0
+        strings = []
+        for (name, _) in globalNames:
+            strings.append('/* %i */ "%s\\0"' % (currentOffset, name))
+            currentOffset += len(name) + 1 # Add trailing null.
+        define = fill("""
+            const uint32_t WebIDLGlobalNameHash::sCount = ${count};
+
+            const char WebIDLGlobalNameHash::sNames[] =
+              $*{strings}
+
+            """,
+            count=len(globalNames),
+            strings="\n".join(strings) + ";\n")
+
+        CGGeneric.__init__(self, define=define)
+
+
+class CGRegisterGlobalNames(CGAbstractMethod):
+    def __init__(self, config):
+        CGAbstractMethod.__init__(self, None, 'RegisterWebIDLGlobalNames',
+                                  'void', [])
+        self.config = config
+
+    def definition_body(self):
+        def getCheck(desc):
+            if not desc.isExposedConditionally():
+                return "nullptr"
+            return "%sBinding::ConstructorEnabled" % desc.name
+
+        define = ""
+        currentOffset = 0
+        for (name, desc) in getGlobalNames(self.config):
+            length = len(name)
+            define += "WebIDLGlobalNameHash::Register(%i, %i, %sBinding::DefineDOMInterface, %s);\n" % (currentOffset, length, desc.name, getCheck(desc))
+            currentOffset += length + 1 # Add trailing null.
+        return define
+
+
+def dependencySortObjects(objects, dependencyGetter, nameGetter):
+    """
+    Sort IDL objects with dependencies on each other such that if A
+    depends on B then B will come before A.  This is needed for
+    declaring C++ classes in the right order, for example.  Objects
+    that have no dependencies are just sorted by name.
+
+    objects should be something that can produce a set of objects
+    (e.g. a set, iterator, list, etc).
+
+    dependencyGetter is something that, given an object, should return
+    the set of objects it depends on.
+    """
+    # XXXbz this will fail if we have two webidl files F1 and F2 such that F1
+    # declares an object which depends on an object in F2, and F2 declares an
+    # object (possibly a different one!) that depends on an object in F1.  The
+    # good news is that I expect this to never happen.
+    sortedObjects = []
+    objects = set(objects)
+    while len(objects) != 0:
+        # Find the dictionaries that don't depend on anything else
+        # anymore and move them over.
+        toMove = [o for o in objects if
+                  len(dependencyGetter(o) & objects) == 0]
+        if len(toMove) == 0:
+            raise TypeError("Loop in dependency graph\n" +
+                            "\n".join(o.location for o in objects))
+        objects = objects - set(toMove)
+        sortedObjects.extend(sorted(toMove, key=nameGetter))
+    return sortedObjects
+
+
+class ForwardDeclarationBuilder:
+    """
+    Create a canonical representation of a set of namespaced forward
+    declarations.
+    """
+    def __init__(self):
+        """
+        The set of declarations is represented as a tree of nested namespaces.
+        Each tree node has a set of declarations |decls| and a dict |children|.
+        Each declaration is a pair consisting of the class name and a boolean
+        that is true iff the class is really a struct. |children| maps the
+        names of inner namespaces to the declarations in that namespace.
+        """
+        self.decls = set()
+        self.children = {}
+
+    def _ensureNonTemplateType(self, type):
+        if "<" in type:
+            # This is a templated type.  We don't really know how to
+            # forward-declare those, and trying to do it naively is not going to
+            # go well (e.g. we may have :: characters inside the type we're
+            # templated on!).  Just bail out.
+            raise TypeError("Attempt to use ForwardDeclarationBuilder on "
+                            "templated type %s.  We don't know how to do that "
+                            "yet." % type)
+
+    def _listAdd(self, namespaces, name, isStruct=False):
+        """
+        Add a forward declaration, where |namespaces| is a list of namespaces.
+        |name| should not contain any other namespaces.
+        """
+        if namespaces:
+            child = self.children.setdefault(namespaces[0], ForwardDeclarationBuilder())
+            child._listAdd(namespaces[1:], name, isStruct)
+        else:
+            assert '::' not in name
+            self.decls.add((name, isStruct))
+
+    def addInMozillaDom(self, name, isStruct=False):
+        """
+        Add a forward declaration to the mozilla::dom:: namespace. |name| should not
+        contain any other namespaces.
+        """
+        self._ensureNonTemplateType(name);
+        self._listAdd(["mozilla", "dom"], name, isStruct)
+
+    def add(self, nativeType, isStruct=False):
+        """
+        Add a forward declaration, where |nativeType| is a string containing
+        the type and its namespaces, in the usual C++ way.
+        """
+        self._ensureNonTemplateType(nativeType);
+        components = nativeType.split('::')
+        self._listAdd(components[:-1], components[-1], isStruct)
+
+    def _build(self, atTopLevel):
+        """
+        Return a codegenerator for the forward declarations.
+        """
+        decls = []
+        if self.decls:
+            decls.append(CGList([CGClassForwardDeclare(cname, isStruct)
+                                 for cname, isStruct in sorted(self.decls)]))
+        for namespace, child in sorted(self.children.iteritems()):
+            decls.append(CGNamespace(namespace, child._build(atTopLevel=False), declareOnly=True))
+
+        cg = CGList(decls, "\n")
+        if not atTopLevel and len(decls) + len(self.decls) > 1:
+            cg = CGWrapper(cg, pre='\n', post='\n')
+        return cg
+
+    def build(self):
+        return self._build(atTopLevel=True)
+
+    def forwardDeclareForType(self, t, config):
+        t = t.unroll()
+        if t.isGeckoInterface():
+            name = t.inner.identifier.name
+            try:
+                desc = config.getDescriptor(name)
+                self.add(desc.nativeType)
+            except NoSuchDescriptorError:
+                pass
+
+        # Note: Spidermonkey interfaces are typedefs, so can't be
+        # forward-declared
+        elif t.isCallback():
+            self.addInMozillaDom(t.callback.identifier.name)
+        elif t.isDictionary():
+            self.addInMozillaDom(t.inner.identifier.name, isStruct=True)
+        elif t.isCallbackInterface():
+            self.addInMozillaDom(t.inner.identifier.name)
+        elif t.isUnion():
+            # Forward declare both the owning and non-owning version,
+            # since we don't know which one we might want
+            self.addInMozillaDom(CGUnionStruct.unionTypeName(t, False))
+            self.addInMozillaDom(CGUnionStruct.unionTypeName(t, True))
+        elif t.isMozMap():
+            self.forwardDeclareForType(t.inner, config)
+        # Don't need to do anything for void, primitive, string, any or object.
+        # There may be some other cases we are missing.
+
+
+class CGForwardDeclarations(CGWrapper):
+    """
+    Code generate the forward declarations for a header file.
+    additionalDeclarations is a list of tuples containing a classname and a
+    boolean. If the boolean is true we will declare a struct, otherwise we'll
+    declare a class.
+    """
+    def __init__(self, config, descriptors, callbacks,
+                 dictionaries, callbackInterfaces, additionalDeclarations=[]):
+        builder = ForwardDeclarationBuilder()
+
+        # Needed for at least Wrap.
+        for d in descriptors:
+            # If this is a generated iterator interface, we only create these
+            # in the generated bindings, and don't need to forward declare.
+            if d.interface.isIteratorInterface():
+                continue
+            builder.add(d.nativeType)
+            # If we're an interface and we have a maplike/setlike declaration,
+            # we'll have helper functions exposed to the native side of our
+            # bindings, which will need to show up in the header. If either of
+            # our key/value types are interfaces, they'll be passed as
+            # arguments to helper functions, and they'll need to be forward
+            # declared in the header.
+            if d.interface.maplikeOrSetlikeOrIterable:
+                if d.interface.maplikeOrSetlikeOrIterable.hasKeyType():
+                    builder.forwardDeclareForType(d.interface.maplikeOrSetlikeOrIterable.keyType,
+                                                  config)
+                if d.interface.maplikeOrSetlikeOrIterable.hasValueType():
+                    builder.forwardDeclareForType(d.interface.maplikeOrSetlikeOrIterable.valueType,
+                                                  config)
+
+        # We just about always need NativePropertyHooks
+        builder.addInMozillaDom("NativePropertyHooks", isStruct=True)
+        builder.addInMozillaDom("ProtoAndIfaceCache")
+        # Add the atoms cache type, even if we don't need it.
+        for d in descriptors:
+            # Iterators have native types that are template classes, so
+            # creating an 'Atoms' cache type doesn't work for them, and is one
+            # of the cases where we don't need it anyways.
+            if d.interface.isIteratorInterface():
+                continue
+            builder.add(d.nativeType + "Atoms", isStruct=True)
+
+        for callback in callbacks:
+            builder.addInMozillaDom(callback.identifier.name)
+            for t in getTypesFromCallback(callback):
+                builder.forwardDeclareForType(t, config)
+
+        for d in callbackInterfaces:
+            builder.add(d.nativeType)
+            builder.add(d.nativeType + "Atoms", isStruct=True)
+            for t in getTypesFromDescriptor(d):
+                builder.forwardDeclareForType(t, config)
+
+        for d in dictionaries:
+            if len(d.members) > 0:
+                builder.addInMozillaDom(d.identifier.name + "Atoms", isStruct=True)
+            for t in getTypesFromDictionary(d):
+                builder.forwardDeclareForType(t, config)
+
+        for className, isStruct in additionalDeclarations:
+            builder.add(className, isStruct=isStruct)
+
+        CGWrapper.__init__(self, builder.build())
+
+
+class CGBindingRoot(CGThing):
+    """
+    Root codegen class for binding generation. Instantiate the class, and call
+    declare or define to generate header or cpp code (respectively).
+    """
+    def __init__(self, config, prefix, webIDLFile):
+        bindingHeaders = dict.fromkeys((
+            'mozilla/dom/NonRefcountedDOMObject.h',
+            ),
+            True)
+        bindingDeclareHeaders = dict.fromkeys((
+            'mozilla/dom/BindingDeclarations.h',
+            'mozilla/dom/Nullable.h',
+            'mozilla/ErrorResult.h',
+            ),
+            True)
+
+        descriptors = config.getDescriptors(webIDLFile=webIDLFile,
+                                            hasInterfaceOrInterfacePrototypeObject=True)
+
+        unionTypes = UnionsForFile(config, webIDLFile)
+
+        (unionHeaders, unionImplheaders, unionDeclarations, traverseMethods,
+         unlinkMethods, unionStructs) = UnionTypes(unionTypes, config)
+
+        bindingDeclareHeaders.update(dict.fromkeys(unionHeaders, True))
+        bindingHeaders.update(dict.fromkeys(unionImplheaders, True))
+        bindingDeclareHeaders["mozilla/dom/UnionMember.h"] = len(unionStructs) > 0
+        bindingDeclareHeaders["mozilla/dom/FakeString.h"] = len(unionStructs) > 0
+        # BindingUtils.h is only needed for SetToObject.
+        # If it stops being inlined or stops calling CallerSubsumes
+        # both this bit and the bit in UnionTypes can be removed.
+        bindingDeclareHeaders["mozilla/dom/BindingUtils.h"] = any(d.isObject() for t in unionTypes
+                                                                  for d in t.flatMemberTypes)
+        bindingDeclareHeaders["mozilla/dom/IterableIterator.h"] = any(d.interface.isIteratorInterface() or
+                                                                      d.interface.isIterable() for d in descriptors)
+
+        def descriptorHasCrossOriginProperties(desc):
+            def hasCrossOriginProperty(m):
+                props = memberProperties(m, desc)
+                return (props.isCrossOriginMethod or
+                        props.isCrossOriginGetter or
+                        props.isCrossOriginSetter)
+
+            return any(hasCrossOriginProperty(m) for m in desc.interface.members)
+
+        bindingDeclareHeaders["jsapi.h"] = any(descriptorHasCrossOriginProperties(d) for d in descriptors)
+        bindingDeclareHeaders["jspubtd.h"] = not bindingDeclareHeaders["jsapi.h"]
+        bindingDeclareHeaders["js/RootingAPI.h"] = not bindingDeclareHeaders["jsapi.h"]
+
+        def descriptorRequiresPreferences(desc):
+            iface = desc.interface
+            return any(m.getExtendedAttribute("Pref") for m in iface.members + [iface])
+
+        def descriptorDeprecated(desc):
+            iface = desc.interface
+            return any(m.getExtendedAttribute("Deprecated") for m in iface.members + [iface])
+
+        bindingHeaders["nsIDocument.h"] = any(
+            descriptorDeprecated(d) for d in descriptors)
+        bindingHeaders["mozilla/Preferences.h"] = any(
+            descriptorRequiresPreferences(d) for d in descriptors)
+        bindingHeaders["mozilla/dom/DOMJSProxyHandler.h"] = any(
+            d.concrete and d.proxy for d in descriptors)
+
+        def descriptorHasChromeOnly(desc):
+            ctor = desc.interface.ctor()
+
+            return (any(isChromeOnly(a) or needsContainsHack(a) or
+                        needsCallerType(a)
+                        for a in desc.interface.members) or
+                    desc.interface.getExtendedAttribute("ChromeOnly") is not None or
+                    # JS-implemented interfaces with an interface object get a
+                    # chromeonly _create method.  And interfaces with an
+                    # interface object might have a ChromeOnly constructor.
+                    (desc.interface.hasInterfaceObject() and
+                     (desc.interface.isJSImplemented() or
+                      (ctor and isChromeOnly(ctor)))) or
+                    # JS-implemented interfaces with clearable cached
+                    # attrs have chromeonly _clearFoo methods.
+                    (desc.interface.isJSImplemented() and
+                     any(clearableCachedAttrs(desc))))
+
+        # XXXkhuey ugly hack but this is going away soon.
+        bindingHeaders['xpcprivate.h'] = webIDLFile.endswith("EventTarget.webidl")
+
+        hasThreadChecks = any(d.hasThreadChecks() for d in descriptors)
+        bindingHeaders["nsThreadUtils.h"] = hasThreadChecks
+
+        dictionaries = config.getDictionaries(webIDLFile)
+
+        def dictionaryHasChromeOnly(dictionary):
+            while dictionary:
+                if (any(isChromeOnly(m) for m in dictionary.members)):
+                    return True
+                dictionary = dictionary.parent
+            return False
+
+        bindingHeaders["nsContentUtils.h"] = (
+            any(descriptorHasChromeOnly(d) for d in descriptors) or
+            any(dictionaryHasChromeOnly(d) for d in dictionaries))
+        hasNonEmptyDictionaries = any(
+            len(dict.members) > 0 for dict in dictionaries)
+        callbacks = config.getCallbacks(webIDLFile)
+        callbackDescriptors = config.getDescriptors(webIDLFile=webIDLFile,
+                                                    isCallback=True)
+        jsImplemented = config.getDescriptors(webIDLFile=webIDLFile,
+                                              isJSImplemented=True)
+        bindingDeclareHeaders["nsWeakReference.h"] = jsImplemented
+        bindingHeaders["nsIGlobalObject.h"] = jsImplemented
+        bindingHeaders["AtomList.h"] = hasNonEmptyDictionaries or jsImplemented or callbackDescriptors
+
+        def descriptorClearsPropsInSlots(descriptor):
+            if not descriptor.wrapperCache:
+                return False
+            return any(m.isAttr() and m.getExtendedAttribute("StoreInSlot")
+                       for m in descriptor.interface.members)
+        bindingHeaders["nsJSUtils.h"] = any(descriptorClearsPropsInSlots(d) for d in descriptors)
+
+        # Do codegen for all the enums
+        enums = config.getEnums(webIDLFile)
+        cgthings = [CGEnum(e) for e in enums]
+
+        hasCode = (descriptors or callbackDescriptors or dictionaries or
+                   callbacks)
+        bindingHeaders["mozilla/dom/BindingUtils.h"] = hasCode
+        bindingHeaders["mozilla/OwningNonNull.h"] = hasCode
+        bindingHeaders["mozilla/dom/BindingDeclarations.h"] = (
+            not hasCode and enums)
+
+        bindingHeaders["WrapperFactory.h"] = descriptors
+        bindingHeaders["mozilla/dom/DOMJSClass.h"] = descriptors
+        bindingHeaders["mozilla/dom/ScriptSettings.h"] = dictionaries  # AutoJSAPI
+        # Ensure we see our enums in the generated .cpp file, for the ToJSValue
+        # method body.  Also ensure that we see jsapi.h.
+        if enums:
+            bindingHeaders[CGHeaders.getDeclarationFilename(enums[0])] = True
+            bindingHeaders["jsapi.h"] = True
+
+        # For things that have [UseCounter]
+        def descriptorRequiresTelemetry(desc):
+            iface = desc.interface
+            return any(m.getExtendedAttribute("UseCounter") for m in iface.members)
+        bindingHeaders["mozilla/UseCounter.h"] = any(
+            descriptorRequiresTelemetry(d) for d in descriptors)
+        bindingHeaders["mozilla/dom/SimpleGlobalObject.h"] = any(
+            CGDictionary.dictionarySafeToJSONify(d) for d in dictionaries)
+        bindingHeaders["XrayWrapper.h"] = any(
+            d.wantsXrays and d.wantsXrayExpandoClass for d in descriptors)
+        bindingHeaders["mozilla/dom/XrayExpandoClass.h"] = any(
+            d.wantsXrays for d in descriptors)
+
+        cgthings.extend(traverseMethods)
+        cgthings.extend(unlinkMethods)
+
+        # Do codegen for all the dictionaries.  We have to be a bit careful
+        # here, because we have to generate these in order from least derived
+        # to most derived so that class inheritance works out.  We also have to
+        # generate members before the dictionary that contains them.
+
+        def getDependenciesFromType(type):
+            if type.isDictionary():
+                return set([type.unroll().inner])
+            if type.isSequence():
+                return getDependenciesFromType(type.unroll())
+            if type.isUnion():
+                return set([type.unroll()])
+            return set()
+
+        def getDependencies(unionTypeOrDictionary):
+            if isinstance(unionTypeOrDictionary, IDLDictionary):
+                deps = set()
+                if unionTypeOrDictionary.parent:
+                    deps.add(unionTypeOrDictionary.parent)
+                for member in unionTypeOrDictionary.members:
+                    deps |= getDependenciesFromType(member.type)
+                return deps
+
+            assert unionTypeOrDictionary.isType() and unionTypeOrDictionary.isUnion()
+            deps = set()
+            for member in unionTypeOrDictionary.flatMemberTypes:
+                deps |= getDependenciesFromType(member)
+            return deps
+
+        def getName(unionTypeOrDictionary):
+            if isinstance(unionTypeOrDictionary, IDLDictionary):
+                return unionTypeOrDictionary.identifier.name
+
+            assert unionTypeOrDictionary.isType() and unionTypeOrDictionary.isUnion()
+            return unionTypeOrDictionary.name
+
+        for t in dependencySortObjects(dictionaries + unionStructs, getDependencies, getName):
+            if t.isDictionary():
+                cgthings.append(CGDictionary(t, config))
+            else:
+                assert t.isUnion()
+                cgthings.append(CGUnionStruct(t, config))
+                cgthings.append(CGUnionStruct(t, config, True))
+
+        # Do codegen for all the callbacks.
+        cgthings.extend(CGCallbackFunction(c, config) for c in callbacks)
+
+        cgthings.extend([CGNamespace('binding_detail', CGFastCallback(c))
+                         for c in callbacks])
+
+        # Do codegen for all the descriptors
+        cgthings.extend([CGDescriptor(x) for x in descriptors])
+
+        # Do codegen for all the callback interfaces.
+        cgthings.extend([CGCallbackInterface(x) for x in callbackDescriptors])
+
+        cgthings.extend([CGNamespace('binding_detail',
+                                     CGFastCallback(x.interface))
+                         for x in callbackDescriptors])
+
+        # Do codegen for JS implemented classes
+        def getParentDescriptor(desc):
+            if not desc.interface.parent:
+                return set()
+            return {desc.getDescriptor(desc.interface.parent.identifier.name)}
+        for x in dependencySortObjects(jsImplemented, getParentDescriptor,
+                                       lambda d: d.interface.identifier.name):
+            cgthings.append(CGCallbackInterface(x, typedArraysAreStructs=True))
+            cgthings.append(CGJSImplClass(x))
+
+        # And make sure we have the right number of newlines at the end
+        curr = CGWrapper(CGList(cgthings, "\n\n"), post="\n\n")
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, pre="\n"))
+
+        curr = CGList([CGForwardDeclarations(config, descriptors,
+                                             callbacks,
+                                             dictionaries,
+                                             callbackDescriptors + jsImplemented,
+                                             additionalDeclarations=unionDeclarations),
+                       curr],
+                      "\n")
+
+        # Add header includes.
+        bindingHeaders = [header
+                          for header, include in bindingHeaders.iteritems()
+                          if include]
+        bindingDeclareHeaders = [header
+                                 for header, include in bindingDeclareHeaders.iteritems()
+                                 if include]
+
+        curr = CGHeaders(descriptors,
+                         dictionaries,
+                         callbacks,
+                         callbackDescriptors,
+                         bindingDeclareHeaders,
+                         bindingHeaders,
+                         prefix,
+                         curr,
+                         config,
+                         jsImplemented)
+
+        # Add include guards.
+        curr = CGIncludeGuard(prefix, curr)
+
+        # Add the auto-generated comment.
+        curr = CGWrapper(
+            curr,
+            pre=(AUTOGENERATED_WITH_SOURCE_WARNING_COMMENT %
+                 os.path.basename(webIDLFile)))
+
+        # Store the final result.
+        self.root = curr
+
+    def declare(self):
+        return stripTrailingWhitespace(self.root.declare())
+
+    def define(self):
+        return stripTrailingWhitespace(self.root.define())
+
+    def deps(self):
+        return self.root.deps()
+
+
+class CGNativeMember(ClassMethod):
+    def __init__(self, descriptorProvider, member, name, signature, extendedAttrs,
+                 breakAfter=True, passJSBitsAsNeeded=True, visibility="public",
+                 typedArraysAreStructs=True, variadicIsSequence=False,
+                 resultNotAddRefed=False,
+                 virtual=False,
+                 override=False):
+        """
+        If typedArraysAreStructs is false, typed arrays will be passed as
+        JS::Handle<JSObject*>.  If it's true they will be passed as one of the
+        dom::TypedArray subclasses.
+
+        If passJSBitsAsNeeded is false, we don't automatically pass in a
+        JSContext* or a JSObject* based on the return and argument types.  We
+        can still pass it based on 'implicitJSContext' annotations.
+        """
+        self.descriptorProvider = descriptorProvider
+        self.member = member
+        self.extendedAttrs = extendedAttrs
+        self.resultAlreadyAddRefed = not resultNotAddRefed
+        self.passJSBitsAsNeeded = passJSBitsAsNeeded
+        self.typedArraysAreStructs = typedArraysAreStructs
+        self.variadicIsSequence = variadicIsSequence
+        breakAfterSelf = "\n" if breakAfter else ""
+        ClassMethod.__init__(self, name,
+                             self.getReturnType(signature[0], False),
+                             self.getArgs(signature[0], signature[1]),
+                             static=member.isStatic(),
+                             # Mark our getters, which are attrs that
+                             # have a non-void return type, as const.
+                             const=(not member.isStatic() and member.isAttr() and
+                                    not signature[0].isVoid()),
+                             breakAfterReturnDecl=" ",
+                             breakAfterSelf=breakAfterSelf,
+                             visibility=visibility,
+                             virtual=virtual,
+                             override=override)
+
+    def getReturnType(self, type, isMember):
+        return self.getRetvalInfo(type, isMember)[0]
+
+    def getRetvalInfo(self, type, isMember):
+        """
+        Returns a tuple:
+
+        The first element is the type declaration for the retval
+
+        The second element is a default value that can be used on error returns.
+        For cases whose behavior depends on isMember, the second element will be
+        None if isMember is true.
+
+        The third element is a template for actually returning a value stored in
+        "${declName}" and "${holderName}".  This means actually returning it if
+        we're not outparam, else assigning to the "retval" outparam.  If
+        isMember is true, this can be None, since in that case the caller will
+        never examine this value.
+        """
+        if type.isVoid():
+            return "void", "", ""
+        if type.isPrimitive() and type.tag() in builtinNames:
+            result = CGGeneric(builtinNames[type.tag()])
+            defaultReturnArg = "0"
+            if type.nullable():
+                result = CGTemplatedType("Nullable", result)
+                defaultReturnArg = ""
+            return (result.define(),
+                    "%s(%s)" % (result.define(), defaultReturnArg),
+                    "return ${declName};\n")
+        if type.isDOMString() or type.isUSVString():
+            if isMember:
+                # No need for a third element in the isMember case
+                return "nsString", None, None
+            # Outparam
+            return "void", "", "aRetVal = ${declName};\n"
+        if type.isByteString():
+            if isMember:
+                # No need for a third element in the isMember case
+                return "nsCString", None, None
+            # Outparam
+            return "void", "", "aRetVal = ${declName};\n"
+        if type.isEnum():
+            enumName = type.unroll().inner.identifier.name
+            if type.nullable():
+                enumName = CGTemplatedType("Nullable",
+                                           CGGeneric(enumName)).define()
+                defaultValue = "%s()" % enumName
+            else:
+                defaultValue = "%s(0)" % enumName
+            return enumName, defaultValue, "return ${declName};\n"
+        if type.isGeckoInterface():
+            iface = type.unroll().inner
+            result = CGGeneric(self.descriptorProvider.getDescriptor(
+                iface.identifier.name).prettyNativeType)
+            if self.resultAlreadyAddRefed:
+                if isMember:
+                    holder = "RefPtr"
+                else:
+                    holder = "already_AddRefed"
+                if memberReturnsNewObject(self.member) or isMember:
+                    warning = ""
+                else:
+                    warning = "// Return a raw pointer here to avoid refcounting, but make sure it's safe (the object should be kept alive by the callee).\n"
+                result = CGWrapper(result,
+                                   pre=("%s%s<" % (warning, holder)),
+                                   post=">")
+            else:
+                result = CGWrapper(result, post="*")
+            # Since we always force an owning type for callback return values,
+            # our ${declName} is an OwningNonNull or RefPtr.  So we can just
+            # .forget() to get our already_AddRefed.
+            return result.define(), "nullptr", "return ${declName}.forget();\n"
+        if type.isCallback():
+            return ("already_AddRefed<%s>" % type.unroll().callback.identifier.name,
+                    "nullptr", "return ${declName}.forget();\n")
+        if type.isAny():
+            if isMember:
+                # No need for a third element in the isMember case
+                return "JS::Value", None, None
+            # Outparam
+            return "void", "", "aRetVal.set(${declName});\n"
+
+        if type.isObject():
+            if isMember:
+                # No need for a third element in the isMember case
+                return "JSObject*", None, None
+            return "void", "", "aRetVal.set(${declName});\n"
+        if type.isSpiderMonkeyInterface():
+            if isMember:
+                # No need for a third element in the isMember case
+                return "JSObject*", None, None
+            if type.nullable():
+                returnCode = "${declName}.IsNull() ? nullptr : ${declName}.Value().Obj()"
+            else:
+                returnCode = "${declName}.Obj()"
+            return "void", "", "aRetVal.set(%s);\n" % returnCode
+        if type.isSequence():
+            # If we want to handle sequence-of-sequences return values, we're
+            # going to need to fix example codegen to not produce nsTArray<void>
+            # for the relevant argument...
+            assert not isMember
+            # Outparam.
+            if type.nullable():
+                returnCode = dedent("""
+                    if (${declName}.IsNull()) {
+                      aRetVal.SetNull();
+                    } else {
+                      aRetVal.SetValue().SwapElements(${declName}.Value());
+                    }
+                    """)
+            else:
+                returnCode = "aRetVal.SwapElements(${declName});\n"
+            return "void", "", returnCode
+        if type.isMozMap():
+            # If we want to handle MozMap-of-MozMap return values, we're
+            # going to need to fix example codegen to not produce MozMap<void>
+            # for the relevant argument...
+            assert not isMember
+            # In this case we convert directly into our outparam to start with
+            return "void", "", ""
+        if type.isDate():
+            result = CGGeneric("Date")
+            if type.nullable():
+                result = CGTemplatedType("Nullable", result)
+            return (result.define(), "%s()" % result.define(),
+                    "return ${declName};\n")
+        if type.isDictionary():
+            if isMember:
+                # Only the first member of the tuple matters here, but return
+                # bogus values for the others in case someone decides to use
+                # them.
+                return CGDictionary.makeDictionaryName(type.inner), None, None
+            # In this case we convert directly into our outparam to start with
+            return "void", "", ""
+        if type.isUnion():
+            if isMember:
+                # Only the first member of the tuple matters here, but return
+                # bogus values for the others in case someone decides to use
+                # them.
+                return CGUnionStruct.unionTypeDecl(type, True), None, None
+            # In this case we convert directly into our outparam to start with
+            return "void", "", ""
+
+        raise TypeError("Don't know how to declare return value for %s" %
+                        type)
+
+    def getArgs(self, returnType, argList):
+        args = [self.getArg(arg) for arg in argList]
+        # Now the outparams
+        if returnType.isDOMString() or returnType.isUSVString():
+            args.append(Argument("nsString&", "aRetVal"))
+        elif returnType.isByteString():
+            args.append(Argument("nsCString&", "aRetVal"))
+        elif returnType.isSequence():
+            nullable = returnType.nullable()
+            if nullable:
+                returnType = returnType.inner
+            # And now the actual underlying type
+            elementDecl = self.getReturnType(returnType.inner, True)
+            type = CGTemplatedType("nsTArray", CGGeneric(elementDecl))
+            if nullable:
+                type = CGTemplatedType("Nullable", type)
+            args.append(Argument("%s&" % type.define(), "aRetVal"))
+        elif returnType.isMozMap():
+            nullable = returnType.nullable()
+            if nullable:
+                returnType = returnType.inner
+            # And now the actual underlying type
+            elementDecl = self.getReturnType(returnType.inner, True)
+            type = CGTemplatedType("MozMap", CGGeneric(elementDecl))
+            if nullable:
+                type = CGTemplatedType("Nullable", type)
+            args.append(Argument("%s&" % type.define(), "aRetVal"))
+        elif returnType.isDictionary():
+            nullable = returnType.nullable()
+            if nullable:
+                returnType = returnType.inner
+            dictType = CGGeneric(CGDictionary.makeDictionaryName(returnType.inner))
+            if nullable:
+                dictType = CGTemplatedType("Nullable", dictType)
+            args.append(Argument("%s&" % dictType.define(), "aRetVal"))
+        elif returnType.isUnion():
+            args.append(Argument("%s&" %
+                                 CGUnionStruct.unionTypeDecl(returnType, True),
+                                 "aRetVal"))
+        elif returnType.isAny():
+            args.append(Argument("JS::MutableHandle<JS::Value>", "aRetVal"))
+        elif returnType.isObject() or returnType.isSpiderMonkeyInterface():
+            args.append(Argument("JS::MutableHandle<JSObject*>", "aRetVal"))
+
+        # And the nsIPrincipal
+        if self.member.getExtendedAttribute('NeedsSubjectPrincipal'):
+            # Cheat and assume self.descriptorProvider is a descriptor
+            if self.descriptorProvider.interface.isExposedInAnyWorker():
+                args.append(Argument("Maybe<nsIPrincipal*>", "aSubjectPrincipal"))
+            else:
+                args.append(Argument("nsIPrincipal&", "aPrincipal"))
+        # And the caller type, if desired.
+        if needsCallerType(self.member):
+            args.append(Argument("CallerType", "aCallerType"))
+        # And the ErrorResult
+        if 'infallible' not in self.extendedAttrs:
+            # Use aRv so it won't conflict with local vars named "rv"
+            args.append(Argument("ErrorResult&", "aRv"))
+        # The legacycaller thisval
+        if self.member.isMethod() and self.member.isLegacycaller():
+            # If it has an identifier, we can't deal with it yet
+            assert self.member.isIdentifierLess()
+            args.insert(0, Argument("const JS::Value&", "aThisVal"))
+        # And jscontext bits.
+        if needCx(returnType, argList, self.extendedAttrs,
+                  self.passJSBitsAsNeeded, self.member.isStatic()):
+            args.insert(0, Argument("JSContext*", "cx"))
+            if needScopeObject(returnType, argList, self.extendedAttrs,
+                               self.descriptorProvider.wrapperCache,
+                               self.passJSBitsAsNeeded,
+                               self.member.getExtendedAttribute("StoreInSlot")):
+                args.insert(1, Argument("JS::Handle<JSObject*>", "obj"))
+        # And if we're static, a global
+        if self.member.isStatic():
+            args.insert(0, Argument("const GlobalObject&", "global"))
+        return args
+
+    def doGetArgType(self, type, optional, isMember):
+        """
+        The main work of getArgType.  Returns a string type decl, whether this
+        is a const ref, as well as whether the type should be wrapped in
+        Nullable as needed.
+
+        isMember can be false or one of the strings "Sequence", "Variadic",
+                 "MozMap"
+        """
+        if type.isSequence():
+            nullable = type.nullable()
+            if nullable:
+                type = type.inner
+            elementType = type.inner
+            argType = self.getArgType(elementType, False, "Sequence")[0]
+            decl = CGTemplatedType("Sequence", argType)
+            return decl.define(), True, True
+
+        if type.isMozMap():
+            nullable = type.nullable()
+            if nullable:
+                type = type.inner
+            elementType = type.inner
+            argType = self.getArgType(elementType, False, "MozMap")[0]
+            decl = CGTemplatedType("MozMap", argType)
+            return decl.define(), True, True
+
+        if type.isUnion():
+            # unionTypeDecl will handle nullable types, so return False for
+            # auto-wrapping in Nullable
+            return CGUnionStruct.unionTypeDecl(type, isMember), True, False
+
+        if type.isGeckoInterface() and not type.isCallbackInterface():
+            iface = type.unroll().inner
+            argIsPointer = type.nullable() or iface.isExternal()
+            forceOwningType = (iface.isCallback() or isMember or
+                               iface.identifier.name == "Promise")
+            if argIsPointer:
+                if (optional or isMember) and forceOwningType:
+                    typeDecl = "RefPtr<%s>"
+                else:
+                    typeDecl = "%s*"
+            else:
+                if optional or isMember:
+                    if forceOwningType:
+                        typeDecl = "OwningNonNull<%s>"
+                    else:
+                        typeDecl = "NonNull<%s>"
+                else:
+                    typeDecl = "%s&"
+            return ((typeDecl %
+                     self.descriptorProvider.getDescriptor(iface.identifier.name).prettyNativeType),
+                    False, False)
+
+        if type.isSpiderMonkeyInterface():
+            if not self.typedArraysAreStructs:
+                return "JS::Handle<JSObject*>", False, False
+
+            # Unroll for the name, in case we're nullable.
+            return type.unroll().name, True, True
+
+        if type.isDOMString() or type.isUSVString():
+            if isMember:
+                declType = "nsString"
+            else:
+                declType = "nsAString"
+            return declType, True, False
+
+        if type.isByteString():
+            declType = "nsCString"
+            return declType, True, False
+
+        if type.isEnum():
+            return type.unroll().inner.identifier.name, False, True
+
+        if type.isCallback() or type.isCallbackInterface():
+            forceOwningType = optional or isMember
+            if type.nullable():
+                if forceOwningType:
+                    declType = "RefPtr<%s>"
+                else:
+                    declType = "%s*"
+            else:
+                if forceOwningType:
+                    declType = "OwningNonNull<%s>"
+                else:
+                    declType = "%s&"
+            if type.isCallback():
+                name = type.unroll().callback.identifier.name
+            else:
+                name = type.unroll().inner.identifier.name
+            return declType % name, False, False
+
+        if type.isAny():
+            # Don't do the rooting stuff for variadics for now
+            if isMember:
+                declType = "JS::Value"
+            else:
+                declType = "JS::Handle<JS::Value>"
+            return declType, False, False
+
+        if type.isObject():
+            if isMember:
+                declType = "JSObject*"
+            else:
+                declType = "JS::Handle<JSObject*>"
+            return declType, False, False
+
+        if type.isDictionary():
+            typeName = CGDictionary.makeDictionaryName(type.inner)
+            return typeName, True, True
+
+        if type.isDate():
+            return "Date", False, True
+
+        assert type.isPrimitive()
+
+        return builtinNames[type.tag()], False, True
+
+    def getArgType(self, type, optional, isMember):
+        """
+        Get the type of an argument declaration.  Returns the type CGThing, and
+        whether this should be a const ref.
+
+        isMember can be False, "Sequence", or "Variadic"
+        """
+        decl, ref, handleNullable = self.doGetArgType(type, optional, isMember)
+        decl = CGGeneric(decl)
+        if handleNullable and type.nullable():
+            decl = CGTemplatedType("Nullable", decl)
+            ref = True
+        if isMember == "Variadic":
+            arrayType = "Sequence" if self.variadicIsSequence else "nsTArray"
+            decl = CGTemplatedType(arrayType, decl)
+            ref = True
+        elif optional:
+            # Note: All variadic args claim to be optional, but we can just use
+            # empty arrays to represent them not being present.
+            decl = CGTemplatedType("Optional", decl)
+            ref = True
+        return (decl, ref)
+
+    def getArg(self, arg):
+        """
+        Get the full argument declaration for an argument
+        """
+        decl, ref = self.getArgType(arg.type, arg.canHaveMissingValue(),
+                                    "Variadic" if arg.variadic else False)
+        if ref:
+            decl = CGWrapper(decl, pre="const ", post="&")
+
+        return Argument(decl.define(), arg.identifier.name)
+
+    def arguments(self):
+        return self.member.signatures()[0][1]
+
+
+class CGExampleMethod(CGNativeMember):
+    def __init__(self, descriptor, method, signature, isConstructor, breakAfter=True):
+        CGNativeMember.__init__(self, descriptor, method,
+                                CGSpecializedMethod.makeNativeName(descriptor,
+                                                                   method),
+                                signature,
+                                descriptor.getExtendedAttributes(method),
+                                breakAfter=breakAfter,
+                                variadicIsSequence=True)
+
+    def declare(self, cgClass):
+        assert self.member.isMethod()
+        # We skip declaring ourselves if this is a maplike/setlike/iterable
+        # method, because those get implemented automatically by the binding
+        # machinery, so the implementor of the interface doesn't have to worry
+        # about it.
+        if self.member.isMaplikeOrSetlikeOrIterableMethod():
+            return ''
+        return CGNativeMember.declare(self, cgClass);
+
+    def define(self, cgClass):
+        return ''
+
+
+class CGExampleGetter(CGNativeMember):
+    def __init__(self, descriptor, attr):
+        CGNativeMember.__init__(self, descriptor, attr,
+                                CGSpecializedGetter.makeNativeName(descriptor,
+                                                                   attr),
+                                (attr.type, []),
+                                descriptor.getExtendedAttributes(attr,
+                                                                 getter=True))
+
+    def declare(self, cgClass):
+        assert self.member.isAttr()
+        # We skip declaring ourselves if this is a maplike/setlike attr (in
+        # practice, "size"), because those get implemented automatically by the
+        # binding machinery, so the implementor of the interface doesn't have to
+        # worry about it.
+        if self.member.isMaplikeOrSetlikeAttr():
+            return ''
+        return CGNativeMember.declare(self, cgClass);
+
+    def define(self, cgClass):
+        return ''
+
+
+class CGExampleSetter(CGNativeMember):
+    def __init__(self, descriptor, attr):
+        CGNativeMember.__init__(self, descriptor, attr,
+                                CGSpecializedSetter.makeNativeName(descriptor,
+                                                                   attr),
+                                (BuiltinTypes[IDLBuiltinType.Types.void],
+                                 [FakeArgument(attr.type, attr)]),
+                                descriptor.getExtendedAttributes(attr,
+                                                                 setter=True))
+
+    def define(self, cgClass):
+        return ''
+
+
+class CGBindingImplClass(CGClass):
+    """
+    Common codegen for generating a C++ implementation of a WebIDL interface
+    """
+    def __init__(self, descriptor, cgMethod, cgGetter, cgSetter, wantGetParent=True, wrapMethodName="WrapObject", skipStaticMethods=False):
+        """
+        cgMethod, cgGetter and cgSetter are classes used to codegen methods,
+        getters and setters.
+        """
+        self.descriptor = descriptor
+        self._deps = descriptor.interface.getDeps()
+
+        iface = descriptor.interface
+
+        self.methodDecls = []
+
+        def appendMethod(m, isConstructor=False):
+            sigs = m.signatures()
+            for s in sigs[:-1]:
+                # Don't put a blank line after overloads, until we
+                # get to the last one.
+                self.methodDecls.append(cgMethod(descriptor, m, s,
+                                                 isConstructor,
+                                                 breakAfter=False))
+            self.methodDecls.append(cgMethod(descriptor, m, sigs[-1],
+                                             isConstructor))
+
+        if iface.ctor():
+            appendMethod(iface.ctor(), isConstructor=True)
+        for n in iface.namedConstructors:
+            appendMethod(n, isConstructor=True)
+        for m in iface.members:
+            if m.isMethod():
+                if m.isIdentifierLess():
+                    continue
+                if not m.isStatic() or not skipStaticMethods:
+                    appendMethod(m)
+            elif m.isAttr():
+                self.methodDecls.append(cgGetter(descriptor, m))
+                if not m.readonly:
+                    self.methodDecls.append(cgSetter(descriptor, m))
+
+        # Now do the special operations
+        def appendSpecialOperation(name, op):
+            if op is None:
+                return
+            if name == "IndexedCreator" or name == "NamedCreator":
+                # These are identical to the setters
+                return
+            assert len(op.signatures()) == 1
+            returnType, args = op.signatures()[0]
+            # Make a copy of the args, since we plan to modify them.
+            args = list(args)
+            if op.isGetter() or op.isDeleter():
+                # This is a total hack.  The '&' belongs with the
+                # type, not the name!  But it works, and is simpler
+                # than trying to somehow make this pretty.
+                args.append(FakeArgument(BuiltinTypes[IDLBuiltinType.Types.boolean],
+                                         op, name="&found"))
+            if name == "Stringifier":
+                if op.isIdentifierLess():
+                    # XXXbz I wish we were consistent about our renaming here.
+                    name = "Stringify"
+                else:
+                    # We already added this method
+                    return
+            if name == "LegacyCaller":
+                if op.isIdentifierLess():
+                    # XXXbz I wish we were consistent about our renaming here.
+                    name = "LegacyCall"
+                else:
+                    # We already added this method
+                    return
+            if name == "Jsonifier":
+                # We already added this method
+                return
+            self.methodDecls.append(
+                CGNativeMember(descriptor, op,
+                               name,
+                               (returnType, args),
+                               descriptor.getExtendedAttributes(op)))
+        # Sort things by name so we get stable ordering in the output.
+        ops = descriptor.operations.items()
+        ops.sort(key=lambda x: x[0])
+        for name, op in ops:
+            appendSpecialOperation(name, op)
+        # If we support indexed properties, then we need a Length()
+        # method so we know which indices are supported.
+        if descriptor.supportsIndexedProperties():
+            # But we don't need it if we already have an infallible
+            # "length" attribute, which we often do.
+            haveLengthAttr = any(
+                m for m in iface.members if m.isAttr() and
+                CGSpecializedGetter.makeNativeName(descriptor, m) == "Length")
+            if not haveLengthAttr:
+                self.methodDecls.append(
+                    CGNativeMember(descriptor, FakeMember(),
+                                   "Length",
+                                   (BuiltinTypes[IDLBuiltinType.Types.unsigned_long],
+                                    []),
+                                   {"infallible": True}))
+        # And if we support named properties we need to be able to
+        # enumerate the supported names.
+        if descriptor.supportsNamedProperties():
+            self.methodDecls.append(
+                CGNativeMember(
+                    descriptor, FakeMember(),
+                    "GetSupportedNames",
+                    (IDLSequenceType(None,
+                                     BuiltinTypes[IDLBuiltinType.Types.domstring]),
+                     []),
+                    {"infallible": True}))
+
+        wrapArgs = [Argument('JSContext*', 'aCx'),
+                    Argument('JS::Handle<JSObject*>', 'aGivenProto')]
+        if not descriptor.wrapperCache:
+            wrapReturnType = "bool"
+            wrapArgs.append(Argument('JS::MutableHandle<JSObject*>',
+                                     'aReflector'))
+        else:
+            wrapReturnType = "JSObject*"
+        self.methodDecls.insert(0,
+                                ClassMethod(wrapMethodName, wrapReturnType,
+                                            wrapArgs, virtual=descriptor.wrapperCache,
+                                            breakAfterReturnDecl=" ",
+                                            override=descriptor.wrapperCache,
+                                            body=self.getWrapObjectBody()))
+        if wantGetParent:
+            self.methodDecls.insert(0,
+                                    ClassMethod("GetParentObject",
+                                                self.getGetParentObjectReturnType(),
+                                                [], const=True,
+                                                breakAfterReturnDecl=" ",
+                                                body=self.getGetParentObjectBody()))
+
+        # Invoke  CGClass.__init__ in any subclasses afterwards to do the actual codegen.
+
+    def getWrapObjectBody(self):
+        return None
+
+    def getGetParentObjectReturnType(self):
+        return ("// TODO: return something sensible here, and change the return type\n"
+                "%s*" % self.descriptor.nativeType.split('::')[-1])
+
+    def getGetParentObjectBody(self):
+        return None
+
+    def deps(self):
+        return self._deps
+
+
+class CGExampleClass(CGBindingImplClass):
+    """
+    Codegen for the actual example class implementation for this descriptor
+    """
+    def __init__(self, descriptor):
+        CGBindingImplClass.__init__(self, descriptor,
+                                    CGExampleMethod, CGExampleGetter, CGExampleSetter,
+                                    wantGetParent=descriptor.wrapperCache)
+
+        self.parentIface = descriptor.interface.parent
+        if self.parentIface:
+            self.parentDesc = descriptor.getDescriptor(
+                self.parentIface.identifier.name)
+            bases = [ClassBase(self.nativeLeafName(self.parentDesc))]
+        else:
+            bases = [ClassBase("nsISupports /* or NonRefcountedDOMObject if this is a non-refcounted object */")]
+            if descriptor.wrapperCache:
+                bases.append(ClassBase("nsWrapperCache /* Change wrapperCache in the binding configuration if you don't want this */"))
+
+        destructorVisibility = "protected"
+        if self.parentIface:
+            extradeclarations = (
+                "public:\n"
+                "  NS_DECL_ISUPPORTS_INHERITED\n"
+                "  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(%s, %s)\n"
+                "\n" % (self.nativeLeafName(descriptor),
+                        self.nativeLeafName(self.parentDesc)))
+        else:
+            extradeclarations = (
+                "public:\n"
+                "  NS_DECL_CYCLE_COLLECTING_ISUPPORTS\n"
+                "  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(%s)\n"
+                "\n" % self.nativeLeafName(descriptor))
+
+        if descriptor.interface.hasChildInterfaces():
+            decorators = ""
+        else:
+            decorators = "final"
+
+        CGClass.__init__(self, self.nativeLeafName(descriptor),
+                         bases=bases,
+                         constructors=[ClassConstructor([],
+                                                        visibility="public")],
+                         destructor=ClassDestructor(visibility=destructorVisibility),
+                         methods=self.methodDecls,
+                         decorators=decorators,
+                         extradeclarations=extradeclarations)
+
+    def define(self):
+        # Just override CGClass and do our own thing
+        ctordtor = dedent("""
+            ${nativeType}::${nativeType}()
+            {
+                // Add |MOZ_COUNT_CTOR(${nativeType});| for a non-refcounted object.
+            }
+
+            ${nativeType}::~${nativeType}()
+            {
+                // Add |MOZ_COUNT_DTOR(${nativeType});| for a non-refcounted object.
+            }
+            """)
+
+        if self.parentIface:
+            ccImpl = dedent("""
+
+                // Only needed for refcounted objects.
+                # error "If you don't have members that need cycle collection,
+                # then remove all the cycle collection bits from this
+                # implementation and the corresponding header.  If you do, you
+                # want NS_IMPL_CYCLE_COLLECTION_INHERITED(${nativeType},
+                # ${parentType}, your, members, here)"
+                NS_IMPL_ADDREF_INHERITED(${nativeType}, ${parentType})
+                NS_IMPL_RELEASE_INHERITED(${nativeType}, ${parentType})
+                NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(${nativeType})
+                NS_INTERFACE_MAP_END_INHERITING(${parentType})
+
+                """)
+        else:
+            ccImpl = dedent("""
+
+                // Only needed for refcounted objects.
+                NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE_0(${nativeType})
+                NS_IMPL_CYCLE_COLLECTING_ADDREF(${nativeType})
+                NS_IMPL_CYCLE_COLLECTING_RELEASE(${nativeType})
+                NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(${nativeType})
+                  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+                  NS_INTERFACE_MAP_ENTRY(nsISupports)
+                NS_INTERFACE_MAP_END
+
+                """)
+
+        if self.descriptor.wrapperCache:
+            reflectorArg = ""
+            reflectorPassArg = ""
+            returnType = "JSObject*"
+        else:
+            reflectorArg = ", JS::MutableHandle<JSObject*> aReflector"
+            reflectorPassArg = ", aReflector"
+            returnType = "bool"
+        classImpl = ccImpl + ctordtor + "\n" + dedent("""
+            ${returnType}
+            ${nativeType}::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto${reflectorArg})
+            {
+              return ${ifaceName}Binding::Wrap(aCx, this, aGivenProto${reflectorPassArg});
+            }
+
+            """)
+        return string.Template(classImpl).substitute(
+            ifaceName=self.descriptor.name,
+            nativeType=self.nativeLeafName(self.descriptor),
+            parentType=self.nativeLeafName(self.parentDesc) if self.parentIface else "",
+            returnType=returnType,
+            reflectorArg=reflectorArg,
+            reflectorPassArg=reflectorPassArg)
+
+    @staticmethod
+    def nativeLeafName(descriptor):
+        return descriptor.nativeType.split('::')[-1]
+
+
+class CGExampleRoot(CGThing):
+    """
+    Root codegen class for example implementation generation.  Instantiate the
+    class and call declare or define to generate header or cpp code,
+    respectively.
+    """
+    def __init__(self, config, interfaceName):
+        descriptor = config.getDescriptor(interfaceName)
+
+        self.root = CGWrapper(CGExampleClass(descriptor),
+                              pre="\n", post="\n")
+
+        self.root = CGNamespace.build(["mozilla", "dom"], self.root)
+
+        builder = ForwardDeclarationBuilder()
+        for member in descriptor.interface.members:
+            if not member.isAttr() and not member.isMethod():
+                continue
+            if member.isStatic():
+                builder.addInMozillaDom("GlobalObject")
+            if member.isAttr() and not member.isMaplikeOrSetlikeAttr():
+                builder.forwardDeclareForType(member.type, config)
+            else:
+                assert member.isMethod()
+                if not member.isMaplikeOrSetlikeOrIterableMethod():
+                    for sig in member.signatures():
+                        builder.forwardDeclareForType(sig[0], config)
+                        for arg in sig[1]:
+                            builder.forwardDeclareForType(arg.type, config)
+
+        self.root = CGList([builder.build(),
+                            self.root], "\n")
+
+        # Throw in our #includes
+        self.root = CGHeaders([], [], [], [],
+                              ["nsWrapperCache.h",
+                               "nsCycleCollectionParticipant.h",
+                               "mozilla/Attributes.h",
+                               "mozilla/ErrorResult.h",
+                               "mozilla/dom/BindingDeclarations.h",
+                               "js/TypeDecls.h"],
+                              ["mozilla/dom/%s.h" % interfaceName,
+                               ("mozilla/dom/%s" %
+                                CGHeaders.getDeclarationFilename(descriptor.interface))], "", self.root)
+
+        # And now some include guards
+        self.root = CGIncludeGuard(interfaceName, self.root)
+
+        # And our license block comes before everything else
+        self.root = CGWrapper(self.root, pre=dedent("""
+            /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+            /* vim:set ts=2 sw=2 sts=2 et cindent: */
+            /* This Source Code Form is subject to the terms of the Mozilla Public
+             * License, v. 2.0. If a copy of the MPL was not distributed with this
+             * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+            """))
+
+    def declare(self):
+        return self.root.declare()
+
+    def define(self):
+        return self.root.define()
+
+
+def jsImplName(name):
+    return name + "JSImpl"
+
+
+class CGJSImplMember(CGNativeMember):
+    """
+    Base class for generating code for the members of the implementation class
+    for a JS-implemented WebIDL interface.
+    """
+    def __init__(self, descriptorProvider, member, name, signature,
+                 extendedAttrs, breakAfter=True, passJSBitsAsNeeded=True,
+                 visibility="public", variadicIsSequence=False,
+                 virtual=False, override=False):
+        CGNativeMember.__init__(self, descriptorProvider, member, name,
+                                signature, extendedAttrs, breakAfter=breakAfter,
+                                passJSBitsAsNeeded=passJSBitsAsNeeded,
+                                visibility=visibility,
+                                variadicIsSequence=variadicIsSequence,
+                                virtual=virtual,
+                                override=override)
+        self.body = self.getImpl()
+
+    def getArgs(self, returnType, argList):
+        args = CGNativeMember.getArgs(self, returnType, argList)
+        args.append(Argument("JSCompartment*", "aCompartment", "nullptr"))
+        return args
+
+
+class CGJSImplMethod(CGJSImplMember):
+    """
+    Class for generating code for the methods for a JS-implemented WebIDL
+    interface.
+    """
+    def __init__(self, descriptor, method, signature, isConstructor, breakAfter=True):
+        virtual = False
+        override = False
+        if (method.identifier.name == "eventListenerWasAdded" or
+            method.identifier.name == "eventListenerWasRemoved"):
+            virtual = True
+            override = True
+
+        self.signature = signature
+        self.descriptor = descriptor
+        self.isConstructor = isConstructor
+        CGJSImplMember.__init__(self, descriptor, method,
+                                CGSpecializedMethod.makeNativeName(descriptor,
+                                                                   method),
+                                signature,
+                                descriptor.getExtendedAttributes(method),
+                                breakAfter=breakAfter,
+                                variadicIsSequence=True,
+                                passJSBitsAsNeeded=False,
+                                virtual=virtual,
+                                override=override)
+
+    def getArgs(self, returnType, argList):
+        if self.isConstructor:
+            # Skip the JSCompartment bits for constructors; it's handled
+            # manually in getImpl.
+            return CGNativeMember.getArgs(self, returnType, argList)
+        return CGJSImplMember.getArgs(self, returnType, argList)
+
+    def getImpl(self):
+        args = self.getArgs(self.signature[0], self.signature[1])
+        if not self.isConstructor:
+            return 'return mImpl->%s(%s);\n' % (self.name, ", ".join(arg.name for arg in args))
+
+        assert self.descriptor.interface.isJSImplemented()
+        if self.name != 'Constructor':
+            raise TypeError("Named constructors are not supported for JS implemented WebIDL. See bug 851287.")
+        if len(self.signature[1]) != 0:
+            # The first two arguments to the constructor implementation are not
+            # arguments to the WebIDL constructor, so don't pass them to __Init()
+            assert args[0].argType == 'const GlobalObject&'
+            assert args[1].argType == 'JSContext*'
+            constructorArgs = [arg.name for arg in args[2:]]
+            constructorArgs.append("js::GetObjectCompartment(scopeObj)")
+            initCall = fill(
+                """
+                // Wrap the object before calling __Init so that __DOM_IMPL__ is available.
+                JS::Rooted<JSObject*> scopeObj(cx, globalHolder->GetGlobalJSObject());
+                MOZ_ASSERT(js::IsObjectInContextCompartment(scopeObj, cx));
+                JS::Rooted<JS::Value> wrappedVal(cx);
+                if (!GetOrCreateDOMReflector(cx, impl, &wrappedVal)) {
+                  //XXX Assertion disabled for now, see bug 991271.
+                  MOZ_ASSERT(true || JS_IsExceptionPending(cx));
+                  aRv.Throw(NS_ERROR_UNEXPECTED);
+                  return nullptr;
+                }
+                // Initialize the object with the constructor arguments.
+                impl->mImpl->__Init(${args});
+                if (aRv.Failed()) {
+                  return nullptr;
+                }
+                """,
+                args=", ".join(constructorArgs))
+        else:
+            initCall = ""
+        return genConstructorBody(self.descriptor, initCall)
+
+
+def genConstructorBody(descriptor, initCall=""):
+    return fill(
+        """
+        JS::Rooted<JSObject*> jsImplObj(cx);
+        nsCOMPtr<nsIGlobalObject> globalHolder =
+          ConstructJSImplementation("${contractId}", global, &jsImplObj, aRv);
+        if (aRv.Failed()) {
+          return nullptr;
+        }
+        // Build the C++ implementation.
+        RefPtr<${implClass}> impl = new ${implClass}(jsImplObj, globalHolder);
+        $*{initCall}
+        return impl.forget();
+        """,
+        contractId=descriptor.interface.getJSImplementation(),
+        implClass=descriptor.name,
+        initCall=initCall)
+
+
+# We're always fallible
+def callbackGetterName(attr, descriptor):
+    return "Get" + MakeNativeName(
+        descriptor.binaryNameFor(attr.identifier.name))
+
+
+def callbackSetterName(attr, descriptor):
+    return "Set" + MakeNativeName(
+        descriptor.binaryNameFor(attr.identifier.name))
+
+
+class CGJSImplClearCachedValueMethod(CGAbstractBindingMethod):
+    def __init__(self, descriptor, attr):
+        if attr.getExtendedAttribute("StoreInSlot"):
+            raise TypeError("[StoreInSlot] is not supported for JS-implemented WebIDL. See bug 1056325.")
+
+        CGAbstractBindingMethod.__init__(self, descriptor,
+                                         MakeJSImplClearCachedValueNativeName(attr),
+                                         JSNativeArguments())
+        self.attr = attr
+
+    def generate_code(self):
+        return CGGeneric(fill(
+            """
+            ${bindingNamespace}::${fnName}(self);
+            args.rval().setUndefined();
+            return true;
+            """,
+            bindingNamespace=toBindingNamespace(self.descriptor.name),
+            fnName=MakeClearCachedValueNativeName(self.attr)))
+
+
+class CGJSImplGetter(CGJSImplMember):
+    """
+    Class for generating code for the getters of attributes for a JS-implemented
+    WebIDL interface.
+    """
+    def __init__(self, descriptor, attr):
+        CGJSImplMember.__init__(self, descriptor, attr,
+                                CGSpecializedGetter.makeNativeName(descriptor,
+                                                                   attr),
+                                (attr.type, []),
+                                descriptor.getExtendedAttributes(attr,
+                                                                 getter=True),
+                                passJSBitsAsNeeded=False)
+
+    def getImpl(self):
+        callbackArgs = [arg.name for arg in self.getArgs(self.member.type, [])]
+        return 'return mImpl->%s(%s);\n' % (
+            callbackGetterName(self.member, self.descriptorProvider),
+            ", ".join(callbackArgs))
+
+
+class CGJSImplSetter(CGJSImplMember):
+    """
+    Class for generating code for the setters of attributes for a JS-implemented
+    WebIDL interface.
+    """
+    def __init__(self, descriptor, attr):
+        CGJSImplMember.__init__(self, descriptor, attr,
+                                CGSpecializedSetter.makeNativeName(descriptor,
+                                                                   attr),
+                                (BuiltinTypes[IDLBuiltinType.Types.void],
+                                 [FakeArgument(attr.type, attr)]),
+                                descriptor.getExtendedAttributes(attr,
+                                                                 setter=True),
+                                passJSBitsAsNeeded=False)
+
+    def getImpl(self):
+        callbackArgs = [arg.name for arg in self.getArgs(BuiltinTypes[IDLBuiltinType.Types.void],
+                                                         [FakeArgument(self.member.type, self.member)])]
+        return 'mImpl->%s(%s);\n' % (
+            callbackSetterName(self.member, self.descriptorProvider),
+            ", ".join(callbackArgs))
+
+
+class CGJSImplClass(CGBindingImplClass):
+    def __init__(self, descriptor):
+        CGBindingImplClass.__init__(self, descriptor, CGJSImplMethod, CGJSImplGetter, CGJSImplSetter, skipStaticMethods=True)
+
+        if descriptor.interface.parent:
+            parentClass = descriptor.getDescriptor(
+                descriptor.interface.parent.identifier.name).jsImplParent
+            baseClasses = [ClassBase(parentClass)]
+            isupportsDecl = "NS_DECL_ISUPPORTS_INHERITED\n"
+            ccDecl = ("NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(%s, %s)\n" %
+                      (descriptor.name, parentClass))
+            constructorBody = dedent("""
+                // Make sure we're an nsWrapperCache already
+                MOZ_ASSERT(static_cast<nsWrapperCache*>(this));
+                // And that our ancestor has not called SetIsNotDOMBinding()
+                MOZ_ASSERT(IsDOMBinding());
+                """)
+            extradefinitions = fill(
+                """
+                NS_IMPL_CYCLE_COLLECTION_INHERITED(${ifaceName}, ${parentClass}, mImpl, mParent)
+                NS_IMPL_ADDREF_INHERITED(${ifaceName}, ${parentClass})
+                NS_IMPL_RELEASE_INHERITED(${ifaceName}, ${parentClass})
+                NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(${ifaceName})
+                NS_INTERFACE_MAP_END_INHERITING(${parentClass})
+                """,
+                ifaceName=self.descriptor.name,
+                parentClass=parentClass)
+        else:
+            baseClasses = [ClassBase("nsSupportsWeakReference"),
+                           ClassBase("nsWrapperCache")]
+            isupportsDecl = "NS_DECL_CYCLE_COLLECTING_ISUPPORTS\n"
+            ccDecl = ("NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(%s)\n" %
+                      descriptor.name)
+            extradefinitions = fill(
+                """
+                NS_IMPL_CYCLE_COLLECTION_CLASS(${ifaceName})
+                NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(${ifaceName})
+                  NS_IMPL_CYCLE_COLLECTION_UNLINK(mImpl)
+                  NS_IMPL_CYCLE_COLLECTION_UNLINK(mParent)
+                  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+                  tmp->ClearWeakReferences();
+                NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+                NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(${ifaceName})
+                  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mImpl)
+                  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mParent)
+                  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+                NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+                NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(${ifaceName})
+                NS_IMPL_CYCLE_COLLECTING_ADDREF(${ifaceName})
+                NS_IMPL_CYCLE_COLLECTING_RELEASE(${ifaceName})
+                NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(${ifaceName})
+                  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+                  NS_INTERFACE_MAP_ENTRY(nsISupports)
+                  NS_INTERFACE_MAP_ENTRY(nsISupportsWeakReference)
+                NS_INTERFACE_MAP_END
+                """,
+                ifaceName=self.descriptor.name)
+
+        extradeclarations = fill(
+            """
+            public:
+              $*{isupportsDecl}
+              $*{ccDecl}
+
+            private:
+              RefPtr<${jsImplName}> mImpl;
+              nsCOMPtr<nsISupports> mParent;
+
+            """,
+            isupportsDecl=isupportsDecl,
+            ccDecl=ccDecl,
+            jsImplName=jsImplName(descriptor.name))
+
+        if descriptor.interface.hasChildInterfaces():
+            decorators = ""
+            # We need a protected virtual destructor our subclasses can use
+            destructor = ClassDestructor(virtual=True, visibility="protected")
+        else:
+            decorators = "final"
+            destructor = ClassDestructor(virtual=False, visibility="private")
+
+        baseConstructors = [
+            ("mImpl(new %s(nullptr, aJSImplObject, /* aIncumbentGlobal = */ nullptr))" %
+             jsImplName(descriptor.name)),
+            "mParent(aParent)"]
+        parentInterface = descriptor.interface.parent
+        while parentInterface:
+            if parentInterface.isJSImplemented():
+                baseConstructors.insert(
+                    0, "%s(aJSImplObject, aParent)" % parentClass)
+                break
+            parentInterface = parentInterface.parent
+        if not parentInterface and descriptor.interface.parent:
+            # We only have C++ ancestors, so only pass along the window
+            baseConstructors.insert(0,
+                                    "%s(aParent)" % parentClass)
+
+        constructor = ClassConstructor(
+            [Argument("JS::Handle<JSObject*>", "aJSImplObject"),
+             Argument("nsIGlobalObject*", "aParent")],
+            visibility="public",
+            baseConstructors=baseConstructors)
+
+        self.methodDecls.append(
+            ClassMethod("_Create",
+                        "bool",
+                        JSNativeArguments(),
+                        static=True,
+                        body=self.getCreateFromExistingBody()))
+
+        CGClass.__init__(self, descriptor.name,
+                         bases=baseClasses,
+                         constructors=[constructor],
+                         destructor=destructor,
+                         methods=self.methodDecls,
+                         decorators=decorators,
+                         extradeclarations=extradeclarations,
+                         extradefinitions=extradefinitions)
+
+    def getWrapObjectBody(self):
+        return fill(
+            """
+            JS::Rooted<JSObject*> obj(aCx, ${name}Binding::Wrap(aCx, this, aGivenProto));
+            if (!obj) {
+              return nullptr;
+            }
+
+            // Now define it on our chrome object
+            JSAutoCompartment ac(aCx, mImpl->Callback());
+            if (!JS_WrapObject(aCx, &obj)) {
+              return nullptr;
+            }
+            if (!JS_DefineProperty(aCx, mImpl->Callback(), "__DOM_IMPL__", obj, 0)) {
+              return nullptr;
+            }
+            return obj;
+            """,
+            name=self.descriptor.name)
+
+    def getGetParentObjectReturnType(self):
+        return "nsISupports*"
+
+    def getGetParentObjectBody(self):
+        return "return mParent;\n"
+
+    def getCreateFromExistingBody(self):
+        # XXXbz we could try to get parts of this (e.g. the argument
+        # conversions) auto-generated by somehow creating an IDLMethod and
+        # adding it to our interface, but we'd still need to special-case the
+        # implementation slightly to have it not try to forward to the JS
+        # object...
+        return fill(
+            """
+            JS::CallArgs args = JS::CallArgsFromVp(argc, vp);
+            if (args.length() < 2) {
+              return ThrowErrorMessage(cx, MSG_MISSING_ARGUMENTS, "${ifaceName}._create");
+            }
+            if (!args[0].isObject()) {
+              return ThrowErrorMessage(cx, MSG_NOT_OBJECT, "Argument 1 of ${ifaceName}._create");
+            }
+            if (!args[1].isObject()) {
+              return ThrowErrorMessage(cx, MSG_NOT_OBJECT, "Argument 2 of ${ifaceName}._create");
+            }
+
+            // GlobalObject will go through wrappers as needed for us, and
+            // is simpler than the right UnwrapArg incantation.
+            GlobalObject global(cx, &args[0].toObject());
+            if (global.Failed()) {
+              return false;
+            }
+            nsCOMPtr<nsIGlobalObject> globalHolder = do_QueryInterface(global.GetAsSupports());
+            MOZ_ASSERT(globalHolder);
+            JS::Rooted<JSObject*> arg(cx, &args[1].toObject());
+            RefPtr<${implName}> impl = new ${implName}(arg, globalHolder);
+            MOZ_ASSERT(js::IsObjectInContextCompartment(arg, cx));
+            return GetOrCreateDOMReflector(cx, impl, args.rval());
+            """,
+            ifaceName=self.descriptor.interface.identifier.name,
+            implName=self.descriptor.name)
+
+
+def isJSImplementedDescriptor(descriptorProvider):
+    return (isinstance(descriptorProvider, Descriptor) and
+            descriptorProvider.interface.isJSImplemented())
+
+
+class CGCallback(CGClass):
+    def __init__(self, idlObject, descriptorProvider, baseName, methods,
+                 getters=[], setters=[]):
+        self.baseName = baseName
+        self._deps = idlObject.getDeps()
+        self.idlObject = idlObject
+        self.name = idlObject.identifier.name
+        if isJSImplementedDescriptor(descriptorProvider):
+            self.name = jsImplName(self.name)
+        # For our public methods that needThisHandling we want most of the
+        # same args and the same return type as what CallbackMember
+        # generates.  So we want to take advantage of all its
+        # CGNativeMember infrastructure, but that infrastructure can't deal
+        # with templates and most especially template arguments.  So just
+        # cheat and have CallbackMember compute all those things for us.
+        realMethods = []
+        for method in methods:
+            if not isinstance(method, CallbackMember) or not method.needThisHandling:
+                realMethods.append(method)
+            else:
+                realMethods.extend(self.getMethodImpls(method))
+        realMethods.append(
+            ClassMethod("operator==", "bool",
+                        [Argument("const %s&" % self.name, "aOther")],
+                        inline=True, bodyInHeader=True,
+                        const=True,
+                        body=("return %s::operator==(aOther);\n" % baseName)))
+        CGClass.__init__(self, self.name,
+                         bases=[ClassBase(baseName)],
+                         constructors=self.getConstructors(),
+                         methods=realMethods+getters+setters)
+
+    def getConstructors(self):
+        if (not self.idlObject.isInterface() and
+            not self.idlObject._treatNonObjectAsNull):
+            body = "MOZ_ASSERT(JS::IsCallable(mCallback));\n"
+        else:
+            # Not much we can assert about it, other than not being null, and
+            # CallbackObject does that already.
+            body = ""
+        return [
+            ClassConstructor(
+                [Argument("JSContext*", "aCx"),
+                 Argument("JS::Handle<JSObject*>", "aCallback"),
+                 Argument("nsIGlobalObject*", "aIncumbentGlobal")],
+                bodyInHeader=True,
+                visibility="public",
+                explicit=True,
+                baseConstructors=[
+                    "%s(aCx, aCallback, aIncumbentGlobal)" % self.baseName,
+                ],
+                body=body),
+            ClassConstructor(
+                [Argument("JSContext*", "aCx"),
+                 Argument("JS::Handle<JSObject*>", "aCallback"),
+                 Argument("nsIGlobalObject*", "aIncumbentGlobal"),
+                 Argument("const FastCallbackConstructor&", "")],
+                bodyInHeader=True,
+                visibility="public",
+                explicit=True,
+                baseConstructors=[
+                    "%s(aCx, aCallback, aIncumbentGlobal, FastCallbackConstructor())" % self.baseName,
+                ],
+                body=body),
+            ClassConstructor(
+                [Argument("JS::Handle<JSObject*>", "aCallback"),
+                 Argument("JS::Handle<JSObject*>", "aAsyncStack"),
+                 Argument("nsIGlobalObject*", "aIncumbentGlobal")],
+                bodyInHeader=True,
+                visibility="public",
+                explicit=True,
+                baseConstructors=[
+                    "%s(aCallback, aAsyncStack, aIncumbentGlobal)" % self.baseName,
+                ],
+                body=body)]
+
+    def getMethodImpls(self, method):
+        assert method.needThisHandling
+        args = list(method.args)
+        # Strip out the JSContext*/JSObject* args
+        # that got added.
+        assert args[0].name == "cx" and args[0].argType == "JSContext*"
+        assert args[1].name == "aThisVal" and args[1].argType == "JS::Handle<JS::Value>"
+        args = args[2:]
+
+        # Now remember which index the ErrorResult argument is at;
+        # we'll need this below.
+        assert args[-1].name == "aRv" and args[-1].argType == "ErrorResult&"
+        rvIndex = len(args) - 1
+        assert rvIndex >= 0
+
+        # Record the names of all the arguments, so we can use them when we call
+        # the private method.
+        argnames = [arg.name for arg in args]
+        argnamesWithThis = ["s.GetContext()", "thisValJS"] + argnames
+        argnamesWithoutThis = ["s.GetContext()", "JS::UndefinedHandleValue"] + argnames
+        # Now that we've recorded the argnames for our call to our private
+        # method, insert our optional argument for the execution reason.
+        args.append(Argument("const char*", "aExecutionReason",
+                             "nullptr"))
+
+        # Make copies of the arg list for the two "without rv" overloads.  Note
+        # that those don't need aExceptionHandling or aCompartment arguments
+        # because those would make not sense anyway: the only sane thing to do
+        # with exceptions in the "without rv" cases is to report them.
+        argsWithoutRv = list(args)
+        argsWithoutRv.pop(rvIndex)
+        argsWithoutThisAndRv = list(argsWithoutRv)
+
+        # Add the potional argument for deciding whether the CallSetup should
+        # re-throw exceptions on aRv.
+        args.append(Argument("ExceptionHandling", "aExceptionHandling",
+                             "eReportExceptions"))
+        # And the argument for communicating when exceptions should really be
+        # rethrown.  In particular, even when aExceptionHandling is
+        # eRethrowExceptions they won't get rethrown if aCompartment is provided
+        # and its principal doesn't subsume either the callback or the
+        # exception.
+        args.append(Argument("JSCompartment*", "aCompartment", "nullptr"))
+        # And now insert our template argument.
+        argsWithoutThis = list(args)
+        args.insert(0, Argument("const T&",  "thisVal"))
+        argsWithoutRv.insert(0, Argument("const T&",  "thisVal"))
+
+        argnamesWithoutThisAndRv = [arg.name for arg in argsWithoutThisAndRv]
+        argnamesWithoutThisAndRv.insert(rvIndex, "rv");
+        # If we just leave things like that, and have no actual arguments in the
+        # IDL, we will end up trying to call the templated "without rv" overload
+        # with "rv" as the thisVal.  That's no good.  So explicitly append the
+        # aExceptionHandling and aCompartment values we need to end up matching
+        # the signature of our non-templated "with rv" overload.
+        argnamesWithoutThisAndRv.extend(["eReportExceptions", "nullptr"])
+
+        argnamesWithoutRv = [arg.name for arg in argsWithoutRv]
+        # Note that we need to insert at rvIndex + 1, since we inserted a
+        # thisVal arg at the start.
+        argnamesWithoutRv.insert(rvIndex + 1, "rv")
+
+        errorReturn = method.getDefaultRetval()
+
+        setupCall = fill(
+            """
+            if (!aExecutionReason) {
+              aExecutionReason = "${executionReason}";
+            }
+            CallSetup s(this, aRv, aExecutionReason, aExceptionHandling, aCompartment);
+            if (!s.GetContext()) {
+              MOZ_ASSERT(aRv.Failed());
+              return${errorReturn};
+            }
+            """,
+            errorReturn=errorReturn,
+            executionReason=method.getPrettyName())
+
+        bodyWithThis = fill(
+            """
+            $*{setupCall}
+            JS::Rooted<JS::Value> thisValJS(s.GetContext());
+            if (!ToJSValue(s.GetContext(), thisVal, &thisValJS)) {
+              aRv.Throw(NS_ERROR_FAILURE);
+              return${errorReturn};
+            }
+            return ${methodName}(${callArgs});
+            """,
+            setupCall=setupCall,
+            errorReturn=errorReturn,
+            methodName=method.name,
+            callArgs=", ".join(argnamesWithThis))
+        bodyWithoutThis = fill(
+            """
+            $*{setupCall}
+            return ${methodName}(${callArgs});
+            """,
+            setupCall=setupCall,
+            errorReturn=errorReturn,
+            methodName=method.name,
+            callArgs=", ".join(argnamesWithoutThis))
+        bodyWithThisWithoutRv = fill(
+            """
+            IgnoredErrorResult rv;
+            return ${methodName}(${callArgs});
+            """,
+            methodName=method.name,
+            callArgs=", ".join(argnamesWithoutRv))
+        bodyWithoutThisAndRv = fill(
+            """
+            IgnoredErrorResult rv;
+            return ${methodName}(${callArgs});
+            """,
+            methodName=method.name,
+            callArgs=", ".join(argnamesWithoutThisAndRv))
+
+        return [ClassMethod(method.name, method.returnType, args,
+                            bodyInHeader=True,
+                            templateArgs=["typename T"],
+                            body=bodyWithThis),
+                ClassMethod(method.name, method.returnType, argsWithoutThis,
+                            bodyInHeader=True,
+                            body=bodyWithoutThis),
+                ClassMethod(method.name, method.returnType, argsWithoutRv,
+                            bodyInHeader=True,
+                            templateArgs=["typename T"],
+                            body=bodyWithThisWithoutRv),
+                ClassMethod(method.name, method.returnType, argsWithoutThisAndRv,
+                            bodyInHeader=True,
+                            body=bodyWithoutThisAndRv),
+                method]
+
+    def deps(self):
+        return self._deps
+
+
+class CGCallbackFunction(CGCallback):
+    def __init__(self, callback, descriptorProvider):
+        self.callback = callback
+        CGCallback.__init__(self, callback, descriptorProvider,
+                            "CallbackFunction",
+                            methods=[CallCallback(callback, descriptorProvider)])
+
+    def getConstructors(self):
+        return CGCallback.getConstructors(self) + [
+            ClassConstructor(
+                [Argument("CallbackFunction*", "aOther")],
+                bodyInHeader=True,
+                visibility="public",
+                explicit=True,
+                baseConstructors=["CallbackFunction(aOther)"])]
+
+
+class CGFastCallback(CGClass):
+    def __init__(self, idlObject):
+        self._deps = idlObject.getDeps()
+        baseName = idlObject.identifier.name
+        constructor = ClassConstructor(
+            [Argument("JSContext*", "aCx"),
+             Argument("JS::Handle<JSObject*>", "aCallback"),
+             Argument("nsIGlobalObject*", "aIncumbentGlobal")],
+            bodyInHeader=True,
+            visibility="public",
+            explicit=True,
+            baseConstructors=[
+                "%s(aCx, aCallback, aIncumbentGlobal, FastCallbackConstructor())" %
+                baseName,
+            ],
+            body="")
+
+        traceMethod = ClassMethod("Trace", "void",
+                                  [Argument("JSTracer*", "aTracer")],
+                                  inline=True,
+                                  bodyInHeader=True,
+                                  visibility="public",
+                                  body="%s::Trace(aTracer);\n" % baseName)
+        holdMethod = ClassMethod("HoldJSObjectsIfMoreThanOneOwner", "void",
+                                 [],
+                                 inline=True,
+                                 bodyInHeader=True,
+                                 visibility="public",
+                                 body=(
+                                     "%s::HoldJSObjectsIfMoreThanOneOwner();\n" %
+                                     baseName))
+
+        CGClass.__init__(self, "Fast%s" % baseName,
+                         bases=[ClassBase(baseName)],
+                         constructors=[constructor],
+                         methods=[traceMethod, holdMethod])
+
+    def deps(self):
+        return self._deps
+
+
+class CGCallbackInterface(CGCallback):
+    def __init__(self, descriptor, typedArraysAreStructs=False):
+        iface = descriptor.interface
+        attrs = [m for m in iface.members if m.isAttr() and not m.isStatic()]
+        getters = [CallbackGetter(a, descriptor, typedArraysAreStructs)
+                   for a in attrs]
+        setters = [CallbackSetter(a, descriptor, typedArraysAreStructs)
+                   for a in attrs if not a.readonly]
+        methods = [m for m in iface.members
+                   if m.isMethod() and not m.isStatic() and not m.isIdentifierLess()]
+        methods = [CallbackOperation(m, sig, descriptor, typedArraysAreStructs)
+                   for m in methods for sig in m.signatures()]
+        if iface.isJSImplemented() and iface.ctor():
+            sigs = descriptor.interface.ctor().signatures()
+            if len(sigs) != 1:
+                raise TypeError("We only handle one constructor.  See bug 869268.")
+            methods.append(CGJSImplInitOperation(sigs[0], descriptor))
+        if any(m.isAttr() or m.isMethod() for m in iface.members) or (iface.isJSImplemented() and iface.ctor()):
+            methods.append(initIdsClassMethod([descriptor.binaryNameFor(m.identifier.name)
+                                               for m in iface.members
+                                               if m.isAttr() or m.isMethod()] +
+                                              (["__init"] if iface.isJSImplemented() and iface.ctor() else []),
+                                              iface.identifier.name + "Atoms"))
+        CGCallback.__init__(self, iface, descriptor, "CallbackInterface",
+                            methods, getters=getters, setters=setters)
+
+
+class FakeMember():
+    def __init__(self, name=None):
+        self.treatNullAs = "Default"
+        if name is not None:
+            self.identifier = FakeIdentifier(name)
+
+    def isStatic(self):
+        return False
+
+    def isAttr(self):
+        return False
+
+    def isMethod(self):
+        return False
+
+    def getExtendedAttribute(self, name):
+        # Claim to be a [NewObject] so we can avoid the "return a raw pointer"
+        # comments CGNativeMember codegen would otherwise stick in.
+        if name == "NewObject":
+            return True
+        return None
+
+
+class CallbackMember(CGNativeMember):
+    # XXXbz It's OK to use CallbackKnownNotGray for wrapScope because
+    # CallSetup already handled the unmark-gray bits for us. we don't have
+    # anything better to use for 'obj', really...
+    def __init__(self, sig, name, descriptorProvider, needThisHandling,
+                 rethrowContentException=False, typedArraysAreStructs=False,
+                 wrapScope='CallbackKnownNotGray()'):
+        """
+        needThisHandling is True if we need to be able to accept a specified
+        thisObj, False otherwise.
+        """
+        assert not rethrowContentException or not needThisHandling
+
+        self.retvalType = sig[0]
+        self.originalSig = sig
+        args = sig[1]
+        self.argCount = len(args)
+        if self.argCount > 0:
+            # Check for variadic arguments
+            lastArg = args[self.argCount-1]
+            if lastArg.variadic:
+                self.argCountStr = ("(%d - 1) + %s.Length()" %
+                                    (self.argCount, lastArg.identifier.name))
+            else:
+                self.argCountStr = "%d" % self.argCount
+        self.needThisHandling = needThisHandling
+        # If needThisHandling, we generate ourselves as private and the caller
+        # will handle generating public versions that handle the "this" stuff.
+        visibility = "private" if needThisHandling else "public"
+        self.rethrowContentException = rethrowContentException
+
+        self.wrapScope = wrapScope
+        # We don't care, for callback codegen, whether our original member was
+        # a method or attribute or whatnot.  Just always pass FakeMember()
+        # here.
+        CGNativeMember.__init__(self, descriptorProvider, FakeMember(),
+                                name, (self.retvalType, args),
+                                extendedAttrs={},
+                                passJSBitsAsNeeded=False,
+                                visibility=visibility,
+                                typedArraysAreStructs=typedArraysAreStructs)
+        # We have to do all the generation of our body now, because
+        # the caller relies on us throwing if we can't manage it.
+        self.exceptionCode = ("aRv.Throw(NS_ERROR_UNEXPECTED);\n"
+                              "return%s;\n" % self.getDefaultRetval())
+        self.body = self.getImpl()
+
+    def getImpl(self):
+        setupCall = self.getCallSetup()
+        declRval = self.getRvalDecl()
+        if self.argCount > 0:
+            argvDecl = fill(
+                """
+                JS::AutoValueVector argv(cx);
+                if (!argv.resize(${argCount})) {
+                  aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+                  return${errorReturn};
+                }
+                """,
+                argCount=self.argCountStr,
+                errorReturn=self.getDefaultRetval())
+        else:
+            # Avoid weird 0-sized arrays
+            argvDecl = ""
+        convertArgs = self.getArgConversions()
+        doCall = self.getCall()
+        returnResult = self.getResultConversion()
+
+        return setupCall + declRval + argvDecl + convertArgs + doCall + returnResult
+
+    def getResultConversion(self):
+        replacements = {
+            "val": "rval",
+            "holderName": "rvalHolder",
+            "declName": "rvalDecl",
+            # We actually want to pass in a null scope object here, because
+            # wrapping things into our current compartment (that of mCallback)
+            # is what we want.
+            "obj": "nullptr",
+            "passedToJSImpl": "false"
+        }
+
+        if isJSImplementedDescriptor(self.descriptorProvider):
+            isCallbackReturnValue = "JSImpl"
+        else:
+            isCallbackReturnValue = "Callback"
+        sourceDescription = "return value of %s" % self.getPrettyName()
+        convertType = instantiateJSToNativeConversion(
+            getJSToNativeConversionInfo(self.retvalType,
+                                        self.descriptorProvider,
+                                        exceptionCode=self.exceptionCode,
+                                        isCallbackReturnValue=isCallbackReturnValue,
+                                        # Allow returning a callback type that
+                                        # allows non-callable objects.
+                                        allowTreatNonCallableAsNull=True,
+                                        sourceDescription=sourceDescription),
+            replacements)
+        assignRetval = string.Template(
+            self.getRetvalInfo(self.retvalType,
+                               False)[2]).substitute(replacements)
+        type = convertType.define()
+        return type + assignRetval
+
+    def getArgConversions(self):
+        # Just reget the arglist from self.originalSig, because our superclasses
+        # just have way to many members they like to clobber, so I can't find a
+        # safe member name to store it in.
+        argConversions = [self.getArgConversion(i, arg)
+                          for i, arg in enumerate(self.originalSig[1])]
+        if not argConversions:
+            return "\n"
+
+        # Do them back to front, so our argc modifications will work
+        # correctly, because we examine trailing arguments first.
+        argConversions.reverse()
+        # Wrap each one in a scope so that any locals it has don't leak out, and
+        # also so that we can just "break;" for our successCode.
+        argConversions = [CGWrapper(CGIndenter(CGGeneric(c)),
+                                    pre="do {\n",
+                                    post="} while (0);\n")
+                          for c in argConversions]
+        if self.argCount > 0:
+            argConversions.insert(0, self.getArgcDecl())
+        # And slap them together.
+        return CGList(argConversions, "\n").define() + "\n"
+
+    def getArgConversion(self, i, arg):
+        argval = arg.identifier.name
+
+        if arg.variadic:
+            argval = argval + "[idx]"
+            jsvalIndex = "%d + idx" % i
+        else:
+            jsvalIndex = "%d" % i
+            if arg.canHaveMissingValue():
+                argval += ".Value()"
+        if arg.type.isDOMString():
+            # XPConnect string-to-JS conversion wants to mutate the string.  So
+            # let's give it a string it can mutate
+            # XXXbz if we try to do a sequence of strings, this will kinda fail.
+            result = "mutableStr"
+            prepend = "nsString mutableStr(%s);\n" % argval
+        else:
+            result = argval
+            prepend = ""
+
+        try:
+            conversion = prepend + wrapForType(
+                arg.type, self.descriptorProvider,
+                {
+                    'result': result,
+                    'successCode': "continue;\n" if arg.variadic else "break;\n",
+                    'jsvalRef': "argv[%s]" % jsvalIndex,
+                    'jsvalHandle': "argv[%s]" % jsvalIndex,
+                    'obj': self.wrapScope,
+                    'returnsNewObject': False,
+                    'exceptionCode': self.exceptionCode,
+                    'typedArraysAreStructs': self.typedArraysAreStructs
+                })
+        except MethodNotNewObjectError as err:
+            raise TypeError("%s being passed as an argument to %s but is not "
+                            "wrapper cached, so can't be reliably converted to "
+                            "a JS object." %
+                            (err.typename, self.getPrettyName()))
+        if arg.variadic:
+            conversion = fill(
+                """
+                for (uint32_t idx = 0; idx < ${arg}.Length(); ++idx) {
+                  $*{conversion}
+                }
+                break;
+                """,
+                arg=arg.identifier.name,
+                conversion=conversion)
+        elif arg.canHaveMissingValue():
+            conversion = fill(
+                """
+                if (${argName}.WasPassed()) {
+                  $*{conversion}
+                } else if (argc == ${iPlus1}) {
+                  // This is our current trailing argument; reduce argc
+                  --argc;
+                } else {
+                  argv[${i}].setUndefined();
+                }
+                """,
+                argName=arg.identifier.name,
+                conversion=conversion,
+                iPlus1=i + 1,
+                i=i)
+        return conversion
+
+    def getDefaultRetval(self):
+        default = self.getRetvalInfo(self.retvalType, False)[1]
+        if len(default) != 0:
+            default = " " + default
+        return default
+
+    def getArgs(self, returnType, argList):
+        args = CGNativeMember.getArgs(self, returnType, argList)
+        if not self.needThisHandling:
+            # Since we don't need this handling, we're the actual method that
+            # will be called, so we need an aRethrowExceptions argument.
+            if not self.rethrowContentException:
+                args.append(Argument("const char*", "aExecutionReason",
+                                     "nullptr"))
+                args.append(Argument("ExceptionHandling", "aExceptionHandling",
+                                     "eReportExceptions"))
+            args.append(Argument("JSCompartment*", "aCompartment", "nullptr"))
+            return args
+        # We want to allow the caller to pass in a "this" value, as
+        # well as a JSContext.
+        return [Argument("JSContext*", "cx"),
+                Argument("JS::Handle<JS::Value>", "aThisVal")] + args
+
+    def getCallSetup(self):
+        if self.needThisHandling:
+            # It's been done for us already
+            return ""
+        callSetup = "CallSetup s(this, aRv"
+        if self.rethrowContentException:
+            # getArgs doesn't add the aExceptionHandling argument but does add
+            # aCompartment for us.
+            callSetup += ', "%s", eRethrowContentExceptions, aCompartment, /* aIsJSImplementedWebIDL = */ ' % self.getPrettyName()
+            callSetup += toStringBool(isJSImplementedDescriptor(self.descriptorProvider))
+        else:
+            callSetup += ', "%s", aExceptionHandling, aCompartment' % self.getPrettyName()
+        callSetup += ");\n"
+        return fill(
+            """
+            $*{callSetup}
+            JSContext* cx = s.GetContext();
+            if (!cx) {
+              MOZ_ASSERT(aRv.Failed());
+              return${errorReturn};
+            }
+            """,
+            callSetup=callSetup,
+            errorReturn=self.getDefaultRetval())
+
+    def getArgcDecl(self):
+        return CGGeneric("unsigned argc = %s;\n" % self.argCountStr)
+
+    @staticmethod
+    def ensureASCIIName(idlObject):
+        type = "attribute" if idlObject.isAttr() else "operation"
+        if re.match("[^\x20-\x7E]", idlObject.identifier.name):
+            raise SyntaxError('Callback %s name "%s" contains non-ASCII '
+                              "characters.  We can't handle that.  %s" %
+                              (type, idlObject.identifier.name,
+                               idlObject.location))
+        if re.match('"', idlObject.identifier.name):
+            raise SyntaxError("Callback %s name '%s' contains "
+                              "double-quote character.  We can't handle "
+                              "that.  %s" %
+                              (type, idlObject.identifier.name,
+                               idlObject.location))
+
+
+class CallbackMethod(CallbackMember):
+    def __init__(self, sig, name, descriptorProvider, needThisHandling,
+                 rethrowContentException=False, typedArraysAreStructs=False):
+        CallbackMember.__init__(self, sig, name, descriptorProvider,
+                                needThisHandling, rethrowContentException,
+                                typedArraysAreStructs=typedArraysAreStructs)
+
+    def getRvalDecl(self):
+        return "JS::Rooted<JS::Value> rval(cx, JS::UndefinedValue());\n"
+
+    def getCall(self):
+        if self.argCount > 0:
+            args = "JS::HandleValueArray::subarray(argv, 0, argc)"
+        else:
+            args = "JS::HandleValueArray::empty()"
+
+        return fill(
+            """
+            $*{declCallable}
+            $*{declThis}
+            if (${callGuard}!JS::Call(cx, ${thisVal}, callable,
+                          ${args}, &rval)) {
+              aRv.NoteJSContextException(cx);
+              return${errorReturn};
+            }
+            """,
+            declCallable=self.getCallableDecl(),
+            declThis=self.getThisDecl(),
+            callGuard=self.getCallGuard(),
+            thisVal=self.getThisVal(),
+            args=args,
+            errorReturn=self.getDefaultRetval())
+
+
+class CallCallback(CallbackMethod):
+    def __init__(self, callback, descriptorProvider):
+        self.callback = callback
+        CallbackMethod.__init__(self, callback.signatures()[0], "Call",
+                                descriptorProvider, needThisHandling=True)
+
+    def getThisDecl(self):
+        return ""
+
+    def getThisVal(self):
+        return "aThisVal"
+
+    def getCallableDecl(self):
+        return "JS::Rooted<JS::Value> callable(cx, JS::ObjectValue(*mCallback));\n"
+
+    def getPrettyName(self):
+        return self.callback.identifier.name
+
+    def getCallGuard(self):
+        if self.callback._treatNonObjectAsNull:
+            return "JS::IsCallable(mCallback) && "
+        return ""
+
+
+class CallbackOperationBase(CallbackMethod):
+    """
+    Common class for implementing various callback operations.
+    """
+    def __init__(self, signature, jsName, nativeName, descriptor,
+                 singleOperation, rethrowContentException=False,
+                 typedArraysAreStructs=False):
+        self.singleOperation = singleOperation
+        self.methodName = descriptor.binaryNameFor(jsName)
+        CallbackMethod.__init__(self, signature, nativeName, descriptor,
+                                singleOperation, rethrowContentException,
+                                typedArraysAreStructs=typedArraysAreStructs)
+
+    def getThisDecl(self):
+        if not self.singleOperation:
+            return "JS::Rooted<JS::Value> thisValue(cx, JS::ObjectValue(*mCallback));\n"
+        # This relies on getCallableDecl declaring a boolean
+        # isCallable in the case when we're a single-operation
+        # interface.
+        return dedent("""
+            JS::Rooted<JS::Value> thisValue(cx, isCallable ? aThisVal.get()
+                                                           : JS::ObjectValue(*mCallback));
+            """)
+
+    def getThisVal(self):
+        return "thisValue"
+
+    def getCallableDecl(self):
+        getCallableFromProp = fill(
+            """
+            ${atomCacheName}* atomsCache = GetAtomCache<${atomCacheName}>(cx);
+            if ((!*reinterpret_cast<jsid**>(atomsCache) && !InitIds(cx, atomsCache)) ||
+                !GetCallableProperty(cx, atomsCache->${methodAtomName}, &callable)) {
+              aRv.Throw(NS_ERROR_UNEXPECTED);
+              return${errorReturn};
+            }
+            """,
+            methodAtomName=CGDictionary.makeIdName(self.methodName),
+            atomCacheName=self.descriptorProvider.interface.identifier.name + "Atoms",
+            errorReturn=self.getDefaultRetval())
+        if not self.singleOperation:
+            return 'JS::Rooted<JS::Value> callable(cx);\n' + getCallableFromProp
+        return fill(
+            """
+            bool isCallable = JS::IsCallable(mCallback);
+            JS::Rooted<JS::Value> callable(cx);
+            if (isCallable) {
+              callable = JS::ObjectValue(*mCallback);
+            } else {
+              $*{getCallableFromProp}
+            }
+            """,
+            getCallableFromProp=getCallableFromProp)
+
+    def getCallGuard(self):
+        return ""
+
+
+class CallbackOperation(CallbackOperationBase):
+    """
+    Codegen actual WebIDL operations on callback interfaces.
+    """
+    def __init__(self, method, signature, descriptor, typedArraysAreStructs):
+        self.ensureASCIIName(method)
+        self.method = method
+        jsName = method.identifier.name
+        CallbackOperationBase.__init__(self, signature,
+                                       jsName,
+                                       MakeNativeName(descriptor.binaryNameFor(jsName)),
+                                       descriptor, descriptor.interface.isSingleOperationInterface(),
+                                       rethrowContentException=descriptor.interface.isJSImplemented(),
+                                       typedArraysAreStructs=typedArraysAreStructs)
+
+    def getPrettyName(self):
+        return "%s.%s" % (self.descriptorProvider.interface.identifier.name,
+                          self.method.identifier.name)
+
+
+class CallbackAccessor(CallbackMember):
+    """
+    Shared superclass for CallbackGetter and CallbackSetter.
+    """
+    def __init__(self, attr, sig, name, descriptor, typedArraysAreStructs):
+        self.ensureASCIIName(attr)
+        self.attrName = attr.identifier.name
+        CallbackMember.__init__(self, sig, name, descriptor,
+                                needThisHandling=False,
+                                rethrowContentException=descriptor.interface.isJSImplemented(),
+                                typedArraysAreStructs=typedArraysAreStructs)
+
+    def getPrettyName(self):
+        return "%s.%s" % (self.descriptorProvider.interface.identifier.name,
+                          self.attrName)
+
+
+class CallbackGetter(CallbackAccessor):
+    def __init__(self, attr, descriptor, typedArraysAreStructs):
+        CallbackAccessor.__init__(self, attr,
+                                  (attr.type, []),
+                                  callbackGetterName(attr, descriptor),
+                                  descriptor,
+                                  typedArraysAreStructs)
+
+    def getRvalDecl(self):
+        return "JS::Rooted<JS::Value> rval(cx, JS::UndefinedValue());\n"
+
+    def getCall(self):
+        return fill(
+            """
+            JS::Rooted<JSObject *> callback(cx, mCallback);
+            ${atomCacheName}* atomsCache = GetAtomCache<${atomCacheName}>(cx);
+            if ((!*reinterpret_cast<jsid**>(atomsCache) && !InitIds(cx, atomsCache)) ||
+                !JS_GetPropertyById(cx, callback, atomsCache->${attrAtomName}, &rval)) {
+              aRv.Throw(NS_ERROR_UNEXPECTED);
+              return${errorReturn};
+            }
+            """,
+            atomCacheName=self.descriptorProvider.interface.identifier.name + "Atoms",
+            attrAtomName=CGDictionary.makeIdName(self.descriptorProvider.binaryNameFor(self.attrName)),
+            errorReturn=self.getDefaultRetval())
+
+
+class CallbackSetter(CallbackAccessor):
+    def __init__(self, attr, descriptor, typedArraysAreStructs):
+        CallbackAccessor.__init__(self, attr,
+                                  (BuiltinTypes[IDLBuiltinType.Types.void],
+                                   [FakeArgument(attr.type, attr)]),
+                                  callbackSetterName(attr, descriptor),
+                                  descriptor, typedArraysAreStructs)
+
+    def getRvalDecl(self):
+        # We don't need an rval
+        return ""
+
+    def getCall(self):
+        return fill(
+            """
+            MOZ_ASSERT(argv.length() == 1);
+            ${atomCacheName}* atomsCache = GetAtomCache<${atomCacheName}>(cx);
+            if ((!*reinterpret_cast<jsid**>(atomsCache) && !InitIds(cx, atomsCache)) ||
+                !JS_SetPropertyById(cx, CallbackKnownNotGray(), atomsCache->${attrAtomName}, argv[0])) {
+              aRv.Throw(NS_ERROR_UNEXPECTED);
+              return${errorReturn};
+            }
+            """,
+            atomCacheName=self.descriptorProvider.interface.identifier.name + "Atoms",
+            attrAtomName=CGDictionary.makeIdName(self.descriptorProvider.binaryNameFor(self.attrName)),
+            errorReturn=self.getDefaultRetval())
+
+    def getArgcDecl(self):
+        return None
+
+
+class CGJSImplInitOperation(CallbackOperationBase):
+    """
+    Codegen the __Init() method used to pass along constructor arguments for JS-implemented WebIDL.
+    """
+    def __init__(self, sig, descriptor):
+        assert sig in descriptor.interface.ctor().signatures()
+        CallbackOperationBase.__init__(self, (BuiltinTypes[IDLBuiltinType.Types.void], sig[1]),
+                                       "__init", "__Init", descriptor,
+                                       singleOperation=False,
+                                       rethrowContentException=True,
+                                       typedArraysAreStructs=True)
+
+    def getPrettyName(self):
+        return "__init"
+
+
+def getMaplikeOrSetlikeErrorReturn(helperImpl):
+    """
+    Generate return values based on whether a maplike or setlike generated
+    method is an interface method (which returns bool) or a helper function
+    (which uses ErrorResult).
+    """
+    if helperImpl:
+        return dedent(
+            """
+            aRv.Throw(NS_ERROR_UNEXPECTED);
+            return%s;
+            """ % helperImpl.getDefaultRetval())
+    return "return false;\n"
+
+
+def getMaplikeOrSetlikeBackingObject(descriptor, maplikeOrSetlike, helperImpl=None):
+    """
+    Generate code to get/create a JS backing object for a maplike/setlike
+    declaration from the declaration slot.
+    """
+    func_prefix = maplikeOrSetlike.maplikeOrSetlikeOrIterableType.title()
+    ret = fill(
+        """
+        JS::Rooted<JSObject*> backingObj(cx);
+        bool created = false;
+        if (!Get${func_prefix}BackingObject(cx, obj, ${slot}, &backingObj, &created)) {
+          $*{errorReturn}
+        }
+        if (created) {
+          PreserveWrapper<${selfType}>(self);
+        }
+        """,
+        slot=memberReservedSlot(maplikeOrSetlike, descriptor),
+        func_prefix=func_prefix,
+        errorReturn=getMaplikeOrSetlikeErrorReturn(helperImpl),
+        selfType=descriptor.nativeType)
+    return ret
+
+
+def getMaplikeOrSetlikeSizeGetterBody(descriptor, attr):
+    """
+    Creates the body for the size getter method of maplike/setlike interfaces.
+    """
+    # We should only have one declaration attribute currently
+    assert attr.identifier.name == "size"
+    assert attr.isMaplikeOrSetlikeAttr()
+    return fill(
+        """
+        $*{getBackingObj}
+        uint32_t result = JS::${funcPrefix}Size(cx, backingObj);
+        MOZ_ASSERT(!JS_IsExceptionPending(cx));
+        args.rval().setNumber(result);
+        return true;
+        """,
+        getBackingObj=getMaplikeOrSetlikeBackingObject(descriptor,
+                                                       attr.maplikeOrSetlike),
+        funcPrefix=attr.maplikeOrSetlike.prefix)
+
+
+class CGMaplikeOrSetlikeMethodGenerator(CGThing):
+    """
+    Creates methods for maplike/setlike interfaces. It is expected that all
+    methods will be have a maplike/setlike object attached. Unwrapping/wrapping
+    will be taken care of by the usual method generation machinery in
+    CGMethodCall/CGPerSignatureCall. Functionality is filled in here instead of
+    using CGCallGenerator.
+    """
+    def __init__(self, descriptor, maplikeOrSetlike, methodName,
+                 helperImpl=None):
+        CGThing.__init__(self)
+        # True if this will be the body of a C++ helper function.
+        self.helperImpl = helperImpl
+        self.descriptor = descriptor
+        self.maplikeOrSetlike = maplikeOrSetlike
+        self.cgRoot = CGList([])
+        impl_method_name = methodName
+        if impl_method_name[0] == "_":
+            # double underscore means this is a js-implemented chrome only rw
+            # function. Truncate the double underscore so calling the right
+            # underlying JSAPI function still works.
+            impl_method_name = impl_method_name[2:]
+        self.cgRoot.append(CGGeneric(
+            getMaplikeOrSetlikeBackingObject(self.descriptor,
+                                             self.maplikeOrSetlike,
+                                             self.helperImpl)))
+        self.returnStmt = getMaplikeOrSetlikeErrorReturn(self.helperImpl)
+
+        # Generates required code for the method. Method descriptions included
+        # in definitions below. Throw if we don't have a method to fill in what
+        # we're looking for.
+        try:
+            methodGenerator = getattr(self, impl_method_name)
+        except AttributeError:
+            raise TypeError("Missing %s method definition '%s'" %
+                            (self.maplikeOrSetlike.maplikeOrSetlikeType,
+                             methodName))
+        # Method generator returns tuple, containing:
+        #
+        # - a list of CGThings representing setup code for preparing to call
+        #   the JS API function
+        # - a list of arguments needed for the JS API function we're calling
+        # - list of code CGThings needed for return value conversion.
+        (setupCode, arguments, setResult) = methodGenerator()
+
+        # Create the actual method call, and then wrap it with the code to
+        # return the value if needed.
+        funcName = (self.maplikeOrSetlike.prefix +
+                    MakeNativeName(impl_method_name))
+        # Append the list of setup code CGThings
+        self.cgRoot.append(CGList(setupCode))
+        # Create the JS API call
+        self.cgRoot.append(CGWrapper(
+            CGGeneric(fill(
+                """
+                if (!JS::${funcName}(${args})) {
+                  $*{errorReturn}
+                }
+                """,
+                funcName=funcName,
+                args=", ".join(["cx", "backingObj"] + arguments),
+                errorReturn=self.returnStmt))))
+        # Append result conversion
+        self.cgRoot.append(CGList(setResult))
+
+    def mergeTuples(self, a, b):
+        """
+        Expecting to take 2 tuples were all elements are lists, append the lists in
+        the second tuple to the lists in the first.
+        """
+        return tuple([x + y for x, y in zip(a, b)])
+
+    def appendArgConversion(self, name):
+        """
+        Generate code to convert arguments to JS::Values, so they can be
+        passed into JSAPI functions.
+        """
+        return CGGeneric(fill(
+            """
+            JS::Rooted<JS::Value> ${name}Val(cx);
+            if (!ToJSValue(cx, ${name}, &${name}Val)) {
+              $*{errorReturn}
+            }
+            """,
+            name=name,
+            errorReturn=self.returnStmt))
+
+    def appendKeyArgConversion(self):
+        """
+        Generates the key argument for methods. Helper functions will use
+        an AutoValueVector, while interface methods have seperate JS::Values.
+        """
+        if self.helperImpl:
+            return ([], ["argv[0]"], [])
+        return ([self.appendArgConversion("arg0")], ["arg0Val"], [])
+
+    def appendKeyAndValueArgConversion(self):
+        """
+        Generates arguments for methods that require a key and value. Helper
+        functions will use an AutoValueVector, while interface methods have
+        seperate JS::Values.
+        """
+        r = self.appendKeyArgConversion()
+        if self.helperImpl:
+            return self.mergeTuples(r, ([], ["argv[1]"], []))
+        return self.mergeTuples(r, ([self.appendArgConversion("arg1")],
+                                    ["arg1Val"],
+                                    []))
+
+    def appendIteratorResult(self):
+        """
+        Generate code to output JSObject* return values, needed for functions that
+        return iterators. Iterators cannot currently be wrapped via Xrays. If
+        something that would return an iterator is called via Xray, fail early.
+        """
+        # TODO: Bug 1173651 - Remove check once bug 1023984 is fixed.
+        code = CGGeneric(dedent(
+            """
+            // TODO (Bug 1173651): Xrays currently cannot wrap iterators. Change
+            // after bug 1023984 is fixed.
+            if (xpc::WrapperFactory::IsXrayWrapper(obj)) {
+              JS_ReportErrorASCII(cx, "Xray wrapping of iterators not supported.");
+              return false;
+            }
+            JS::Rooted<JSObject*> result(cx);
+            JS::Rooted<JS::Value> v(cx);
+            """))
+        arguments = "&v"
+        setResult = CGGeneric(dedent(
+            """
+            result = &v.toObject();
+            """))
+        return ([code], [arguments], [setResult])
+
+    def appendSelfResult(self):
+        """
+        Generate code to return the interface object itself.
+        """
+        code = CGGeneric(dedent(
+            """
+            JS::Rooted<JSObject*> result(cx);
+            """))
+        setResult = CGGeneric(dedent(
+            """
+            result = obj;
+            """))
+        return ([code], [], [setResult])
+
+    def appendBoolResult(self):
+        if self.helperImpl:
+            return ([CGGeneric()], ["&aRetVal"], [])
+        return ([CGGeneric("bool result;\n")], ["&result"], [])
+
+    def forEach(self):
+        """
+        void forEach(callback c, any thisval);
+
+        ForEach takes a callback, and a possible value to use as 'this'. The
+        callback needs to take value, key, and the interface object
+        implementing maplike/setlike. In order to make sure that the third arg
+        is our interface object instead of the map/set backing object, we
+        create a js function with the callback and original object in its
+        storage slots, then use a helper function in BindingUtils to make sure
+        the callback is called correctly.
+        """
+        assert(not self.helperImpl)
+        code = [CGGeneric(dedent(
+            """
+            // Create a wrapper function.
+            JSFunction* func = js::NewFunctionWithReserved(cx, ForEachHandler, 3, 0, nullptr);
+            if (!func) {
+              return false;
+            }
+            JS::Rooted<JSObject*> funcObj(cx, JS_GetFunctionObject(func));
+            JS::Rooted<JS::Value> funcVal(cx, JS::ObjectValue(*funcObj));
+            js::SetFunctionNativeReserved(funcObj, FOREACH_CALLBACK_SLOT,
+                                          JS::ObjectValue(*arg0));
+            js::SetFunctionNativeReserved(funcObj, FOREACH_MAPLIKEORSETLIKEOBJ_SLOT,
+                                          JS::ObjectValue(*obj));
+            """))]
+        arguments = ["funcVal", "arg1"]
+        return (code, arguments, [])
+
+    def set(self):
+        """
+        object set(key, value);
+
+        Maplike only function, takes key and sets value to it, returns
+        interface object unless being called from a C++ helper.
+        """
+        assert self.maplikeOrSetlike.isMaplike()
+        r = self.appendKeyAndValueArgConversion()
+        if self.helperImpl:
+            return r
+        return self.mergeTuples(r, self.appendSelfResult())
+
+    def add(self):
+        """
+        object add(value);
+
+        Setlike only function, adds value to set, returns interface object
+        unless being called from a C++ helper
+        """
+        assert self.maplikeOrSetlike.isSetlike()
+        r = self.appendKeyArgConversion()
+        if self.helperImpl:
+            return r
+        return self.mergeTuples(r, self.appendSelfResult())
+
+    def get(self):
+        """
+        type? get(key);
+
+        Retrieves a value from a backing object based on the key. Returns value
+        if key is in backing object, undefined otherwise.
+        """
+        assert self.maplikeOrSetlike.isMaplike()
+        r = self.appendKeyArgConversion()
+        code = [CGGeneric(dedent(
+            """
+            JS::Rooted<JS::Value> result(cx);
+            """))]
+        arguments = ["&result"]
+        return self.mergeTuples(r, (code, arguments, []))
+
+    def has(self):
+        """
+        bool has(key);
+
+        Check if an entry exists in the backing object. Returns true if value
+        exists in backing object, false otherwise.
+        """
+        return self.mergeTuples(self.appendKeyArgConversion(),
+                                self.appendBoolResult())
+
+    def keys(self):
+        """
+        object keys();
+
+        Returns new object iterator with all keys from backing object.
+        """
+        return self.appendIteratorResult()
+
+    def values(self):
+        """
+        object values();
+
+        Returns new object iterator with all values from backing object.
+        """
+        return self.appendIteratorResult()
+
+    def entries(self):
+        """
+        object entries();
+
+        Returns new object iterator with all keys and values from backing
+        object. Keys will be null for set.
+        """
+        return self.appendIteratorResult()
+
+    def clear(self):
+        """
+        void clear();
+
+        Removes all entries from map/set.
+        """
+        return ([], [], [])
+
+    def delete(self):
+        """
+        bool delete(key);
+
+        Deletes an entry from the backing object. Returns true if value existed
+        in backing object, false otherwise.
+        """
+        return self.mergeTuples(self.appendKeyArgConversion(),
+                                self.appendBoolResult())
+
+    def define(self):
+        return self.cgRoot.define()
+
+
+class CGMaplikeOrSetlikeHelperFunctionGenerator(CallbackMember):
+    """
+    Generates code to allow C++ to perform operations on backing objects. Gets
+    a context from the binding wrapper, turns arguments into JS::Values (via
+    CallbackMember/CGNativeMember argument conversion), then uses
+    CGMaplikeOrSetlikeMethodGenerator to generate the body.
+
+    """
+
+    class HelperFunction(CGAbstractMethod):
+        """
+        Generates context retrieval code and rooted JSObject for interface for
+        CGMaplikeOrSetlikeMethodGenerator to use
+        """
+        def __init__(self, descriptor, name, args, code, needsBoolReturn=False):
+            self.code = code
+            CGAbstractMethod.__init__(self, descriptor, name,
+                                      "bool" if needsBoolReturn else "void",
+                                      args)
+
+        def definition_body(self):
+            return self.code
+
+    def __init__(self, descriptor, maplikeOrSetlike, name, needsKeyArg=False,
+                 needsValueArg=False, needsBoolReturn=False):
+        args = []
+        self.maplikeOrSetlike = maplikeOrSetlike
+        self.needsBoolReturn = needsBoolReturn
+        if needsKeyArg:
+            args.append(FakeArgument(maplikeOrSetlike.keyType, None, 'aKey'))
+        if needsValueArg:
+            assert needsKeyArg
+            args.append(FakeArgument(maplikeOrSetlike.valueType, None, 'aValue'))
+        # Run CallbackMember init function to generate argument conversion code.
+        # wrapScope is set to 'obj' when generating maplike or setlike helper
+        # functions, as we don't have access to the CallbackPreserveColor
+        # method.
+        CallbackMember.__init__(self,
+                                [BuiltinTypes[IDLBuiltinType.Types.void], args],
+                                name, descriptor, False,
+                                wrapScope='obj')
+        # Wrap CallbackMember body code into a CGAbstractMethod to make
+        # generation easier.
+        self.implMethod = CGMaplikeOrSetlikeHelperFunctionGenerator.HelperFunction(
+            descriptor, name, self.args, self.body, needsBoolReturn)
+
+    def getCallSetup(self):
+        return dedent(
+            """
+            MOZ_ASSERT(self);
+            AutoJSAPI jsapi;
+            jsapi.Init();
+            JSContext* cx = jsapi.cx();
+            // It's safe to use UnprivilegedJunkScopeOrWorkerGlobal here because
+            // all we want is to wrap into _some_ scope and then unwrap to find
+            // the reflector, and wrapping has no side-effects.
+            JSAutoCompartment tempCompartment(cx, binding_detail::UnprivilegedJunkScopeOrWorkerGlobal());
+            JS::Rooted<JS::Value> v(cx);
+            if(!ToJSValue(cx, self, &v)) {
+              aRv.Throw(NS_ERROR_UNEXPECTED);
+              return%s;
+            }
+            // This is a reflector, but due to trying to name things
+            // similarly across method generators, it's called obj here.
+            JS::Rooted<JSObject*> obj(cx);
+            obj = js::UncheckedUnwrap(&v.toObject(), /* stopAtWindowProxy = */ false);
+            JSAutoCompartment reflectorCompartment(cx, obj);
+            """ % self.getDefaultRetval())
+
+    def getArgs(self, returnType, argList):
+        # We don't need the context or the value. We'll generate those instead.
+        args = CGNativeMember.getArgs(self, returnType, argList)
+        # Prepend a pointer to the binding object onto the arguments
+        return [Argument(self.descriptorProvider.nativeType + "*", "self")] + args
+
+    def getResultConversion(self):
+        if self.needsBoolReturn:
+            return "return aRetVal;\n"
+        return "return;\n"
+
+    def getRvalDecl(self):
+        if self.needsBoolReturn:
+            return "bool aRetVal;\n"
+        return ""
+
+    def getArgcDecl(self):
+        # Don't need argc for anything.
+        return None
+
+    def getDefaultRetval(self):
+        if self.needsBoolReturn:
+            return " false"
+        return ""
+
+    def getCall(self):
+        return CGMaplikeOrSetlikeMethodGenerator(self.descriptorProvider,
+                                                 self.maplikeOrSetlike,
+                                                 self.name.lower(),
+                                                 helperImpl=self).define()
+
+    def getPrettyName(self):
+        return self.name
+
+    def declare(self):
+        return self.implMethod.declare()
+
+    def define(self):
+        return self.implMethod.define()
+
+
+class CGMaplikeOrSetlikeHelperGenerator(CGNamespace):
+    """
+    Declares and defines convenience methods for accessing backing objects on
+    setlike/maplike interface. Generates function signatures, un/packs
+    backing objects from slot, etc.
+    """
+    def __init__(self, descriptor, maplikeOrSetlike):
+        self.descriptor = descriptor
+        # Since iterables are folded in with maplike/setlike, make sure we've
+        # got the right type here.
+        assert maplikeOrSetlike.isMaplike() or maplikeOrSetlike.isSetlike()
+        self.maplikeOrSetlike = maplikeOrSetlike
+        self.namespace = "%sHelpers" % (self.maplikeOrSetlike.maplikeOrSetlikeOrIterableType.title())
+        self.helpers = [
+            CGMaplikeOrSetlikeHelperFunctionGenerator(descriptor,
+                                                      maplikeOrSetlike,
+                                                      "Clear"),
+            CGMaplikeOrSetlikeHelperFunctionGenerator(descriptor,
+                                                      maplikeOrSetlike,
+                                                      "Delete",
+                                                      needsKeyArg=True,
+                                                      needsBoolReturn=True),
+            CGMaplikeOrSetlikeHelperFunctionGenerator(descriptor,
+                                                      maplikeOrSetlike,
+                                                      "Has",
+                                                      needsKeyArg=True,
+                                                      needsBoolReturn=True)]
+        if self.maplikeOrSetlike.isMaplike():
+            self.helpers.append(
+                CGMaplikeOrSetlikeHelperFunctionGenerator(descriptor,
+                                                          maplikeOrSetlike,
+                                                          "Set",
+                                                          needsKeyArg=True,
+                                                          needsValueArg=True))
+        else:
+            assert(self.maplikeOrSetlike.isSetlike())
+            self.helpers.append(
+                CGMaplikeOrSetlikeHelperFunctionGenerator(descriptor,
+                                                          maplikeOrSetlike,
+                                                          "Add",
+                                                          needsKeyArg=True))
+        CGNamespace.__init__(self, self.namespace, CGList(self.helpers))
+
+
+class CGIterableMethodGenerator(CGGeneric):
+    """
+    Creates methods for iterable interfaces. Unwrapping/wrapping
+    will be taken care of by the usual method generation machinery in
+    CGMethodCall/CGPerSignatureCall. Functionality is filled in here instead of
+    using CGCallGenerator.
+    """
+    def __init__(self, descriptor, iterable, methodName):
+        if methodName == "forEach":
+            CGGeneric.__init__(self, fill(
+                """
+                if (!JS::IsCallable(arg0)) {
+                  ThrowErrorMessage(cx, MSG_NOT_CALLABLE, "Argument 1 of ${ifaceName}.forEach");
+                  return false;
+                }
+                JS::AutoValueArray<3> callArgs(cx);
+                callArgs[2].setObject(*obj);
+                JS::Rooted<JS::Value> ignoredReturnVal(cx);
+                for (size_t i = 0; i < self->GetIterableLength(); ++i) {
+                  if (!ToJSValue(cx, self->GetValueAtIndex(i), callArgs[0])) {
+                    return false;
+                  }
+                  if (!ToJSValue(cx, self->GetKeyAtIndex(i), callArgs[1])) {
+                    return false;
+                  }
+                  if (!JS::Call(cx, arg1, arg0, JS::HandleValueArray(callArgs),
+                                &ignoredReturnVal)) {
+                    return false;
+                  }
+                }
+                """,
+                ifaceName=descriptor.interface.identifier.name))
+            return
+        CGGeneric.__init__(self, fill(
+            """
+            typedef ${iterClass} itrType;
+            RefPtr<itrType> result(new itrType(self,
+                                                 itrType::IterableIteratorType::${itrMethod},
+                                                 &${ifaceName}IteratorBinding::Wrap));
+            """,
+            iterClass=iteratorNativeType(descriptor),
+            ifaceName=descriptor.interface.identifier.name,
+            itrMethod=methodName.title()))
+
+
+class GlobalGenRoots():
+    """
+    Roots for global codegen.
+
+    To generate code, call the method associated with the target, and then
+    call the appropriate define/declare method.
+    """
+
+    @staticmethod
+    def GeneratedAtomList(config):
+        # Atom enum
+        dictionaries = config.dictionaries
+
+        structs = []
+
+        def memberToAtomCacheMember(binaryNameFor, m):
+            binaryMemberName = binaryNameFor(m.identifier.name)
+            return ClassMember(CGDictionary.makeIdName(binaryMemberName),
+                               "PinnedStringId", visibility="public")
+
+        def buildAtomCacheStructure(idlobj, binaryNameFor, members):
+            classMembers = [memberToAtomCacheMember(binaryNameFor, m)
+                            for m in members]
+            structName = idlobj.identifier.name + "Atoms"
+            return (structName,
+                    CGWrapper(CGClass(structName,
+                                      bases=None,
+                                      isStruct=True,
+                                      members=classMembers), post='\n'))
+
+        for dict in dictionaries:
+            if len(dict.members) == 0:
+                continue
+
+            structs.append(buildAtomCacheStructure(dict, lambda x: x, dict.members))
+
+        for d in (config.getDescriptors(isJSImplemented=True) +
+                  config.getDescriptors(isCallback=True)):
+            members = [m for m in d.interface.members if m.isAttr() or m.isMethod()]
+            if d.interface.isJSImplemented() and d.interface.ctor():
+                # We'll have an __init() method.
+                members.append(FakeMember('__init'))
+            if len(members) == 0:
+                continue
+
+            structs.append(buildAtomCacheStructure(d.interface,
+                                                   lambda x: d.binaryNameFor(x),
+                                                   members))
+
+        structs.sort()
+        generatedStructs = [struct for structName, struct in structs]
+        structNames = [structName for structName, struct in structs]
+
+        mainStruct = CGWrapper(CGClass("PerThreadAtomCache",
+                                       bases=[ClassBase(structName) for structName in structNames],
+                                       isStruct=True),
+                               post='\n')
+
+        structs = CGList(generatedStructs + [mainStruct])
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(structs, pre='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add include statement for PinnedStringId.
+        declareIncludes = ['mozilla/dom/BindingUtils.h']
+        curr = CGHeaders([], [], [], [], declareIncludes, [], 'GeneratedAtomList',
+                         curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('GeneratedAtomList', curr)
+
+        # Add the auto-generated comment.
+        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def GeneratedEventList(config):
+        eventList = CGList([])
+        for generatedEvent in config.generatedEvents:
+            eventList.append(CGGeneric(declare=("GENERATED_EVENT(%s)\n" % generatedEvent)))
+        return eventList
+
+    @staticmethod
+    def PrototypeList(config):
+
+        # Prototype ID enum.
+        descriptorsWithPrototype = config.getDescriptors(hasInterfacePrototypeObject=True)
+        protos = [d.name for d in descriptorsWithPrototype]
+        idEnum = CGNamespacedEnum('id', 'ID', ['_ID_Start'] + protos,
+                                  [0, '_ID_Start'])
+        idEnum = CGList([idEnum])
+
+        def fieldSizeAssert(amount, jitInfoField, message):
+            maxFieldValue = "(uint64_t(1) << (sizeof(((JSJitInfo*)nullptr)->%s) * 8))" % jitInfoField
+            return CGGeneric(declare="static_assert(%s < %s, \"%s\");\n\n"
+                             % (amount, maxFieldValue, message))
+
+        idEnum.append(fieldSizeAssert("id::_ID_Count", "protoID",
+                                      "Too many prototypes!"))
+
+        # Wrap all of that in our namespaces.
+        idEnum = CGNamespace.build(['mozilla', 'dom', 'prototypes'],
+                                   CGWrapper(idEnum, pre='\n'))
+        idEnum = CGWrapper(idEnum, post='\n')
+
+        curr = CGList([CGGeneric(define="#include <stdint.h>\n\n"),
+                       idEnum])
+
+        # Let things know the maximum length of the prototype chain.
+        maxMacroName = "MAX_PROTOTYPE_CHAIN_LENGTH"
+        maxMacro = CGGeneric(declare="#define " + maxMacroName + " " + str(config.maxProtoChainLength))
+        curr.append(CGWrapper(maxMacro, post='\n\n'))
+        curr.append(fieldSizeAssert(maxMacroName, "depth",
+                                    "Some inheritance chain is too long!"))
+
+        # Constructor ID enum.
+        constructors = [d.name for d in config.getDescriptors(hasInterfaceObject=True)]
+        idEnum = CGNamespacedEnum('id', 'ID', ['_ID_Start'] + constructors,
+                                  ['prototypes::id::_ID_Count', '_ID_Start'])
+
+        # Wrap all of that in our namespaces.
+        idEnum = CGNamespace.build(['mozilla', 'dom', 'constructors'],
+                                   CGWrapper(idEnum, pre='\n'))
+        idEnum = CGWrapper(idEnum, post='\n')
+
+        curr.append(idEnum)
+
+        # Named properties object enum.
+        namedPropertiesObjects = [d.name for d in config.getDescriptors(hasNamedPropertiesObject=True)]
+        idEnum = CGNamespacedEnum('id', 'ID', ['_ID_Start'] + namedPropertiesObjects,
+                                  ['constructors::id::_ID_Count', '_ID_Start'])
+
+        # Wrap all of that in our namespaces.
+        idEnum = CGNamespace.build(['mozilla', 'dom', 'namedpropertiesobjects'],
+                                   CGWrapper(idEnum, pre='\n'))
+        idEnum = CGWrapper(idEnum, post='\n')
+
+        curr.append(idEnum)
+
+        traitsDecls = [CGGeneric(declare=dedent("""
+            template <prototypes::ID PrototypeID>
+            struct PrototypeTraits;
+            """))]
+        traitsDecls.extend(CGPrototypeTraitsClass(d) for d in descriptorsWithPrototype)
+
+        ifaceNamesWithProto = [d.interface.identifier.name
+                               for d in descriptorsWithPrototype]
+        traitsDecls.append(CGStringTable("NamesOfInterfacesWithProtos",
+                                         ifaceNamesWithProto))
+
+        traitsDecl = CGNamespace.build(['mozilla', 'dom'],
+                                       CGList(traitsDecls))
+
+        curr.append(traitsDecl)
+
+        # Add include guards.
+        curr = CGIncludeGuard('PrototypeList', curr)
+
+        # Add the auto-generated comment.
+        curr = CGWrapper(curr, pre=AUTOGENERATED_WARNING_COMMENT)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def RegisterBindings(config):
+
+        curr = CGList([CGGlobalNamesString(config), CGRegisterGlobalNames(config)])
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, post='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add the includes
+        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
+                          for desc in config.getDescriptors(hasInterfaceObject=True,
+                                                            isExposedInWindow=True,
+                                                            register=True)]
+        defineIncludes.append('mozilla/dom/WebIDLGlobalNameHash.h')
+        defineIncludes.extend([CGHeaders.getDeclarationFilename(desc.interface)
+                               for desc in config.getDescriptors(isNavigatorProperty=True,
+                                                                 register=True)])
+        curr = CGHeaders([], [], [], [], [], defineIncludes, 'RegisterBindings',
+                         curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('RegisterBindings', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def RegisterWorkerBindings(config):
+
+        curr = CGRegisterWorkerBindings(config)
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, post='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add the includes
+        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
+                          for desc in config.getDescriptors(hasInterfaceObject=True,
+                                                            register=True,
+                                                            isExposedInAnyWorker=True)]
+
+        curr = CGHeaders([], [], [], [], [], defineIncludes,
+                         'RegisterWorkerBindings', curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('RegisterWorkerBindings', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def RegisterWorkerDebuggerBindings(config):
+
+        curr = CGRegisterWorkerDebuggerBindings(config)
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, post='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add the includes
+        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
+                          for desc in config.getDescriptors(hasInterfaceObject=True,
+                                                            register=True,
+                                                            isExposedInWorkerDebugger=True)]
+
+        curr = CGHeaders([], [], [], [], [], defineIncludes,
+                         'RegisterWorkerDebuggerBindings', curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('RegisterWorkerDebuggerBindings', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def RegisterWorkletBindings(config):
+
+        curr = CGRegisterWorkletBindings(config)
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, post='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add the includes
+        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
+                          for desc in config.getDescriptors(hasInterfaceObject=True,
+                                                            register=True,
+                                                            isExposedInAnyWorklet=True)]
+
+        curr = CGHeaders([], [], [], [], [], defineIncludes,
+                         'RegisterWorkletBindings', curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('RegisterWorkletBindings', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def ResolveSystemBinding(config):
+
+        curr = CGResolveSystemBinding(config)
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'],
+                                 CGWrapper(curr, post='\n'))
+        curr = CGWrapper(curr, post='\n')
+
+        # Add the includes
+        defineIncludes = [CGHeaders.getDeclarationFilename(desc.interface)
+                          for desc in config.getDescriptors(hasInterfaceObject=True,
+                                                            register=True,
+                                                            isExposedInSystemGlobals=True)]
+        defineIncludes.append("nsThreadUtils.h")  # For NS_IsMainThread
+        defineIncludes.append("js/Id.h")  # For jsid
+        defineIncludes.append("mozilla/dom/BindingUtils.h")  # AtomizeAndPinJSString
+
+        curr = CGHeaders([], [], [], [], [], defineIncludes,
+                         'ResolveSystemBinding', curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('ResolveSystemBinding', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def UnionTypes(config):
+        unionTypes = UnionsForFile(config, None)
+        (includes, implincludes, declarations,
+         traverseMethods, unlinkMethods,
+         unionStructs) = UnionTypes(unionTypes, config)
+
+        unions = CGList(traverseMethods +
+                        unlinkMethods +
+                        [CGUnionStruct(t, config) for t in unionStructs] +
+                        [CGUnionStruct(t, config, True) for t in unionStructs],
+                        "\n")
+
+        includes.add("mozilla/OwningNonNull.h")
+        includes.add("mozilla/dom/UnionMember.h")
+        includes.add("mozilla/dom/BindingDeclarations.h")
+        # BindingUtils.h is only needed for SetToObject.
+        # If it stops being inlined or stops calling CallerSubsumes
+        # both this bit and the bit in CGBindingRoot can be removed.
+        includes.add("mozilla/dom/BindingUtils.h")
+        implincludes.add("mozilla/dom/PrimitiveConversions.h")
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'], unions)
+
+        curr = CGWrapper(curr, post='\n')
+
+        builder = ForwardDeclarationBuilder()
+        for className, isStruct in declarations:
+            builder.add(className, isStruct=isStruct)
+
+        curr = CGList([builder.build(), curr], "\n")
+
+        curr = CGHeaders([], [], [], [], includes, implincludes, 'UnionTypes',
+                         curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('UnionTypes', curr)
+
+        # Done.
+        return curr
+
+    @staticmethod
+    def UnionConversions(config):
+        unionTypes = []
+        for l in config.unionsPerFilename.itervalues():
+            unionTypes.extend(l)
+        unionTypes.sort(key=lambda u: u.name)
+        headers, unions = UnionConversions(unionTypes,
+                                           config)
+
+        # Wrap all of that in our namespaces.
+        curr = CGNamespace.build(['mozilla', 'dom'], unions)
+
+        curr = CGWrapper(curr, post='\n')
+
+        headers.update(["nsDebug.h", "mozilla/dom/UnionTypes.h"])
+        curr = CGHeaders([], [], [], [], headers, [], 'UnionConversions', curr)
+
+        # Add include guards.
+        curr = CGIncludeGuard('UnionConversions', curr)
+
+        # Done.
+        return curr
+
+
+# Code generator for simple events
+class CGEventGetter(CGNativeMember):
+    def __init__(self, descriptor, attr):
+        ea = descriptor.getExtendedAttributes(attr, getter=True)
+        CGNativeMember.__init__(self, descriptor, attr,
+                                CGSpecializedGetter.makeNativeName(descriptor,
+                                                                   attr),
+                                (attr.type, []),
+                                ea,
+                                resultNotAddRefed=not attr.type.isSequence())
+        self.body = self.getMethodBody()
+
+    def getArgs(self, returnType, argList):
+        if 'infallible' not in self.extendedAttrs:
+            raise TypeError("Event code generator does not support [Throws]!")
+        if not self.member.isAttr():
+            raise TypeError("Event code generator does not support methods")
+        if self.member.isStatic():
+            raise TypeError("Event code generators does not support static attributes")
+        return CGNativeMember.getArgs(self, returnType, argList)
+
+    def getMethodBody(self):
+        type = self.member.type
+        memberName = CGDictionary.makeMemberName(self.member.identifier.name)
+        if (type.isPrimitive() and type.tag() in builtinNames) or type.isEnum() or type.isGeckoInterface():
+            return "return " + memberName + ";\n"
+        if type.isDOMString() or type.isByteString() or type.isUSVString():
+            return "aRetVal = " + memberName + ";\n"
+        if type.isSpiderMonkeyInterface() or type.isObject():
+            return fill(
+                """
+                if (${memberName}) {
+                  JS::ExposeObjectToActiveJS(${memberName});
+                }
+                aRetVal.set(${memberName});
+                return;
+                """,
+                memberName=memberName)
+        if type.isAny():
+            return fill(
+                """
+                ${selfName}(aRetVal);
+                """,
+                selfName=self.name)
+        if type.isUnion():
+            return "aRetVal = " + memberName + ";\n"
+        if type.isSequence():
+            return "aRetVal = " + memberName + ";\n"
+        raise TypeError("Event code generator does not support this type!")
+
+    def declare(self, cgClass):
+        if getattr(self.member, "originatingInterface",
+                   cgClass.descriptor.interface) != cgClass.descriptor.interface:
+            return ""
+        return CGNativeMember.declare(self, cgClass)
+
+    def define(self, cgClass):
+        if getattr(self.member, "originatingInterface",
+                   cgClass.descriptor.interface) != cgClass.descriptor.interface:
+            return ""
+        return CGNativeMember.define(self, cgClass)
+
+
+class CGEventSetter(CGNativeMember):
+    def __init__(self):
+        raise TypeError("Event code generator does not support setters!")
+
+
+class CGEventMethod(CGNativeMember):
+    def __init__(self, descriptor, method, signature, isConstructor, breakAfter=True):
+        self.isInit = False
+
+        CGNativeMember.__init__(self, descriptor, method,
+                                CGSpecializedMethod.makeNativeName(descriptor,
+                                                                   method),
+                                signature,
+                                descriptor.getExtendedAttributes(method),
+                                breakAfter=breakAfter,
+                                variadicIsSequence=True)
+        self.originalArgs = list(self.args)
+
+        iface = descriptor.interface
+        allowed = isConstructor
+        if not allowed and iface.getExtendedAttribute("LegacyEventInit"):
+            # Allow it, only if it fits the initFooEvent profile exactly
+            # We could check the arg types but it's not worth the effort.
+            if (method.identifier.name == "init" + iface.identifier.name and
+                signature[1][0].type.isDOMString() and
+                signature[1][1].type.isBoolean() and
+                signature[1][2].type.isBoolean() and
+                # -3 on the left to ignore the type, bubbles, and cancelable parameters
+                # -1 on the right to ignore the .trusted property which bleeds through
+                # here because it is [Unforgeable].
+                len(signature[1]) - 3 == len(filter(lambda x: x.isAttr(), iface.members)) - 1):
+                allowed = True
+                self.isInit = True
+
+        if not allowed:
+            raise TypeError("Event code generator does not support methods!")
+
+    def getArgs(self, returnType, argList):
+        args = [self.getArg(arg) for arg in argList]
+        return args
+
+    def getArg(self, arg):
+        decl, ref = self.getArgType(arg.type,
+                                    arg.canHaveMissingValue(),
+                                    "Variadic" if arg.variadic else False)
+        if ref:
+            decl = CGWrapper(decl, pre="const ", post="&")
+
+        name = arg.identifier.name
+        name = "a" + name[0].upper() + name[1:]
+        return Argument(decl.define(), name)
+
+    def declare(self, cgClass):
+        if self.isInit:
+            constructorForNativeCaller = ""
+        else:
+            self.args = list(self.originalArgs)
+            self.args.insert(0, Argument("mozilla::dom::EventTarget*", "aOwner"))
+            constructorForNativeCaller = CGNativeMember.declare(self, cgClass)
+
+        self.args = list(self.originalArgs)
+        if needCx(None, self.arguments(), [], considerTypes=True, static=True):
+            self.args.insert(0, Argument("JSContext*", "aCx"))
+        if not self.isInit:
+            self.args.insert(0, Argument("const GlobalObject&", "aGlobal"))
+            self.args.append(Argument('ErrorResult&', 'aRv'))
+        return constructorForNativeCaller + CGNativeMember.declare(self, cgClass)
+
+    def defineInit(self, cgClass):
+        iface = self.descriptorProvider.interface
+        members = ""
+        while iface.identifier.name != "Event":
+            i = 3  # Skip the boilerplate args: type, bubble,s cancelable.
+            for m in iface.members:
+                if m.isAttr():
+                    # We need to initialize all the member variables that do
+                    # not come from Event.
+                    if getattr(m, "originatingInterface",
+                               iface).identifier.name == "Event":
+                        continue
+                    name = CGDictionary.makeMemberName(m.identifier.name)
+                    members += "%s = %s;\n" % (name, self.args[i].name)
+                    i += 1
+            iface = iface.parent
+
+        self.body = fill(
+            """
+            InitEvent(${typeArg}, ${bubblesArg}, ${cancelableArg});
+            ${members}
+            """,
+            typeArg=self.args[0].name,
+            bubblesArg=self.args[1].name,
+            cancelableArg=self.args[2].name,
+            members=members)
+
+        return CGNativeMember.define(self, cgClass)
+
+    def define(self, cgClass):
+        self.args = list(self.originalArgs)
+        if self.isInit:
+            return self.defineInit(cgClass)
+        members = ""
+        holdJS = ""
+        iface = self.descriptorProvider.interface
+        while iface.identifier.name != "Event":
+            for m in self.descriptorProvider.getDescriptor(iface.identifier.name).interface.members:
+                if m.isAttr():
+                    # We initialize all the other member variables in the
+                    # Constructor except those ones coming from the Event.
+                    if getattr(m, "originatingInterface",
+                               cgClass.descriptor.interface).identifier.name == "Event":
+                        continue
+                    name = CGDictionary.makeMemberName(m.identifier.name)
+                    if m.type.isSequence():
+                        # For sequences we may not be able to do a simple
+                        # assignment because the underlying types may not match.
+                        # For example, the argument can be a
+                        # Sequence<OwningNonNull<SomeInterface>> while our
+                        # member is an nsTArray<RefPtr<SomeInterface>>.  So
+                        # use AppendElements, which is actually a template on
+                        # the incoming type on nsTArray and does the right thing
+                        # for this case.
+                        target = name
+                        source = "%s.%s" % (self.args[1].name, name)
+                        sequenceCopy = "e->%s.AppendElements(%s);\n"
+                        if m.type.nullable():
+                            sequenceCopy = CGIfWrapper(
+                                CGGeneric(sequenceCopy),
+                                "!%s.IsNull()" % source).define()
+                            target += ".SetValue()"
+                            source += ".Value()"
+                        members += sequenceCopy % (target, source)
+                    elif m.type.isSpiderMonkeyInterface():
+                        srcname = "%s.%s" % (self.args[1].name, name)
+                        if m.type.nullable():
+                            members += fill(
+                                """
+                                if (${srcname}.IsNull()) {
+                                  e->${varname} = nullptr;
+                                } else {
+                                  e->${varname} = ${srcname}.Value().Obj();
+                                }
+                                """,
+                                varname=name,
+                                srcname=srcname)
+                        else:
+                            members += fill(
+                                """
+                                e->${varname}.set(${srcname}.Obj());
+                                """,
+                                varname=name, srcname=srcname)
+                    else:
+                        members += "e->%s = %s.%s;\n" % (name, self.args[1].name, name)
+                    if m.type.isAny() or m.type.isObject() or m.type.isSpiderMonkeyInterface():
+                        holdJS = "mozilla::HoldJSObjects(e.get());\n"
+            iface = iface.parent
+
+        self.body = fill(
+            """
+            RefPtr<${nativeType}> e = new ${nativeType}(aOwner);
+            bool trusted = e->Init(aOwner);
+            e->InitEvent(${eventType}, ${eventInit}.mBubbles, ${eventInit}.mCancelable);
+            $*{members}
+            e->SetTrusted(trusted);
+            e->SetComposed(${eventInit}.mComposed);
+            $*{holdJS}
+            return e.forget();
+            """,
+            nativeType=self.descriptorProvider.nativeType.split('::')[-1],
+            eventType=self.args[0].name,
+            eventInit=self.args[1].name,
+            members=members,
+            holdJS=holdJS)
+
+        self.args.insert(0, Argument("mozilla::dom::EventTarget*", "aOwner"))
+        constructorForNativeCaller = CGNativeMember.define(self, cgClass) + "\n"
+        self.args = list(self.originalArgs)
+        self.body = fill(
+            """
+            nsCOMPtr<mozilla::dom::EventTarget> owner = do_QueryInterface(aGlobal.GetAsSupports());
+            return Constructor(owner, ${arg0}, ${arg1});
+            """,
+            arg0=self.args[0].name,
+            arg1=self.args[1].name)
+        if needCx(None, self.arguments(), [], considerTypes=True, static=True):
+            self.args.insert(0, Argument("JSContext*", "aCx"))
+        self.args.insert(0, Argument("const GlobalObject&", "aGlobal"))
+        self.args.append(Argument('ErrorResult&', 'aRv'))
+        return constructorForNativeCaller + CGNativeMember.define(self, cgClass)
+
+
+class CGEventClass(CGBindingImplClass):
+    """
+    Codegen for the actual Event class implementation for this descriptor
+    """
+    def __init__(self, descriptor):
+        CGBindingImplClass.__init__(self, descriptor, CGEventMethod, CGEventGetter, CGEventSetter, False, "WrapObjectInternal")
+        members = []
+        extraMethods = []
+        for m in descriptor.interface.members:
+            if m.isAttr():
+                if m.type.isAny():
+                    # Add a getter that doesn't need a JSContext.  Note that we
+                    # don't need to do this if our originating interface is not
+                    # the descriptor's interface, because in that case we
+                    # wouldn't generate the getter that _does_ need a JSContext
+                    # either.
+                    extraMethods.append(
+                        ClassMethod(
+                            CGSpecializedGetter.makeNativeName(descriptor, m),
+                            "void",
+                            [Argument("JS::MutableHandle<JS::Value>",
+                                      "aRetVal")],
+                            const=True,
+                            body=fill(
+                                """
+                                JS::ExposeValueToActiveJS(${memberName});
+                                aRetVal.set(${memberName});
+                                """,
+                                memberName=CGDictionary.makeMemberName(m.identifier.name))))
+                if getattr(m, "originatingInterface",
+                           descriptor.interface) != descriptor.interface:
+                    continue
+                nativeType = self.getNativeTypeForIDLType(m.type).define()
+                members.append(ClassMember(CGDictionary.makeMemberName(m.identifier.name),
+                               nativeType,
+                               visibility="private",
+                               body="body"))
+
+        parent = self.descriptor.interface.parent
+        self.parentType = self.descriptor.getDescriptor(parent.identifier.name).nativeType.split('::')[-1]
+        baseDeclarations = fill(
+            """
+            public:
+              NS_DECL_ISUPPORTS_INHERITED
+              NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_INHERITED(${nativeType}, ${parentType})
+            protected:
+              virtual ~${nativeType}();
+              explicit ${nativeType}(mozilla::dom::EventTarget* aOwner);
+
+            """,
+            nativeType=self.descriptor.nativeType.split('::')[-1],
+            parentType=self.parentType)
+
+        className = descriptor.nativeType.split('::')[-1]
+        asConcreteTypeMethod = ClassMethod("As%s" % className,
+                                           "%s*" % className,
+                                           [],
+                                           virtual=True,
+                                           body="return this;\n",
+                                           breakAfterReturnDecl=" ",
+                                           override=True)
+        extraMethods.append(asConcreteTypeMethod)
+
+        CGClass.__init__(self, className,
+                         bases=[ClassBase(self.parentType)],
+                         methods=extraMethods+self.methodDecls,
+                         members=members,
+                         extradeclarations=baseDeclarations)
+
+    def getWrapObjectBody(self):
+        return "return %sBinding::Wrap(aCx, this, aGivenProto);\n" % self.descriptor.name
+
+    def implTraverse(self):
+        retVal = ""
+        for m in self.descriptor.interface.members:
+            # Unroll the type so we pick up sequences of interfaces too.
+            if m.isAttr() and idlTypeNeedsCycleCollection(m.type):
+                retVal += ("  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(" +
+                           CGDictionary.makeMemberName(m.identifier.name) +
+                           ")\n")
+        return retVal
+
+    def implUnlink(self):
+        retVal = ""
+        for m in self.descriptor.interface.members:
+            if m.isAttr():
+                name = CGDictionary.makeMemberName(m.identifier.name)
+                # Unroll the type so we pick up sequences of interfaces too.
+                if idlTypeNeedsCycleCollection(m.type):
+                    retVal += "  NS_IMPL_CYCLE_COLLECTION_UNLINK(" + name + ")\n"
+                elif m.type.isAny():
+                    retVal += "  tmp->" + name + ".setUndefined();\n"
+                elif m.type.isObject() or m.type.isSpiderMonkeyInterface():
+                    retVal += "  tmp->" + name + " = nullptr;\n"
+        return retVal
+
+    def implTrace(self):
+        retVal = ""
+        for m in self.descriptor.interface.members:
+            if m.isAttr():
+                name = CGDictionary.makeMemberName(m.identifier.name)
+                if m.type.isAny() or m.type.isObject() or m.type.isSpiderMonkeyInterface():
+                    retVal += "  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(" + name + ")\n"
+                elif typeNeedsRooting(m.type):
+                    raise TypeError("Need to implement tracing for event "
+                                    "member of type %s" % m.type)
+        return retVal
+
+    def define(self):
+        dropJS = ""
+        for m in self.descriptor.interface.members:
+            if m.isAttr():
+                member = CGDictionary.makeMemberName(m.identifier.name)
+                if m.type.isAny():
+                    dropJS += member + " = JS::UndefinedValue();\n"
+                elif m.type.isObject() or m.type.isSpiderMonkeyInterface():
+                    dropJS += member + " = nullptr;\n"
+        if dropJS != "":
+            dropJS += "mozilla::DropJSObjects(this);\n"
+        # Just override CGClass and do our own thing
+        nativeType = self.descriptor.nativeType.split('::')[-1]
+        ctorParams = ("aOwner, nullptr, nullptr" if self.parentType == "Event"
+                      else "aOwner")
+
+        classImpl = fill(
+            """
+
+            NS_IMPL_CYCLE_COLLECTION_CLASS(${nativeType})
+
+            NS_IMPL_ADDREF_INHERITED(${nativeType}, ${parentType})
+            NS_IMPL_RELEASE_INHERITED(${nativeType}, ${parentType})
+
+            NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN_INHERITED(${nativeType}, ${parentType})
+            $*{traverse}
+            NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+            NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN_INHERITED(${nativeType}, ${parentType})
+            $*{trace}
+            NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+            NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN_INHERITED(${nativeType}, ${parentType})
+            $*{unlink}
+            NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+            NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION_INHERITED(${nativeType})
+            NS_INTERFACE_MAP_END_INHERITING(${parentType})
+
+            ${nativeType}::${nativeType}(mozilla::dom::EventTarget* aOwner)
+              : ${parentType}(${ctorParams})
+            {
+            }
+
+            ${nativeType}::~${nativeType}()
+            {
+              $*{dropJS}
+            }
+
+            """,
+            ifaceName=self.descriptor.name,
+            nativeType=nativeType,
+            ctorParams=ctorParams,
+            parentType=self.parentType,
+            traverse=self.implTraverse(),
+            unlink=self.implUnlink(),
+            trace=self.implTrace(),
+            dropJS=dropJS)
+        return classImpl + CGBindingImplClass.define(self)
+
+    def getNativeTypeForIDLType(self, type):
+        if type.isPrimitive() and type.tag() in builtinNames:
+            nativeType = CGGeneric(builtinNames[type.tag()])
+            if type.nullable():
+                nativeType = CGTemplatedType("Nullable", nativeType)
+        elif type.isEnum():
+            nativeType = CGGeneric(type.unroll().inner.identifier.name)
+            if type.nullable():
+                nativeType = CGTemplatedType("Nullable", nativeType)
+        elif type.isDOMString() or type.isUSVString():
+            nativeType = CGGeneric("nsString")
+        elif type.isByteString():
+            nativeType = CGGeneric("nsCString")
+        elif type.isGeckoInterface():
+            iface = type.unroll().inner
+            nativeType = self.descriptor.getDescriptor(
+                iface.identifier.name).nativeType
+            # Now trim off unnecessary namespaces
+            nativeType = nativeType.split("::")
+            if nativeType[0] == "mozilla":
+                nativeType.pop(0)
+                if nativeType[0] == "dom":
+                    nativeType.pop(0)
+            nativeType = CGWrapper(CGGeneric("::".join(nativeType)), pre="RefPtr<", post=">")
+        elif type.isAny():
+            nativeType = CGGeneric("JS::Heap<JS::Value>")
+        elif type.isObject() or type.isSpiderMonkeyInterface():
+            nativeType = CGGeneric("JS::Heap<JSObject*>")
+        elif type.isUnion():
+            nativeType = CGGeneric(CGUnionStruct.unionTypeDecl(type, True))
+        elif type.isSequence():
+            if type.nullable():
+                innerType = type.inner.inner
+            else:
+                innerType = type.inner
+            if (not innerType.isPrimitive() and not innerType.isEnum() and
+                not innerType.isDOMString() and not innerType.isByteString() and
+                not innerType.isGeckoInterface()):
+                raise TypeError("Don't know how to properly manage GC/CC for "
+                                "event member of type %s" %
+                                type)
+            nativeType = CGTemplatedType(
+                "nsTArray",
+                self.getNativeTypeForIDLType(innerType))
+            if type.nullable():
+                nativeType = CGTemplatedType("Nullable", nativeType)
+        else:
+            raise TypeError("Don't know how to declare event member of type %s" %
+                            type)
+        return nativeType
+
+
+class CGEventRoot(CGThing):
+    def __init__(self, config, interfaceName):
+        descriptor = config.getDescriptor(interfaceName)
+
+        self.root = CGWrapper(CGEventClass(descriptor),
+                              pre="\n", post="\n")
+
+        self.root = CGNamespace.build(["mozilla", "dom"], self.root)
+
+        self.root = CGList([CGClassForwardDeclare("JSContext", isStruct=True),
+                            self.root])
+
+        parent = descriptor.interface.parent.identifier.name
+
+        # Throw in our #includes
+        self.root = CGHeaders(
+            [descriptor],
+            [],
+            [],
+            [],
+            [
+                config.getDescriptor(parent).headerFile,
+                "mozilla/Attributes.h",
+                "mozilla/ErrorResult.h",
+                "mozilla/dom/%sBinding.h" % interfaceName,
+                'mozilla/dom/BindingUtils.h',
+                ],
+            [
+                "%s.h" % interfaceName,
+                "js/GCAPI.h",
+                'mozilla/dom/Nullable.h',
+            ],
+            "", self.root, config)
+
+        # And now some include guards
+        self.root = CGIncludeGuard(interfaceName, self.root)
+
+        self.root = CGWrapper(
+            self.root,
+            pre=(AUTOGENERATED_WITH_SOURCE_WARNING_COMMENT %
+                 os.path.basename(descriptor.interface.filename())))
+
+        self.root = CGWrapper(self.root, pre=dedent("""
+            /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+            /* vim:set ts=2 sw=2 sts=2 et cindent: */
+            /* This Source Code Form is subject to the terms of the Mozilla Public
+             * License, v. 2.0. If a copy of the MPL was not distributed with this
+             * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+            """))
+
+    def declare(self):
+        return self.root.declare()
+
+    def define(self):
+        return self.root.define()
diff --git a/dom/bindings/Configuration.py b/dom/bindings/Configuration.py
new file mode 100644
index 000000000..5c96580a1
--- /dev/null
+++ b/dom/bindings/Configuration.py
@@ -0,0 +1,791 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from WebIDL import IDLImplementsStatement
+import os
+from collections import defaultdict
+
+autogenerated_comment = "/* THIS FILE IS AUTOGENERATED - DO NOT EDIT */\n"
+
+
+class DescriptorProvider:
+    """
+    A way of getting descriptors for interface names.  Subclasses must
+    have a getDescriptor method callable with the interface name only.
+    """
+    def __init__(self):
+        pass
+
+
+class Configuration(DescriptorProvider):
+    """
+    Represents global configuration state based on IDL parse data and
+    the configuration file.
+    """
+    def __init__(self, filename, parseData, generatedEvents=[]):
+        DescriptorProvider.__init__(self)
+
+        # Read the configuration file.
+        glbl = {}
+        execfile(filename, glbl)
+        config = glbl['DOMInterfaces']
+
+        # Build descriptors for all the interfaces we have in the parse data.
+        # This allows callers to specify a subset of interfaces by filtering
+        # |parseData|.
+        self.descriptors = []
+        self.interfaces = {}
+        self.descriptorsByName = {}
+        self.optimizedOutDescriptorNames = set()
+        self.generatedEvents = generatedEvents
+        self.maxProtoChainLength = 0
+        for thing in parseData:
+            if isinstance(thing, IDLImplementsStatement):
+                # Our build system doesn't support dep build involving
+                # addition/removal of "implements" statements that appear in a
+                # different .webidl file than their LHS interface.  Make sure we
+                # don't have any of those.
+                #
+                # But whitelist a RHS that is LegacyQueryInterface,
+                # since people shouldn't be adding any of those.
+                if (thing.implementor.filename() != thing.filename() and
+                    thing.implementee.identifier.name != "LegacyQueryInterface"):
+                    raise TypeError(
+                        "The binding build system doesn't really support "
+                        "'implements' statements which don't appear in the "
+                        "file in which the left-hand side of the statement is "
+                        "defined.  Don't do this unless your right-hand side "
+                        "is LegacyQueryInterface.\n"
+                        "%s\n"
+                        "%s" %
+                        (thing.location, thing.implementor.location))
+
+            assert not thing.isType()
+
+            if not thing.isInterface() and not thing.isNamespace():
+                continue
+            iface = thing
+            self.interfaces[iface.identifier.name] = iface
+            if iface.identifier.name not in config:
+                # Completely skip consequential interfaces with no descriptor
+                # if they have no interface object because chances are we
+                # don't need to do anything interesting with them.
+                if iface.isConsequential() and not iface.hasInterfaceObject():
+                    self.optimizedOutDescriptorNames.add(iface.identifier.name)
+                    continue
+                entry = {}
+            else:
+                entry = config[iface.identifier.name]
+            assert not isinstance(entry, list)
+            desc = Descriptor(self, iface, entry)
+            self.descriptors.append(desc)
+            # Setting up descriptorsByName while iterating through interfaces
+            # means we can get the nativeType of iterable interfaces without
+            # having to do multiple loops.
+            assert desc.interface.identifier.name not in self.descriptorsByName
+            self.descriptorsByName[desc.interface.identifier.name] = desc
+
+        # Keep the descriptor list sorted for determinism.
+        self.descriptors.sort(lambda x, y: cmp(x.name, y.name))
+
+
+        self.descriptorsByFile = {}
+        for d in self.descriptors:
+            self.descriptorsByFile.setdefault(d.interface.filename(),
+                                              []).append(d)
+
+        self.enums = [e for e in parseData if e.isEnum()]
+
+        self.dictionaries = [d for d in parseData if d.isDictionary()]
+        self.callbacks = [c for c in parseData if
+                          c.isCallback() and not c.isInterface()]
+
+        # Dictionary mapping from a union type name to a set of filenames where
+        # union types with that name are used.
+        self.filenamesPerUnion = defaultdict(set)
+
+        # Dictionary mapping from a filename to a list of types for
+        # the union types used in that file. If a union type is used
+        # in multiple files then it will be added to the list for the
+        # None key. Note that the list contains a type for every use
+        # of a union type, so there can be multiple entries with union
+        # types that have the same name.
+        self.unionsPerFilename = defaultdict(list)
+
+        for (t, _) in getAllTypes(self.descriptors, self.dictionaries, self.callbacks):
+            while True:
+                if t.isMozMap():
+                    t = t.inner
+                elif t.unroll() != t:
+                    t = t.unroll()
+                elif t.isPromise():
+                    t = t.promiseInnerType()
+                else:
+                    break
+            if t.isUnion():
+                filenamesForUnion = self.filenamesPerUnion[t.name]
+                if t.filename() not in filenamesForUnion:
+                    # We have a to be a bit careful: some of our built-in
+                    # typedefs are for unions, and those unions end up with
+                    # "<unknown>" as the filename.  If that happens, we don't
+                    # want to try associating this union with one particular
+                    # filename, since there isn't one to associate it with,
+                    # really.
+                    if t.filename() == "<unknown>":
+                        uniqueFilenameForUnion = None
+                    elif len(filenamesForUnion) == 0:
+                        # This is the first file that we found a union with this
+                        # name in, record the union as part of the file.
+                        uniqueFilenameForUnion = t.filename()
+                    else:
+                        # We already found a file that contains a union with
+                        # this name.
+                        if len(filenamesForUnion) == 1:
+                            # This is the first time we found a union with this
+                            # name in another file.
+                            for f in filenamesForUnion:
+                                # Filter out unions with this name from the
+                                # unions for the file where we previously found
+                                # them.
+                                unionsForFilename = self.unionsPerFilename[f]
+                                unionsForFilename = filter(lambda u: u.name != t.name,
+                                                           unionsForFilename)
+                                if len(unionsForFilename) == 0:
+                                    del self.unionsPerFilename[f]
+                                else:
+                                    self.unionsPerFilename[f] = unionsForFilename
+                        # Unions with this name appear in multiple files, record
+                        # the filename as None, so that we can detect that.
+                        uniqueFilenameForUnion = None
+                    self.unionsPerFilename[uniqueFilenameForUnion].append(t)
+                    filenamesForUnion.add(t.filename())
+
+    def getInterface(self, ifname):
+        return self.interfaces[ifname]
+
+    def getDescriptors(self, **filters):
+        """Gets the descriptors that match the given filters."""
+        curr = self.descriptors
+        # Collect up our filters, because we may have a webIDLFile filter that
+        # we always want to apply first.
+        tofilter = []
+        for key, val in filters.iteritems():
+            if key == 'webIDLFile':
+                # Special-case this part to make it fast, since most of our
+                # getDescriptors calls are conditioned on a webIDLFile.  We may
+                # not have this key, in which case we have no descriptors
+                # either.
+                curr = self.descriptorsByFile.get(val, [])
+                continue
+            elif key == 'hasInterfaceObject':
+                getter = lambda x: (not x.interface.isExternal() and
+                                    x.interface.hasInterfaceObject())
+            elif key == 'hasInterfacePrototypeObject':
+                getter = lambda x: (not x.interface.isExternal() and
+                                    x.interface.hasInterfacePrototypeObject())
+            elif key == 'hasInterfaceOrInterfacePrototypeObject':
+                getter = lambda x: x.hasInterfaceOrInterfacePrototypeObject()
+            elif key == 'isCallback':
+                getter = lambda x: x.interface.isCallback()
+            elif key == 'isExternal':
+                getter = lambda x: x.interface.isExternal()
+            elif key == 'isJSImplemented':
+                getter = lambda x: x.interface.isJSImplemented()
+            elif key == 'isNavigatorProperty':
+                getter = lambda x: x.interface.isNavigatorProperty()
+            elif key == 'isExposedInAnyWorker':
+                getter = lambda x: x.interface.isExposedInAnyWorker()
+            elif key == 'isExposedInWorkerDebugger':
+                getter = lambda x: x.interface.isExposedInWorkerDebugger()
+            elif key == 'isExposedInAnyWorklet':
+                getter = lambda x: x.interface.isExposedInAnyWorklet()
+            elif key == 'isExposedInSystemGlobals':
+                getter = lambda x: x.interface.isExposedInSystemGlobals()
+            elif key == 'isExposedInWindow':
+                getter = lambda x: x.interface.isExposedInWindow()
+            else:
+                # Have to watch out: just closing over "key" is not enough,
+                # since we're about to mutate its value
+                getter = (lambda attrName: lambda x: getattr(x, attrName))(key)
+            tofilter.append((getter, val))
+        for f in tofilter:
+            curr = filter(lambda x: f[0](x) == f[1], curr)
+        return curr
+
+    def getEnums(self, webIDLFile):
+        return filter(lambda e: e.filename() == webIDLFile, self.enums)
+
+    def getDictionaries(self, webIDLFile):
+        return filter(lambda d: d.filename() == webIDLFile, self.dictionaries)
+
+    def getCallbacks(self, webIDLFile):
+        return filter(lambda c: c.filename() == webIDLFile, self.callbacks)
+
+    def getDescriptor(self, interfaceName):
+        """
+        Gets the appropriate descriptor for the given interface name.
+        """
+        # We may have optimized out this descriptor, but the chances of anyone
+        # asking about it are then slim.  Put the check for that _after_ we've
+        # done our normal lookup.  But that means we have to do our normal
+        # lookup in a way that will not throw if it fails.
+        d = self.descriptorsByName.get(interfaceName, None)
+        if d:
+            return d
+
+        if interfaceName in self.optimizedOutDescriptorNames:
+            raise NoSuchDescriptorError(
+                "No descriptor for '%s', which is a mixin ([NoInterfaceObject] "
+                "and a consequential interface) without an explicit "
+                "Bindings.conf annotation." % interfaceName)
+
+        raise NoSuchDescriptorError("For " + interfaceName + " found no matches")
+
+
+class NoSuchDescriptorError(TypeError):
+    def __init__(self, str):
+        TypeError.__init__(self, str)
+
+
+def methodReturnsJSObject(method):
+    assert method.isMethod()
+    if method.returnsPromise():
+        return True
+
+    for signature in method.signatures():
+        returnType = signature[0]
+        if returnType.isObject() or returnType.isSpiderMonkeyInterface():
+            return True
+
+    return False
+
+
+def MemberIsUnforgeable(member, descriptor):
+    # Note: "or" and "and" return either their LHS or RHS, not
+    # necessarily booleans.  Make sure to return a boolean from this
+    # method, because callers will compare its return value to
+    # booleans.
+    return bool((member.isAttr() or member.isMethod()) and
+                not member.isStatic() and
+                (member.isUnforgeable() or
+                 descriptor.interface.getExtendedAttribute("Unforgeable")))
+
+
+class Descriptor(DescriptorProvider):
+    """
+    Represents a single descriptor for an interface. See Bindings.conf.
+    """
+    def __init__(self, config, interface, desc):
+        DescriptorProvider.__init__(self)
+        self.config = config
+        self.interface = interface
+
+        self.wantsXrays = (not interface.isExternal() and
+                           interface.isExposedInWindow())
+
+        if self.wantsXrays:
+            # We could try to restrict self.wantsXrayExpandoClass further.  For
+            # example, we could set it to false if all of our slots store
+            # Gecko-interface-typed things, because we don't use Xray expando
+            # slots for those.  But note that we would need to check the types
+            # of not only the members of "interface" but also of all its
+            # ancestors, because those can have members living in our slots too.
+            # For now, do the simple thing.
+            self.wantsXrayExpandoClass = (interface.totalMembersInSlots != 0)
+
+        # Read the desc, and fill in the relevant defaults.
+        ifaceName = self.interface.identifier.name
+        # For generated iterator interfaces for other iterable interfaces, we
+        # just use IterableIterator as the native type, templated on the
+        # nativeType of the iterable interface. That way we can have a
+        # templated implementation for all the duplicated iterator
+        # functionality.
+        if self.interface.isIteratorInterface():
+            itrName = self.interface.iterableInterface.identifier.name
+            itrDesc = self.getDescriptor(itrName)
+            nativeTypeDefault = iteratorNativeType(itrDesc)
+
+        elif self.interface.isExternal():
+            nativeTypeDefault = "nsIDOM" + ifaceName
+        else:
+            nativeTypeDefault = "mozilla::dom::" + ifaceName
+
+        self.nativeType = desc.get('nativeType', nativeTypeDefault)
+        # Now create a version of nativeType that doesn't have extra
+        # mozilla::dom:: at the beginning.
+        prettyNativeType = self.nativeType.split("::")
+        if prettyNativeType[0] == "mozilla":
+            prettyNativeType.pop(0)
+            if prettyNativeType[0] == "dom":
+                prettyNativeType.pop(0)
+        self.prettyNativeType = "::".join(prettyNativeType)
+
+        self.jsImplParent = desc.get('jsImplParent', self.nativeType)
+
+        # Do something sane for JSObject
+        if self.nativeType == "JSObject":
+            headerDefault = "js/TypeDecls.h"
+        elif self.interface.isCallback() or self.interface.isJSImplemented():
+            # A copy of CGHeaders.getDeclarationFilename; we can't
+            # import it here, sadly.
+            # Use our local version of the header, not the exported one, so that
+            # test bindings, which don't export, will work correctly.
+            basename = os.path.basename(self.interface.filename())
+            headerDefault = basename.replace('.webidl', 'Binding.h')
+        else:
+            if not self.interface.isExternal() and self.interface.getExtendedAttribute("HeaderFile"):
+                headerDefault = self.interface.getExtendedAttribute("HeaderFile")[0]
+            elif self.interface.isIteratorInterface():
+                headerDefault = "mozilla/dom/IterableIterator.h"
+            else:
+                headerDefault = self.nativeType
+                headerDefault = headerDefault.replace("::", "/") + ".h"
+        self.headerFile = desc.get('headerFile', headerDefault)
+        self.headerIsDefault = self.headerFile == headerDefault
+        if self.jsImplParent == self.nativeType:
+            self.jsImplParentHeader = self.headerFile
+        else:
+            self.jsImplParentHeader = self.jsImplParent.replace("::", "/") + ".h"
+
+        self.notflattened = desc.get('notflattened', False)
+        self.register = desc.get('register', True)
+
+        self.hasXPConnectImpls = desc.get('hasXPConnectImpls', False)
+
+        # If we're concrete, we need to crawl our ancestor interfaces and mark
+        # them as having a concrete descendant.
+        self.concrete = (not self.interface.isExternal() and
+                         not self.interface.isCallback() and
+                         not self.interface.isNamespace() and
+                         desc.get('concrete', True))
+        self.hasUnforgeableMembers = (self.concrete and
+                                      any(MemberIsUnforgeable(m, self) for m in
+                                          self.interface.members))
+        self.operations = {
+            'IndexedGetter': None,
+            'IndexedSetter': None,
+            'IndexedCreator': None,
+            'IndexedDeleter': None,
+            'NamedGetter': None,
+            'NamedSetter': None,
+            'NamedCreator': None,
+            'NamedDeleter': None,
+            'Stringifier': None,
+            'LegacyCaller': None,
+            'Jsonifier': None
+            }
+
+        # Stringifiers and jsonifiers need to be set up whether an interface is
+        # concrete or not, because they're actually prototype methods and hence
+        # can apply to instances of descendant interfaces.  Legacy callers and
+        # named/indexed operations only need to be set up on concrete
+        # interfaces, since they affect the JSClass we end up using, not the
+        # prototype object.
+        def addOperation(operation, m):
+            if not self.operations[operation]:
+                self.operations[operation] = m
+
+        # Since stringifiers go on the prototype, we only need to worry
+        # about our own stringifier, not those of our ancestor interfaces.
+        if not self.interface.isExternal():
+            for m in self.interface.members:
+                if m.isMethod() and m.isStringifier():
+                    addOperation('Stringifier', m)
+                if m.isMethod() and m.isJsonifier():
+                    addOperation('Jsonifier', m)
+
+        if self.concrete:
+            self.proxy = False
+            iface = self.interface
+            for m in iface.members:
+                # Don't worry about inheriting legacycallers either: in
+                # practice these are on most-derived prototypes.
+                if m.isMethod() and m.isLegacycaller():
+                    if not m.isIdentifierLess():
+                        raise TypeError("We don't support legacycaller with "
+                                        "identifier.\n%s" % m.location)
+                    if len(m.signatures()) != 1:
+                        raise TypeError("We don't support overloaded "
+                                        "legacycaller.\n%s" % m.location)
+                    addOperation('LegacyCaller', m)
+            while iface:
+                for m in iface.members:
+                    if not m.isMethod():
+                        continue
+
+                    def addIndexedOrNamedOperation(operation, m):
+                        if m.isIndexed():
+                            operation = 'Indexed' + operation
+                        else:
+                            assert m.isNamed()
+                            operation = 'Named' + operation
+                        addOperation(operation, m)
+
+                    if m.isGetter():
+                        addIndexedOrNamedOperation('Getter', m)
+                    if m.isSetter():
+                        addIndexedOrNamedOperation('Setter', m)
+                    if m.isCreator():
+                        addIndexedOrNamedOperation('Creator', m)
+                    if m.isDeleter():
+                        addIndexedOrNamedOperation('Deleter', m)
+                    if m.isLegacycaller() and iface != self.interface:
+                        raise TypeError("We don't support legacycaller on "
+                                        "non-leaf interface %s.\n%s" %
+                                        (iface, iface.location))
+
+                iface.setUserData('hasConcreteDescendant', True)
+                iface = iface.parent
+
+            self.proxy = (self.supportsIndexedProperties() or
+                          (self.supportsNamedProperties() and
+                           not self.hasNamedPropertiesObject) or
+                          self.hasNonOrdinaryGetPrototypeOf())
+
+            if self.proxy:
+                if (not self.operations['IndexedGetter'] and
+                    (self.operations['IndexedSetter'] or
+                     self.operations['IndexedDeleter'] or
+                     self.operations['IndexedCreator'])):
+                    raise SyntaxError("%s supports indexed properties but does "
+                                      "not have an indexed getter.\n%s" %
+                                      (self.interface, self.interface.location))
+                if (not self.operations['NamedGetter'] and
+                    (self.operations['NamedSetter'] or
+                     self.operations['NamedDeleter'] or
+                     self.operations['NamedCreator'])):
+                    raise SyntaxError("%s supports named properties but does "
+                                      "not have a named getter.\n%s" %
+                                      (self.interface, self.interface.location))
+                iface = self.interface
+                while iface:
+                    iface.setUserData('hasProxyDescendant', True)
+                    iface = iface.parent
+
+        if desc.get('wantsQI', None) is not None:
+            self._wantsQI = desc.get('wantsQI', None)
+        self.wrapperCache = (not self.interface.isCallback() and
+                             not self.interface.isIteratorInterface() and
+                             desc.get('wrapperCache', True))
+        # Nasty temporary hack for supporting both DOM and SpiderMonkey promises
+        # without too much pain
+        if self.interface.identifier.name == "Promise":
+            assert self.wrapperCache
+            # But really, we're only wrappercached if we have an interface
+            # object (that is, when we're not using SpiderMonkey promises).
+            self.wrapperCache = self.interface.hasInterfaceObject()
+
+        self.name = interface.identifier.name
+
+        # self.extendedAttributes is a dict of dicts, keyed on
+        # all/getterOnly/setterOnly and then on member name. Values are an
+        # array of extended attributes.
+        self.extendedAttributes = {'all': {}, 'getterOnly': {}, 'setterOnly': {}}
+
+        def addExtendedAttribute(attribute, config):
+            def add(key, members, attribute):
+                for member in members:
+                    self.extendedAttributes[key].setdefault(member, []).append(attribute)
+
+            if isinstance(config, dict):
+                for key in ['all', 'getterOnly', 'setterOnly']:
+                    add(key, config.get(key, []), attribute)
+            elif isinstance(config, list):
+                add('all', config, attribute)
+            else:
+                assert isinstance(config, str)
+                if config == '*':
+                    iface = self.interface
+                    while iface:
+                        add('all', map(lambda m: m.name, iface.members), attribute)
+                        iface = iface.parent
+                else:
+                    add('all', [config], attribute)
+
+        if self.interface.isJSImplemented():
+            addExtendedAttribute('implicitJSContext', ['constructor'])
+        else:
+            for attribute in ['implicitJSContext']:
+                addExtendedAttribute(attribute, desc.get(attribute, {}))
+
+        if self.interface.identifier.name == 'Navigator':
+            for m in self.interface.members:
+                if m.isAttr() and m.navigatorObjectGetter:
+                    # These getters call ConstructNavigatorObject to construct
+                    # the value, and ConstructNavigatorObject needs a JSContext.
+                    self.extendedAttributes['all'].setdefault(m.identifier.name, []).append('implicitJSContext')
+
+        self._binaryNames = desc.get('binaryNames', {})
+        self._binaryNames.setdefault('__legacycaller', 'LegacyCall')
+        self._binaryNames.setdefault('__stringifier', 'Stringify')
+
+        if not self.interface.isExternal():
+            def isTestInterface(iface):
+                return (iface.identifier.name in ["TestInterface",
+                                                  "TestJSImplInterface",
+                                                  "TestRenamedInterface"])
+
+            for member in self.interface.members:
+                if not member.isAttr() and not member.isMethod():
+                    continue
+                binaryName = member.getExtendedAttribute("BinaryName")
+                if binaryName:
+                    assert isinstance(binaryName, list)
+                    assert len(binaryName) == 1
+                    self._binaryNames.setdefault(member.identifier.name,
+                                                 binaryName[0])
+
+        # Build the prototype chain.
+        self.prototypeChain = []
+        parent = interface
+        while parent:
+            self.prototypeChain.insert(0, parent.identifier.name)
+            parent = parent.parent
+        config.maxProtoChainLength = max(config.maxProtoChainLength,
+                                         len(self.prototypeChain))
+
+    def binaryNameFor(self, name):
+        return self._binaryNames.get(name, name)
+
+    @property
+    def prototypeNameChain(self):
+        return map(lambda p: self.getDescriptor(p).name, self.prototypeChain)
+
+    @property
+    def parentPrototypeName(self):
+        if len(self.prototypeChain) == 1:
+            return None
+        return self.getDescriptor(self.prototypeChain[-2]).name
+
+    def hasInterfaceOrInterfacePrototypeObject(self):
+
+        # Forward-declared interfaces don't need either interface object or
+        # interface prototype object as they're going to use QI.
+        if self.interface.isExternal():
+            return False
+
+        return self.interface.hasInterfaceObject() or self.interface.hasInterfacePrototypeObject()
+
+    @property
+    def hasNamedPropertiesObject(self):
+        if self.interface.isExternal():
+            return False
+
+        return self.isGlobal() and self.supportsNamedProperties()
+
+    def getExtendedAttributes(self, member, getter=False, setter=False):
+        def ensureValidThrowsExtendedAttribute(attr):
+            if (attr is not None and attr is not True):
+                raise TypeError("Unknown value for 'Throws': " + attr[0])
+
+        def maybeAppendInfallibleToAttrs(attrs, throws):
+            ensureValidThrowsExtendedAttribute(throws)
+            if throws is None:
+                attrs.append("infallible")
+
+        name = member.identifier.name
+        throws = self.interface.isJSImplemented() or member.getExtendedAttribute("Throws")
+        if member.isMethod():
+            # JSObject-returning [NewObject] methods must be fallible,
+            # since they have to (fallibly) allocate the new JSObject.
+            if (member.getExtendedAttribute("NewObject") and
+                methodReturnsJSObject(member)):
+                throws = True
+            attrs = self.extendedAttributes['all'].get(name, [])
+            maybeAppendInfallibleToAttrs(attrs, throws)
+            return attrs
+
+        assert member.isAttr()
+        assert bool(getter) != bool(setter)
+        key = 'getterOnly' if getter else 'setterOnly'
+        attrs = self.extendedAttributes['all'].get(name, []) + self.extendedAttributes[key].get(name, [])
+        if throws is None:
+            throwsAttr = "GetterThrows" if getter else "SetterThrows"
+            throws = member.getExtendedAttribute(throwsAttr)
+        maybeAppendInfallibleToAttrs(attrs, throws)
+        return attrs
+
+    def supportsIndexedProperties(self):
+        return self.operations['IndexedGetter'] is not None
+
+    def supportsNamedProperties(self):
+        return self.operations['NamedGetter'] is not None
+
+    def hasNonOrdinaryGetPrototypeOf(self):
+        return self.interface.getExtendedAttribute("NonOrdinaryGetPrototypeOf")
+
+    def needsHeaderInclude(self):
+        """
+        An interface doesn't need a header file if it is not concrete, not
+        pref-controlled, has no prototype object, has no static methods or
+        attributes and has no parent.  The parent matters because we assert
+        things about refcounting that depend on the actual underlying type if we
+        have a parent.
+
+        """
+        return (self.interface.isExternal() or self.concrete or
+                self.interface.hasInterfacePrototypeObject() or
+                any((m.isAttr() or m.isMethod()) and m.isStatic() for m in self.interface.members) or
+                self.interface.parent)
+
+    def hasThreadChecks(self):
+        # isExposedConditionally does not necessarily imply thread checks
+        # (since at least [SecureContext] is independent of them), but we're
+        # only used to decide whether to include nsThreadUtils.h, so we don't
+        # worry about that.
+        return ((self.isExposedConditionally() and
+                 not self.interface.isExposedInWindow()) or
+                self.interface.isExposedInSomeButNotAllWorkers())
+
+    def isExposedConditionally(self):
+        return (self.interface.isExposedConditionally() or
+                self.interface.isExposedInSomeButNotAllWorkers())
+
+    def needsXrayResolveHooks(self):
+        """
+        Generally, any interface with NeedResolve needs Xray
+        resolveOwnProperty and enumerateOwnProperties hooks.  But for
+        the special case of plugin-loading elements, we do NOT want
+        those, because we don't want to instantiate plug-ins simply
+        due to chrome touching them and that's all those hooks do on
+        those elements.  So we special-case those here.
+        """
+        return (self.interface.getExtendedAttribute("NeedResolve") and
+                self.interface.identifier.name not in ["HTMLObjectElement",
+                                                       "HTMLEmbedElement",
+                                                       "HTMLAppletElement"])
+    def needsXrayNamedDeleterHook(self):
+        return self.operations["NamedDeleter"] is not None
+
+    def needsSpecialGenericOps(self):
+        """
+        Returns true if this descriptor requires generic ops other than
+        GenericBindingMethod/GenericBindingGetter/GenericBindingSetter.
+
+        In practice we need to do this if our this value might be an XPConnect
+        object or if we need to coerce null/undefined to the global.
+        """
+        return self.hasXPConnectImpls or self.interface.isOnGlobalProtoChain()
+
+    def isGlobal(self):
+        """
+        Returns true if this is the primary interface for a global object
+        of some sort.
+        """
+        return (self.interface.getExtendedAttribute("Global") or
+                self.interface.getExtendedAttribute("PrimaryGlobal"))
+
+    @property
+    def namedPropertiesEnumerable(self):
+        """
+        Returns whether this interface should have enumerable named properties
+        """
+        assert self.proxy
+        assert self.supportsNamedProperties()
+        iface = self.interface
+        while iface:
+            if iface.getExtendedAttribute("LegacyUnenumerableNamedProperties"):
+                return False
+            iface = iface.parent
+        return True
+
+    @property
+    def registersGlobalNamesOnWindow(self):
+        return (not self.interface.isExternal() and
+                self.interface.hasInterfaceObject() and
+                self.interface.isExposedInWindow() and
+                self.register)
+
+    def getDescriptor(self, interfaceName):
+        """
+        Gets the appropriate descriptor for the given interface name.
+        """
+        return self.config.getDescriptor(interfaceName)
+
+
+# Some utility methods
+def getTypesFromDescriptor(descriptor):
+    """
+    Get all argument and return types for all members of the descriptor
+    """
+    members = [m for m in descriptor.interface.members]
+    if descriptor.interface.ctor():
+        members.append(descriptor.interface.ctor())
+    members.extend(descriptor.interface.namedConstructors)
+    signatures = [s for m in members if m.isMethod() for s in m.signatures()]
+    types = []
+    for s in signatures:
+        assert len(s) == 2
+        (returnType, arguments) = s
+        types.append(returnType)
+        types.extend(a.type for a in arguments)
+
+    types.extend(a.type for a in members if a.isAttr())
+
+    if descriptor.interface.maplikeOrSetlikeOrIterable:
+        maplikeOrSetlikeOrIterable = descriptor.interface.maplikeOrSetlikeOrIterable
+        if maplikeOrSetlikeOrIterable.hasKeyType():
+            types.append(maplikeOrSetlikeOrIterable.keyType)
+        if maplikeOrSetlikeOrIterable.hasValueType():
+            types.append(maplikeOrSetlikeOrIterable.valueType)
+    return types
+
+
+def getFlatTypes(types):
+    retval = set()
+    for type in types:
+        type = type.unroll()
+        if type.isUnion():
+            retval |= set(type.flatMemberTypes)
+        else:
+            retval.add(type)
+    return retval
+
+
+def getTypesFromDictionary(dictionary):
+    """
+    Get all member types for this dictionary
+    """
+    types = []
+    curDict = dictionary
+    while curDict:
+        types.extend([m.type for m in curDict.members])
+        curDict = curDict.parent
+    return types
+
+
+def getTypesFromCallback(callback):
+    """
+    Get the types this callback depends on: its return type and the
+    types of its arguments.
+    """
+    sig = callback.signatures()[0]
+    types = [sig[0]]  # Return type
+    types.extend(arg.type for arg in sig[1])  # Arguments
+    return types
+
+
+def getAllTypes(descriptors, dictionaries, callbacks):
+    """
+    Generate all the types we're dealing with.  For each type, a tuple
+    containing type, dictionary is yielded.  The dictionary can be None if the
+    type does not come from a dictionary.
+    """
+    for d in descriptors:
+        if d.interface.isExternal():
+            continue
+        for t in getTypesFromDescriptor(d):
+            yield (t, None)
+    for dictionary in dictionaries:
+        for t in getTypesFromDictionary(dictionary):
+            yield (t, dictionary)
+    for callback in callbacks:
+        for t in getTypesFromCallback(callback):
+            yield (t, None)
+
+def iteratorNativeType(descriptor):
+    assert descriptor.interface.isIterable()
+    iterableDecl = descriptor.interface.maplikeOrSetlikeOrIterable
+    assert iterableDecl.isPairIterator()
+    return "mozilla::dom::IterableIterator<%s>" % descriptor.nativeType
diff --git a/dom/bindings/DOMJSClass.h b/dom/bindings/DOMJSClass.h
new file mode 100644
index 000000000..6e779840f
--- /dev/null
+++ b/dom/bindings/DOMJSClass.h
@@ -0,0 +1,467 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_DOMJSClass_h
+#define mozilla_dom_DOMJSClass_h
+
+#include "jsfriendapi.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+
+#include "mozilla/dom/PrototypeList.h" // auto-generated
+
+#include "mozilla/dom/JSSlots.h"
+
+class nsCycleCollectionParticipant;
+
+// All DOM globals must have a slot at DOM_PROTOTYPE_SLOT.
+#define DOM_PROTOTYPE_SLOT JSCLASS_GLOBAL_SLOT_COUNT
+
+// Keep this count up to date with any extra global slots added above.
+#define DOM_GLOBAL_SLOTS 1
+
+// We use these flag bits for the new bindings.
+#define JSCLASS_DOM_GLOBAL JSCLASS_USERBIT1
+#define JSCLASS_IS_DOMIFACEANDPROTOJSCLASS JSCLASS_USERBIT2
+
+namespace mozilla {
+namespace dom {
+
+/**
+ * Returns true if code running in the given JSContext is allowed to access
+ * [SecureContext] API on the given JSObject.
+ *
+ * [SecureContext] API exposure is restricted to use by code in a Secure
+ * Contexts:
+ *
+ *   https://w3c.github.io/webappsec-secure-contexts/
+ *
+ * Since we want [SecureContext] exposure to depend on the privileges of the
+ * running code (rather than the privileges of an object's creator), this
+ * function checks to see whether the given JSContext's Compartment is flagged
+ * as a Secure Context.  That allows us to make sure that system principal code
+ * (which is marked as a Secure Context) can access Secure Context API on an
+ * object in a different compartment, regardless of whether the other
+ * compartment is a Secure Context or not.
+ *
+ * Checking the JSContext's Compartment doesn't work for expanded principal
+ * globals accessing a Secure Context web page though (e.g. those used by frame
+ * scripts).  To handle that we fall back to checking whether the JSObject came
+ * from a Secure Context.
+ *
+ * Note: We'd prefer this function to live in BindingUtils.h, but we need to
+ * call it in this header, and BindingUtils.h includes us (i.e. we'd have a
+ * circular dependency between headers if it lived there).
+ */
+inline bool
+IsSecureContextOrObjectIsFromSecureContext(JSContext* aCx, JSObject* aObj)
+{
+  return JS::CompartmentCreationOptionsRef(js::GetContextCompartment(aCx)).secureContext() ||
+         JS::CompartmentCreationOptionsRef(js::GetObjectCompartment(aObj)).secureContext();
+}
+
+typedef bool
+(* ResolveOwnProperty)(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                       JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                       JS::MutableHandle<JS::PropertyDescriptor> desc);
+
+typedef bool
+(* EnumerateOwnProperties)(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                           JS::Handle<JSObject*> obj,
+                           JS::AutoIdVector& props);
+
+typedef bool
+(* DeleteNamedProperty)(JSContext* cx, JS::Handle<JSObject*> wrapper,
+                        JS::Handle<JSObject*> obj, JS::Handle<jsid> id,
+                        JS::ObjectOpResult& opresult);
+
+// Returns true if the given global is of a type whose bit is set in
+// aNonExposedGlobals.
+bool
+IsNonExposedGlobal(JSContext* aCx, JSObject* aGlobal,
+                   uint32_t aNonExposedGlobals);
+
+struct ConstantSpec
+{
+  const char* name;
+  JS::Value value;
+};
+
+typedef bool (*PropertyEnabled)(JSContext* cx, JSObject* global);
+
+namespace GlobalNames {
+// The names of our possible globals.  These are the names of the actual
+// interfaces, not of the global names used to refer to them in IDL [Exposed]
+// annotations.
+static const uint32_t Window = 1u << 0;
+static const uint32_t BackstagePass = 1u << 1;
+static const uint32_t DedicatedWorkerGlobalScope = 1u << 2;
+static const uint32_t SharedWorkerGlobalScope = 1u << 3;
+static const uint32_t ServiceWorkerGlobalScope = 1u << 4;
+static const uint32_t WorkerDebuggerGlobalScope = 1u << 5;
+static const uint32_t WorkletGlobalScope = 1u << 6;
+} // namespace GlobalNames
+
+struct PrefableDisablers {
+  inline bool isEnabled(JSContext* cx, JS::Handle<JSObject*> obj) const {
+    // Reading "enabled" on a worker thread is technically undefined behavior,
+    // because it's written only on main threads, with no barriers of any sort.
+    // So we want to avoid doing that.  But we don't particularly want to make
+    // expensive NS_IsMainThread calls here.
+    //
+    // The good news is that "enabled" is only written for things that have a
+    // Pref annotation, and such things can never be exposed on non-Window
+    // globals; our IDL parser enforces that.  So as long as we check our
+    // exposure set before checking "enabled" we will be ok.
+    if (nonExposedGlobals &&
+        IsNonExposedGlobal(cx, js::GetGlobalForObjectCrossCompartment(obj),
+                           nonExposedGlobals)) {
+      return false;
+    }
+    if (!enabled) {
+      return false;
+    }
+    if (secureContext && !IsSecureContextOrObjectIsFromSecureContext(cx, obj)) {
+      return false;
+    }
+    if (enabledFunc &&
+        !enabledFunc(cx, js::GetGlobalForObjectCrossCompartment(obj))) {
+      return false;
+    }
+    return true;
+  }
+
+  // A boolean indicating whether this set of specs is enabled. Not const
+  // because it will change at runtime if the corresponding pref is changed.
+  bool enabled;
+
+  // A boolean indicating whether a Secure Context is required.
+  const bool secureContext;
+
+  // Bitmask of global names that we should not be exposed in.
+  const uint16_t nonExposedGlobals;
+
+  // A function pointer to a function that can say the property is disabled
+  // even if "enabled" is set to true.  If the pointer is null the value of
+  // "enabled" is used as-is.
+  const PropertyEnabled enabledFunc;
+};
+
+template<typename T>
+struct Prefable {
+  inline bool isEnabled(JSContext* cx, JS::Handle<JSObject*> obj) const {
+    if (MOZ_LIKELY(!disablers)) {
+      return true;
+    }
+    return disablers->isEnabled(cx, obj);
+  }
+
+  // Things that can disable this set of specs. |nullptr| means "cannot be
+  // disabled".
+  PrefableDisablers* const disablers;
+
+  // Array of specs, terminated in whatever way is customary for T.
+  // Null to indicate a end-of-array for Prefable, when such an
+  // indicator is needed.
+  const T* const specs;
+};
+
+// Conceptually, NativeProperties has seven (Prefable<T>*, jsid*, T*) trios
+// (where T is one of JSFunctionSpec, JSPropertySpec, or ConstantSpec), one for
+// each of: static methods and attributes, methods and attributes, unforgeable
+// methods and attributes, and constants.
+//
+// That's 21 pointers, but in most instances most of the trios are all null,
+// and there are many instances. To save space we use a variable-length type,
+// NativePropertiesN<N>, to hold the data and getters to access it. It has N
+// actual trios (stored in trios[]), plus four bits for each of the 7 possible
+// trios: 1 bit that states if that trio is present, and 3 that state that
+// trio's offset (if present) in trios[].
+//
+// All trio accesses should be done via the getters, which contain assertions
+// that check we don't overrun the end of the struct. (The trio data members are
+// public only so they can be statically initialized.) These assertions should
+// never fail so long as (a) accesses to the variable-length part are guarded by
+// appropriate Has*() calls, and (b) all instances are well-formed, i.e. the
+// value of N matches the number of mHas* members that are true.
+//
+// Finally, we define a typedef of NativePropertiesN<7>, NativeProperties, which
+// we use as a "base" type used to refer to all instances of NativePropertiesN.
+// (7 is used because that's the maximum valid parameter, though any other
+// value 1..6 could also be used.) This is reasonable because of the
+// aforementioned assertions in the getters. Upcast() is used to convert
+// specific instances to this "base" type.
+//
+template <int N>
+struct NativePropertiesN {
+  // Trio structs are stored in the trios[] array, and each element in the
+  // array could require a different T. Therefore, we can't use the correct
+  // type for mPrefables and mSpecs. Instead we use void* and cast to the
+  // correct type in the getters.
+  struct Trio {
+    const /*Prefable<const T>*/ void* const mPrefables;
+    const jsid* const mIds;
+    const /*T*/ void* const mSpecs;
+  };
+
+  const int32_t iteratorAliasMethodIndex;
+
+  constexpr const NativePropertiesN<7>* Upcast() const {
+    return reinterpret_cast<const NativePropertiesN<7>*>(this);
+  }
+
+#define DO(SpecT, FieldName) \
+public: \
+  /* The bitfields indicating the trio's presence and (if present) offset. */ \
+  const uint32_t mHas##FieldName##s:1; \
+  const uint32_t m##FieldName##sOffset:3; \
+private: \
+  const Trio* FieldName##sTrio() const { \
+    MOZ_ASSERT(Has##FieldName##s()); \
+    return &trios[m##FieldName##sOffset]; \
+  } \
+public: \
+  bool Has##FieldName##s() const { \
+    return mHas##FieldName##s; \
+  } \
+  const Prefable<const SpecT>* FieldName##s() const { \
+    return static_cast<const Prefable<const SpecT>*> \
+                      (FieldName##sTrio()->mPrefables); \
+  } \
+  const jsid* FieldName##Ids() const { \
+    return FieldName##sTrio()->mIds; \
+  } \
+  const SpecT* FieldName##Specs() const { \
+    return static_cast<const SpecT*>(FieldName##sTrio()->mSpecs); \
+  }
+
+  DO(JSFunctionSpec, StaticMethod)
+  DO(JSPropertySpec, StaticAttribute)
+  DO(JSFunctionSpec, Method)
+  DO(JSPropertySpec, Attribute)
+  DO(JSFunctionSpec, UnforgeableMethod)
+  DO(JSPropertySpec, UnforgeableAttribute)
+  DO(ConstantSpec,   Constant)
+
+#undef DO
+
+  const Trio trios[N];
+};
+
+// Ensure the struct has the expected size. The 8 is for the
+// iteratorAliasMethodIndex plus the bitfields; the rest is for trios[].
+static_assert(sizeof(NativePropertiesN<1>) == 8 +  3*sizeof(void*), "1 size");
+static_assert(sizeof(NativePropertiesN<2>) == 8 +  6*sizeof(void*), "2 size");
+static_assert(sizeof(NativePropertiesN<3>) == 8 +  9*sizeof(void*), "3 size");
+static_assert(sizeof(NativePropertiesN<4>) == 8 + 12*sizeof(void*), "4 size");
+static_assert(sizeof(NativePropertiesN<5>) == 8 + 15*sizeof(void*), "5 size");
+static_assert(sizeof(NativePropertiesN<6>) == 8 + 18*sizeof(void*), "6 size");
+static_assert(sizeof(NativePropertiesN<7>) == 8 + 21*sizeof(void*), "7 size");
+
+// The "base" type.
+typedef NativePropertiesN<7> NativeProperties;
+
+struct NativePropertiesHolder
+{
+  const NativeProperties* regular;
+  const NativeProperties* chromeOnly;
+};
+
+// Helper structure for Xrays for DOM binding objects. The same instance is used
+// for instances, interface objects and interface prototype objects of a
+// specific interface.
+struct NativePropertyHooks
+{
+  // The hook to call for resolving indexed or named properties. May be null if
+  // there can't be any.
+  ResolveOwnProperty mResolveOwnProperty;
+  // The hook to call for enumerating indexed or named properties. May be null
+  // if there can't be any.
+  EnumerateOwnProperties mEnumerateOwnProperties;
+  // The hook to call to delete a named property.  May be null if there are no
+  // named properties or no named property deleter.  On success (true return)
+  // the "found" argument will be set to true if there was in fact such a named
+  // property and false otherwise.  If it's set to false, the caller is expected
+  // to proceed with whatever deletion behavior it would have if there were no
+  // named properties involved at all (i.e. if the hook were null).  If it's set
+  // to true, it will indicate via opresult whether the delete actually
+  // succeeded.
+  DeleteNamedProperty mDeleteNamedProperty;
+
+  // The property arrays for this interface.
+  NativePropertiesHolder mNativeProperties;
+
+  // This will be set to the ID of the interface prototype object for the
+  // interface, if it has one. If it doesn't have one it will be set to
+  // prototypes::id::_ID_Count.
+  prototypes::ID mPrototypeID;
+
+  // This will be set to the ID of the interface object for the interface, if it
+  // has one. If it doesn't have one it will be set to
+  // constructors::id::_ID_Count.
+  constructors::ID mConstructorID;
+
+  // The NativePropertyHooks instance for the parent interface (for
+  // ShimInterfaceInfo).
+  const NativePropertyHooks* mProtoHooks;
+
+  // The JSClass to use for expandos on our Xrays.  Can be null, in which case
+  // Xrays will use a default class of their choice.
+  const JSClass* mXrayExpandoClass;
+};
+
+enum DOMObjectType : uint8_t {
+  eInstance,
+  eGlobalInstance,
+  eInterface,
+  eInterfacePrototype,
+  eGlobalInterfacePrototype,
+  eNamedPropertiesObject
+};
+
+inline
+bool
+IsInstance(DOMObjectType type)
+{
+  return type == eInstance || type == eGlobalInstance;
+}
+
+inline
+bool
+IsInterfacePrototype(DOMObjectType type)
+{
+  return type == eInterfacePrototype || type == eGlobalInterfacePrototype;
+}
+
+typedef JSObject* (*AssociatedGlobalGetter)(JSContext* aCx,
+                                            JS::Handle<JSObject*> aObj);
+
+typedef JSObject* (*ProtoGetter)(JSContext* aCx);
+
+/**
+ * Returns a handle to the relevant WebIDL prototype object for the current
+ * compartment global (which may be a handle to null on out of memory).  Once
+ * allocated, the prototype object is guaranteed to exist as long as the global
+ * does, since the global traces its array of WebIDL prototypes and
+ * constructors.
+ */
+typedef JS::Handle<JSObject*> (*ProtoHandleGetter)(JSContext* aCx);
+
+// Special JSClass for reflected DOM objects.
+struct DOMJSClass
+{
+  // It would be nice to just inherit from JSClass, but that precludes pure
+  // compile-time initialization of the form |DOMJSClass = {...};|, since C++
+  // only allows brace initialization for aggregate/POD types.
+  const js::Class mBase;
+
+  // A list of interfaces that this object implements, in order of decreasing
+  // derivedness.
+  const prototypes::ID mInterfaceChain[MAX_PROTOTYPE_CHAIN_LENGTH];
+
+  // We store the DOM object in reserved slot with index DOM_OBJECT_SLOT or in
+  // the proxy private if we use a proxy object.
+  // Sometimes it's an nsISupports and sometimes it's not; this class tells
+  // us which it is.
+  const bool mDOMObjectIsISupports;
+
+  const NativePropertyHooks* mNativeHooks;
+
+  // A callback to find the associated global for our C++ object.  Note that
+  // this is used in cases when that global is _changing_, so it will not match
+  // the global of the JSObject* passed in to this function!
+  AssociatedGlobalGetter mGetAssociatedGlobal;
+  ProtoHandleGetter mGetProto;
+
+  // This stores the CC participant for the native, null if this class does not
+  // implement cycle collection or if it inherits from nsISupports (we can get
+  // the CC participant by QI'ing in that case).
+  nsCycleCollectionParticipant* mParticipant;
+
+  static const DOMJSClass* FromJSClass(const JSClass* base) {
+    MOZ_ASSERT(base->flags & JSCLASS_IS_DOMJSCLASS);
+    return reinterpret_cast<const DOMJSClass*>(base);
+  }
+
+  static const DOMJSClass* FromJSClass(const js::Class* base) {
+    return FromJSClass(Jsvalify(base));
+  }
+
+  const JSClass* ToJSClass() const { return Jsvalify(&mBase); }
+};
+
+// Special JSClass for DOM interface and interface prototype objects.
+struct DOMIfaceAndProtoJSClass
+{
+  // It would be nice to just inherit from js::Class, but that precludes pure
+  // compile-time initialization of the form
+  // |DOMJSInterfaceAndPrototypeClass = {...};|, since C++ only allows brace
+  // initialization for aggregate/POD types.
+  const js::Class mBase;
+
+  // Either eInterface, eInterfacePrototype, eGlobalInterfacePrototype or
+  // eNamedPropertiesObject.
+  DOMObjectType mType; // uint8_t
+
+  // Boolean indicating whether this object wants a @@hasInstance property
+  // pointing to InterfaceHasInstance defined on it.  Only ever true for the
+  // eInterface case.
+  bool wantsInterfaceHasInstance;
+
+  const prototypes::ID mPrototypeID; // uint16_t
+  const uint32_t mDepth;
+
+  const NativePropertyHooks* mNativeHooks;
+
+  // The value to return for toString() on this interface or interface prototype
+  // object.
+  const char* mToString;
+
+  ProtoGetter mGetParentProto;
+
+  static const DOMIfaceAndProtoJSClass* FromJSClass(const JSClass* base) {
+    MOZ_ASSERT(base->flags & JSCLASS_IS_DOMIFACEANDPROTOJSCLASS);
+    return reinterpret_cast<const DOMIfaceAndProtoJSClass*>(base);
+  }
+  static const DOMIfaceAndProtoJSClass* FromJSClass(const js::Class* base) {
+    return FromJSClass(Jsvalify(base));
+  }
+
+  const JSClass* ToJSClass() const { return Jsvalify(&mBase); }
+};
+
+class ProtoAndIfaceCache;
+
+inline bool
+DOMGlobalHasProtoAndIFaceCache(JSObject* global)
+{
+  MOZ_ASSERT(js::GetObjectClass(global)->flags & JSCLASS_DOM_GLOBAL);
+  // This can be undefined if we GC while creating the global
+  return !js::GetReservedSlot(global, DOM_PROTOTYPE_SLOT).isUndefined();
+}
+
+inline bool
+HasProtoAndIfaceCache(JSObject* global)
+{
+  if (!(js::GetObjectClass(global)->flags & JSCLASS_DOM_GLOBAL)) {
+    return false;
+  }
+  return DOMGlobalHasProtoAndIFaceCache(global);
+}
+
+inline ProtoAndIfaceCache*
+GetProtoAndIfaceCache(JSObject* global)
+{
+  MOZ_ASSERT(js::GetObjectClass(global)->flags & JSCLASS_DOM_GLOBAL);
+  return static_cast<ProtoAndIfaceCache*>(
+    js::GetReservedSlot(global, DOM_PROTOTYPE_SLOT).toPrivate());
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_DOMJSClass_h */
diff --git a/dom/bindings/DOMJSProxyHandler.cpp b/dom/bindings/DOMJSProxyHandler.cpp
new file mode 100644
index 000000000..65e540bc1
--- /dev/null
+++ b/dom/bindings/DOMJSProxyHandler.cpp
@@ -0,0 +1,362 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/DOMJSProxyHandler.h"
+#include "xpcpublic.h"
+#include "xpcprivate.h"
+#include "XPCWrapper.h"
+#include "WrapperFactory.h"
+#include "nsDOMClassInfo.h"
+#include "nsWrapperCacheInlines.h"
+#include "mozilla/dom/BindingUtils.h"
+
+#include "jsapi.h"
+
+using namespace JS;
+
+namespace mozilla {
+namespace dom {
+
+jsid s_length_id = JSID_VOID;
+
+bool
+DefineStaticJSVals(JSContext* cx)
+{
+  return AtomizeAndPinJSString(cx, s_length_id, "length");
+}
+
+const char DOMProxyHandler::family = 0;
+
+js::DOMProxyShadowsResult
+DOMProxyShadows(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id)
+{
+  JS::Rooted<JSObject*> expando(cx, DOMProxyHandler::GetExpandoObject(proxy));
+  JS::Value v = js::GetProxyExtra(proxy, JSPROXYSLOT_EXPANDO);
+  bool isOverrideBuiltins = !v.isObject() && !v.isUndefined();
+  if (expando) {
+    bool hasOwn;
+    if (!JS_AlreadyHasOwnPropertyById(cx, expando, id, &hasOwn))
+      return js::ShadowCheckFailed;
+
+    if (hasOwn) {
+      return isOverrideBuiltins ?
+        js::ShadowsViaIndirectExpando : js::ShadowsViaDirectExpando;
+    }
+  }
+
+  if (!isOverrideBuiltins) {
+    // Our expando, if any, didn't shadow, so we're not shadowing at all.
+    return js::DoesntShadow;
+  }
+
+  bool hasOwn;
+  if (!GetProxyHandler(proxy)->hasOwn(cx, proxy, id, &hasOwn))
+    return js::ShadowCheckFailed;
+
+  return hasOwn ? js::Shadows : js::DoesntShadowUnique;
+}
+
+// Store the information for the specialized ICs.
+struct SetDOMProxyInformation
+{
+  SetDOMProxyInformation() {
+    js::SetDOMProxyInformation((const void*) &DOMProxyHandler::family,
+                               JSPROXYSLOT_EXPANDO, DOMProxyShadows);
+  }
+};
+
+SetDOMProxyInformation gSetDOMProxyInformation;
+
+// static
+void
+DOMProxyHandler::ClearExternalRefsForWrapperRelease(JSObject* obj)
+{
+  MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
+  JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
+  if (v.isUndefined()) {
+    // No expando.
+    return;
+  }
+
+  // See EnsureExpandoObject for the work we're trying to undo here.
+
+  if (v.isObject()) {
+    // Drop us from the DOM expando hashtable.  Don't worry about clearing our
+    // slot reference to the expando; we're about to die anyway.
+    xpc::ObjectScope(obj)->RemoveDOMExpandoObject(obj);
+    return;
+  }
+
+  // Prevent having a dangling pointer to our expando from the
+  // ExpandoAndGeneration.
+  js::ExpandoAndGeneration* expandoAndGeneration =
+    static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
+  expandoAndGeneration->expando = UndefinedValue();
+}
+
+// static
+JSObject*
+DOMProxyHandler::GetAndClearExpandoObject(JSObject* obj)
+{
+  MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
+  JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
+  if (v.isUndefined()) {
+    return nullptr;
+  }
+
+  if (v.isObject()) {
+    js::SetProxyExtra(obj, JSPROXYSLOT_EXPANDO, UndefinedValue());
+    xpc::ObjectScope(obj)->RemoveDOMExpandoObject(obj);
+  } else {
+    js::ExpandoAndGeneration* expandoAndGeneration =
+      static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
+    v = expandoAndGeneration->expando;
+    if (v.isUndefined()) {
+      return nullptr;
+    }
+    // We have to expose v to active JS here.  The reason for that is that we
+    // might be in the middle of a GC right now.  If our proxy hasn't been
+    // traced yet, when it _does_ get traced it won't trace the expando, since
+    // we're breaking that link.  But the Rooted we're presumably being placed
+    // into is also not going to trace us, because Rooted marking is done at
+    // the very beginning of the GC.  In that situation, we need to manually
+    // mark the expando as live here.  JS::ExposeValueToActiveJS will do just
+    // that for us.
+    //
+    // We don't need to do this in the non-expandoAndGeneration case, because
+    // in that case our value is stored in a slot and slots will already mark
+    // the old thing live when the value in the slot changes.
+    JS::ExposeValueToActiveJS(v);
+    expandoAndGeneration->expando = UndefinedValue();
+  }
+
+
+  return &v.toObject();
+}
+
+// static
+JSObject*
+DOMProxyHandler::EnsureExpandoObject(JSContext* cx, JS::Handle<JSObject*> obj)
+{
+  NS_ASSERTION(IsDOMProxy(obj), "expected a DOM proxy object");
+  JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
+  if (v.isObject()) {
+    return &v.toObject();
+  }
+
+  js::ExpandoAndGeneration* expandoAndGeneration;
+  if (!v.isUndefined()) {
+    expandoAndGeneration = static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
+    if (expandoAndGeneration->expando.isObject()) {
+      return &expandoAndGeneration->expando.toObject();
+    }
+  } else {
+    expandoAndGeneration = nullptr;
+  }
+
+  JS::Rooted<JSObject*> expando(cx,
+    JS_NewObjectWithGivenProto(cx, nullptr, nullptr));
+  if (!expando) {
+    return nullptr;
+  }
+
+  nsISupports* native = UnwrapDOMObject<nsISupports>(obj);
+  nsWrapperCache* cache;
+  CallQueryInterface(native, &cache);
+  if (expandoAndGeneration) {
+    cache->PreserveWrapper(native);
+    expandoAndGeneration->expando.setObject(*expando);
+
+    return expando;
+  }
+
+  if (!xpc::ObjectScope(obj)->RegisterDOMExpandoObject(obj)) {
+    return nullptr;
+  }
+
+  cache->SetPreservingWrapper(true);
+  js::SetProxyExtra(obj, JSPROXYSLOT_EXPANDO, ObjectValue(*expando));
+
+  return expando;
+}
+
+bool
+DOMProxyHandler::preventExtensions(JSContext* cx, JS::Handle<JSObject*> proxy,
+                                   JS::ObjectOpResult& result) const
+{
+  // always extensible per WebIDL
+  return result.failCantPreventExtensions();
+}
+
+bool
+DOMProxyHandler::isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible) const
+{
+  *extensible = true;
+  return true;
+}
+
+bool
+BaseDOMProxyHandler::getOwnPropertyDescriptor(JSContext* cx,
+                                              JS::Handle<JSObject*> proxy,
+                                              JS::Handle<jsid> id,
+                                              MutableHandle<PropertyDescriptor> desc) const
+{
+  return getOwnPropDescriptor(cx, proxy, id, /* ignoreNamedProps = */ false,
+                              desc);
+}
+
+bool
+DOMProxyHandler::defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                                Handle<PropertyDescriptor> desc,
+                                JS::ObjectOpResult &result, bool *defined) const
+{
+  if (desc.hasGetterObject() && desc.setter() == JS_StrictPropertyStub) {
+    return result.failGetterOnly();
+  }
+
+  if (xpc::WrapperFactory::IsXrayWrapper(proxy)) {
+    return result.succeed();
+  }
+
+  JS::Rooted<JSObject*> expando(cx, EnsureExpandoObject(cx, proxy));
+  if (!expando) {
+    return false;
+  }
+
+  if (!JS_DefinePropertyById(cx, expando, id, desc, result)) {
+    return false;
+  }
+  *defined = true;
+  return true;
+}
+
+bool
+DOMProxyHandler::set(JSContext *cx, Handle<JSObject*> proxy, Handle<jsid> id,
+                     Handle<JS::Value> v, Handle<JS::Value> receiver,
+                     ObjectOpResult &result) const
+{
+  MOZ_ASSERT(!xpc::WrapperFactory::IsXrayWrapper(proxy),
+             "Should not have a XrayWrapper here");
+  bool done;
+  if (!setCustom(cx, proxy, id, v, &done)) {
+    return false;
+  }
+  if (done) {
+    return result.succeed();
+  }
+
+  // Make sure to ignore our named properties when checking for own
+  // property descriptors for a set.
+  JS::Rooted<PropertyDescriptor> ownDesc(cx);
+  if (!getOwnPropDescriptor(cx, proxy, id, /* ignoreNamedProps = */ true,
+                            &ownDesc)) {
+    return false;
+  }
+  return js::SetPropertyIgnoringNamedGetter(cx, proxy, id, v, receiver, ownDesc, result);
+}
+
+bool
+DOMProxyHandler::delete_(JSContext* cx, JS::Handle<JSObject*> proxy,
+                         JS::Handle<jsid> id, JS::ObjectOpResult &result) const
+{
+  JS::Rooted<JSObject*> expando(cx);
+  if (!xpc::WrapperFactory::IsXrayWrapper(proxy) && (expando = GetExpandoObject(proxy))) {
+    return JS_DeletePropertyById(cx, expando, id, result);
+  }
+
+  return result.succeed();
+}
+
+bool
+BaseDOMProxyHandler::watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                           JS::Handle<JSObject*> callable) const
+{
+  return js::WatchGuts(cx, proxy, id, callable);
+}
+
+bool
+BaseDOMProxyHandler::unwatch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id) const
+{
+  return js::UnwatchGuts(cx, proxy, id);
+}
+
+bool
+BaseDOMProxyHandler::ownPropertyKeys(JSContext* cx,
+                                     JS::Handle<JSObject*> proxy,
+                                     JS::AutoIdVector& props) const
+{
+  return ownPropNames(cx, proxy, JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, props);
+}
+
+bool
+BaseDOMProxyHandler::getPrototypeIfOrdinary(JSContext* cx, JS::Handle<JSObject*> proxy,
+                                            bool* isOrdinary,
+                                            JS::MutableHandle<JSObject*> proto) const
+{
+  *isOrdinary = true;
+  proto.set(GetStaticPrototype(proxy));
+  return true;
+}
+
+bool
+BaseDOMProxyHandler::getOwnEnumerablePropertyKeys(JSContext* cx,
+                                                  JS::Handle<JSObject*> proxy,
+                                                  JS::AutoIdVector& props) const
+{
+  return ownPropNames(cx, proxy, JSITER_OWNONLY, props);
+}
+
+bool
+DOMProxyHandler::setCustom(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                           JS::Handle<JS::Value> v, bool *done) const
+{
+  *done = false;
+  return true;
+}
+
+//static
+JSObject *
+DOMProxyHandler::GetExpandoObject(JSObject *obj)
+{
+  MOZ_ASSERT(IsDOMProxy(obj), "expected a DOM proxy object");
+  JS::Value v = js::GetProxyExtra(obj, JSPROXYSLOT_EXPANDO);
+  if (v.isObject()) {
+    return &v.toObject();
+  }
+
+  if (v.isUndefined()) {
+    return nullptr;
+  }
+
+  js::ExpandoAndGeneration* expandoAndGeneration =
+    static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
+  v = expandoAndGeneration->expando;
+  return v.isUndefined() ? nullptr : &v.toObject();
+}
+
+void
+ShadowingDOMProxyHandler::trace(JSTracer* trc, JSObject* proxy) const
+{
+  DOMProxyHandler::trace(trc, proxy);
+
+  MOZ_ASSERT(IsDOMProxy(proxy), "expected a DOM proxy object");
+  JS::Value v = js::GetProxyExtra(proxy, JSPROXYSLOT_EXPANDO);
+  MOZ_ASSERT(!v.isObject(), "Should not have expando object directly!");
+
+  if (v.isUndefined()) {
+    // This can happen if we GC while creating our object, before we get a
+    // chance to set up its JSPROXYSLOT_EXPANDO slot.
+    return;
+  }
+
+  js::ExpandoAndGeneration* expandoAndGeneration =
+    static_cast<js::ExpandoAndGeneration*>(v.toPrivate());
+  JS::TraceEdge(trc, &expandoAndGeneration->expando,
+                "Shadowing DOM proxy expando");
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/DOMJSProxyHandler.h b/dom/bindings/DOMJSProxyHandler.h
new file mode 100644
index 000000000..1781649cc
--- /dev/null
+++ b/dom/bindings/DOMJSProxyHandler.h
@@ -0,0 +1,268 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_DOMJSProxyHandler_h
+#define mozilla_dom_DOMJSProxyHandler_h
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Likely.h"
+
+#include "jsapi.h"
+#include "js/Proxy.h"
+#include "nsString.h"
+
+#define DOM_PROXY_OBJECT_SLOT js::PROXY_PRIVATE_SLOT
+
+namespace mozilla {
+namespace dom {
+
+enum {
+  /**
+   * DOM proxies have an extra slot for the expando object at index
+   * JSPROXYSLOT_EXPANDO.
+   *
+   * The expando object is a plain JSObject whose properties correspond to
+   * "expandos" (custom properties set by the script author).
+   *
+   * The exact value stored in the JSPROXYSLOT_EXPANDO slot depends on whether
+   * the interface is annotated with the [OverrideBuiltins] extended attribute.
+   *
+   * If it is, the proxy is initialized with a PrivateValue, which contains a
+   * pointer to a js::ExpandoAndGeneration object; this contains a pointer to
+   * the actual expando object as well as the "generation" of the object.  The
+   * proxy handler will trace the expando object stored in the
+   * js::ExpandoAndGeneration while the proxy itself is alive.
+   *
+   * If it is not, the proxy is initialized with an UndefinedValue. In
+   * EnsureExpandoObject, it is set to an ObjectValue that points to the
+   * expando object directly. (It is set back to an UndefinedValue only when
+   * the object is about to die.)
+   */
+  JSPROXYSLOT_EXPANDO = 0
+};
+
+template<typename T> struct Prefable;
+
+class BaseDOMProxyHandler : public js::BaseProxyHandler
+{
+public:
+  explicit constexpr BaseDOMProxyHandler(const void* aProxyFamily, bool aHasPrototype = false)
+    : js::BaseProxyHandler(aProxyFamily, aHasPrototype)
+  {}
+
+  // Implementations of methods that can be implemented in terms of
+  // other lower-level methods.
+  bool getOwnPropertyDescriptor(JSContext* cx, JS::Handle<JSObject*> proxy,
+                                JS::Handle<jsid> id,
+                                JS::MutableHandle<JS::PropertyDescriptor> desc) const override;
+  virtual bool ownPropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
+                               JS::AutoIdVector &props) const override;
+
+  virtual bool getPrototypeIfOrdinary(JSContext* cx, JS::Handle<JSObject*> proxy,
+                                      bool* isOrdinary,
+                                      JS::MutableHandle<JSObject*> proto) const override;
+
+  // We override getOwnEnumerablePropertyKeys() and implement it directly
+  // instead of using the default implementation, which would call
+  // ownPropertyKeys and then filter out the non-enumerable ones. This avoids
+  // unnecessary work during enumeration.
+  virtual bool getOwnEnumerablePropertyKeys(JSContext* cx, JS::Handle<JSObject*> proxy,
+                                            JS::AutoIdVector &props) const override;
+
+  bool watch(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+             JS::Handle<JSObject*> callable) const override;
+  bool unwatch(JSContext* cx, JS::Handle<JSObject*> proxy,
+               JS::Handle<jsid> id) const override;
+
+protected:
+  // Hook for subclasses to implement shared ownPropertyKeys()/keys()
+  // functionality.  The "flags" argument is either JSITER_OWNONLY (for keys())
+  // or JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS (for
+  // ownPropertyKeys()).
+  virtual bool ownPropNames(JSContext* cx, JS::Handle<JSObject*> proxy,
+                            unsigned flags,
+                            JS::AutoIdVector& props) const = 0;
+
+  // Hook for subclasses to allow set() to ignore named props while other things
+  // that look at property descriptors see them.  This is intentionally not
+  // named getOwnPropertyDescriptor to avoid subclasses that override it hiding
+  // our public getOwnPropertyDescriptor.
+  virtual bool getOwnPropDescriptor(JSContext* cx,
+                                    JS::Handle<JSObject*> proxy,
+                                    JS::Handle<jsid> id,
+                                    bool ignoreNamedProps,
+                                    JS::MutableHandle<JS::PropertyDescriptor> desc) const = 0;
+};
+
+class DOMProxyHandler : public BaseDOMProxyHandler
+{
+public:
+  constexpr DOMProxyHandler()
+    : BaseDOMProxyHandler(&family)
+  {}
+
+  bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                      JS::Handle<JS::PropertyDescriptor> desc,
+                      JS::ObjectOpResult &result) const override
+  {
+    bool unused;
+    return defineProperty(cx, proxy, id, desc, result, &unused);
+  }
+  virtual bool defineProperty(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                              JS::Handle<JS::PropertyDescriptor> desc,
+                              JS::ObjectOpResult &result, bool *defined) const;
+  bool delete_(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+               JS::ObjectOpResult &result) const override;
+  bool preventExtensions(JSContext* cx, JS::Handle<JSObject*> proxy,
+                         JS::ObjectOpResult& result) const override;
+  bool isExtensible(JSContext *cx, JS::Handle<JSObject*> proxy, bool *extensible)
+                    const override;
+  bool set(JSContext *cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+           JS::Handle<JS::Value> v, JS::Handle<JS::Value> receiver, JS::ObjectOpResult &result)
+           const override;
+
+  /*
+   * If assigning to proxy[id] hits a named setter with OverrideBuiltins or
+   * an indexed setter, call it and set *done to true on success. Otherwise, set
+   * *done to false.
+   */
+  virtual bool setCustom(JSContext* cx, JS::Handle<JSObject*> proxy, JS::Handle<jsid> id,
+                         JS::Handle<JS::Value> v, bool *done) const;
+
+  /*
+   * Get the expando object for the given DOM proxy.
+   */
+  static JSObject* GetExpandoObject(JSObject* obj);
+
+  /*
+   * Clear the "external references" to this object.  If you are not
+   * nsWrapperCAche::ReleaseWrapper, you do NOT want to be calling this method.
+   *
+   * XXXbz if we nixed the DOM expando hash and just had a finalizer that
+   * cleared out the value in the ExpandoAndGeneration in the shadowing case,
+   * could we just get rid of this function altogether?
+   */
+  static void ClearExternalRefsForWrapperRelease(JSObject* obj);
+
+  /*
+   * Clear the expando object for the given DOM proxy and return it.  This
+   * function will ensure that the returned object is exposed to active JS if
+   * the given object is exposed.
+   *
+   * GetAndClearExpandoObject does not DROP or clear the preserving wrapper
+   * flag.
+   */
+  static JSObject* GetAndClearExpandoObject(JSObject* obj);
+
+  /*
+   * Ensure that the given proxy (obj) has an expando object, and return it.
+   * Returns null on failure.
+   */
+  static JSObject* EnsureExpandoObject(JSContext* cx,
+                                       JS::Handle<JSObject*> obj);
+
+  static const char family;
+};
+
+// Class used by shadowing handlers (the ones that have [OverrideBuiltins].
+// This handles tracing the expando in ExpandoAndGeneration.
+class ShadowingDOMProxyHandler : public DOMProxyHandler
+{
+  virtual void trace(JSTracer* trc, JSObject* proxy) const override;
+};
+
+inline bool IsDOMProxy(JSObject *obj)
+{
+    const js::Class* clasp = js::GetObjectClass(obj);
+    return clasp->isProxy() &&
+           js::GetProxyHandler(obj)->family() == &DOMProxyHandler::family;
+}
+
+inline const DOMProxyHandler*
+GetDOMProxyHandler(JSObject* obj)
+{
+  MOZ_ASSERT(IsDOMProxy(obj));
+  return static_cast<const DOMProxyHandler*>(js::GetProxyHandler(obj));
+}
+
+extern jsid s_length_id;
+
+// A return value of UINT32_MAX indicates "not an array index".  Note, in
+// particular, that UINT32_MAX itself is not a valid array index in general.
+inline uint32_t
+GetArrayIndexFromId(JSContext* cx, JS::Handle<jsid> id)
+{
+  // Much like js::IdIsIndex, except with a fast path for "length" and another
+  // fast path for starting with a lowercase ascii char.  Is that second one
+  // really needed?  I guess it is because StringIsArrayIndex is out of line...
+  if (MOZ_LIKELY(JSID_IS_INT(id))) {
+    return JSID_TO_INT(id);
+  }
+  if (MOZ_LIKELY(id == s_length_id)) {
+    return UINT32_MAX;
+  }
+  if (MOZ_UNLIKELY(!JSID_IS_ATOM(id))) {
+    return UINT32_MAX;
+  }
+
+  JSLinearString* str = js::AtomToLinearString(JSID_TO_ATOM(id));
+  char16_t s;
+  {
+    JS::AutoCheckCannotGC nogc;
+    if (js::LinearStringHasLatin1Chars(str)) {
+      s = *js::GetLatin1LinearStringChars(nogc, str);
+    } else {
+      s = *js::GetTwoByteLinearStringChars(nogc, str);
+    }
+  }
+  if (MOZ_LIKELY((unsigned)s >= 'a' && (unsigned)s <= 'z'))
+    return UINT32_MAX;
+
+  uint32_t i;
+  return js::StringIsArrayIndex(str, &i) ? i : UINT32_MAX;
+}
+
+inline bool
+IsArrayIndex(uint32_t index)
+{
+  return index < UINT32_MAX;
+}
+
+inline void
+FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
+                       JSObject* obj, bool readonly, bool enumerable = true)
+{
+  desc.object().set(obj);
+  desc.setAttributes((readonly ? JSPROP_READONLY : 0) |
+                     (enumerable ? JSPROP_ENUMERATE : 0));
+  desc.setGetter(nullptr);
+  desc.setSetter(nullptr);
+}
+
+inline void
+FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
+                       JSObject* obj, const JS::Value& v,
+                       bool readonly, bool enumerable = true)
+{
+  desc.value().set(v);
+  FillPropertyDescriptor(desc, obj, readonly, enumerable);
+}
+
+inline void
+FillPropertyDescriptor(JS::MutableHandle<JS::PropertyDescriptor> desc,
+                       JSObject* obj, unsigned attributes, const JS::Value& v)
+{
+  desc.object().set(obj);
+  desc.value().set(v);
+  desc.setAttributes(attributes);
+  desc.setGetter(nullptr);
+  desc.setSetter(nullptr);
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_DOMProxyHandler_h */
diff --git a/dom/bindings/DOMString.h b/dom/bindings/DOMString.h
new file mode 100644
index 000000000..72c8445ec
--- /dev/null
+++ b/dom/bindings/DOMString.h
@@ -0,0 +1,245 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_DOMString_h
+#define mozilla_dom_DOMString_h
+
+#include "nsStringGlue.h"
+#include "nsStringBuffer.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "nsDOMString.h"
+#include "nsIAtom.h"
+
+namespace mozilla {
+namespace dom {
+
+/**
+ * A class for representing string return values.  This can be either passed to
+ * callees that have an nsString or nsAString out param or passed to a callee
+ * that actually knows about this class and can work with it.  Such a callee may
+ * call SetStringBuffer or SetEphemeralStringBuffer or SetOwnedString or
+ * SetOwnedAtom on this object.  It's only OK to call
+ * SetStringBuffer/SetOwnedString/SetOwnedAtom if the caller of the method in
+ * question plans to keep holding a strong ref to the stringbuffer involved,
+ * whether it's a raw nsStringBuffer, or stored inside the string or atom being
+ * passed.  In the string/atom cases that means the caller must own the string
+ * or atom, and not mutate it (in the string case) for the lifetime of the
+ * DOMString.
+ *
+ * The proper way to store a value in this class is to either to do nothing
+ * (which leaves this as an empty string), to call
+ * SetStringBuffer/SetEphemeralStringBuffer with a non-null stringbuffer, to
+ * call SetOwnedString, to call SetOwnedAtom, to call SetNull(), or to call
+ * AsAString() and set the value in the resulting nsString.  These options are
+ * mutually exclusive! Don't do more than one of them.
+ *
+ * The proper way to extract a value is to check IsNull().  If not null, then
+ * check HasStringBuffer().  If that's true, check for a zero length, and if the
+ * length is nonzero call StringBuffer().  If the length is zero this is the
+ * empty string.  If HasStringBuffer() returns false, call AsAString() and get
+ * the value from that.
+ */
+class MOZ_STACK_CLASS DOMString {
+public:
+  DOMString()
+    : mStringBuffer(nullptr)
+    , mLength(0)
+    , mIsNull(false)
+    , mStringBufferOwned(false)
+  {}
+  ~DOMString()
+  {
+    MOZ_ASSERT(!mString || !mStringBuffer,
+               "Shouldn't have both present!");
+    if (mStringBufferOwned) {
+      MOZ_ASSERT(mStringBuffer);
+      mStringBuffer->Release();
+    }
+  }
+
+  operator nsString&()
+  {
+    return AsAString();
+  }
+
+  // It doesn't make any sense to convert a DOMString to a const nsString or
+  // nsAString reference; this class is meant for outparams only.
+  operator const nsString&() = delete;
+  operator const nsAString&() = delete;
+
+  nsString& AsAString()
+  {
+    MOZ_ASSERT(!mStringBuffer, "We already have a stringbuffer?");
+    MOZ_ASSERT(!mIsNull, "We're already set as null");
+    if (!mString) {
+      mString.emplace();
+    }
+    return *mString;
+  }
+
+  bool HasStringBuffer() const
+  {
+    MOZ_ASSERT(!mString || !mStringBuffer,
+               "Shouldn't have both present!");
+    MOZ_ASSERT(!mIsNull, "Caller should have checked IsNull() first");
+    return !mString;
+  }
+
+  // Get the stringbuffer.  This can only be called if HasStringBuffer()
+  // returned true and StringBufferLength() is nonzero.  If that's true, it will
+  // never return null.  Note that constructing a string from this
+  // nsStringBuffer with length given by StringBufferLength() might give you
+  // something that is not null-terminated.
+  nsStringBuffer* StringBuffer() const
+  {
+    MOZ_ASSERT(!mIsNull, "Caller should have checked IsNull() first");
+    MOZ_ASSERT(HasStringBuffer(),
+               "Don't ask for the stringbuffer if we don't have it");
+    MOZ_ASSERT(StringBufferLength() != 0, "Why are you asking for this?");
+    MOZ_ASSERT(mStringBuffer,
+               "If our length is nonzero, we better have a stringbuffer.");
+    return mStringBuffer;
+  }
+
+  // Get the length of the stringbuffer.  Can only be called if
+  // HasStringBuffer().
+  uint32_t StringBufferLength() const
+  {
+    MOZ_ASSERT(HasStringBuffer(), "Don't call this if there is no stringbuffer");
+    return mLength;
+  }
+
+  // Tell the DOMString to relinquish ownership of its nsStringBuffer to the
+  // caller.  Can only be called if HasStringBuffer().
+  void RelinquishBufferOwnership()
+  {
+    MOZ_ASSERT(HasStringBuffer(), "Don't call this if there is no stringbuffer");
+    if (mStringBufferOwned) {
+      // Just hand that ref over.
+      mStringBufferOwned = false;
+    } else {
+      // Caller should end up holding a ref.
+      mStringBuffer->AddRef();
+    }
+  }
+
+  // Initialize the DOMString to a (nsStringBuffer, length) pair.  The length
+  // does NOT have to be the full length of the (null-terminated) string in the
+  // nsStringBuffer.
+  void SetStringBuffer(nsStringBuffer* aStringBuffer, uint32_t aLength)
+  {
+    MOZ_ASSERT(mString.isNothing(), "We already have a string?");
+    MOZ_ASSERT(!mIsNull, "We're already set as null");
+    MOZ_ASSERT(!mStringBuffer, "Setting stringbuffer twice?");
+    MOZ_ASSERT(aStringBuffer, "Why are we getting null?");
+    mStringBuffer = aStringBuffer;
+    mLength = aLength;
+  }
+
+  // Like SetStringBuffer, but holds a reference to the nsStringBuffer.
+  void SetEphemeralStringBuffer(nsStringBuffer* aStringBuffer, uint32_t aLength)
+  {
+    // We rely on SetStringBuffer to ensure our state invariants.
+    SetStringBuffer(aStringBuffer, aLength);
+    aStringBuffer->AddRef();
+    mStringBufferOwned = true;
+  }
+
+  void SetOwnedString(const nsAString& aString)
+  {
+    MOZ_ASSERT(mString.isNothing(), "We already have a string?");
+    MOZ_ASSERT(!mIsNull, "We're already set as null");
+    MOZ_ASSERT(!mStringBuffer, "Setting stringbuffer twice?");
+    nsStringBuffer* buf = nsStringBuffer::FromString(aString);
+    if (buf) {
+      SetStringBuffer(buf, aString.Length());
+    } else if (aString.IsVoid()) {
+      SetNull();
+    } else if (!aString.IsEmpty()) {
+      AsAString() = aString;
+    }
+  }
+
+  enum NullHandling
+  {
+    eTreatNullAsNull,
+    eTreatNullAsEmpty,
+    eNullNotExpected
+  };
+
+  void SetOwnedAtom(nsIAtom* aAtom, NullHandling aNullHandling)
+  {
+    MOZ_ASSERT(mString.isNothing(), "We already have a string?");
+    MOZ_ASSERT(!mIsNull, "We're already set as null");
+    MOZ_ASSERT(!mStringBuffer, "Setting stringbuffer twice?");
+    MOZ_ASSERT(aAtom || aNullHandling != eNullNotExpected);
+    if (aNullHandling == eNullNotExpected || aAtom) {
+      SetStringBuffer(aAtom->GetStringBuffer(), aAtom->GetLength());
+    } else if (aNullHandling == eTreatNullAsNull) {
+      SetNull();
+    }
+  }
+
+  void SetNull()
+  {
+    MOZ_ASSERT(!mStringBuffer, "Should have no stringbuffer if null");
+    MOZ_ASSERT(mString.isNothing(), "Should have no string if null");
+    mIsNull = true;
+  }
+
+  bool IsNull() const
+  {
+    MOZ_ASSERT(!mStringBuffer || mString.isNothing(),
+               "How could we have a stringbuffer and a nonempty string?");
+    return mIsNull || (mString && mString->IsVoid());
+  }
+
+  void ToString(nsAString& aString)
+  {
+    if (IsNull()) {
+      SetDOMStringToNull(aString);
+    } else if (HasStringBuffer()) {
+      if (StringBufferLength() == 0) {
+        aString.Truncate();
+      } else {
+        // Don't share the nsStringBuffer with aString if the result would not
+        // be null-terminated.
+        nsStringBuffer* buf = StringBuffer();
+        uint32_t len = StringBufferLength();
+        auto chars = static_cast<char16_t*>(buf->Data());
+        if (chars[len] == '\0') {
+          // Safe to share the buffer.
+          buf->ToString(len, aString);
+        } else {
+          // We need to copy, unfortunately.
+          aString.Assign(chars, len);
+        }
+      }
+    } else {
+      aString = AsAString();
+    }
+  }
+
+private:
+  // We need to be able to act like a string as needed
+  Maybe<nsAutoString> mString;
+
+  // For callees that know we exist, we can be a stringbuffer/length/null-flag
+  // triple.
+  nsStringBuffer* MOZ_UNSAFE_REF("The ways in which this can be safe are "
+                                 "documented above and enforced through "
+                                 "assertions") mStringBuffer;
+  uint32_t mLength;
+  bool mIsNull;
+  bool mStringBufferOwned;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_DOMString_h
diff --git a/dom/bindings/Date.cpp b/dom/bindings/Date.cpp
new file mode 100644
index 000000000..8c8d50b33
--- /dev/null
+++ b/dom/bindings/Date.cpp
@@ -0,0 +1,49 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/Date.h"
+
+#include "jsapi.h" // for JS_ObjectIsDate
+#include "jsfriendapi.h" // for DateGetMsecSinceEpoch
+#include "js/Date.h" // for JS::NewDateObject, JS::ClippedTime, JS::TimeClip
+#include "js/RootingAPI.h" // for Rooted, MutableHandle
+#include "js/Value.h" // for Value
+#include "mozilla/FloatingPoint.h" // for IsNaN, UnspecifiedNaN
+
+namespace mozilla {
+namespace dom {
+
+bool
+Date::SetTimeStamp(JSContext* aCx, JSObject* aObject)
+{
+  JS::Rooted<JSObject*> obj(aCx, aObject);
+
+  double msecs;
+  if (!js::DateGetMsecSinceEpoch(aCx, obj, &msecs)) {
+    return false;
+  }
+
+  JS::ClippedTime time = JS::TimeClip(msecs);
+  MOZ_ASSERT(NumbersAreIdentical(msecs, time.toDouble()));
+
+  mMsecSinceEpoch = time;
+  return true;
+}
+
+bool
+Date::ToDateObject(JSContext* aCx, JS::MutableHandle<JS::Value> aRval) const
+{
+  JSObject* obj = JS::NewDateObject(aCx, mMsecSinceEpoch);
+  if (!obj) {
+    return false;
+  }
+
+  aRval.setObject(*obj);
+  return true;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/Date.h b/dom/bindings/Date.h
new file mode 100644
index 000000000..66c893e4d
--- /dev/null
+++ b/dom/bindings/Date.h
@@ -0,0 +1,61 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* Representation for dates. */
+
+#ifndef mozilla_dom_Date_h
+#define mozilla_dom_Date_h
+
+#include "js/Date.h"
+#include "js/TypeDecls.h"
+
+namespace mozilla {
+namespace dom {
+
+class Date
+{
+public:
+  Date() {}
+  explicit Date(JS::ClippedTime aMilliseconds)
+    : mMsecSinceEpoch(aMilliseconds)
+  {}
+
+  bool IsUndefined() const
+  {
+    return !mMsecSinceEpoch.isValid();
+  }
+
+  JS::ClippedTime TimeStamp() const
+  {
+    return mMsecSinceEpoch;
+  }
+
+  // Returns an integer in the range [-8.64e15, +8.64e15] (-0 excluded), *or*
+  // returns NaN.  DO NOT ASSUME THIS IS FINITE!
+  double ToDouble() const
+  {
+    return mMsecSinceEpoch.toDouble();
+  }
+
+  void SetTimeStamp(JS::ClippedTime aMilliseconds)
+  {
+    mMsecSinceEpoch = aMilliseconds;
+  }
+
+  // Can return false if CheckedUnwrap fails.  This will NOT throw;
+  // callers should do it as needed.
+  bool SetTimeStamp(JSContext* aCx, JSObject* aObject);
+
+  bool ToDateObject(JSContext* aCx, JS::MutableHandle<JS::Value> aRval) const;
+
+private:
+  JS::ClippedTime mMsecSinceEpoch;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_Date_h
diff --git a/dom/bindings/ErrorIPCUtils.h b/dom/bindings/ErrorIPCUtils.h
new file mode 100644
index 000000000..0e60d8174
--- /dev/null
+++ b/dom/bindings/ErrorIPCUtils.h
@@ -0,0 +1,84 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "ipc/IPCMessageUtils.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Move.h"
+
+#ifndef IPC_ErrorIPCUtils_h
+#define IPC_ErrorIPCUtils_h
+
+namespace IPC {
+
+template<>
+struct ParamTraits<mozilla::dom::ErrNum> :
+  public ContiguousEnumSerializer<mozilla::dom::ErrNum,
+                                  mozilla::dom::ErrNum(0),
+                                  mozilla::dom::ErrNum(mozilla::dom::Err_Limit)> {};
+
+template<>
+struct ParamTraits<mozilla::ErrorResult>
+{
+  typedef mozilla::ErrorResult paramType;
+
+  static void Write(Message* aMsg, const paramType& aParam)
+  {
+    // It should be the case that mMightHaveUnreportedJSException can only be
+    // true when we're expecting a JS exception.  We cannot send such messages
+    // over the IPC channel since there is no sane way of transferring the JS
+    // value over to the other side.  Callers should never do that.
+    MOZ_ASSERT_IF(aParam.IsJSException(), aParam.mMightHaveUnreportedJSException);
+    if (aParam.IsJSException()
+#ifdef DEBUG
+        || aParam.mMightHaveUnreportedJSException
+#endif
+        ) {
+      MOZ_CRASH("Cannot encode an ErrorResult representing a Javascript exception");
+    }
+
+    WriteParam(aMsg, aParam.mResult);
+    WriteParam(aMsg, aParam.IsErrorWithMessage());
+    WriteParam(aMsg, aParam.IsDOMException());
+    if (aParam.IsErrorWithMessage()) {
+      aParam.SerializeMessage(aMsg);
+    } else if (aParam.IsDOMException()) {
+      aParam.SerializeDOMExceptionInfo(aMsg);
+    }
+  }
+
+  static bool Read(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
+  {
+    paramType readValue;
+    if (!ReadParam(aMsg, aIter, &readValue.mResult)) {
+      return false;
+    }
+    bool hasMessage = false;
+    if (!ReadParam(aMsg, aIter, &hasMessage)) {
+      return false;
+    }
+    bool hasDOMExceptionInfo = false;
+    if (!ReadParam(aMsg, aIter, &hasDOMExceptionInfo)) {
+      return false;
+    }
+    if (hasMessage && hasDOMExceptionInfo) {
+      // Shouldn't have both!
+      return false;
+    }
+    if (hasMessage && !readValue.DeserializeMessage(aMsg, aIter)) {
+      return false;
+    } else if (hasDOMExceptionInfo &&
+               !readValue.DeserializeDOMExceptionInfo(aMsg, aIter)) {
+      return false;
+    }
+    *aResult = Move(readValue);
+    return true;
+  }
+};
+
+} // namespace IPC
+
+#endif
diff --git a/dom/bindings/ErrorResult.h b/dom/bindings/ErrorResult.h
new file mode 100644
index 000000000..c45e7ea3b
--- /dev/null
+++ b/dom/bindings/ErrorResult.h
@@ -0,0 +1,587 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A set of structs for tracking exceptions that need to be thrown to JS:
+ * ErrorResult and IgnoredErrorResult.
+ *
+ * Conceptually, these structs represent either success or an exception in the
+ * process of being thrown.  This means that a failing ErrorResult _must_ be
+ * handled in one of the following ways before coming off the stack:
+ *
+ * 1) Suppressed via SuppressException().
+ * 2) Converted to a pure nsresult return value via StealNSResult().
+ * 3) Converted to an actual pending exception on a JSContext via
+ *    MaybeSetPendingException.
+ * 4) Converted to an exception JS::Value (probably to then reject a Promise
+ *    with) via dom::ToJSValue.
+ *
+ * An IgnoredErrorResult will automatically do the first of those four things.
+ */
+
+#ifndef mozilla_ErrorResult_h
+#define mozilla_ErrorResult_h
+
+#include <stdarg.h>
+
+#include "js/GCAnnotations.h"
+#include "js/Value.h"
+#include "nscore.h"
+#include "nsStringGlue.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Move.h"
+#include "nsTArray.h"
+#include "nsISupportsImpl.h"
+
+namespace IPC {
+class Message;
+template <typename> struct ParamTraits;
+} // namespace IPC
+class PickleIterator;
+
+namespace mozilla {
+
+namespace dom {
+
+enum ErrNum {
+#define MSG_DEF(_name, _argc, _exn, _str) \
+  _name,
+#include "mozilla/dom/Errors.msg"
+#undef MSG_DEF
+  Err_Limit
+};
+
+// Debug-only compile-time table of the number of arguments of each error, for use in static_assert.
+#if defined(DEBUG) && (defined(__clang__) || defined(__GNUC__))
+uint16_t constexpr ErrorFormatNumArgs[] = {
+#define MSG_DEF(_name, _argc, _exn, _str) \
+  _argc,
+#include "mozilla/dom/Errors.msg"
+#undef MSG_DEF
+};
+#endif
+
+uint16_t
+GetErrorArgCount(const ErrNum aErrorNumber);
+
+namespace binding_detail {
+void ThrowErrorMessage(JSContext* aCx, const unsigned aErrorNumber, ...);
+} // namespace binding_detail
+
+template<typename... Ts>
+inline bool
+ThrowErrorMessage(JSContext* aCx, const ErrNum aErrorNumber, Ts&&... aArgs)
+{
+  binding_detail::ThrowErrorMessage(aCx, static_cast<const unsigned>(aErrorNumber),
+                                    mozilla::Forward<Ts>(aArgs)...);
+  return false;
+}
+
+struct StringArrayAppender
+{
+  static void Append(nsTArray<nsString>& aArgs, uint16_t aCount)
+  {
+    MOZ_RELEASE_ASSERT(aCount == 0, "Must give at least as many string arguments as are required by the ErrNum.");
+  }
+
+  template<typename... Ts>
+  static void Append(nsTArray<nsString>& aArgs, uint16_t aCount, const nsAString& aFirst, Ts&&... aOtherArgs)
+  {
+    if (aCount == 0) {
+      MOZ_ASSERT(false, "There should not be more string arguments provided than are required by the ErrNum.");
+      return;
+    }
+    aArgs.AppendElement(aFirst);
+    Append(aArgs, aCount - 1, Forward<Ts>(aOtherArgs)...);
+  }
+};
+
+} // namespace dom
+
+class ErrorResult;
+
+namespace binding_danger {
+
+/**
+ * Templated implementation class for various ErrorResult-like things.  The
+ * instantiations differ only in terms of their cleanup policies (used in the
+ * destructor), which they can specify via the template argument.  Note that
+ * this means it's safe to reinterpret_cast between the instantiations unless
+ * you plan to invoke the destructor through such a cast pointer.
+ *
+ * A cleanup policy consists of two booleans: whether to assert that we've been
+ * reported or suppressed, and whether to then go ahead and suppress the
+ * exception.
+ */
+template<typename CleanupPolicy>
+class TErrorResult {
+public:
+  TErrorResult()
+    : mResult(NS_OK)
+#ifdef DEBUG
+    , mMightHaveUnreportedJSException(false)
+    , mUnionState(HasNothing)
+#endif
+  {
+  }
+
+  ~TErrorResult() {
+    AssertInOwningThread();
+
+    if (CleanupPolicy::assertHandled) {
+      // Consumers should have called one of MaybeSetPendingException
+      // (possibly via ToJSValue), StealNSResult, and SuppressException
+      AssertReportedOrSuppressed();
+    }
+
+    if (CleanupPolicy::suppress) {
+      SuppressException();
+    }
+
+    // And now assert that we're in a good final state.
+    AssertReportedOrSuppressed();
+  }
+
+  TErrorResult(TErrorResult&& aRHS)
+    // Initialize mResult and whatever else we need to default-initialize, so
+    // the ClearUnionData call in our operator= will do the right thing
+    // (nothing).
+    : TErrorResult()
+  {
+    *this = Move(aRHS);
+  }
+  TErrorResult& operator=(TErrorResult&& aRHS);
+
+  explicit TErrorResult(nsresult aRv)
+    : TErrorResult()
+  {
+    AssignErrorCode(aRv);
+  }
+
+  operator ErrorResult&();
+
+  void Throw(nsresult rv) {
+    MOZ_ASSERT(NS_FAILED(rv), "Please don't try throwing success");
+    AssignErrorCode(rv);
+  }
+
+  // Duplicate our current state on the given TErrorResult object.  Any
+  // existing errors or messages on the target will be suppressed before
+  // cloning.  Our own error state remains unchanged.
+  void CloneTo(TErrorResult& aRv) const;
+
+  // Use SuppressException when you want to suppress any exception that might be
+  // on the TErrorResult.  After this call, the TErrorResult will be back a "no
+  // exception thrown" state.
+  void SuppressException();
+
+  // Use StealNSResult() when you want to safely convert the TErrorResult to
+  // an nsresult that you will then return to a caller.  This will
+  // SuppressException(), since there will no longer be a way to report it.
+  nsresult StealNSResult() {
+    nsresult rv = ErrorCode();
+    SuppressException();
+    // Don't propagate out our internal error codes that have special meaning.
+    if (rv == NS_ERROR_TYPE_ERR ||
+        rv == NS_ERROR_RANGE_ERR ||
+        rv == NS_ERROR_DOM_JS_EXCEPTION ||
+        rv == NS_ERROR_DOM_DOMEXCEPTION) {
+      // What about NS_ERROR_DOM_EXCEPTION_ON_JSCONTEXT?  I guess that can be
+      // legitimately passed on through....
+      // What to pick here?
+      return NS_ERROR_DOM_INVALID_STATE_ERR;
+    }
+
+    return rv;
+  }
+
+  // Use MaybeSetPendingException to convert a TErrorResult to a pending
+  // exception on the given JSContext.  This is the normal "throw an exception"
+  // codepath.
+  //
+  // The return value is false if the TErrorResult represents success, true
+  // otherwise.  This does mean that in JSAPI method implementations you can't
+  // just use this as |return rv.MaybeSetPendingException(cx)| (though you could
+  // |return !rv.MaybeSetPendingException(cx)|), but in practice pretty much any
+  // consumer would want to do some more work on the success codepath.  So
+  // instead the way you use this is:
+  //
+  //   if (rv.MaybeSetPendingException(cx)) {
+  //     bail out here
+  //   }
+  //   go on to do something useful
+  //
+  // The success path is inline, since it should be the common case and we don't
+  // want to pay the price of a function call in some of the consumers of this
+  // method in the common case.
+  //
+  // Note that a true return value does NOT mean there is now a pending
+  // exception on aCx, due to uncatchable exceptions.  It should still be
+  // considered equivalent to a JSAPI failure in terms of what callers should do
+  // after true is returned.
+  //
+  // After this call, the TErrorResult will no longer return true from Failed(),
+  // since the exception will have moved to the JSContext.
+  bool MaybeSetPendingException(JSContext* cx)
+  {
+    WouldReportJSException();
+    if (!Failed()) {
+      return false;
+    }
+
+    SetPendingException(cx);
+    return true;
+  }
+
+  // Use StealExceptionFromJSContext to convert a pending exception on a
+  // JSContext to a TErrorResult.  This function must be called only when a
+  // JSAPI operation failed.  It assumes that lack of pending exception on the
+  // JSContext means an uncatchable exception was thrown.
+  //
+  // Codepaths that might call this method must call MightThrowJSException even
+  // if the relevant JSAPI calls do not fail.
+  //
+  // When this function returns, JS_IsExceptionPending(cx) will definitely be
+  // false.
+  void StealExceptionFromJSContext(JSContext* cx);
+
+  template<dom::ErrNum errorNumber, typename... Ts>
+  void ThrowTypeError(Ts&&... messageArgs)
+  {
+    ThrowErrorWithMessage<errorNumber>(NS_ERROR_TYPE_ERR,
+                                       Forward<Ts>(messageArgs)...);
+  }
+
+  template<dom::ErrNum errorNumber, typename... Ts>
+  void ThrowRangeError(Ts&&... messageArgs)
+  {
+    ThrowErrorWithMessage<errorNumber>(NS_ERROR_RANGE_ERR,
+                                       Forward<Ts>(messageArgs)...);
+  }
+
+  bool IsErrorWithMessage() const { return ErrorCode() == NS_ERROR_TYPE_ERR || ErrorCode() == NS_ERROR_RANGE_ERR; }
+
+  // Facilities for throwing a preexisting JS exception value via this
+  // TErrorResult.  The contract is that any code which might end up calling
+  // ThrowJSException() or StealExceptionFromJSContext() must call
+  // MightThrowJSException() even if no exception is being thrown.  Code that
+  // conditionally calls ToJSValue on this TErrorResult only if Failed() must
+  // first call WouldReportJSException even if this TErrorResult has not failed.
+  //
+  // The exn argument to ThrowJSException can be in any compartment.  It does
+  // not have to be in the compartment of cx.  If someone later uses it, they
+  // will wrap it into whatever compartment they're working in, as needed.
+  void ThrowJSException(JSContext* cx, JS::Handle<JS::Value> exn);
+  bool IsJSException() const { return ErrorCode() == NS_ERROR_DOM_JS_EXCEPTION; }
+
+  // Facilities for throwing a DOMException.  If an empty message string is
+  // passed to ThrowDOMException, the default message string for the given
+  // nsresult will be used.  The passed-in string must be UTF-8.  The nsresult
+  // passed in must be one we create DOMExceptions for; otherwise you may get an
+  // XPConnect Exception.
+  void ThrowDOMException(nsresult rv, const nsACString& message = EmptyCString());
+  bool IsDOMException() const { return ErrorCode() == NS_ERROR_DOM_DOMEXCEPTION; }
+
+  // Flag on the TErrorResult that whatever needs throwing has been
+  // thrown on the JSContext already and we should not mess with it.
+  // If nothing was thrown, this becomes an uncatchable exception.
+  void NoteJSContextException(JSContext* aCx);
+
+  // Check whether the TErrorResult says to just throw whatever is on
+  // the JSContext already.
+  bool IsJSContextException() {
+    return ErrorCode() == NS_ERROR_DOM_EXCEPTION_ON_JSCONTEXT;
+  }
+
+  // Support for uncatchable exceptions.
+  void ThrowUncatchableException() {
+    Throw(NS_ERROR_UNCATCHABLE_EXCEPTION);
+  }
+  bool IsUncatchableException() const {
+    return ErrorCode() == NS_ERROR_UNCATCHABLE_EXCEPTION;
+  }
+
+  void MOZ_ALWAYS_INLINE MightThrowJSException()
+  {
+#ifdef DEBUG
+    mMightHaveUnreportedJSException = true;
+#endif
+  }
+  void MOZ_ALWAYS_INLINE WouldReportJSException()
+  {
+#ifdef DEBUG
+    mMightHaveUnreportedJSException = false;
+#endif
+  }
+
+  // In the future, we can add overloads of Throw that take more
+  // interesting things, like strings or DOM exception types or
+  // something if desired.
+
+  // Backwards-compat to make conversion simpler.  We don't call
+  // Throw() here because people can easily pass success codes to
+  // this.
+  void operator=(nsresult rv) {
+    AssignErrorCode(rv);
+  }
+
+  bool Failed() const {
+    return NS_FAILED(mResult);
+  }
+
+  bool ErrorCodeIs(nsresult rv) const {
+    return mResult == rv;
+  }
+
+  // For use in logging ONLY.
+  uint32_t ErrorCodeAsInt() const {
+    return static_cast<uint32_t>(ErrorCode());
+  }
+
+protected:
+  nsresult ErrorCode() const {
+    return mResult;
+  }
+
+private:
+#ifdef DEBUG
+  enum UnionState {
+    HasMessage,
+    HasDOMExceptionInfo,
+    HasJSException,
+    HasNothing
+  };
+#endif // DEBUG
+
+  friend struct IPC::ParamTraits<TErrorResult>;
+  friend struct IPC::ParamTraits<ErrorResult>;
+  void SerializeMessage(IPC::Message* aMsg) const;
+  bool DeserializeMessage(const IPC::Message* aMsg, PickleIterator* aIter);
+
+  void SerializeDOMExceptionInfo(IPC::Message* aMsg) const;
+  bool DeserializeDOMExceptionInfo(const IPC::Message* aMsg, PickleIterator* aIter);
+
+  // Helper method that creates a new Message for this TErrorResult,
+  // and returns the arguments array from that Message.
+  nsTArray<nsString>& CreateErrorMessageHelper(const dom::ErrNum errorNumber, nsresult errorType);
+
+  template<dom::ErrNum errorNumber, typename... Ts>
+  void ThrowErrorWithMessage(nsresult errorType, Ts&&... messageArgs)
+  {
+#if defined(DEBUG) && (defined(__clang__) || defined(__GNUC__))
+    static_assert(dom::ErrorFormatNumArgs[errorNumber] == sizeof...(messageArgs),
+                  "Pass in the right number of arguments");
+#endif
+
+    ClearUnionData();
+
+    nsTArray<nsString>& messageArgsArray = CreateErrorMessageHelper(errorNumber, errorType);
+    uint16_t argCount = dom::GetErrorArgCount(errorNumber);
+    dom::StringArrayAppender::Append(messageArgsArray, argCount,
+                                     Forward<Ts>(messageArgs)...);
+#ifdef DEBUG
+    mUnionState = HasMessage;
+#endif // DEBUG
+  }
+
+  MOZ_ALWAYS_INLINE void AssertInOwningThread() const {
+#ifdef DEBUG
+    NS_ASSERT_OWNINGTHREAD(TErrorResult);
+#endif
+  }
+
+  void AssignErrorCode(nsresult aRv) {
+    MOZ_ASSERT(aRv != NS_ERROR_TYPE_ERR, "Use ThrowTypeError()");
+    MOZ_ASSERT(aRv != NS_ERROR_RANGE_ERR, "Use ThrowRangeError()");
+    MOZ_ASSERT(!IsErrorWithMessage(), "Don't overwrite errors with message");
+    MOZ_ASSERT(aRv != NS_ERROR_DOM_JS_EXCEPTION, "Use ThrowJSException()");
+    MOZ_ASSERT(!IsJSException(), "Don't overwrite JS exceptions");
+    MOZ_ASSERT(aRv != NS_ERROR_DOM_DOMEXCEPTION, "Use ThrowDOMException()");
+    MOZ_ASSERT(!IsDOMException(), "Don't overwrite DOM exceptions");
+    MOZ_ASSERT(aRv != NS_ERROR_XPC_NOT_ENOUGH_ARGS, "May need to bring back ThrowNotEnoughArgsError");
+    MOZ_ASSERT(aRv != NS_ERROR_DOM_EXCEPTION_ON_JSCONTEXT,
+               "Use NoteJSContextException");
+    // Don't trust people anyway, though.
+    if (aRv == NS_ERROR_TYPE_ERR ||
+        aRv == NS_ERROR_RANGE_ERR ||
+        aRv == NS_ERROR_DOM_JS_EXCEPTION ||
+        aRv == NS_ERROR_DOM_DOMEXCEPTION) {
+      mResult = NS_ERROR_UNEXPECTED;
+    } else {
+      mResult = aRv;
+    }
+  }
+
+  void ClearMessage();
+  void ClearDOMExceptionInfo();
+
+  // ClearUnionData will try to clear the data in our
+  // mMessage/mJSException/mDOMExceptionInfo union.  After this the union may be
+  // in an uninitialized state (e.g. mMessage or mDOMExceptionInfo may be
+  // pointing to deleted memory) and the caller must either reinitialize it or
+  // change mResult to something that will not involve us touching the union
+  // anymore.
+  void ClearUnionData();
+
+  // Implementation of MaybeSetPendingException for the case when we're a
+  // failure result.
+  void SetPendingException(JSContext* cx);
+
+  // Methods for setting various specific kinds of pending exceptions.
+  void SetPendingExceptionWithMessage(JSContext* cx);
+  void SetPendingJSException(JSContext* cx);
+  void SetPendingDOMException(JSContext* cx);
+  void SetPendingGenericErrorException(JSContext* cx);
+
+  MOZ_ALWAYS_INLINE void AssertReportedOrSuppressed()
+  {
+    MOZ_ASSERT(!Failed());
+    MOZ_ASSERT(!mMightHaveUnreportedJSException);
+    MOZ_ASSERT(mUnionState == HasNothing);
+  }
+
+  // Special values of mResult:
+  // NS_ERROR_TYPE_ERR -- ThrowTypeError() called on us.
+  // NS_ERROR_RANGE_ERR -- ThrowRangeError() called on us.
+  // NS_ERROR_DOM_JS_EXCEPTION -- ThrowJSException() called on us.
+  // NS_ERROR_UNCATCHABLE_EXCEPTION -- ThrowUncatchableException called on us.
+  // NS_ERROR_DOM_DOMEXCEPTION -- ThrowDOMException() called on us.
+  nsresult mResult;
+
+  struct Message;
+  struct DOMExceptionInfo;
+  // mMessage is set by ThrowErrorWithMessage and reported (and deallocated) by
+  // SetPendingExceptionWithMessage.
+  // mJSException is set (and rooted) by ThrowJSException and reported
+  // (and unrooted) by SetPendingJSException.
+  // mDOMExceptionInfo is set by ThrowDOMException and reported
+  // (and deallocated) by SetPendingDOMException.
+  union {
+    Message* mMessage; // valid when IsErrorWithMessage()
+    JS::Value mJSException; // valid when IsJSException()
+    DOMExceptionInfo* mDOMExceptionInfo; // valid when IsDOMException()
+  };
+
+#ifdef DEBUG
+  // Used to keep track of codepaths that might throw JS exceptions,
+  // for assertion purposes.
+  bool mMightHaveUnreportedJSException;
+
+  // Used to keep track of what's stored in our union right now.  Note
+  // that this may be set to HasNothing even if our mResult suggests
+  // we should have something, if we have already cleaned up the
+  // something.
+  UnionState mUnionState;
+
+  // The thread that created this TErrorResult
+  NS_DECL_OWNINGTHREAD;
+#endif
+
+  // Not to be implemented, to make sure people always pass this by
+  // reference, not by value.
+  TErrorResult(const TErrorResult&) = delete;
+  void operator=(const TErrorResult&) = delete;
+};
+
+struct JustAssertCleanupPolicy {
+  static const bool assertHandled = true;
+  static const bool suppress = false;
+};
+
+struct AssertAndSuppressCleanupPolicy {
+  static const bool assertHandled = true;
+  static const bool suppress = true;
+};
+
+struct JustSuppressCleanupPolicy {
+  static const bool assertHandled = false;
+  static const bool suppress = true;
+};
+
+} // namespace binding_danger
+
+// A class people should normally use on the stack when they plan to actually
+// do something with the exception.
+class ErrorResult :
+    public binding_danger::TErrorResult<binding_danger::AssertAndSuppressCleanupPolicy>
+{
+  typedef binding_danger::TErrorResult<binding_danger::AssertAndSuppressCleanupPolicy> BaseErrorResult;
+
+public:
+  ErrorResult()
+    : BaseErrorResult()
+  {}
+
+  ErrorResult(ErrorResult&& aRHS)
+    : BaseErrorResult(Move(aRHS))
+  {}
+
+  explicit ErrorResult(nsresult aRv)
+    : BaseErrorResult(aRv)
+  {}
+
+  void operator=(nsresult rv)
+  {
+    BaseErrorResult::operator=(rv);
+  }
+
+  ErrorResult& operator=(ErrorResult&& aRHS)
+  {
+    BaseErrorResult::operator=(Move(aRHS));
+    return *this;
+  }
+
+private:
+  // Not to be implemented, to make sure people always pass this by
+  // reference, not by value.
+  ErrorResult(const ErrorResult&) = delete;
+  void operator=(const ErrorResult&) = delete;
+};
+
+template<typename CleanupPolicy>
+binding_danger::TErrorResult<CleanupPolicy>::operator ErrorResult&()
+{
+  return *static_cast<ErrorResult*>(
+     reinterpret_cast<TErrorResult<AssertAndSuppressCleanupPolicy>*>(this));
+}
+
+// A class for use when an ErrorResult should just automatically be ignored.
+// This doesn't inherit from ErrorResult so we don't make two separate calls to
+// SuppressException.
+class IgnoredErrorResult :
+    public binding_danger::TErrorResult<binding_danger::JustSuppressCleanupPolicy>
+{
+};
+
+/******************************************************************************
+ ** Macros for checking results
+ ******************************************************************************/
+
+#define ENSURE_SUCCESS(res, ret)                                          \
+  do {                                                                    \
+    if (res.Failed()) {                                                   \
+      nsCString msg;                                                      \
+      msg.AppendPrintf("ENSURE_SUCCESS(%s, %s) failed with "              \
+                       "result 0x%X", #res, #ret, res.ErrorCodeAsInt());  \
+      NS_WARNING(msg.get());                                              \
+      return ret;                                                         \
+    }                                                                     \
+  } while(0)
+
+#define ENSURE_SUCCESS_VOID(res)                                          \
+  do {                                                                    \
+    if (res.Failed()) {                                                   \
+      nsCString msg;                                                      \
+      msg.AppendPrintf("ENSURE_SUCCESS_VOID(%s) failed with "             \
+                       "result 0x%X", #res, res.ErrorCodeAsInt());        \
+      NS_WARNING(msg.get());                                              \
+      return;                                                             \
+    }                                                                     \
+  } while(0)
+
+} // namespace mozilla
+
+#endif /* mozilla_ErrorResult_h */
diff --git a/dom/bindings/Errors.msg b/dom/bindings/Errors.msg
new file mode 100644
index 000000000..142ccfdd6
--- /dev/null
+++ b/dom/bindings/Errors.msg
@@ -0,0 +1,107 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * The format for each error message is:
+ *
+ * MSG_DEF(<SYMBOLIC_NAME>, <ARGUMENT_COUNT>, <JS_EXN_TYPE>, <FORMAT_STRING>)
+ *
+ * where
+ *
+ * <SYMBOLIC_NAME> is a legal C++ identifer that will be used in the source.
+ *
+ * <ARGUMENT_COUNT> is an integer literal specifying the total number of
+ * replaceable arguments in the following format string.
+ *
+ * <JS_EXN_TYPE> is a JSExnType which specifies which kind of error the JS
+ * engine should throw.
+ *
+ * <FORMAT_STRING> is a string literal, containing <ARGUMENT_COUNT> sequences
+ * {X} where X  is an integer representing the argument number that will
+ * be replaced with a string value when the error is reported.
+ */
+
+MSG_DEF(MSG_INVALID_ENUM_VALUE, 3, JSEXN_TYPEERR, "{0} '{1}' is not a valid value for enumeration {2}.")
+MSG_DEF(MSG_MISSING_ARGUMENTS, 1, JSEXN_TYPEERR, "Not enough arguments to {0}.")
+MSG_DEF(MSG_NOT_OBJECT, 1, JSEXN_TYPEERR, "{0} is not an object.")
+MSG_DEF(MSG_NOT_CALLABLE, 1, JSEXN_TYPEERR, "{0} is not callable.")
+MSG_DEF(MSG_NOT_CONSTRUCTOR, 1, JSEXN_TYPEERR, "{0} is not a constructor.")
+MSG_DEF(MSG_DOES_NOT_IMPLEMENT_INTERFACE, 2, JSEXN_TYPEERR, "{0} does not implement interface {1}.")
+MSG_DEF(MSG_METHOD_THIS_DOES_NOT_IMPLEMENT_INTERFACE, 2, JSEXN_TYPEERR, "'{0}' called on an object that does not implement interface {1}.")
+MSG_DEF(MSG_METHOD_THIS_UNWRAPPING_DENIED, 1, JSEXN_TYPEERR, "Permission to call '{0}' denied.")
+MSG_DEF(MSG_THIS_DOES_NOT_IMPLEMENT_INTERFACE, 1, JSEXN_TYPEERR, "\"this\" object does not implement interface {0}.")
+MSG_DEF(MSG_NOT_IN_UNION, 2, JSEXN_TYPEERR, "{0} could not be converted to any of: {1}.")
+MSG_DEF(MSG_ILLEGAL_CONSTRUCTOR, 0, JSEXN_TYPEERR, "Illegal constructor.")
+MSG_DEF(MSG_CONSTRUCTOR_WITHOUT_NEW, 1, JSEXN_TYPEERR, "Constructor {0} requires 'new'")
+MSG_DEF(MSG_ENFORCE_RANGE_NON_FINITE, 1, JSEXN_TYPEERR, "Non-finite value is out of range for {0}.")
+MSG_DEF(MSG_ENFORCE_RANGE_OUT_OF_RANGE, 1, JSEXN_TYPEERR, "Value is out of range for {0}.")
+MSG_DEF(MSG_NOT_SEQUENCE, 1, JSEXN_TYPEERR, "{0} can't be converted to a sequence.")
+MSG_DEF(MSG_NOT_DICTIONARY, 1, JSEXN_TYPEERR, "{0} can't be converted to a dictionary.")
+MSG_DEF(MSG_OVERLOAD_RESOLUTION_FAILED, 3, JSEXN_TYPEERR, "Argument {0} is not valid for any of the {1}-argument overloads of {2}.")
+MSG_DEF(MSG_GLOBAL_NOT_NATIVE, 0, JSEXN_TYPEERR, "Global is not a native object.")
+MSG_DEF(MSG_ENCODING_NOT_SUPPORTED, 1, JSEXN_RANGEERR, "The given encoding '{0}' is not supported.")
+MSG_DEF(MSG_DOM_ENCODING_NOT_UTF, 0, JSEXN_RANGEERR, "The encoding must be utf-8, utf-16, or utf-16be.")
+MSG_DEF(MSG_DOM_DECODING_FAILED, 0, JSEXN_TYPEERR, "Decoding failed.")
+MSG_DEF(MSG_NOT_FINITE, 1, JSEXN_TYPEERR, "{0} is not a finite floating-point value.")
+MSG_DEF(MSG_INVALID_VERSION, 0, JSEXN_TYPEERR, "0 (Zero) is not a valid database version.")
+MSG_DEF(MSG_INVALID_BYTESTRING, 2, JSEXN_TYPEERR, "Cannot convert string to ByteString because the character"
+        " at index {0} has value {1} which is greater than 255.")
+MSG_DEF(MSG_NOT_DATE, 1, JSEXN_TYPEERR, "{0} is not a date.")
+MSG_DEF(MSG_INVALID_ADVANCE_COUNT, 0, JSEXN_TYPEERR, "0 (Zero) is not a valid advance count.")
+MSG_DEF(MSG_DEFINEPROPERTY_ON_GSP, 0, JSEXN_TYPEERR, "Not allowed to define a property on the named properties object.")
+MSG_DEF(MSG_INVALID_URL, 1, JSEXN_TYPEERR, "{0} is not a valid URL.")
+MSG_DEF(MSG_URL_HAS_CREDENTIALS, 1, JSEXN_TYPEERR, "{0} is an url with embedded credentials.")
+MSG_DEF(MSG_METADATA_NOT_CONFIGURED, 0, JSEXN_TYPEERR, "Either size or lastModified should be true.")
+MSG_DEF(MSG_INVALID_READ_SIZE, 0, JSEXN_TYPEERR, "0 (Zero) is not a valid read size.")
+MSG_DEF(MSG_HEADERS_IMMUTABLE, 0, JSEXN_TYPEERR, "Headers are immutable and cannot be modified.")
+MSG_DEF(MSG_INVALID_HEADER_NAME, 1, JSEXN_TYPEERR, "{0} is an invalid header name.")
+MSG_DEF(MSG_INVALID_HEADER_VALUE, 1, JSEXN_TYPEERR, "{0} is an invalid header value.")
+MSG_DEF(MSG_INVALID_HEADER_SEQUENCE, 0, JSEXN_TYPEERR, "Headers require name/value tuples when being initialized by a sequence.")
+MSG_DEF(MSG_PERMISSION_DENIED_TO_PASS_ARG, 1, JSEXN_TYPEERR, "Permission denied to pass cross-origin object as {0}.")
+MSG_DEF(MSG_MISSING_REQUIRED_DICTIONARY_MEMBER, 1, JSEXN_TYPEERR, "Missing required {0}.")
+MSG_DEF(MSG_REQUEST_INTEGRITY_METADATA_NOT_EMPTY, 0, JSEXN_TYPEERR, "Request integrity metadata should be an empty string when in no-cors mode.")
+MSG_DEF(MSG_INVALID_REQUEST_METHOD, 1, JSEXN_TYPEERR, "Invalid request method {0}.")
+MSG_DEF(MSG_INVALID_REQUEST_MODE, 1, JSEXN_TYPEERR, "Invalid request mode {0}.")
+MSG_DEF(MSG_INVALID_REFERRER_URL, 1, JSEXN_TYPEERR, "Invalid referrer URL {0}.")
+MSG_DEF(MSG_CROSS_ORIGIN_REFERRER_URL, 2, JSEXN_TYPEERR, "Referrer URL {0} cannot be cross-origin to the entry settings object ({1}).")
+MSG_DEF(MSG_FETCH_BODY_CONSUMED_ERROR, 0, JSEXN_TYPEERR, "Body has already been consumed.")
+MSG_DEF(MSG_RESPONSE_INVALID_STATUSTEXT_ERROR, 0, JSEXN_TYPEERR, "Response statusText may not contain newline or carriage return.")
+MSG_DEF(MSG_FETCH_FAILED, 0, JSEXN_TYPEERR, "NetworkError when attempting to fetch resource.")
+MSG_DEF(MSG_NO_BODY_ALLOWED_FOR_GET_AND_HEAD, 0, JSEXN_TYPEERR, "HEAD or GET Request cannot have a body.")
+MSG_DEF(MSG_RESPONSE_NULL_STATUS_WITH_BODY, 0, JSEXN_TYPEERR, "Response body is given with a null body status.")
+MSG_DEF(MSG_DEFINE_NON_CONFIGURABLE_PROP_ON_WINDOW, 0, JSEXN_TYPEERR, "Not allowed to define a non-configurable property on the WindowProxy object")
+MSG_DEF(MSG_INVALID_ZOOMANDPAN_VALUE_ERROR, 0, JSEXN_RANGEERR, "Invalid zoom and pan value.")
+MSG_DEF(MSG_INVALID_TRANSFORM_ANGLE_ERROR, 0, JSEXN_RANGEERR, "Invalid transform angle.")
+MSG_DEF(MSG_INVALID_RESPONSE_STATUSCODE_ERROR, 0, JSEXN_RANGEERR, "Invalid response status code.")
+MSG_DEF(MSG_INVALID_REDIRECT_STATUSCODE_ERROR, 0, JSEXN_RANGEERR, "Invalid redirect status code.")
+MSG_DEF(MSG_INVALID_URL_SCHEME, 2, JSEXN_TYPEERR, "{0} URL {1} must be either http:// or https://.")
+MSG_DEF(MSG_RESPONSE_URL_IS_NULL, 0, JSEXN_TYPEERR, "Cannot set Response.finalURL when Response.url is null.")
+MSG_DEF(MSG_RESPONSE_HAS_VARY_STAR, 0, JSEXN_TYPEERR, "Invalid Response object with a 'Vary: *' header.")
+MSG_DEF(MSG_BAD_FORMDATA, 0, JSEXN_TYPEERR, "Could not parse content as FormData.")
+MSG_DEF(MSG_NO_ACTIVE_WORKER, 1, JSEXN_TYPEERR, "No active worker for scope {0}.")
+MSG_DEF(MSG_NOTIFICATION_PERMISSION_DENIED, 0, JSEXN_TYPEERR, "Permission to show Notification denied.")
+MSG_DEF(MSG_NOTIFICATION_NO_CONSTRUCTOR_IN_SERVICEWORKER, 0, JSEXN_TYPEERR, "Notification constructor cannot be used in ServiceWorkerGlobalScope. Use registration.showNotification() instead.")
+MSG_DEF(MSG_INVALID_SCOPE, 2, JSEXN_TYPEERR, "Invalid scope trying to resolve {0} with base URL {1}.")
+MSG_DEF(MSG_INVALID_KEYFRAME_OFFSETS, 0, JSEXN_TYPEERR, "Keyframes with specified offsets must be in order and all be in the range [0, 1].")
+MSG_DEF(MSG_ILLEGAL_PROMISE_CONSTRUCTOR, 0, JSEXN_TYPEERR, "Non-constructor value passed to NewPromiseCapability.")
+MSG_DEF(MSG_PROMISE_CAPABILITY_HAS_SOMETHING_ALREADY, 0, JSEXN_TYPEERR, "GetCapabilitiesExecutor function already invoked with non-undefined values.")
+MSG_DEF(MSG_PROMISE_RESOLVE_FUNCTION_NOT_CALLABLE, 0, JSEXN_TYPEERR, "A Promise subclass passed a non-callable value as the resolve function.")
+MSG_DEF(MSG_PROMISE_REJECT_FUNCTION_NOT_CALLABLE, 0, JSEXN_TYPEERR, "A Promise subclass passed a non-callable value as the reject function.")
+MSG_DEF(MSG_PROMISE_ARG_NOT_ITERABLE, 1, JSEXN_TYPEERR, "{0} is not iterable")
+MSG_DEF(MSG_IS_NOT_PROMISE, 1, JSEXN_TYPEERR, "{0} is not a Promise")
+MSG_DEF(MSG_SW_INSTALL_ERROR, 2, JSEXN_TYPEERR, "ServiceWorker script at {0} for scope {1} encountered an error during installation.")
+MSG_DEF(MSG_SW_SCRIPT_THREW, 2, JSEXN_TYPEERR, "ServiceWorker script at {0} for scope {1} threw an exception during script evaluation.")
+MSG_DEF(MSG_TYPEDARRAY_IS_SHARED, 1, JSEXN_TYPEERR, "{0} can't be a typed array on SharedArrayBuffer")
+MSG_DEF(MSG_CACHE_ADD_FAILED_RESPONSE, 3, JSEXN_TYPEERR, "Cache got {0} response with bad status {1} while trying to add request {2}")
+MSG_DEF(MSG_SW_UPDATE_BAD_REGISTRATION, 2, JSEXN_TYPEERR, "Failed to update the ServiceWorker for scope {0} because the registration has been {1} since the update was scheduled.")
+MSG_DEF(MSG_INVALID_DURATION_ERROR, 1, JSEXN_TYPEERR, "Invalid duration '{0}'.")
+MSG_DEF(MSG_INVALID_EASING_ERROR, 1, JSEXN_TYPEERR, "Invalid easing '{0}'.")
+MSG_DEF(MSG_INVALID_SPACING_MODE_ERROR, 1, JSEXN_TYPEERR, "Invalid spacing '{0}'.")
+MSG_DEF(MSG_USELESS_SETTIMEOUT, 1, JSEXN_TYPEERR, "Useless {0} call (missing quotes around argument?)")
+MSG_DEF(MSG_TOKENLIST_NO_SUPPORTED_TOKENS, 2, JSEXN_TYPEERR, "{0} attribute of <{1}> does not define any supported tokens")
+MSG_DEF(MSG_CACHE_STREAM_CLOSED, 0, JSEXN_TYPEERR, "Response body is a cache file stream that has already been closed.")
+MSG_DEF(MSG_TIME_VALUE_OUT_OF_RANGE, 1, JSEXN_TYPEERR, "{0} is outside the supported range for time values.")
+MSG_DEF(MSG_ONLY_IF_CACHED_WITHOUT_SAME_ORIGIN, 1, JSEXN_TYPEERR, "Request mode '{0}' was used, but request cache mode 'only-if-cached' can only be used with request mode 'same-origin'.")
+MSG_DEF(MSG_THRESHOLD_RANGE_ERROR, 0, JSEXN_RANGEERR, "Threshold values must all be in the range [0, 1].")
+MSG_DEF(MSG_CACHE_OPEN_FAILED, 0, JSEXN_TYPEERR, "CacheStorage.open() failed to access the storage system.")
diff --git a/dom/bindings/Exceptions.cpp b/dom/bindings/Exceptions.cpp
new file mode 100644
index 000000000..a3f807688
--- /dev/null
+++ b/dom/bindings/Exceptions.cpp
@@ -0,0 +1,709 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/Exceptions.h"
+
+#include "js/GCAPI.h"
+#include "js/TypeDecls.h"
+#include "jsapi.h"
+#include "jsprf.h"
+#include "mozilla/CycleCollectedJSContext.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/ScriptSettings.h"
+#include "nsIProgrammingLanguage.h"
+#include "nsPIDOMWindow.h"
+#include "nsServiceManagerUtils.h"
+#include "nsThreadUtils.h"
+#include "XPCWrapper.h"
+#include "WorkerPrivate.h"
+#include "nsContentUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+// Throw the given exception value if it's safe.  If it's not safe, then
+// synthesize and throw a new exception value for NS_ERROR_UNEXPECTED.  The
+// incoming value must be in the compartment of aCx.  This function guarantees
+// that an exception is pending on aCx when it returns.
+static void
+ThrowExceptionValueIfSafe(JSContext* aCx, JS::Handle<JS::Value> exnVal,
+                          nsIException* aOriginalException)
+{
+  MOZ_ASSERT(aOriginalException);
+
+  if (!exnVal.isObject()) {
+    JS_SetPendingException(aCx, exnVal);
+    return;
+  }
+
+  JS::Rooted<JSObject*> exnObj(aCx, &exnVal.toObject());
+  MOZ_ASSERT(js::IsObjectInContextCompartment(exnObj, aCx),
+             "exnObj needs to be in the right compartment for the "
+             "CheckedUnwrap thing to make sense");
+
+  if (js::CheckedUnwrap(exnObj)) {
+    // This is an object we're allowed to work with, so just go ahead and throw
+    // it.
+    JS_SetPendingException(aCx, exnVal);
+    return;
+  }
+
+  // We could probably Throw(aCx, NS_ERROR_UNEXPECTED) here, and it would do the
+  // right thing due to there not being an existing exception on the runtime at
+  // this point, but it's clearer to explicitly do the thing we want done.  This
+  // is also why we don't just call ThrowExceptionObject on the Exception we
+  // create: it would do the right thing, but that fact is not obvious.
+  RefPtr<Exception> syntheticException =
+    CreateException(aCx, NS_ERROR_UNEXPECTED);
+  JS::Rooted<JS::Value> syntheticVal(aCx);
+  if (!GetOrCreateDOMReflector(aCx, syntheticException, &syntheticVal)) {
+    return;
+  }
+  MOZ_ASSERT(syntheticVal.isObject() &&
+             !js::IsWrapper(&syntheticVal.toObject()),
+             "Must have a reflector here, not a wrapper");
+  JS_SetPendingException(aCx, syntheticVal);
+}
+
+void
+ThrowExceptionObject(JSContext* aCx, nsIException* aException)
+{
+  // See if we really have an Exception.
+  nsCOMPtr<Exception> exception = do_QueryInterface(aException);
+  if (exception) {
+    ThrowExceptionObject(aCx, exception);
+    return;
+  }
+
+  // We only have an nsIException (probably an XPCWrappedJS).  Fall back on old
+  // wrapping.
+  MOZ_ASSERT(NS_IsMainThread());
+
+  JS::Rooted<JS::Value> val(aCx);
+  if (!WrapObject(aCx, aException, &NS_GET_IID(nsIException), &val)) {
+    return;
+  }
+
+  ThrowExceptionValueIfSafe(aCx, val, aException);
+}
+
+void
+ThrowExceptionObject(JSContext* aCx, Exception* aException)
+{
+  JS::Rooted<JS::Value> thrown(aCx);
+
+  // If we stored the original thrown JS value in the exception
+  // (see XPCConvert::ConstructException) and we are in a web context
+  // (i.e., not chrome), rethrow the original value. This only applies to JS
+  // implemented components so we only need to check for this on the main
+  // thread.
+  if (NS_IsMainThread() && !nsContentUtils::IsCallerChrome() &&
+      aException->StealJSVal(thrown.address())) {
+    // Now check for the case when thrown is a number which matches
+    // aException->GetResult().  This would indicate that what actually got
+    // thrown was an nsresult value.  In that situation, we should go back
+    // through dom::Throw with that nsresult value, because it will make sure to
+    // create the right sort of Exception or DOMException, with the right
+    // global.
+    if (thrown.isNumber()) {
+      nsresult exceptionResult;
+      if (NS_SUCCEEDED(aException->GetResult(&exceptionResult)) &&
+          double(exceptionResult) == thrown.toNumber()) {
+        Throw(aCx, exceptionResult);
+        return;
+      }
+    }
+    if (!JS_WrapValue(aCx, &thrown)) {
+      return;
+    }
+    ThrowExceptionValueIfSafe(aCx, thrown, aException);
+    return;
+  }
+
+  if (!GetOrCreateDOMReflector(aCx, aException, &thrown)) {
+    return;
+  }
+
+  ThrowExceptionValueIfSafe(aCx, thrown, aException);
+}
+
+bool
+Throw(JSContext* aCx, nsresult aRv, const nsACString& aMessage)
+{
+  if (aRv == NS_ERROR_UNCATCHABLE_EXCEPTION) {
+    // Nuke any existing exception on aCx, to make sure we're uncatchable.
+    JS_ClearPendingException(aCx);
+    return false;
+  }
+
+  if (JS_IsExceptionPending(aCx)) {
+    // Don't clobber the existing exception.
+    return false;
+  }
+
+  CycleCollectedJSContext* context = CycleCollectedJSContext::Get();
+  nsCOMPtr<nsIException> existingException = context->GetPendingException();
+  // Make sure to clear the pending exception now.  Either we're going to reuse
+  // it (and we already grabbed it), or we plan to throw something else and this
+  // pending exception is no longer relevant.
+  context->SetPendingException(nullptr);
+
+  // Ignore the pending exception if we have a non-default message passed in.
+  if (aMessage.IsEmpty() && existingException) {
+    nsresult nr;
+    if (NS_SUCCEEDED(existingException->GetResult(&nr)) &&
+        aRv == nr) {
+      // Reuse the existing exception.
+      ThrowExceptionObject(aCx, existingException);
+      return false;
+    }
+  }
+
+  RefPtr<Exception> finalException = CreateException(aCx, aRv, aMessage);
+  MOZ_ASSERT(finalException);
+
+  ThrowExceptionObject(aCx, finalException);
+  return false;
+}
+
+void
+ThrowAndReport(nsPIDOMWindowInner* aWindow, nsresult aRv)
+{
+  MOZ_ASSERT(aRv != NS_ERROR_UNCATCHABLE_EXCEPTION,
+             "Doesn't make sense to report uncatchable exceptions!");
+  AutoJSAPI jsapi;
+  if (NS_WARN_IF(!jsapi.Init(aWindow))) {
+    return;
+  }
+
+  Throw(jsapi.cx(), aRv);
+}
+
+already_AddRefed<Exception>
+CreateException(JSContext* aCx, nsresult aRv, const nsACString& aMessage)
+{
+  // Do we use DOM exceptions for this error code?
+  switch (NS_ERROR_GET_MODULE(aRv)) {
+  case NS_ERROR_MODULE_DOM:
+  case NS_ERROR_MODULE_SVG:
+  case NS_ERROR_MODULE_DOM_XPATH:
+  case NS_ERROR_MODULE_DOM_INDEXEDDB:
+  case NS_ERROR_MODULE_DOM_FILEHANDLE:
+  case NS_ERROR_MODULE_DOM_ANIM:
+  case NS_ERROR_MODULE_DOM_PUSH:
+  case NS_ERROR_MODULE_DOM_MEDIA:
+    if (aMessage.IsEmpty()) {
+      return DOMException::Create(aRv);
+    }
+    return DOMException::Create(aRv, aMessage);
+  default:
+    break;
+  }
+
+  // If not, use the default.
+  RefPtr<Exception> exception =
+    new Exception(aMessage, aRv, EmptyCString(), nullptr, nullptr);
+  return exception.forget();
+}
+
+already_AddRefed<nsIStackFrame>
+GetCurrentJSStack(int32_t aMaxDepth)
+{
+  // is there a current context available?
+  JSContext* cx = nsContentUtils::GetCurrentJSContextForThread();
+
+  if (!cx || !js::GetContextCompartment(cx)) {
+    return nullptr;
+  }
+
+  static const unsigned MAX_FRAMES = 100;
+  if (aMaxDepth < 0) {
+    aMaxDepth = MAX_FRAMES;
+  }
+
+  JS::StackCapture captureMode = aMaxDepth == 0
+    ? JS::StackCapture(JS::AllFrames())
+    : JS::StackCapture(JS::MaxFrames(aMaxDepth));
+
+  return dom::exceptions::CreateStack(cx, mozilla::Move(captureMode));
+}
+
+namespace exceptions {
+
+class JSStackFrame : public nsIStackFrame
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(JSStackFrame)
+  NS_DECL_NSISTACKFRAME
+
+  // aStack must not be null.
+  explicit JSStackFrame(JS::Handle<JSObject*> aStack);
+
+protected:
+  int32_t GetLineno(JSContext* aCx);
+
+  int32_t GetColNo(JSContext* aCx);
+
+private:
+  virtual ~JSStackFrame();
+
+  JS::Heap<JSObject*> mStack;
+  nsString mFormattedStack;
+
+  nsCOMPtr<nsIStackFrame> mCaller;
+  nsCOMPtr<nsIStackFrame> mAsyncCaller;
+  nsString mFilename;
+  nsString mFunname;
+  nsString mAsyncCause;
+  int32_t mLineno;
+  int32_t mColNo;
+
+  bool mFilenameInitialized;
+  bool mFunnameInitialized;
+  bool mLinenoInitialized;
+  bool mColNoInitialized;
+  bool mAsyncCauseInitialized;
+  bool mAsyncCallerInitialized;
+  bool mCallerInitialized;
+  bool mFormattedStackInitialized;
+};
+
+JSStackFrame::JSStackFrame(JS::Handle<JSObject*> aStack)
+  : mStack(aStack)
+  , mLineno(0)
+  , mColNo(0)
+  , mFilenameInitialized(false)
+  , mFunnameInitialized(false)
+  , mLinenoInitialized(false)
+  , mColNoInitialized(false)
+  , mAsyncCauseInitialized(false)
+  , mAsyncCallerInitialized(false)
+  , mCallerInitialized(false)
+  , mFormattedStackInitialized(false)
+{
+  MOZ_ASSERT(mStack);
+
+  mozilla::HoldJSObjects(this);
+}
+
+JSStackFrame::~JSStackFrame()
+{
+  mozilla::DropJSObjects(this);
+}
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(JSStackFrame)
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(JSStackFrame)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mCaller)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK(mAsyncCaller)
+  tmp->mStack = nullptr;
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(JSStackFrame)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mCaller)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mAsyncCaller)
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+NS_IMPL_CYCLE_COLLECTION_TRACE_BEGIN(JSStackFrame)
+  NS_IMPL_CYCLE_COLLECTION_TRACE_JS_MEMBER_CALLBACK(mStack)
+NS_IMPL_CYCLE_COLLECTION_TRACE_END
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(JSStackFrame)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(JSStackFrame)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(JSStackFrame)
+  NS_INTERFACE_MAP_ENTRY(nsIStackFrame)
+  NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+NS_IMETHODIMP JSStackFrame::GetLanguage(uint32_t* aLanguage)
+{
+  *aLanguage = nsIProgrammingLanguage::JAVASCRIPT;
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetLanguageName(nsACString& aLanguageName)
+{
+  aLanguageName.AssignLiteral("JavaScript");
+  return NS_OK;
+}
+
+// Helper method to get the value of a stack property, if it's not already
+// cached.  This will make sure we skip the cache if the access is happening
+// over Xrays.
+//
+// @argument aStack the stack we're working with; must be non-null.
+// @argument aPropGetter the getter function to call.
+// @argument aIsCached whether we've cached this property's value before.
+//
+// @argument [out] aCanCache whether the value can get cached.
+// @argument [out] aUseCachedValue if true, just use the cached value.
+// @argument [out] aValue the value we got from the stack.
+template<typename ReturnType, typename GetterOutParamType>
+static void
+GetValueIfNotCached(JSContext* aCx, const JS::Heap<JSObject*>& aStack,
+                    JS::SavedFrameResult (*aPropGetter)(JSContext*,
+                                                        JS::Handle<JSObject*>,
+                                                        GetterOutParamType,
+                                                        JS::SavedFrameSelfHosted),
+                    bool aIsCached, bool* aCanCache, bool* aUseCachedValue,
+                    ReturnType aValue)
+{
+  MOZ_ASSERT(aStack);
+
+  JS::Rooted<JSObject*> stack(aCx, aStack);
+  // Allow caching if aCx and stack are same-compartment.  Otherwise take the
+  // slow path.
+  *aCanCache = js::GetContextCompartment(aCx) == js::GetObjectCompartment(stack);
+  if (*aCanCache && aIsCached) {
+    *aUseCachedValue = true;
+    return;
+  }
+
+  *aUseCachedValue = false;
+
+  aPropGetter(aCx, stack, aValue, JS::SavedFrameSelfHosted::Exclude);
+}
+
+NS_IMETHODIMP JSStackFrame::GetFilename(JSContext* aCx, nsAString& aFilename)
+{
+  if (!mStack) {
+    aFilename.Truncate();
+    return NS_OK;
+  }
+
+  JS::Rooted<JSString*> filename(aCx);
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameSource,
+                      mFilenameInitialized,
+                      &canCache, &useCachedValue, &filename);
+  if (useCachedValue) {
+    aFilename = mFilename;
+    return NS_OK;
+  }
+
+  nsAutoJSString str;
+  if (!str.init(aCx, filename)) {
+    JS_ClearPendingException(aCx);
+    aFilename.Truncate();
+    return NS_OK;
+  }
+  aFilename = str;
+
+  if (canCache) {
+    mFilename = str;
+    mFilenameInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetName(JSContext* aCx, nsAString& aFunction)
+{
+  if (!mStack) {
+    aFunction.Truncate();
+    return NS_OK;
+  }
+
+  JS::Rooted<JSString*> name(aCx);
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameFunctionDisplayName,
+                      mFunnameInitialized, &canCache, &useCachedValue,
+                      &name);
+
+  if (useCachedValue) {
+    aFunction = mFunname;
+    return NS_OK;
+  }
+
+  if (name) {
+    nsAutoJSString str;
+    if (!str.init(aCx, name)) {
+      JS_ClearPendingException(aCx);
+      aFunction.Truncate();
+      return NS_OK;
+    }
+    aFunction = str;
+  } else {
+    aFunction.SetIsVoid(true);
+  }
+
+  if (canCache) {
+    mFunname = aFunction;
+    mFunnameInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+int32_t
+JSStackFrame::GetLineno(JSContext* aCx)
+{
+  if (!mStack) {
+    return 0;
+  }
+
+  uint32_t line;
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameLine, mLinenoInitialized,
+                      &canCache, &useCachedValue, &line);
+
+  if (useCachedValue) {
+    return mLineno;
+  }
+
+  if (canCache) {
+    mLineno = line;
+    mLinenoInitialized = true;
+  }
+
+  return line;
+}
+
+NS_IMETHODIMP JSStackFrame::GetLineNumber(JSContext* aCx, int32_t* aLineNumber)
+{
+  *aLineNumber = GetLineno(aCx);
+  return NS_OK;
+}
+
+int32_t
+JSStackFrame::GetColNo(JSContext* aCx)
+{
+  if (!mStack) {
+    return 0;
+  }
+
+  uint32_t col;
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameColumn, mColNoInitialized,
+                      &canCache, &useCachedValue, &col);
+
+  if (useCachedValue) {
+    return mColNo;
+  }
+
+  if (canCache) {
+    mColNo = col;
+    mColNoInitialized = true;
+  }
+
+  return col;
+}
+
+NS_IMETHODIMP JSStackFrame::GetColumnNumber(JSContext* aCx,
+                                            int32_t* aColumnNumber)
+{
+  *aColumnNumber = GetColNo(aCx);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetSourceLine(nsACString& aSourceLine)
+{
+  aSourceLine.Truncate();
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetAsyncCause(JSContext* aCx,
+                                          nsAString& aAsyncCause)
+{
+  if (!mStack) {
+    aAsyncCause.Truncate();
+    return NS_OK;
+  }
+
+  JS::Rooted<JSString*> asyncCause(aCx);
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameAsyncCause,
+                      mAsyncCauseInitialized, &canCache, &useCachedValue,
+                      &asyncCause);
+
+  if (useCachedValue) {
+    aAsyncCause = mAsyncCause;
+    return NS_OK;
+  }
+
+  if (asyncCause) {
+    nsAutoJSString str;
+    if (!str.init(aCx, asyncCause)) {
+      JS_ClearPendingException(aCx);
+      aAsyncCause.Truncate();
+      return NS_OK;
+    }
+    aAsyncCause = str;
+  } else {
+    aAsyncCause.SetIsVoid(true);
+  }
+
+  if (canCache) {
+    mAsyncCause = aAsyncCause;
+    mAsyncCauseInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetAsyncCaller(JSContext* aCx,
+                                           nsIStackFrame** aAsyncCaller)
+{
+  if (!mStack) {
+    *aAsyncCaller = nullptr;
+    return NS_OK;
+  }
+
+  JS::Rooted<JSObject*> asyncCallerObj(aCx);
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameAsyncParent,
+                      mAsyncCallerInitialized, &canCache, &useCachedValue,
+                      &asyncCallerObj);
+
+  if (useCachedValue) {
+    NS_IF_ADDREF(*aAsyncCaller = mAsyncCaller);
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIStackFrame> asyncCaller =
+    asyncCallerObj ? new JSStackFrame(asyncCallerObj) : nullptr;
+  asyncCaller.forget(aAsyncCaller);
+
+  if (canCache) {
+    mAsyncCaller = *aAsyncCaller;
+    mAsyncCallerInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetCaller(JSContext* aCx, nsIStackFrame** aCaller)
+{
+  if (!mStack) {
+    *aCaller = nullptr;
+    return NS_OK;
+  }
+
+  JS::Rooted<JSObject*> callerObj(aCx);
+  bool canCache = false, useCachedValue = false;
+  GetValueIfNotCached(aCx, mStack, JS::GetSavedFrameParent, mCallerInitialized,
+                      &canCache, &useCachedValue, &callerObj);
+
+  if (useCachedValue) {
+    NS_IF_ADDREF(*aCaller = mCaller);
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIStackFrame> caller =
+    callerObj ? new JSStackFrame(callerObj) : nullptr;
+  caller.forget(aCaller);
+
+  if (canCache) {
+    mCaller = *aCaller;
+    mCallerInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetFormattedStack(JSContext* aCx, nsAString& aStack)
+{
+  if (!mStack) {
+    aStack.Truncate();
+    return NS_OK;
+  }
+
+  // Sadly we can't use GetValueIfNotCached here, because our getter
+  // returns bool, not JS::SavedFrameResult.  Maybe it's possible to
+  // make the templates more complicated to deal, but in the meantime
+  // let's just inline GetValueIfNotCached here.
+
+  // Allow caching if aCx and stack are same-compartment.  Otherwise take the
+  // slow path.
+  bool canCache =
+    js::GetContextCompartment(aCx) == js::GetObjectCompartment(mStack);
+  if (canCache && mFormattedStackInitialized) {
+    aStack = mFormattedStack;
+    return NS_OK;
+  }
+
+  JS::Rooted<JSObject*> stack(aCx, mStack);
+
+  JS::Rooted<JSString*> formattedStack(aCx);
+  if (!JS::BuildStackString(aCx, stack, &formattedStack)) {
+    JS_ClearPendingException(aCx);
+    aStack.Truncate();
+    return NS_OK;
+  }
+
+  nsAutoJSString str;
+  if (!str.init(aCx, formattedStack)) {
+    JS_ClearPendingException(aCx);
+    aStack.Truncate();
+    return NS_OK;
+  }
+
+  aStack = str;
+
+  if (canCache) {
+    mFormattedStack = str;
+    mFormattedStackInitialized = true;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::GetNativeSavedFrame(JS::MutableHandle<JS::Value> aSavedFrame)
+{
+  aSavedFrame.setObjectOrNull(mStack);
+  return NS_OK;
+}
+
+NS_IMETHODIMP JSStackFrame::ToString(JSContext* aCx, nsACString& _retval)
+{
+  _retval.Truncate();
+
+  nsString filename;
+  nsresult rv = GetFilename(aCx, filename);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (filename.IsEmpty()) {
+    filename.AssignLiteral("<unknown filename>");
+  }
+
+  nsString funname;
+  rv = GetName(aCx, funname);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  if (funname.IsEmpty()) {
+    funname.AssignLiteral("<TOP_LEVEL>");
+  }
+
+  int32_t lineno = GetLineno(aCx);
+
+  static const char format[] = "JS frame :: %s :: %s :: line %d";
+  _retval.AppendPrintf(format,
+                       NS_ConvertUTF16toUTF8(filename).get(),
+                       NS_ConvertUTF16toUTF8(funname).get(),
+                       lineno);
+  return NS_OK;
+}
+
+already_AddRefed<nsIStackFrame>
+CreateStack(JSContext* aCx, JS::StackCapture&& aCaptureMode)
+{
+  JS::Rooted<JSObject*> stack(aCx);
+  if (!JS::CaptureCurrentStack(aCx, &stack, mozilla::Move(aCaptureMode))) {
+    return nullptr;
+  }
+
+  if (!stack) {
+    return nullptr;
+  }
+
+  nsCOMPtr<nsIStackFrame> frame = new JSStackFrame(stack);
+  return frame.forget();
+}
+
+} // namespace exceptions
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/Exceptions.h b/dom/bindings/Exceptions.h
new file mode 100644
index 000000000..521c550f5
--- /dev/null
+++ b/dom/bindings/Exceptions.h
@@ -0,0 +1,69 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Exceptions_h__
+#define mozilla_dom_Exceptions_h__
+
+// DOM exception throwing machinery (for both main thread and workers).
+
+#include <stdint.h>
+#include "jspubtd.h"
+#include "nsIException.h"
+#include "nsStringGlue.h"
+#include "jsapi.h"
+
+class nsIStackFrame;
+class nsPIDOMWindowInner;
+template <class T>
+struct already_AddRefed;
+
+namespace mozilla {
+namespace dom {
+
+class Exception;
+
+// If we're throwing a DOMException and message is empty, the default
+// message for the nsresult in question will be used.
+bool
+Throw(JSContext* cx, nsresult rv, const nsACString& message = EmptyCString());
+
+// Create, throw and report an exception to a given window.
+void
+ThrowAndReport(nsPIDOMWindowInner* aWindow, nsresult aRv);
+
+// Both signatures of ThrowExceptionObject guarantee that an exception is set on
+// aCx before they return.
+void
+ThrowExceptionObject(JSContext* aCx, Exception* aException);
+void
+ThrowExceptionObject(JSContext* aCx, nsIException* aException);
+
+// Create an exception object for the given nsresult and message but don't set
+// it pending on aCx.  If we're throwing a DOMException and aMessage is empty,
+// the default message for the nsresult in question will be used.
+//
+// This never returns null.
+already_AddRefed<Exception>
+CreateException(JSContext* aCx, nsresult aRv,
+                const nsACString& aMessage = EmptyCString());
+
+// aMaxDepth can be used to define a maximal depth for the stack trace. If the
+// value is -1, a default maximal depth will be selected.  Will return null if
+// there is no JS stack right now.
+already_AddRefed<nsIStackFrame>
+GetCurrentJSStack(int32_t aMaxDepth = -1);
+
+// Internal stuff not intended to be widely used.
+namespace exceptions {
+
+already_AddRefed<nsIStackFrame>
+CreateStack(JSContext* aCx, JS::StackCapture&& aCaptureMode);
+
+} // namespace exceptions
+} // namespace dom
+} // namespace mozilla
+
+#endif
diff --git a/dom/bindings/FakeString.h b/dom/bindings/FakeString.h
new file mode 100644
index 000000000..bd92a1bca
--- /dev/null
+++ b/dom/bindings/FakeString.h
@@ -0,0 +1,160 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_FakeString_h__
+#define mozilla_dom_FakeString_h__
+
+#include "nsString.h"
+#include "nsStringBuffer.h"
+#include "mozilla/RefPtr.h"
+
+namespace mozilla {
+namespace dom {
+namespace binding_detail {
+// A struct that has the same layout as an nsString but much faster
+// constructor and destructor behavior. FakeString uses inline storage
+// for small strings and a nsStringBuffer for longer strings.
+struct FakeString {
+  FakeString() :
+    mFlags(nsString::F_TERMINATED)
+  {
+  }
+
+  ~FakeString() {
+    if (mFlags & nsString::F_SHARED) {
+      nsStringBuffer::FromData(mData)->Release();
+    }
+  }
+
+  void Rebind(const nsString::char_type* aData, nsString::size_type aLength) {
+    MOZ_ASSERT(mFlags == nsString::F_TERMINATED);
+    mData = const_cast<nsString::char_type*>(aData);
+    mLength = aLength;
+  }
+
+  // Share aString's string buffer, if it has one; otherwise, make this string
+  // depend upon aString's data.  aString should outlive this instance of
+  // FakeString.
+  void ShareOrDependUpon(const nsAString& aString) {
+    RefPtr<nsStringBuffer> sharedBuffer = nsStringBuffer::FromString(aString);
+    if (!sharedBuffer) {
+      Rebind(aString.Data(), aString.Length());
+    } else {
+      AssignFromStringBuffer(sharedBuffer.forget());
+      mLength = aString.Length();
+    }
+  }
+
+  void Truncate() {
+    MOZ_ASSERT(mFlags == nsString::F_TERMINATED);
+    mData = nsString::char_traits::sEmptyBuffer;
+    mLength = 0;
+  }
+
+  void SetIsVoid(bool aValue) {
+    MOZ_ASSERT(aValue,
+               "We don't support SetIsVoid(false) on FakeString!");
+    Truncate();
+    mFlags |= nsString::F_VOIDED;
+  }
+
+  const nsString::char_type* Data() const
+  {
+    return mData;
+  }
+
+  nsString::char_type* BeginWriting()
+  {
+    return mData;
+  }
+
+  nsString::size_type Length() const
+  {
+    return mLength;
+  }
+
+  // Reserve space to write aLength chars, not including null-terminator.
+  bool SetLength(nsString::size_type aLength, mozilla::fallible_t const&) {
+    // Use mInlineStorage for small strings.
+    if (aLength < sInlineCapacity) {
+      SetData(mInlineStorage);
+    } else {
+      RefPtr<nsStringBuffer> buf = nsStringBuffer::Alloc((aLength + 1) * sizeof(nsString::char_type));
+      if (MOZ_UNLIKELY(!buf)) {
+        return false;
+      }
+
+      AssignFromStringBuffer(buf.forget());
+    }
+    mLength = aLength;
+    mData[mLength] = char16_t(0);
+    return true;
+  }
+
+  // If this ever changes, change the corresponding code in the
+  // Optional<nsAString> specialization as well.
+  const nsAString* ToAStringPtr() const {
+    return reinterpret_cast<const nsString*>(this);
+  }
+
+operator const nsAString& () const {
+    return *reinterpret_cast<const nsString*>(this);
+  }
+
+private:
+  nsAString* ToAStringPtr() {
+    return reinterpret_cast<nsString*>(this);
+  }
+
+  nsString::char_type* mData;
+  nsString::size_type mLength;
+  uint32_t mFlags;
+
+  static const size_t sInlineCapacity = 64;
+  nsString::char_type mInlineStorage[sInlineCapacity];
+
+  FakeString(const FakeString& other) = delete;
+  void operator=(const FakeString& other) = delete;
+
+  void SetData(nsString::char_type* aData) {
+    MOZ_ASSERT(mFlags == nsString::F_TERMINATED);
+    mData = const_cast<nsString::char_type*>(aData);
+  }
+  void AssignFromStringBuffer(already_AddRefed<nsStringBuffer> aBuffer) {
+    SetData(static_cast<nsString::char_type*>(aBuffer.take()->Data()));
+    mFlags = nsString::F_SHARED | nsString::F_TERMINATED;
+  }
+
+  friend class NonNull<nsAString>;
+
+  // A class to use for our static asserts to ensure our object layout
+  // matches that of nsString.
+  class StringAsserter;
+  friend class StringAsserter;
+
+  class StringAsserter : public nsString {
+  public:
+    static void StaticAsserts() {
+      static_assert(offsetof(FakeString, mInlineStorage) ==
+                      sizeof(nsString),
+                    "FakeString should include all nsString members");
+      static_assert(offsetof(FakeString, mData) ==
+                      offsetof(StringAsserter, mData),
+                    "Offset of mData should match");
+      static_assert(offsetof(FakeString, mLength) ==
+                      offsetof(StringAsserter, mLength),
+                    "Offset of mLength should match");
+      static_assert(offsetof(FakeString, mFlags) ==
+                      offsetof(StringAsserter, mFlags),
+                    "Offset of mFlags should match");
+    }
+  };
+};
+} // namespace binding_detail
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_FakeString_h__ */
\ No newline at end of file
diff --git a/dom/bindings/GenerateCSS2PropertiesWebIDL.py b/dom/bindings/GenerateCSS2PropertiesWebIDL.py
new file mode 100644
index 000000000..58ec60c29
--- /dev/null
+++ b/dom/bindings/GenerateCSS2PropertiesWebIDL.py
@@ -0,0 +1,84 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import sys
+import string
+import argparse
+import subprocess
+import buildconfig
+from mozbuild import shellutil
+
+# Generates a line of WebIDL with the given spelling of the property name
+# (whether camelCase, _underscorePrefixed, etc.) and the given array of
+# extended attributes.
+def generateLine(propName, extendedAttrs):
+    return "  [%s] attribute DOMString %s;\n" % (", ".join(extendedAttrs),
+                                                 propName)
+def generate(output, idlFilename, preprocessorHeader):
+    cpp = list(buildconfig.substs['CPP'])
+    cpp += shellutil.split(buildconfig.substs['ACDEFINES'])
+    cpp.append(preprocessorHeader)
+    preprocessed = subprocess.check_output(cpp)
+
+    propList = eval(preprocessed)
+    props = ""
+    for [name, prop, id, flags, pref, proptype] in propList:
+        if "CSS_PROPERTY_INTERNAL" in flags:
+            continue
+        # Unfortunately, even some of the getters here are fallible
+        # (e.g. on nsComputedDOMStyle).
+        extendedAttrs = ["Throws", "TreatNullAs=EmptyString"]
+        if pref is not "":
+            extendedAttrs.append('Pref="%s"' % pref)
+
+        # webkit properties get a capitalized "WebkitFoo" accessor (added here)
+        # as well as a camelcase "webkitFoo" accessor (added next).
+        if (prop.startswith("Webkit")):
+            props += generateLine(prop, extendedAttrs)
+
+        # Generate a line with camelCase spelling of property-name (or capitalized,
+        # for Moz-prefixed properties):
+        if not prop.startswith("Moz"):
+            prop = prop[0].lower() + prop[1:]
+        props += generateLine(prop, extendedAttrs)
+
+        # Per spec, what's actually supposed to happen here is that we're supposed
+        # to have properties for:
+        #
+        # 1) Each supported CSS property name, camelCased.
+        # 2) Each supported name that contains or starts with dashes,
+        #    without any changes to the name.
+        # 3) cssFloat
+        #
+        # Note that "float" will cause a property called "float" to exist due to (1)
+        # in that list.
+        #
+        # In practice, cssFloat is the only case in which "name" doesn't contain
+        # "-" but also doesn't match "prop".  So the above generatePropLine() call
+        # covered (3) and all of (1) except "float".  If we now output attributes
+        # for all the cases where "name" doesn't match "prop", that will cover
+        # "float" and (2).
+        if prop != name:
+            extendedAttrs.append('BinaryName="%s"' % prop)
+            # Throw in a '_' before the attribute name, because some of these
+            # property names collide with IDL reserved words.
+            props += generateLine("_" + name, extendedAttrs)
+
+
+    idlFile = open(idlFilename, "r")
+    idlTemplate = idlFile.read()
+    idlFile.close()
+
+    output.write("/* THIS IS AN AUTOGENERATED FILE.  DO NOT EDIT */\n\n" +
+                 string.Template(idlTemplate).substitute({"props": props}) + '\n')
+
+def main():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('idlFilename', help='IDL property file template')
+    parser.add_argument('preprocessorHeader', help='Header file to pass through the preprocessor')
+    args = parser.parse_args()
+    generate(sys.stdout, args.idlFilename, args.preprocessorHeader)
+
+if __name__ == '__main__':
+    main()
diff --git a/dom/bindings/IterableIterator.cpp b/dom/bindings/IterableIterator.cpp
new file mode 100644
index 000000000..041319638
--- /dev/null
+++ b/dom/bindings/IterableIterator.cpp
@@ -0,0 +1,35 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/IterableIterator.h"
+
+namespace mozilla {
+namespace dom {
+
+// Due to IterableIterator being a templated class, we implement the necessary
+// CC bits in a superclass that IterableIterator then inherits from. This allows
+// us to put the macros outside of the header. The base class has pure virtual
+// functions for Traverse/Unlink that the templated subclasses will override.
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(IterableIteratorBase)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(IterableIteratorBase)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(IterableIteratorBase)
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(IterableIteratorBase)
+  tmp->TraverseHelper(cb);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(IterableIteratorBase)
+  tmp->UnlinkHelper();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(IterableIteratorBase)
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+}
+}
diff --git a/dom/bindings/IterableIterator.h b/dom/bindings/IterableIterator.h
new file mode 100644
index 000000000..1a56cec33
--- /dev/null
+++ b/dom/bindings/IterableIterator.h
@@ -0,0 +1,204 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * The IterableIterator class is used for WebIDL interfaces that have a
+ * iterable<> member defined with two types (so a pair iterator). It handles
+ * the ES6 Iterator-like functions that are generated for the iterable
+ * interface.
+ *
+ * For iterable interfaces with a pair iterator, the implementation class will
+ * need to implement these two functions:
+ *
+ * - size_t GetIterableLength()
+ *   - Returns the number of elements available to iterate over
+ * - [type] GetValueAtIndex(size_t index)
+ *   - Returns the value at the requested index.
+ * - [type] GetKeyAtIndex(size_t index)
+ *   - Returns the key at the requested index
+ *
+ * Examples of iterable interface implementations can be found in the bindings
+ * test directory.
+ */
+
+#ifndef mozilla_dom_IterableIterator_h
+#define mozilla_dom_IterableIterator_h
+
+#include "nsISupports.h"
+#include "nsWrapperCache.h"
+#include "nsPIDOMWindow.h"
+#include "nsCOMPtr.h"
+#include "mozilla/dom/ToJSValue.h"
+#include "jswrapper.h"
+#include "mozilla/dom/IterableIteratorBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+class IterableIteratorBase : public nsISupports
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_CLASS(IterableIteratorBase)
+  typedef enum {
+    Keys = 0,
+    Values,
+    Entries
+  } IterableIteratorType;
+
+  IterableIteratorBase() {}
+  
+protected:
+  virtual ~IterableIteratorBase() {}
+  virtual void UnlinkHelper() = 0;
+  virtual void TraverseHelper(nsCycleCollectionTraversalCallback& cb) = 0;
+};
+
+template <typename T>
+class IterableIterator final : public IterableIteratorBase
+{
+public:
+  typedef bool (*WrapFunc)(JSContext* aCx,
+                           IterableIterator<T>* aObject,
+                           JS::Handle<JSObject*> aGivenProto,
+                           JS::MutableHandle<JSObject*> aReflector);
+
+  explicit IterableIterator(T* aIterableObj,
+                            IterableIteratorType aIteratorType,
+                            WrapFunc aWrapFunc)
+    : mIterableObj(aIterableObj)
+    , mIteratorType(aIteratorType)
+    , mWrapFunc(aWrapFunc)
+    , mIndex(0)
+  {
+    MOZ_ASSERT(mIterableObj);
+    MOZ_ASSERT(mWrapFunc);
+  }
+
+  void
+  Next(JSContext* aCx, JS::MutableHandle<JSObject*> aResult, ErrorResult& aRv)
+  {
+    JS::Rooted<JS::Value> value(aCx, JS::UndefinedValue());
+    if (mIndex >= this->mIterableObj->GetIterableLength()) {
+      DictReturn(aCx, aResult, true, value, aRv);
+      return;
+    }
+    switch (mIteratorType) {
+    case IterableIteratorType::Keys:
+    {
+      if (!ToJSValue(aCx, this->mIterableObj->GetKeyAtIndex(mIndex), &value)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return;
+      }
+      DictReturn(aCx, aResult, false, value, aRv);
+      break;
+    }
+    case IterableIteratorType::Values:
+    {
+      if (!ToJSValue(aCx, this->mIterableObj->GetValueAtIndex(mIndex), &value)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return;
+      }
+      DictReturn(aCx, aResult, false, value, aRv);
+      break;
+    }
+    case IterableIteratorType::Entries:
+    {
+      JS::Rooted<JS::Value> key(aCx);
+      if (!ToJSValue(aCx, this->mIterableObj->GetKeyAtIndex(mIndex), &key)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return;
+      }
+      if (!ToJSValue(aCx, this->mIterableObj->GetValueAtIndex(mIndex), &value)) {
+        aRv.Throw(NS_ERROR_FAILURE);
+        return;
+      }
+      KeyAndValueReturn(aCx, key, value, aResult, aRv);
+      break;
+    }
+    default:
+      MOZ_CRASH("Invalid iterator type!");
+    }
+    ++mIndex;
+  }
+
+  bool
+  WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto, JS::MutableHandle<JSObject*> aObj)
+  {
+    return (*mWrapFunc)(aCx, this, aGivenProto, aObj);
+  }
+
+protected:
+  static void
+  DictReturn(JSContext* aCx, JS::MutableHandle<JSObject*> aResult,
+             bool aDone, JS::Handle<JS::Value> aValue, ErrorResult& aRv)
+  {
+    RootedDictionary<IterableKeyOrValueResult> dict(aCx);
+    dict.mDone = aDone;
+    dict.mValue = aValue;
+    JS::Rooted<JS::Value> dictValue(aCx);
+    if (!ToJSValue(aCx, dict, &dictValue)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+    aResult.set(&dictValue.toObject());
+  }
+
+  static void
+  KeyAndValueReturn(JSContext* aCx, JS::Handle<JS::Value> aKey,
+                    JS::Handle<JS::Value> aValue,
+                    JS::MutableHandle<JSObject*> aResult, ErrorResult& aRv)
+  {
+    RootedDictionary<IterableKeyAndValueResult> dict(aCx);
+    dict.mDone = false;
+    // Dictionary values are a Sequence, which is a FallibleTArray, so we need
+    // to check returns when appending.
+    if (!dict.mValue.AppendElement(aKey, mozilla::fallible)) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+    if (!dict.mValue.AppendElement(aValue, mozilla::fallible)) {
+      aRv.Throw(NS_ERROR_OUT_OF_MEMORY);
+      return;
+    }
+    JS::Rooted<JS::Value> dictValue(aCx);
+    if (!ToJSValue(aCx, dict, &dictValue)) {
+      aRv.Throw(NS_ERROR_FAILURE);
+      return;
+    }
+    aResult.set(&dictValue.toObject());
+  }
+
+protected:
+  virtual ~IterableIterator() {}
+
+  // Since we're templated on a binding, we need to possibly CC it, but can't do
+  // that through macros. So it happens here.
+  virtual void UnlinkHelper() final
+  {
+    mIterableObj = nullptr;
+  }
+
+  virtual void TraverseHelper(nsCycleCollectionTraversalCallback& cb) override
+  {
+    IterableIterator<T>* tmp = this;
+    NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mIterableObj);
+  }
+
+  // Binding Implementation object that we're iterating over.
+  RefPtr<T> mIterableObj;
+  // Tells whether this is a key, value, or entries iterator.
+  IterableIteratorType mIteratorType;
+  // Function pointer to binding-type-specific Wrap() call for this iterator.
+  WrapFunc mWrapFunc;
+  // Current index of iteration.
+  uint32_t mIndex;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_IterableIterator_h
diff --git a/dom/bindings/JSSlots.h b/dom/bindings/JSSlots.h
new file mode 100644
index 000000000..5e19957d6
--- /dev/null
+++ b/dom/bindings/JSSlots.h
@@ -0,0 +1,34 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This file defines various reserved slot indices used by JavaScript
+ * reflections of DOM objects.
+ */
+#ifndef mozilla_dom_DOMSlots_h
+#define mozilla_dom_DOMSlots_h
+
+// We use slot 0 for holding the raw object.  This is safe for both
+// globals and non-globals.
+// NOTE: This is baked into the Ion JIT as 0 in codegen for LGetDOMProperty and
+// LSetDOMProperty. Those constants need to be changed accordingly if this value
+// changes.
+#define DOM_OBJECT_SLOT 0
+
+// The total number of slots non-proxy DOM objects use by default.
+// Specific objects may have more for storing cached values.
+#define DOM_INSTANCE_RESERVED_SLOTS 1
+
+// Interface objects store a number of reserved slots equal to
+// DOM_INTERFACE_SLOTS_BASE + number of named constructors.
+#define DOM_INTERFACE_SLOTS_BASE 0
+
+// Interface prototype objects store a number of reserved slots equal to
+// DOM_INTERFACE_PROTO_SLOTS_BASE or DOM_INTERFACE_PROTO_SLOTS_BASE + 1 if a
+// slot for the unforgeable holder is needed.
+#define DOM_INTERFACE_PROTO_SLOTS_BASE 0
+
+#endif /* mozilla_dom_DOMSlots_h */
diff --git a/dom/bindings/Makefile.in b/dom/bindings/Makefile.in
new file mode 100644
index 000000000..95f267397
--- /dev/null
+++ b/dom/bindings/Makefile.in
@@ -0,0 +1,70 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+webidl_base := $(topsrcdir)/dom/webidl
+
+ifdef COMPILE_ENVIRONMENT
+
+# Generated by moz.build
+include webidlsrcs.mk
+
+# These come from webidlsrcs.mk.
+# TODO Write directly into backend.mk (bug 1281618)
+CPPSRCS += $(globalgen_sources) $(unified_binding_cpp_files)
+
+include $(topsrcdir)/config/rules.mk
+
+# TODO This list should be emitted to a .pp file via
+# GenerateCSS2PropertiesWebIDL.py (bug 1281614)
+css2properties_dependencies = \
+  $(topsrcdir)/layout/style/nsCSSPropList.h \
+  $(topsrcdir)/layout/style/nsCSSPropAliasList.h \
+  $(webidl_base)/CSS2Properties.webidl.in \
+  $(topsrcdir)/layout/style/PythonCSSProps.h \
+  $(srcdir)/GenerateCSS2PropertiesWebIDL.py \
+  $(GLOBAL_DEPS) \
+  $(NULL)
+
+CSS2Properties.webidl: $(css2properties_dependencies)
+
+# Most of the logic for dependencies lives inside Python so it can be
+# used by multiple build backends. We simply have rules to generate
+# and include the .pp file.
+#
+# The generated .pp file contains all the important dependencies such as
+# changes to .webidl or .py files should result in code generation being
+# performed. But we do pull in file-lists.jon to catch file additions.
+codegen_dependencies := \
+  file-lists.json \
+  $(nonstatic_webidl_files) \
+  $(GLOBAL_DEPS) \
+  $(NULL)
+
+include codegen.pp
+
+codegen.pp: $(codegen_dependencies)
+	$(call py_action,webidl,$(srcdir))
+	@$(TOUCH) $@
+
+.PHONY: compiletests
+compiletests:
+	$(call SUBMAKE,libs,test)
+
+endif
+
+GARBAGE += \
+  codegen.pp \
+  codegen.json \
+  parser.out \
+  WebIDLGrammar.pkl \
+  $(wildcard *.h) \
+  $(wildcard *Binding.cpp) \
+  $(wildcard *Event.cpp) \
+  $(wildcard *-event.cpp) \
+  $(wildcard *.webidl) \
+  $(NULL)
+
+DIST_GARBAGE += \
+  file-lists.json \
+  $(NULL)
diff --git a/dom/bindings/MozMap.h b/dom/bindings/MozMap.h
new file mode 100644
index 000000000..1e920c098
--- /dev/null
+++ b/dom/bindings/MozMap.h
@@ -0,0 +1,121 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Class for representing MozMap arguments.  This is an nsTHashtable
+ * under the hood, but we don't want to leak that implementation
+ * detail.
+ */
+
+#ifndef mozilla_dom_MozMap_h
+#define mozilla_dom_MozMap_h
+
+#include "nsTHashtable.h"
+#include "nsHashKeys.h"
+#include "nsStringGlue.h"
+#include "nsTArray.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Move.h"
+
+namespace mozilla {
+namespace dom {
+
+namespace binding_detail {
+template<typename DataType>
+class MozMapEntry : public nsStringHashKey
+{
+public:
+  explicit MozMapEntry(const nsAString* aKeyTypePointer)
+    : nsStringHashKey(aKeyTypePointer)
+  {
+  }
+
+  // Move constructor so we can do MozMaps of MozMaps.
+  MozMapEntry(MozMapEntry<DataType>&& aOther)
+    : nsStringHashKey(aOther),
+      mData(Move(aOther.mData))
+  {
+  }
+
+  DataType mData;
+};
+
+} // namespace binding_detail
+
+template<typename DataType>
+class MozMap : protected nsTHashtable<binding_detail::MozMapEntry<DataType>>
+{
+public:
+  typedef typename binding_detail::MozMapEntry<DataType> EntryType;
+  typedef nsTHashtable<EntryType> Base;
+  typedef MozMap<DataType> SelfType;
+
+  MozMap()
+  {
+  }
+
+  // Move constructor so we can do MozMap of MozMap.
+  MozMap(SelfType&& aOther) :
+    Base(Move(aOther))
+  {
+  }
+
+  // The return value is only safe to use until an AddEntry call.
+  const DataType& Get(const nsAString& aKey) const
+  {
+    const EntryType* ent = this->GetEntry(aKey);
+    MOZ_ASSERT(ent, "Why are you using a key we didn't claim to have?");
+    return ent->mData;
+  }
+
+  DataType& Get(const nsAString& aKey)
+  {
+    EntryType* ent = this->GetEntry(aKey);
+    MOZ_ASSERT(ent, "Why are you using a key we didn't claim to have?");
+    return ent->mData;
+  }
+
+  // The return value is only safe to use until an AddEntry call.
+  const DataType* GetIfExists(const nsAString& aKey) const
+  {
+    const EntryType* ent = this->GetEntry(aKey);
+    if (!ent) {
+      return nullptr;
+    }
+    return &ent->mData;
+  }
+
+  void GetKeys(nsTArray<nsString>& aKeys) const {
+    for (auto iter = this->ConstIter(); !iter.Done(); iter.Next()) {
+      aKeys.AppendElement(iter.Get()->GetKey());
+    }
+  }
+
+  // XXXbz we expose this generic enumerator for tracing.  Otherwise we'd end up
+  // with a dependency on BindingUtils.h here for the SequenceTracer bits.
+  typedef void (* Enumerator)(DataType* aValue, void* aClosure);
+  void EnumerateValues(Enumerator aEnumerator, void *aClosure)
+  {
+    for (auto iter = this->Iter(); !iter.Done(); iter.Next()) {
+      aEnumerator(&iter.Get()->mData, aClosure);
+    }
+  }
+
+  MOZ_MUST_USE
+  DataType* AddEntry(const nsAString& aKey)
+  {
+    EntryType* ent = this->PutEntry(aKey, fallible);
+    if (!ent) {
+      return nullptr;
+    }
+    return &ent->mData;
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_MozMap_h
diff --git a/dom/bindings/NonRefcountedDOMObject.h b/dom/bindings/NonRefcountedDOMObject.h
new file mode 100644
index 000000000..2aef9ce4a
--- /dev/null
+++ b/dom/bindings/NonRefcountedDOMObject.h
@@ -0,0 +1,37 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_NonRefcountedDOMObject_h__
+#define mozilla_dom_NonRefcountedDOMObject_h__
+
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+namespace dom {
+
+// Natives for DOM classes that aren't refcounted need to inherit from this
+// class.
+// If you're seeing objects of this class leak then natives for one of the DOM
+// classes inheriting from it is leaking. If the native for that class has
+// MOZ_COUNT_CTOR/DTOR in its constructor/destructor then it should show up in
+// the leak log too.
+class NonRefcountedDOMObject
+{
+protected:
+  NonRefcountedDOMObject()
+  {
+    MOZ_COUNT_CTOR(NonRefcountedDOMObject);
+  }
+  ~NonRefcountedDOMObject()
+  {
+    MOZ_COUNT_DTOR(NonRefcountedDOMObject);
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_NonRefcountedDOMObject_h__ */
diff --git a/dom/bindings/Nullable.h b/dom/bindings/Nullable.h
new file mode 100644
index 000000000..8d7d46905
--- /dev/null
+++ b/dom/bindings/Nullable.h
@@ -0,0 +1,140 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_Nullable_h
+#define mozilla_dom_Nullable_h
+
+#include "mozilla/Assertions.h"
+#include "nsTArrayForwardDeclare.h"
+#include "mozilla/Move.h"
+#include "mozilla/Maybe.h"
+
+class nsCycleCollectionTraversalCallback;
+
+namespace mozilla {
+namespace dom {
+
+// Support for nullable types
+template <typename T>
+struct Nullable
+{
+private:
+  Maybe<T> mValue;
+
+public:
+  Nullable()
+    : mValue()
+  {}
+
+  MOZ_IMPLICIT Nullable(const decltype(nullptr)&)
+    : mValue()
+  {}
+
+  explicit Nullable(const T& aValue)
+    : mValue()
+  {
+    mValue.emplace(aValue);
+  }
+
+  MOZ_IMPLICIT Nullable(T&& aValue)
+    : mValue()
+  {
+    mValue.emplace(mozilla::Move(aValue));
+  }
+
+  Nullable(Nullable<T>&& aOther)
+    : mValue(mozilla::Move(aOther.mValue))
+  {}
+
+  Nullable(const Nullable<T>& aOther)
+    : mValue(aOther.mValue)
+  {}
+
+  void operator=(const Nullable<T>& aOther)
+  {
+    mValue = aOther.mValue;
+  }
+
+  void SetValue(const T& aArgs)
+  {
+    mValue.reset();
+    mValue.emplace(aArgs);
+  }
+
+  void SetValue(T&& aArgs)
+  {
+    mValue.reset();
+    mValue.emplace(mozilla::Move(aArgs));
+  }
+
+  // For cases when |T| is some type with nontrivial copy behavior, we may want
+  // to get a reference to our internal copy of T and work with it directly
+  // instead of relying on the copying version of SetValue().
+  T& SetValue() {
+    if (mValue.isNothing()) {
+      mValue.emplace();
+    }
+    return mValue.ref();
+  }
+
+  void SetNull() {
+    mValue.reset();
+  }
+
+  const T& Value() const {
+    return mValue.ref();
+  }
+
+  T& Value() {
+    return mValue.ref();
+  }
+
+  bool IsNull() const {
+    return mValue.isNothing();
+  }
+
+  bool Equals(const Nullable<T>& aOtherNullable) const
+  {
+    return mValue == aOtherNullable.mValue;
+  }
+
+  bool operator==(const Nullable<T>& aOtherNullable) const
+  {
+    return Equals(aOtherNullable);
+  }
+
+  bool operator!=(const Nullable<T>& aOtherNullable) const
+  {
+    return !Equals(aOtherNullable);
+  }
+};
+
+
+template<typename T>
+void
+ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
+                            Nullable<T>& aNullable,
+                            const char* aName,
+                            uint32_t aFlags = 0)
+{
+  if (!aNullable.IsNull()) {
+    ImplCycleCollectionTraverse(aCallback, aNullable.Value(), aName, aFlags);
+  }
+}
+
+template<typename T>
+void
+ImplCycleCollectionUnlink(Nullable<T>& aNullable)
+{
+  if (!aNullable.IsNull()) {
+    ImplCycleCollectionUnlink(aNullable.Value());
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_Nullable_h */
diff --git a/dom/bindings/PrimitiveConversions.h b/dom/bindings/PrimitiveConversions.h
new file mode 100644
index 000000000..3da58a877
--- /dev/null
+++ b/dom/bindings/PrimitiveConversions.h
@@ -0,0 +1,359 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Conversions from jsval to primitive values
+ */
+
+#ifndef mozilla_dom_PrimitiveConversions_h
+#define mozilla_dom_PrimitiveConversions_h
+
+#include <limits>
+#include <math.h>
+#include <stdint.h>
+
+#include "jsapi.h"
+#include "js/Conversions.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/ErrorResult.h"
+#include "mozilla/FloatingPoint.h"
+
+namespace mozilla {
+namespace dom {
+
+template<typename T>
+struct TypeName {
+};
+
+template<>
+struct TypeName<int8_t> {
+  static const char* value() {
+    return "byte";
+  }
+};
+template<>
+struct TypeName<uint8_t> {
+  static const char* value() {
+    return "octet";
+  }
+};
+template<>
+struct TypeName<int16_t> {
+  static const char* value() {
+    return "short";
+  }
+};
+template<>
+struct TypeName<uint16_t> {
+  static const char* value() {
+    return "unsigned short";
+  }
+};
+template<>
+struct TypeName<int32_t> {
+  static const char* value() {
+    return "long";
+  }
+};
+template<>
+struct TypeName<uint32_t> {
+  static const char* value() {
+    return "unsigned long";
+  }
+};
+template<>
+struct TypeName<int64_t> {
+  static const char* value() {
+    return "long long";
+  }
+};
+template<>
+struct TypeName<uint64_t> {
+  static const char* value() {
+    return "unsigned long long";
+  }
+};
+
+
+enum ConversionBehavior {
+  eDefault,
+  eEnforceRange,
+  eClamp
+};
+
+template<typename T, ConversionBehavior B>
+struct PrimitiveConversionTraits {
+};
+
+template<typename T>
+struct DisallowedConversion {
+  typedef int jstype;
+  typedef int intermediateType;
+
+private:
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    MOZ_CRASH("This should never be instantiated!");
+  }
+};
+
+struct PrimitiveConversionTraits_smallInt {
+  // The output of JS::ToInt32 is determined as follows:
+  //   1) The value is converted to a double
+  //   2) Anything that's not a finite double returns 0
+  //   3) The double is rounded towards zero to the nearest integer
+  //   4) The resulting integer is reduced mod 2^32.  The output of this
+  //      operation is an integer in the range [0, 2^32).
+  //   5) If the resulting number is >= 2^31, 2^32 is subtracted from it.
+  //
+  // The result of all this is a number in the range [-2^31, 2^31)
+  //
+  // WebIDL conversions for the 8-bit, 16-bit, and 32-bit integer types
+  // are defined in the same way, except that step 4 uses reduction mod
+  // 2^8 and 2^16 for the 8-bit and 16-bit types respectively, and step 5
+  // is only done for the signed types.
+  //
+  // C/C++ define integer conversion semantics to unsigned types as taking
+  // your input integer mod (1 + largest value representable in the
+  // unsigned type).  Since 2^32 is zero mod 2^8, 2^16, and 2^32,
+  // converting to the unsigned int of the relevant width will correctly
+  // perform step 4; in particular, the 2^32 possibly subtracted in step 5
+  // will become 0.
+  //
+  // Once we have step 4 done, we're just going to assume 2s-complement
+  // representation and cast directly to the type we really want.
+  //
+  // So we can cast directly for all unsigned types and for int32_t; for
+  // the smaller-width signed types we need to cast through the
+  // corresponding unsigned type.
+  typedef int32_t jstype;
+  typedef int32_t intermediateType;
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    return JS::ToInt32(cx, v, retval);
+  }
+};
+template<>
+struct PrimitiveConversionTraits<int8_t, eDefault> : PrimitiveConversionTraits_smallInt {
+  typedef uint8_t intermediateType;
+};
+template<>
+struct PrimitiveConversionTraits<uint8_t, eDefault> : PrimitiveConversionTraits_smallInt {
+};
+template<>
+struct PrimitiveConversionTraits<int16_t, eDefault> : PrimitiveConversionTraits_smallInt {
+  typedef uint16_t intermediateType;
+};
+template<>
+struct PrimitiveConversionTraits<uint16_t, eDefault> : PrimitiveConversionTraits_smallInt {
+};
+template<>
+struct PrimitiveConversionTraits<int32_t, eDefault> : PrimitiveConversionTraits_smallInt {
+};
+template<>
+struct PrimitiveConversionTraits<uint32_t, eDefault> : PrimitiveConversionTraits_smallInt {
+};
+
+template<>
+struct PrimitiveConversionTraits<int64_t, eDefault> {
+  typedef int64_t jstype;
+  typedef int64_t intermediateType;
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    return JS::ToInt64(cx, v, retval);
+  }
+};
+
+template<>
+struct PrimitiveConversionTraits<uint64_t, eDefault> {
+  typedef uint64_t jstype;
+  typedef uint64_t intermediateType;
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    return JS::ToUint64(cx, v, retval);
+  }
+};
+
+template<typename T>
+struct PrimitiveConversionTraits_Limits {
+  static inline T min() {
+    return std::numeric_limits<T>::min();
+  }
+  static inline T max() {
+    return std::numeric_limits<T>::max();
+  }
+};
+
+template<>
+struct PrimitiveConversionTraits_Limits<int64_t> {
+  static inline int64_t min() {
+    return -(1LL << 53) + 1;
+  }
+  static inline int64_t max() {
+    return (1LL << 53) - 1;
+  }
+};
+
+template<>
+struct PrimitiveConversionTraits_Limits<uint64_t> {
+  static inline uint64_t min() {
+    return 0;
+  }
+  static inline uint64_t max() {
+    return (1LL << 53) - 1;
+  }
+};
+
+template<typename T, bool (*Enforce)(JSContext* cx, const double& d, T* retval)>
+struct PrimitiveConversionTraits_ToCheckedIntHelper {
+  typedef T jstype;
+  typedef T intermediateType;
+
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    double intermediate;
+    if (!JS::ToNumber(cx, v, &intermediate)) {
+      return false;
+    }
+
+    return Enforce(cx, intermediate, retval);
+  }
+};
+
+template<typename T>
+inline bool
+PrimitiveConversionTraits_EnforceRange(JSContext* cx, const double& d, T* retval)
+{
+  static_assert(std::numeric_limits<T>::is_integer,
+                "This can only be applied to integers!");
+
+  if (!mozilla::IsFinite(d)) {
+    return ThrowErrorMessage(cx, MSG_ENFORCE_RANGE_NON_FINITE, TypeName<T>::value());
+  }
+
+  bool neg = (d < 0);
+  double rounded = floor(neg ? -d : d);
+  rounded = neg ? -rounded : rounded;
+  if (rounded < PrimitiveConversionTraits_Limits<T>::min() ||
+      rounded > PrimitiveConversionTraits_Limits<T>::max()) {
+    return ThrowErrorMessage(cx, MSG_ENFORCE_RANGE_OUT_OF_RANGE, TypeName<T>::value());
+  }
+
+  *retval = static_cast<T>(rounded);
+  return true;
+}
+
+template<typename T>
+struct PrimitiveConversionTraits<T, eEnforceRange> :
+  public PrimitiveConversionTraits_ToCheckedIntHelper<T, PrimitiveConversionTraits_EnforceRange<T> > {
+};
+
+template<typename T>
+inline bool
+PrimitiveConversionTraits_Clamp(JSContext* cx, const double& d, T* retval)
+{
+  static_assert(std::numeric_limits<T>::is_integer,
+                "This can only be applied to integers!");
+
+  if (mozilla::IsNaN(d)) {
+    *retval = 0;
+    return true;
+  }
+  if (d >= PrimitiveConversionTraits_Limits<T>::max()) {
+    *retval = PrimitiveConversionTraits_Limits<T>::max();
+    return true;
+  }
+  if (d <= PrimitiveConversionTraits_Limits<T>::min()) {
+    *retval = PrimitiveConversionTraits_Limits<T>::min();
+    return true;
+  }
+
+  MOZ_ASSERT(mozilla::IsFinite(d));
+
+  // Banker's rounding (round ties towards even).
+  // We move away from 0 by 0.5f and then truncate.  That gets us the right
+  // answer for any starting value except plus or minus N.5.  With a starting
+  // value of that form, we now have plus or minus N+1.  If N is odd, this is
+  // the correct result.  If N is even, plus or minus N is the correct result.
+  double toTruncate = (d < 0) ? d - 0.5 : d + 0.5;
+
+  T truncated = static_cast<T>(toTruncate);
+
+  if (truncated == toTruncate) {
+    /*
+     * It was a tie (since moving away from 0 by 0.5 gave us the exact integer
+     * we want). Since we rounded away from 0, we either already have an even
+     * number or we have an odd number but the number we want is one closer to
+     * 0. So just unconditionally masking out the ones bit should do the trick
+     * to get us the value we want.
+     */
+    truncated &= ~1;
+  }
+
+  *retval = truncated;
+  return true;
+}
+
+template<typename T>
+struct PrimitiveConversionTraits<T, eClamp> :
+  public PrimitiveConversionTraits_ToCheckedIntHelper<T, PrimitiveConversionTraits_Clamp<T> > {
+};
+
+
+template<ConversionBehavior B>
+struct PrimitiveConversionTraits<bool, B> : public DisallowedConversion<bool> {};
+
+template<>
+struct PrimitiveConversionTraits<bool, eDefault> {
+  typedef bool jstype;
+  typedef bool intermediateType;
+  static inline bool converter(JSContext* /* unused */, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    *retval = JS::ToBoolean(v);
+    return true;
+  }
+};
+
+
+template<ConversionBehavior B>
+struct PrimitiveConversionTraits<float, B> : public DisallowedConversion<float> {};
+
+template<ConversionBehavior B>
+struct PrimitiveConversionTraits<double, B> : public DisallowedConversion<double> {};
+
+struct PrimitiveConversionTraits_float {
+  typedef double jstype;
+  typedef double intermediateType;
+  static inline bool converter(JSContext* cx, JS::Handle<JS::Value> v,
+                               jstype* retval) {
+    return JS::ToNumber(cx, v, retval);
+  }
+};
+
+template<>
+struct PrimitiveConversionTraits<float, eDefault> : PrimitiveConversionTraits_float {
+};
+template<>
+struct PrimitiveConversionTraits<double, eDefault> : PrimitiveConversionTraits_float {
+};
+
+
+template<typename T, ConversionBehavior B>
+bool ValueToPrimitive(JSContext* cx, JS::Handle<JS::Value> v, T* retval)
+{
+  typename PrimitiveConversionTraits<T, B>::jstype t;
+  if (!PrimitiveConversionTraits<T, B>::converter(cx, v, &t))
+    return false;
+
+  *retval = static_cast<T>(
+    static_cast<typename PrimitiveConversionTraits<T, B>::intermediateType>(t));
+  return true;
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_PrimitiveConversions_h */
diff --git a/dom/bindings/RootedDictionary.h b/dom/bindings/RootedDictionary.h
new file mode 100644
index 000000000..cf4adaaef
--- /dev/null
+++ b/dom/bindings/RootedDictionary.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_RootedDictionary_h__
+#define mozilla_dom_RootedDictionary_h__
+
+#include "mozilla/GuardObjects.h"
+#include "mozilla/dom/Nullable.h"
+#include "jsapi.h"
+
+namespace mozilla {
+namespace dom {
+
+template<typename T>
+class MOZ_RAII RootedDictionary final : public T,
+                                         private JS::CustomAutoRooter
+{
+public:
+  template <typename CX>
+  explicit RootedDictionary(const CX& cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    T(),
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+
+  virtual void trace(JSTracer *trc) override
+  {
+    this->TraceDictionary(trc);
+  }
+};
+
+template<typename T>
+class MOZ_RAII NullableRootedDictionary final : public Nullable<T>,
+                                                 private JS::CustomAutoRooter
+{
+public:
+  template <typename CX>
+  explicit NullableRootedDictionary(const CX& cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    Nullable<T>(),
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+
+  virtual void trace(JSTracer *trc) override
+  {
+    if (!this->IsNull()) {
+      this->Value().TraceDictionary(trc);
+    }
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_RootedDictionary_h__ */
diff --git a/dom/bindings/RootedOwningNonNull.h b/dom/bindings/RootedOwningNonNull.h
new file mode 100644
index 000000000..890afd74f
--- /dev/null
+++ b/dom/bindings/RootedOwningNonNull.h
@@ -0,0 +1,73 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * An implementation of Rooted for OwningNonNull<T>.  This works by assuming
+ * that T has a Trace() method defined on it which will trace whatever things
+ * inside the T instance need tracing.
+ *
+ * This implementation has one serious drawback: operator= doesn't work right
+ * because it's declared on Rooted directly and expects the type Rooted is
+ * templated over.
+ */
+
+#ifndef mozilla_RootedOwningNonNull_h__
+#define mozilla_RootedOwningNonNull_h__
+
+#include "mozilla/OwningNonNull.h"
+#include "js/GCPolicyAPI.h"
+#include "js/RootingAPI.h"
+
+namespace JS {
+template<typename T>
+struct GCPolicy<mozilla::OwningNonNull<T>>
+{
+  typedef mozilla::OwningNonNull<T> SmartPtrType;
+
+  static SmartPtrType initial()
+  {
+    return SmartPtrType();
+  }
+
+  static void trace(JSTracer* trc, SmartPtrType* tp,
+                    const char* name)
+  {
+    // We have to be very careful here.  Normally, OwningNonNull can't be null.
+    // But binding code can end up in a situation where it sets up a
+    // Rooted<OwningNonNull> and then before it gets a chance to assign to it
+    // (e.g. from the constructor of the thing being assigned) a GC happens.  So
+    // we can land here when *tp stores a null pointer because it's not
+    // initialized.
+    //
+    // So we need to check for that before jumping.
+    if ((*tp).isInitialized()) {
+      (*tp)->Trace(trc);
+    }
+  }
+};
+} // namespace JS
+
+namespace js {
+template<typename T>
+struct RootedBase<mozilla::OwningNonNull<T>>
+{
+  typedef mozilla::OwningNonNull<T> SmartPtrType;
+
+  operator SmartPtrType& () const
+  {
+    auto& self = *static_cast<const JS::Rooted<SmartPtrType>*>(this);
+    return self.get();
+  }
+
+  operator T& () const
+  {
+    auto& self = *static_cast<const JS::Rooted<SmartPtrType>*>(this);
+    return self.get();
+  }
+};
+} // namespace js
+
+#endif /* mozilla_RootedOwningNonNull_h__ */
diff --git a/dom/bindings/RootedRefPtr.h b/dom/bindings/RootedRefPtr.h
new file mode 100644
index 000000000..e27361b24
--- /dev/null
+++ b/dom/bindings/RootedRefPtr.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * An implementation of Rooted for RefPtr<T>.  This works by assuming that T has
+ * a Trace() method defined on it which will trace whatever things inside the T
+ * instance need tracing.
+ *
+ * This implementation has one serious drawback: operator= doesn't work right
+ * because it's declared on Rooted directly and expects the type Rooted is
+ * templated over.
+ */
+
+#ifndef mozilla_RootedRefPtr_h__
+#define mozilla_RootedRefPtr_h__
+
+#include "mozilla/RefPtr.h"
+#include "js/GCPolicyAPI.h"
+#include "js/RootingAPI.h"
+
+namespace JS {
+template<typename T>
+struct GCPolicy<RefPtr<T>>
+{
+  static RefPtr<T> initial() {
+    return RefPtr<T>();
+  }
+
+  static void trace(JSTracer* trc, RefPtr<T>* tp, const char* name)
+  {
+    if (*tp) {
+      (*tp)->Trace(trc);
+    }
+  }
+};
+} // namespace JS
+
+namespace js {
+template<typename T>
+struct RootedBase<RefPtr<T>>
+{
+  operator RefPtr<T>& () const
+  {
+    auto& self = *static_cast<const JS::Rooted<RefPtr<T>>*>(this);
+    return self.get();
+  }
+
+  operator T*() const
+  {
+    auto& self = *static_cast<const JS::Rooted<RefPtr<T>>*>(this);
+    return self.get();
+  }
+};
+} // namespace js
+
+#endif /* mozilla_RootedRefPtr_h__ */
diff --git a/dom/bindings/SimpleGlobalObject.cpp b/dom/bindings/SimpleGlobalObject.cpp
new file mode 100644
index 000000000..6ac397019
--- /dev/null
+++ b/dom/bindings/SimpleGlobalObject.cpp
@@ -0,0 +1,176 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/SimpleGlobalObject.h"
+
+#include "jsapi.h"
+#include "js/Class.h"
+
+#include "nsJSPrincipals.h"
+#include "nsNullPrincipal.h"
+#include "nsThreadUtils.h"
+#include "nsContentUtils.h"
+
+#include "xpcprivate.h"
+
+#include "mozilla/dom/ScriptSettings.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_CLASS(SimpleGlobalObject)
+
+NS_IMPL_CYCLE_COLLECTION_UNLINK_BEGIN(SimpleGlobalObject)
+  NS_IMPL_CYCLE_COLLECTION_UNLINK_PRESERVED_WRAPPER
+  tmp->UnlinkHostObjectURIs();
+NS_IMPL_CYCLE_COLLECTION_UNLINK_END
+
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(SimpleGlobalObject)
+
+  NS_IMPL_CYCLE_COLLECTION_TRAVERSE_SCRIPT_OBJECTS
+  tmp->TraverseHostObjectURIs(cb);
+NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
+
+NS_IMPL_CYCLE_COLLECTION_TRACE_WRAPPERCACHE(SimpleGlobalObject)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(SimpleGlobalObject)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(SimpleGlobalObject)
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(SimpleGlobalObject)
+  NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+  NS_INTERFACE_MAP_ENTRY(nsIGlobalObject)
+NS_INTERFACE_MAP_END
+
+static void
+SimpleGlobal_finalize(js::FreeOp *fop, JSObject *obj)
+{
+  SimpleGlobalObject* globalObject =
+    static_cast<SimpleGlobalObject*>(JS_GetPrivate(obj));
+  NS_RELEASE(globalObject);
+}
+
+static void
+SimpleGlobal_moved(JSObject *obj, const JSObject *old)
+{
+  SimpleGlobalObject* globalObject =
+    static_cast<SimpleGlobalObject*>(JS_GetPrivate(obj));
+  globalObject->UpdateWrapper(obj, old);
+}
+
+static const js::ClassOps SimpleGlobalClassOps = {
+    nullptr,
+    nullptr,
+    nullptr,
+    nullptr,
+    JS_EnumerateStandardClasses,
+    JS_ResolveStandardClass,
+    JS_MayResolveStandardClass,
+    SimpleGlobal_finalize,
+    nullptr,
+    nullptr,
+    nullptr,
+    JS_GlobalObjectTraceHook,
+};
+
+static const js::ClassExtension SimpleGlobalClassExtension = {
+  nullptr,
+  SimpleGlobal_moved
+};
+
+const js::Class SimpleGlobalClass = {
+    "",
+    JSCLASS_GLOBAL_FLAGS |
+    JSCLASS_HAS_PRIVATE |
+    JSCLASS_PRIVATE_IS_NSISUPPORTS |
+    JSCLASS_FOREGROUND_FINALIZE,
+    &SimpleGlobalClassOps,
+    JS_NULL_CLASS_SPEC,
+    &SimpleGlobalClassExtension,
+    JS_NULL_OBJECT_OPS
+};
+
+// static
+JSObject*
+SimpleGlobalObject::Create(GlobalType globalType, JS::Handle<JS::Value> proto)
+{
+  // We can't root our return value with our AutoJSAPI because the rooting
+  // analysis thinks ~AutoJSAPI can GC.  So we need to root in a scope outside
+  // the lifetime of the AutoJSAPI.
+  JS::Rooted<JSObject*> global(RootingCx());
+
+  { // Scope to ensure the AutoJSAPI destructor runs before we end up returning
+    AutoJSAPI jsapi;
+    jsapi.Init();
+    JSContext* cx = jsapi.cx();
+
+    JS::CompartmentOptions options;
+    options.creationOptions().setInvisibleToDebugger(true);
+
+    if (NS_IsMainThread()) {
+      nsCOMPtr<nsIPrincipal> principal = nsNullPrincipal::Create();
+      options.creationOptions().setTrace(xpc::TraceXPCGlobal);
+      global = xpc::CreateGlobalObject(cx, js::Jsvalify(&SimpleGlobalClass),
+                                       nsJSPrincipals::get(principal),
+                                       options);
+    } else {
+      global = JS_NewGlobalObject(cx, js::Jsvalify(&SimpleGlobalClass),
+                                  nullptr,
+                                  JS::DontFireOnNewGlobalHook, options);
+    }
+
+    if (!global) {
+      jsapi.ClearException();
+      return nullptr;
+    }
+
+    JSAutoCompartment ac(cx, global);
+
+    // It's important to create the nsIGlobalObject for our new global before we
+    // start trying to wrap things like the prototype into its compartment,
+    // because the wrap operation relies on the global having its
+    // nsIGlobalObject already.
+    RefPtr<SimpleGlobalObject> globalObject =
+      new SimpleGlobalObject(global, globalType);
+
+    // Pass on ownership of globalObject to |global|.
+    JS_SetPrivate(global, globalObject.forget().take());
+
+    if (proto.isObjectOrNull()) {
+      JS::Rooted<JSObject*> protoObj(cx, proto.toObjectOrNull());
+      if (!JS_WrapObject(cx, &protoObj)) {
+        jsapi.ClearException();
+        return nullptr;
+      }
+
+      if (!JS_SplicePrototype(cx, global, protoObj)) {
+        jsapi.ClearException();
+        return nullptr;
+      }
+    } else if (!proto.isUndefined()) {
+      // Bogus proto.
+      return nullptr;
+    }
+
+    JS_FireOnNewGlobalObject(cx, global);
+  }
+
+  return global;
+}
+
+// static
+SimpleGlobalObject::GlobalType
+SimpleGlobalObject::SimpleGlobalType(JSObject* obj)
+{
+  if (js::GetObjectClass(obj) != &SimpleGlobalClass) {
+    return SimpleGlobalObject::GlobalType::NotSimpleGlobal;
+  }
+
+  SimpleGlobalObject* globalObject =
+    static_cast<SimpleGlobalObject*>(JS_GetPrivate(obj));
+  return globalObject->Type();
+}
+
+} // namespace mozilla
+} // namespace dom
diff --git a/dom/bindings/SimpleGlobalObject.h b/dom/bindings/SimpleGlobalObject.h
new file mode 100644
index 000000000..9781fbfaa
--- /dev/null
+++ b/dom/bindings/SimpleGlobalObject.h
@@ -0,0 +1,99 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * A simplere nsIGlobalObject implementation that can be used to set up a new
+ * global without anything interesting in it other than the JS builtins.  This
+ * is safe to use on both mainthread and worker threads.
+ */
+
+#ifndef mozilla_dom_SimpleGlobalObject_h__
+#define mozilla_dom_SimpleGlobalObject_h__
+
+#include "nsIGlobalObject.h"
+#include "nsWrapperCache.h"
+#include "js/TypeDecls.h"
+#include "nsISupportsImpl.h"
+#include "nsCycleCollectionParticipant.h"
+
+namespace mozilla {
+namespace dom {
+
+class SimpleGlobalObject : public nsIGlobalObject,
+                           public nsWrapperCache
+{
+public:
+  enum class GlobalType {
+    BindingDetail, // Should only be used by DOM bindings code.
+    WorkerDebuggerSandbox,
+    NotSimpleGlobal // Sentinel to be used by BasicGlobalType.
+  };
+
+  // Create a new JS global object that can be used to do some work.  This
+  // global will NOT have any DOM APIs exposed in it, will not be visible to the
+  // debugger, and will not have a useful concept of principals, so don't try to
+  // use it with any DOM objects.  Apart from that, running code with
+  // side-effects is safe in this global.  Importantly, when you are first
+  // handed this global it's guaranteed to have pristine built-ins.  The
+  // corresponding nsIGlobalObject* for this global object will be a
+  // SimpleGlobalObject of the type provided; JS_GetPrivate on the returned
+  // JSObject* will return the SimpleGlobalObject*.
+  //
+  // If the provided prototype value is undefined, it is ignored.  If it's an
+  // object or null, it's set as the prototype of the created global.  If it's
+  // anything else, this function returns null.
+  //
+  // Note that creating new globals is not cheap and should not be done
+  // gratuitously.  Please think carefully before you use this function.
+  static JSObject* Create(GlobalType globalType,
+                          JS::Handle<JS::Value> proto =
+                            JS::UndefinedHandleValue);
+
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS_AMBIGUOUS(SimpleGlobalObject,
+                                                         nsIGlobalObject)
+
+  // Gets the GlobalType of this SimpleGlobalObject.
+  GlobalType Type() const
+  {
+    return mType;
+  }
+
+  // Gets the GlobalType of the SimpleGlobalObject for the given JSObject*, if
+  // the given JSObject* is the global corresponding to a SimpleGlobalObject.
+  // Oherwise, returns GlobalType::NotSimpleGlobal.
+  static GlobalType SimpleGlobalType(JSObject* obj);
+
+  virtual JSObject *GetGlobalJSObject() override
+  {
+    return GetWrapper();
+  }
+
+  virtual JSObject* WrapObject(JSContext* cx,
+                               JS::Handle<JSObject*> aGivenProto) override
+  {
+    MOZ_CRASH("SimpleGlobalObject doesn't use DOM bindings!");
+  }
+
+private:
+  SimpleGlobalObject(JSObject *global, GlobalType type)
+    : mType(type)
+  {
+    SetWrapper(global);
+  }
+
+  virtual ~SimpleGlobalObject()
+  {
+    ClearWrapper();
+  }
+
+  const GlobalType mType;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_SimpleGlobalObject_h__ */
diff --git a/dom/bindings/StructuredClone.cpp b/dom/bindings/StructuredClone.cpp
new file mode 100644
index 000000000..71b4f5c74
--- /dev/null
+++ b/dom/bindings/StructuredClone.cpp
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/StructuredClone.h"
+
+#include "js/StructuredClone.h"
+#include "mozilla/dom/ImageData.h"
+#include "mozilla/dom/StructuredCloneTags.h"
+
+namespace mozilla {
+namespace dom {
+
+JSObject*
+ReadStructuredCloneImageData(JSContext* aCx, JSStructuredCloneReader* aReader)
+{
+  // Read the information out of the stream.
+  uint32_t width, height;
+  JS::Rooted<JS::Value> dataArray(aCx);
+  if (!JS_ReadUint32Pair(aReader, &width, &height) ||
+      !JS_ReadTypedArray(aReader, &dataArray)) {
+    return nullptr;
+  }
+  MOZ_ASSERT(dataArray.isObject());
+
+  // Protect the result from a moving GC in ~nsRefPtr.
+  JS::Rooted<JSObject*> result(aCx);
+  {
+    // Construct the ImageData.
+    RefPtr<ImageData> imageData = new ImageData(width, height,
+                                                  dataArray.toObject());
+    // Wrap it in a JS::Value.
+    if (!imageData->WrapObject(aCx, nullptr, &result)) {
+      return nullptr;
+    }
+  }
+  return result;
+}
+
+bool
+WriteStructuredCloneImageData(JSContext* aCx, JSStructuredCloneWriter* aWriter,
+                              ImageData* aImageData)
+{
+  uint32_t width = aImageData->Width();
+  uint32_t height = aImageData->Height();
+  JS::Rooted<JSObject*> dataArray(aCx, aImageData->GetDataObject());
+
+  JSAutoCompartment ac(aCx, dataArray);
+  JS::Rooted<JS::Value> arrayValue(aCx, JS::ObjectValue(*dataArray));
+  return JS_WriteUint32Pair(aWriter, SCTAG_DOM_IMAGEDATA, 0) &&
+         JS_WriteUint32Pair(aWriter, width, height) &&
+         JS_WriteTypedArray(aWriter, arrayValue);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/StructuredClone.h b/dom/bindings/StructuredClone.h
new file mode 100644
index 000000000..bfd7700c6
--- /dev/null
+++ b/dom/bindings/StructuredClone.h
@@ -0,0 +1,25 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+class JSObject;
+struct JSContext;
+struct JSStructuredCloneReader;
+struct JSStructuredCloneWriter;
+
+namespace mozilla {
+namespace dom {
+
+class ImageData;
+
+JSObject*
+ReadStructuredCloneImageData(JSContext* aCx, JSStructuredCloneReader* aReader);
+
+bool
+WriteStructuredCloneImageData(JSContext* aCx, JSStructuredCloneWriter* aWriter,
+                              ImageData* aImageData);
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/ToJSValue.cpp b/dom/bindings/ToJSValue.cpp
new file mode 100644
index 000000000..d84428fb3
--- /dev/null
+++ b/dom/bindings/ToJSValue.cpp
@@ -0,0 +1,80 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/ToJSValue.h"
+#include "mozilla/dom/DOMException.h"
+#include "mozilla/dom/Exceptions.h"
+#ifdef SPIDERMONKEY_PROMISE
+#include "mozilla/dom/Promise.h"
+#endif // SPIDERMONKEY_PROMISE
+#include "nsAString.h"
+#include "nsContentUtils.h"
+#include "nsStringBuffer.h"
+#include "xpcpublic.h"
+
+namespace mozilla {
+namespace dom {
+
+bool
+ToJSValue(JSContext* aCx, const nsAString& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+// XXXkhuey I'd love to use xpc::NonVoidStringToJsval here, but it requires
+  // a non-const nsAString for silly reasons.
+  nsStringBuffer* sharedBuffer;
+  if (!XPCStringConvert::ReadableToJSVal(aCx, aArgument, &sharedBuffer,
+                                         aValue)) {
+    return false;
+  }
+
+  if (sharedBuffer) {
+    NS_ADDREF(sharedBuffer);
+  }
+
+  return true;
+}
+
+
+bool
+ToJSValue(JSContext* aCx,
+          nsresult aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  RefPtr<Exception> exception = CreateException(aCx, aArgument);
+  return ToJSValue(aCx, exception, aValue);
+}
+
+bool
+ToJSValue(JSContext* aCx,
+          ErrorResult& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  MOZ_ASSERT(aArgument.Failed());
+  MOZ_ASSERT(!aArgument.IsUncatchableException(),
+             "Doesn't make sense to convert uncatchable exception to a JS value!");
+  DebugOnly<bool> throwResult = aArgument.MaybeSetPendingException(aCx);
+  MOZ_ASSERT(throwResult);
+  DebugOnly<bool> getPendingResult = JS_GetPendingException(aCx, aValue);
+  MOZ_ASSERT(getPendingResult);
+  JS_ClearPendingException(aCx);
+  return true;
+}
+
+#ifdef SPIDERMONKEY_PROMISE
+bool
+ToJSValue(JSContext* aCx, Promise& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  aValue.setObject(*aArgument.PromiseObj());
+  return true;
+}
+#endif // SPIDERMONKEY_PROMISE
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/ToJSValue.h b/dom/bindings/ToJSValue.h
new file mode 100644
index 000000000..2021c0b4c
--- /dev/null
+++ b/dom/bindings/ToJSValue.h
@@ -0,0 +1,377 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_ToJSValue_h
+#define mozilla_dom_ToJSValue_h
+
+#include "mozilla/TypeTraits.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/TypedArray.h"
+#include "jsapi.h"
+#include "nsISupports.h"
+#include "nsTArray.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+class Promise;
+
+// If ToJSValue returns false, it must set an exception on the
+// JSContext.
+
+// Accept strings.
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const nsAString& aArgument,
+          JS::MutableHandle<JS::Value> aValue);
+
+// Accept booleans.  But be careful here: if we just have a function that takes
+// a boolean argument, then any pointer that doesn't match one of our other
+// signatures/templates will get treated as a boolean, which is clearly not
+// desirable.  So make this a template that only gets used if the argument type
+// is actually boolean
+template<typename T>
+MOZ_MUST_USE
+typename EnableIf<IsSame<T, bool>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          T aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setBoolean(aArgument);
+  return true;
+}
+
+// Accept integer types
+inline bool
+ToJSValue(JSContext* aCx,
+          int32_t aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setInt32(aArgument);
+  return true;
+}
+
+inline bool
+ToJSValue(JSContext* aCx,
+          uint32_t aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setNumber(aArgument);
+  return true;
+}
+
+inline bool
+ToJSValue(JSContext* aCx,
+          int64_t aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setNumber(double(aArgument));
+  return true;
+}
+
+inline bool
+ToJSValue(JSContext* aCx,
+          uint64_t aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setNumber(double(aArgument));
+  return true;
+}
+
+// accept floating point types
+inline bool
+ToJSValue(JSContext* aCx,
+          float aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setNumber(aArgument);
+  return true;
+}
+
+inline bool
+ToJSValue(JSContext* aCx,
+          double aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setNumber(aArgument);
+  return true;
+}
+
+// Accept CallbackObjects
+MOZ_MUST_USE inline bool
+ToJSValue(JSContext* aCx,
+          CallbackObject& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  aValue.setObject(*aArgument.Callback());
+
+  return MaybeWrapValue(aCx, aValue);
+}
+
+// Accept objects that inherit from nsWrapperCache (e.g. most
+// DOM objects).
+template <class T>
+MOZ_MUST_USE
+typename EnableIf<IsBaseOf<nsWrapperCache, T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          T& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+  // Make sure non-webidl objects don't sneak in here
+  MOZ_ASSERT(aArgument.IsDOMBinding());
+
+  return GetOrCreateDOMReflector(aCx, aArgument, aValue);
+}
+
+// Accept typed arrays built from appropriate nsTArray values
+template<typename T>
+MOZ_MUST_USE
+typename EnableIf<IsBaseOf<AllTypedArraysBase, T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          const TypedArrayCreator<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  JSObject* obj = aArgument.Create(aCx);
+  if (!obj) {
+    return false;
+  }
+  aValue.setObject(*obj);
+  return true;
+}
+
+// Accept objects that inherit from nsISupports but not nsWrapperCache (e.g.
+// DOM File).
+template <class T>
+MOZ_MUST_USE
+typename EnableIf<!IsBaseOf<nsWrapperCache, T>::value &&
+                  !IsBaseOf<CallbackObject, T>::value &&
+                  IsBaseOf<nsISupports, T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          T& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  qsObjectHelper helper(ToSupports(&aArgument), nullptr);
+  JS::Rooted<JSObject*> scope(aCx, JS::CurrentGlobalOrNull(aCx));
+  return XPCOMObjectToJsval(aCx, scope, helper, nullptr, true, aValue);
+}
+
+// Accept nsRefPtr/nsCOMPtr
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const nsCOMPtr<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, *aArgument.get(), aValue);
+}
+
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const RefPtr<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, *aArgument.get(), aValue);
+}
+
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const NonNull<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, *aArgument.get(), aValue);
+}
+
+// Accept WebIDL dictionaries
+template <class T>
+MOZ_MUST_USE
+typename EnableIf<IsBaseOf<DictionaryBase, T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          const T& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return aArgument.ToObjectInternal(aCx, aValue);
+}
+
+// Accept existing JS values (which may not be same-compartment with us
+MOZ_MUST_USE inline bool
+ToJSValue(JSContext* aCx, JS::Handle<JS::Value> aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  aValue.set(aArgument);
+  return MaybeWrapValue(aCx, aValue);
+}
+
+// Accept existing JS values on the Heap (which may not be same-compartment with us
+MOZ_MUST_USE inline bool
+ToJSValue(JSContext* aCx, const JS::Heap<JS::Value>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  aValue.set(aArgument);
+  return MaybeWrapValue(aCx, aValue);
+}
+
+// Accept existing rooted JS values (which may not be same-compartment with us
+MOZ_MUST_USE inline bool
+ToJSValue(JSContext* aCx, const JS::Rooted<JS::Value>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  aValue.set(aArgument);
+  return MaybeWrapValue(aCx, aValue);
+}
+
+// Accept existing rooted JS objects (which may not be same-compartment with
+// us).
+MOZ_MUST_USE inline bool
+ToJSValue(JSContext* aCx, const JS::Rooted<JSObject*>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  aValue.setObjectOrNull(aArgument);
+  return MaybeWrapObjectOrNullValue(aCx, aValue);
+}
+
+// Accept nsresult, for use in rejections, and create an XPCOM
+// exception object representing that nsresult.
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          nsresult aArgument,
+          JS::MutableHandle<JS::Value> aValue);
+
+// Accept ErrorResult, for use in rejections, and create an exception
+// representing the failure.  Note, the ErrorResult must indicate a failure
+// with aArgument.Failure() returning true.
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          ErrorResult& aArgument,
+          JS::MutableHandle<JS::Value> aValue);
+
+// Accept owning WebIDL unions.
+template <typename T>
+MOZ_MUST_USE
+typename EnableIf<IsBaseOf<AllOwningUnionBase, T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          const T& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  JS::Rooted<JSObject*> global(aCx, JS::CurrentGlobalOrNull(aCx));
+  return aArgument.ToJSVal(aCx, global, aValue);
+}
+
+// Accept pointers to other things we accept
+template <typename T>
+MOZ_MUST_USE
+typename EnableIf<IsPointer<T>::value, bool>::Type
+ToJSValue(JSContext* aCx,
+          T aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, *aArgument, aValue);
+}
+
+#ifdef SPIDERMONKEY_PROMISE
+// Accept Promise objects, which need special handling.
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          Promise& aArgument,
+          JS::MutableHandle<JS::Value> aValue);
+#endif // SPIDERMONKEY_PROMISE
+
+// Accept arrays of other things we accept
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          T* aArguments,
+          size_t aLength,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  // Make sure we're called in a compartment
+  MOZ_ASSERT(JS::CurrentGlobalOrNull(aCx));
+
+  JS::AutoValueVector v(aCx);
+  if (!v.resize(aLength)) {
+    return false;
+  }
+  for (size_t i = 0; i < aLength; ++i) {
+    if (!ToJSValue(aCx, aArguments[i], v[i])) {
+      return false;
+    }
+  }
+  JSObject* arrayObj = JS_NewArrayObject(aCx, v);
+  if (!arrayObj) {
+    return false;
+  }
+  aValue.setObject(*arrayObj);
+  return true;
+}
+
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const nsTArray<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, aArgument.Elements(),
+                   aArgument.Length(), aValue);
+}
+
+template <typename T>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const FallibleTArray<T>& aArgument,
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, aArgument.Elements(),
+                   aArgument.Length(), aValue);
+}
+
+template <typename T, int N>
+MOZ_MUST_USE bool
+ToJSValue(JSContext* aCx,
+          const T(&aArgument)[N],
+          JS::MutableHandle<JS::Value> aValue)
+{
+  return ToJSValue(aCx, aArgument, N, aValue);
+}
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_ToJSValue_h */
diff --git a/dom/bindings/TypedArray.h b/dom/bindings/TypedArray.h
new file mode 100644
index 000000000..a86abcd9d
--- /dev/null
+++ b/dom/bindings/TypedArray.h
@@ -0,0 +1,441 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TypedArray_h
+#define mozilla_dom_TypedArray_h
+
+#include "jsapi.h"
+#include "jsfriendapi.h"
+#include "js/RootingAPI.h"
+#include "js/TracingAPI.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Move.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "nsWrapperCache.h"
+
+namespace mozilla {
+namespace dom {
+
+/*
+ * Class that just handles the JSObject storage and tracing for typed arrays
+ */
+struct TypedArrayObjectStorage : AllTypedArraysBase {
+protected:
+  JSObject* mTypedObj;
+  JSObject* mWrappedObj;
+
+  TypedArrayObjectStorage()
+    : mTypedObj(nullptr),
+      mWrappedObj(nullptr)
+  {
+  }
+
+  TypedArrayObjectStorage(TypedArrayObjectStorage&& aOther)
+    : mTypedObj(aOther.mTypedObj),
+      mWrappedObj(aOther.mWrappedObj)
+  {
+    aOther.mTypedObj = nullptr;
+    aOther.mWrappedObj = nullptr;
+  }
+
+public:
+  inline void TraceSelf(JSTracer* trc)
+  {
+    JS::UnsafeTraceRoot(trc, &mTypedObj, "TypedArray.mTypedObj");
+    JS::UnsafeTraceRoot(trc, &mWrappedObj, "TypedArray.mWrappedObj");
+  }
+
+private:
+  TypedArrayObjectStorage(const TypedArrayObjectStorage&) = delete;
+};
+
+/*
+ * Various typed array classes for argument conversion.  We have a base class
+ * that has a way of initializing a TypedArray from an existing typed array, and
+ * a subclass of the base class that supports creation of a relevant typed array
+ * or array buffer object.
+ */
+template<typename T,
+         JSObject* UnwrapArray(JSObject*),
+         void GetLengthAndDataAndSharedness(JSObject*, uint32_t*, bool*, T**)>
+struct TypedArray_base : public TypedArrayObjectStorage {
+  typedef T element_type;
+
+  TypedArray_base()
+    : mData(nullptr),
+      mLength(0),
+      mShared(false),
+      mComputed(false)
+  {
+  }
+
+  TypedArray_base(TypedArray_base&& aOther)
+    : TypedArrayObjectStorage(Move(aOther)),
+      mData(aOther.mData),
+      mLength(aOther.mLength),
+      mShared(aOther.mShared),
+      mComputed(aOther.mComputed)
+  {
+    aOther.mData = nullptr;
+    aOther.mLength = 0;
+    aOther.mShared = false;
+    aOther.mComputed = false;
+  }
+
+private:
+  mutable T* mData;
+  mutable uint32_t mLength;
+  mutable bool mShared;
+  mutable bool mComputed;
+
+public:
+  inline bool Init(JSObject* obj)
+  {
+    MOZ_ASSERT(!inited());
+    mTypedObj = mWrappedObj = UnwrapArray(obj);
+    return inited();
+  }
+
+  inline bool inited() const {
+    return !!mTypedObj;
+  }
+
+  // About shared memory:
+  //
+  // Any DOM TypedArray as well as any DOM ArrayBufferView that does
+  // not represent a JS DataView can map the memory of either a JS
+  // ArrayBuffer or a JS SharedArrayBuffer.  (DataView cannot view
+  // shared memory.)  If the TypedArray maps a SharedArrayBuffer the
+  // Length() and Data() accessors on the DOM view will return zero
+  // and nullptr; to get the actual length and data, call the
+  // LengthAllowShared() and DataAllowShared() accessors instead.
+  //
+  // Two methods are available for determining if a DOM view maps
+  // shared memory.  The IsShared() method is cheap and can be called
+  // if the view has been computed; the JS_GetTypedArraySharedness()
+  // method is slightly more expensive and can be called on the Obj()
+  // value if the view may not have been computed and if the value is
+  // known to represent a JS TypedArray.
+  //
+  // (Just use JS_IsSharedArrayBuffer() to test if any object is of
+  // that type.)
+  //
+  // Code that elects to allow views that map shared memory to be used
+  // -- ie, code that "opts in to shared memory" -- should generally
+  // not access the raw data buffer with standard C++ mechanisms as
+  // that creates the possibility of C++ data races, which is
+  // undefined behavior.  The JS engine will eventually export (bug
+  // 1225033) a suite of methods that avoid undefined behavior.
+  //
+  // Callers of Obj() that do not opt in to shared memory can produce
+  // better diagnostics by checking whether the JSObject in fact maps
+  // shared memory and throwing an error if it does.  However, it is
+  // safe to use the value of Obj() without such checks.
+  //
+  // The DOM TypedArray abstraction prevents the underlying buffer object
+  // from being accessed directly, but JS_GetArrayBufferViewBuffer(Obj())
+  // will obtain the buffer object.  Code that calls that function must
+  // not assume the returned buffer is an ArrayBuffer.  That is guarded
+  // against by an out parameter on that call that communicates the
+  // sharedness of the buffer.
+  //
+  // Finally, note that the buffer memory of a SharedArrayBuffer is
+  // not detachable.
+
+  inline bool IsShared() const {
+    MOZ_ASSERT(mComputed);
+    return mShared;
+  }
+
+  inline T *Data() const {
+    MOZ_ASSERT(mComputed);
+    if (mShared)
+      return nullptr;
+    return mData;
+  }
+
+  inline T *DataAllowShared() const {
+    MOZ_ASSERT(mComputed);
+    return mData;
+  }
+
+  inline uint32_t Length() const {
+    MOZ_ASSERT(mComputed);
+    if (mShared)
+      return 0;
+    return mLength;
+  }
+
+  inline uint32_t LengthAllowShared() const {
+    MOZ_ASSERT(mComputed);
+    return mLength;
+  }
+
+  inline JSObject *Obj() const {
+    MOZ_ASSERT(inited());
+    return mWrappedObj;
+  }
+
+  inline bool WrapIntoNewCompartment(JSContext* cx)
+  {
+    return JS_WrapObject(cx,
+      JS::MutableHandle<JSObject*>::fromMarkedLocation(&mWrappedObj));
+  }
+
+  inline void ComputeLengthAndData() const
+  {
+    MOZ_ASSERT(inited());
+    MOZ_ASSERT(!mComputed);
+    GetLengthAndDataAndSharedness(mTypedObj, &mLength, &mShared, &mData);
+    mComputed = true;
+  }
+
+private:
+  TypedArray_base(const TypedArray_base&) = delete;
+};
+
+template<typename T,
+         JSObject* UnwrapArray(JSObject*),
+         T* GetData(JSObject*, bool* isShared, const JS::AutoCheckCannotGC&),
+         void GetLengthAndDataAndSharedness(JSObject*, uint32_t*, bool*, T**),
+         JSObject* CreateNew(JSContext*, uint32_t)>
+struct TypedArray
+  : public TypedArray_base<T, UnwrapArray, GetLengthAndDataAndSharedness>
+{
+private:
+  typedef TypedArray_base<T, UnwrapArray, GetLengthAndDataAndSharedness> Base;
+
+public:
+  TypedArray()
+    : Base()
+  {}
+
+  TypedArray(TypedArray&& aOther)
+    : Base(Move(aOther))
+  {
+  }
+
+  static inline JSObject*
+  Create(JSContext* cx, nsWrapperCache* creator, uint32_t length,
+         const T* data = nullptr) {
+    JS::Rooted<JSObject*> creatorWrapper(cx);
+    Maybe<JSAutoCompartment> ac;
+    if (creator && (creatorWrapper = creator->GetWrapperPreserveColor())) {
+      ac.emplace(cx, creatorWrapper);
+    }
+
+    return CreateCommon(cx, length, data);
+  }
+
+  static inline JSObject*
+  Create(JSContext* cx, uint32_t length, const T* data = nullptr) {
+    return CreateCommon(cx, length, data);
+  }
+
+private:
+  static inline JSObject*
+  CreateCommon(JSContext* cx, uint32_t length, const T* data) {
+    JSObject* obj = CreateNew(cx, length);
+    if (!obj) {
+      return nullptr;
+    }
+    if (data) {
+      JS::AutoCheckCannotGC nogc;
+      bool isShared;
+      T* buf = static_cast<T*>(GetData(obj, &isShared, nogc));
+      // Data will not be shared, until a construction protocol exists
+      // for constructing shared data.
+      MOZ_ASSERT(!isShared);
+      memcpy(buf, data, length*sizeof(T));
+    }
+    return obj;
+  }
+
+  TypedArray(const TypedArray&) = delete;
+};
+
+template<JSObject* UnwrapArray(JSObject*),
+         void GetLengthAndDataAndSharedness(JSObject*, uint32_t*, bool*,
+                                            uint8_t**),
+         js::Scalar::Type GetViewType(JSObject*)>
+struct ArrayBufferView_base
+  : public TypedArray_base<uint8_t, UnwrapArray, GetLengthAndDataAndSharedness>
+{
+private:
+  typedef TypedArray_base<uint8_t, UnwrapArray, GetLengthAndDataAndSharedness>
+          Base;
+
+public:
+  ArrayBufferView_base()
+    : Base()
+  {
+  }
+
+  ArrayBufferView_base(ArrayBufferView_base&& aOther)
+    : Base(Move(aOther)),
+      mType(aOther.mType)
+  {
+    aOther.mType = js::Scalar::MaxTypedArrayViewType;
+  }
+
+private:
+  js::Scalar::Type mType;
+
+public:
+  inline bool Init(JSObject* obj)
+  {
+    if (!Base::Init(obj)) {
+      return false;
+    }
+
+    mType = GetViewType(this->Obj());
+    return true;
+  }
+
+  inline js::Scalar::Type Type() const
+  {
+    MOZ_ASSERT(this->inited());
+    return mType;
+  }
+};
+
+typedef TypedArray<int8_t, js::UnwrapInt8Array, JS_GetInt8ArrayData,
+                   js::GetInt8ArrayLengthAndData, JS_NewInt8Array>
+        Int8Array;
+typedef TypedArray<uint8_t, js::UnwrapUint8Array, JS_GetUint8ArrayData,
+                   js::GetUint8ArrayLengthAndData, JS_NewUint8Array>
+        Uint8Array;
+typedef TypedArray<uint8_t, js::UnwrapUint8ClampedArray, JS_GetUint8ClampedArrayData,
+                   js::GetUint8ClampedArrayLengthAndData, JS_NewUint8ClampedArray>
+        Uint8ClampedArray;
+typedef TypedArray<int16_t, js::UnwrapInt16Array, JS_GetInt16ArrayData,
+                   js::GetInt16ArrayLengthAndData, JS_NewInt16Array>
+        Int16Array;
+typedef TypedArray<uint16_t, js::UnwrapUint16Array, JS_GetUint16ArrayData,
+                   js::GetUint16ArrayLengthAndData, JS_NewUint16Array>
+        Uint16Array;
+typedef TypedArray<int32_t, js::UnwrapInt32Array, JS_GetInt32ArrayData,
+                   js::GetInt32ArrayLengthAndData, JS_NewInt32Array>
+        Int32Array;
+typedef TypedArray<uint32_t, js::UnwrapUint32Array, JS_GetUint32ArrayData,
+                   js::GetUint32ArrayLengthAndData, JS_NewUint32Array>
+        Uint32Array;
+typedef TypedArray<float, js::UnwrapFloat32Array, JS_GetFloat32ArrayData,
+                   js::GetFloat32ArrayLengthAndData, JS_NewFloat32Array>
+        Float32Array;
+typedef TypedArray<double, js::UnwrapFloat64Array, JS_GetFloat64ArrayData,
+                   js::GetFloat64ArrayLengthAndData, JS_NewFloat64Array>
+        Float64Array;
+typedef ArrayBufferView_base<js::UnwrapArrayBufferView,
+                             js::GetArrayBufferViewLengthAndData,
+                             JS_GetArrayBufferViewType>
+        ArrayBufferView;
+typedef TypedArray<uint8_t, js::UnwrapArrayBuffer, JS_GetArrayBufferData,
+                   js::GetArrayBufferLengthAndData, JS_NewArrayBuffer>
+        ArrayBuffer;
+
+typedef TypedArray<uint8_t, js::UnwrapSharedArrayBuffer, JS_GetSharedArrayBufferData,
+                   js::GetSharedArrayBufferLengthAndData, JS_NewSharedArrayBuffer>
+        SharedArrayBuffer;
+
+// A class for converting an nsTArray to a TypedArray
+// Note: A TypedArrayCreator must not outlive the nsTArray it was created from.
+//       So this is best used to pass from things that understand nsTArray to
+//       things that understand TypedArray, as with Promise::ArgumentToJSValue.
+template<typename TypedArrayType>
+class TypedArrayCreator
+{
+  typedef nsTArray<typename TypedArrayType::element_type> ArrayType;
+
+  public:
+    explicit TypedArrayCreator(const ArrayType& aArray)
+      : mArray(aArray)
+    {}
+
+    JSObject* Create(JSContext* aCx) const
+    {
+      return TypedArrayType::Create(aCx, mArray.Length(), mArray.Elements());
+    }
+
+  private:
+    const ArrayType& mArray;
+};
+
+// A class for rooting an existing TypedArray struct
+template<typename ArrayType>
+class MOZ_RAII TypedArrayRooter : private JS::CustomAutoRooter
+{
+public:
+  template <typename CX>
+  TypedArrayRooter(const CX& cx,
+                   ArrayType* aArray MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+    mArray(aArray)
+  {
+  }
+
+  virtual void trace(JSTracer* trc) override
+  {
+    mArray->TraceSelf(trc);
+  }
+
+private:
+  TypedArrayObjectStorage* const mArray;
+};
+
+// And a specialization for dealing with nullable typed arrays
+template<typename Inner> struct Nullable;
+template<typename ArrayType>
+class MOZ_RAII TypedArrayRooter<Nullable<ArrayType> > :
+    private JS::CustomAutoRooter
+{
+public:
+  template <typename CX>
+  TypedArrayRooter(const CX& cx,
+                   Nullable<ArrayType>* aArray MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    JS::CustomAutoRooter(cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT),
+    mArray(aArray)
+  {
+  }
+
+  virtual void trace(JSTracer* trc) override
+  {
+    if (!mArray->IsNull()) {
+      mArray->Value().TraceSelf(trc);
+    }
+  }
+
+private:
+  Nullable<ArrayType>* const mArray;
+};
+
+// Class for easily setting up a rooted typed array object on the stack
+template<typename ArrayType>
+class MOZ_RAII RootedTypedArray final : public ArrayType,
+                                        private TypedArrayRooter<ArrayType>
+{
+public:
+  template <typename CX>
+  explicit RootedTypedArray(const CX& cx MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    ArrayType(),
+    TypedArrayRooter<ArrayType>(cx, this
+                                MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+
+  template <typename CX>
+  RootedTypedArray(const CX& cx, JSObject* obj MOZ_GUARD_OBJECT_NOTIFIER_PARAM) :
+    ArrayType(obj),
+    TypedArrayRooter<ArrayType>(cx, this
+                                MOZ_GUARD_OBJECT_NOTIFIER_PARAM_TO_PARENT)
+  {
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* mozilla_dom_TypedArray_h */
diff --git a/dom/bindings/UnionMember.h b/dom/bindings/UnionMember.h
new file mode 100644
index 000000000..3842c6eb0
--- /dev/null
+++ b/dom/bindings/UnionMember.h
@@ -0,0 +1,59 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* A class for holding the members of a union. */
+
+#ifndef mozilla_dom_UnionMember_h
+#define mozilla_dom_UnionMember_h
+
+#include "mozilla/Alignment.h"
+
+namespace mozilla {
+namespace dom {
+
+// The union type has an enum to keep track of which of its UnionMembers has
+// been constructed.
+template<class T>
+class UnionMember
+{
+  AlignedStorage2<T> mStorage;
+
+public:
+  T& SetValue()
+  {
+    new (mStorage.addr()) T();
+    return *mStorage.addr();
+  }
+  template <typename T1>
+  T& SetValue(const T1& aValue)
+  {
+    new (mStorage.addr()) T(aValue);
+    return *mStorage.addr();
+  }
+  template<typename T1, typename T2>
+  T& SetValue(const T1& aValue1, const T2& aValue2)
+  {
+    new (mStorage.addr()) T(aValue1, aValue2);
+    return *mStorage.addr();
+  }
+  T& Value()
+  {
+    return *mStorage.addr();
+  }
+  const T& Value() const
+  {
+    return *mStorage.addr();
+  }
+  void Destroy()
+  {
+    mStorage.addr()->~T();
+  }
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_UnionMember_h
diff --git a/dom/bindings/WebIDLGlobalNameHash.cpp b/dom/bindings/WebIDLGlobalNameHash.cpp
new file mode 100644
index 000000000..7477b52e7
--- /dev/null
+++ b/dom/bindings/WebIDLGlobalNameHash.cpp
@@ -0,0 +1,324 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "WebIDLGlobalNameHash.h"
+#include "js/GCAPI.h"
+#include "mozilla/HashFunctions.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/dom/DOMJSProxyHandler.h"
+#include "mozilla/dom/RegisterBindings.h"
+#include "nsIMemoryReporter.h"
+#include "nsTHashtable.h"
+
+namespace mozilla {
+namespace dom {
+
+struct MOZ_STACK_CLASS WebIDLNameTableKey
+{
+  explicit WebIDLNameTableKey(JSFlatString* aJSString)
+    : mLength(js::GetFlatStringLength(aJSString))
+  {
+    mNogc.emplace();
+    JSLinearString* jsString = js::FlatStringToLinearString(aJSString);
+    if (js::LinearStringHasLatin1Chars(jsString)) {
+      mLatin1String = reinterpret_cast<const char*>(
+        js::GetLatin1LinearStringChars(*mNogc, jsString));
+      mTwoBytesString = nullptr;
+      mHash = mLatin1String ? HashString(mLatin1String, mLength) : 0;
+    } else {
+      mLatin1String = nullptr;
+      mTwoBytesString = js::GetTwoByteLinearStringChars(*mNogc, jsString);
+      mHash = mTwoBytesString ? HashString(mTwoBytesString, mLength) : 0;
+    }
+  }
+  explicit WebIDLNameTableKey(const char* aString, size_t aLength)
+    : mLatin1String(aString),
+      mTwoBytesString(nullptr),
+      mLength(aLength),
+      mHash(HashString(aString, aLength))
+  {
+    MOZ_ASSERT(aString[aLength] == '\0');
+  }
+
+  Maybe<JS::AutoCheckCannotGC> mNogc;
+  const char* mLatin1String;
+  const char16_t* mTwoBytesString;
+  size_t mLength;
+  uint32_t mHash;
+};
+
+struct WebIDLNameTableEntry : public PLDHashEntryHdr
+{
+  typedef const WebIDLNameTableKey& KeyType;
+  typedef const WebIDLNameTableKey* KeyTypePointer;
+
+  explicit WebIDLNameTableEntry(KeyTypePointer aKey)
+    : mNameOffset(0),
+      mNameLength(0),
+      mDefine(nullptr),
+      mEnabled(nullptr)
+  {}
+  WebIDLNameTableEntry(WebIDLNameTableEntry&& aEntry)
+    : mNameOffset(aEntry.mNameOffset),
+      mNameLength(aEntry.mNameLength),
+      mDefine(aEntry.mDefine),
+      mEnabled(aEntry.mEnabled)
+  {}
+  ~WebIDLNameTableEntry()
+  {}
+
+  bool KeyEquals(KeyTypePointer aKey) const
+  {
+    if (mNameLength != aKey->mLength) {
+      return false;
+    }
+
+    const char* name = WebIDLGlobalNameHash::sNames + mNameOffset;
+
+    if (aKey->mLatin1String) {
+      return PodEqual(aKey->mLatin1String, name, aKey->mLength);
+    }
+
+    return nsCharTraits<char16_t>::compareASCII(aKey->mTwoBytesString, name,
+                                                aKey->mLength) == 0;
+  }
+
+  static KeyTypePointer KeyToPointer(KeyType aKey)
+  {
+    return &aKey;
+  }
+
+  static PLDHashNumber HashKey(KeyTypePointer aKey)
+  {
+    return aKey->mHash;
+  }
+
+  enum { ALLOW_MEMMOVE = true };
+
+  uint16_t mNameOffset;
+  uint16_t mNameLength;
+  WebIDLGlobalNameHash::DefineGlobalName mDefine;
+  // May be null if enabled unconditionally
+  WebIDLGlobalNameHash::ConstructorEnabled* mEnabled;
+};
+
+static nsTHashtable<WebIDLNameTableEntry>* sWebIDLGlobalNames;
+
+class WebIDLGlobalNamesHashReporter final : public nsIMemoryReporter
+{
+  MOZ_DEFINE_MALLOC_SIZE_OF(MallocSizeOf)
+
+  ~WebIDLGlobalNamesHashReporter() {}
+
+public:
+  NS_DECL_ISUPPORTS
+
+  NS_IMETHOD CollectReports(nsIHandleReportCallback* aHandleReport,
+                            nsISupports* aData, bool aAnonymize) override
+  {
+    int64_t amount =
+      sWebIDLGlobalNames ?
+      sWebIDLGlobalNames->ShallowSizeOfIncludingThis(MallocSizeOf) : 0;
+
+    MOZ_COLLECT_REPORT(
+      "explicit/dom/webidl-globalnames", KIND_HEAP, UNITS_BYTES, amount,
+      "Memory used by the hash table for WebIDL's global names.");
+
+    return NS_OK;
+  }
+};
+
+NS_IMPL_ISUPPORTS(WebIDLGlobalNamesHashReporter, nsIMemoryReporter)
+
+/* static */
+void
+WebIDLGlobalNameHash::Init()
+{
+  sWebIDLGlobalNames = new nsTHashtable<WebIDLNameTableEntry>(sCount);
+  RegisterWebIDLGlobalNames();
+
+  RegisterStrongMemoryReporter(new WebIDLGlobalNamesHashReporter());
+}
+
+/* static */
+void
+WebIDLGlobalNameHash::Shutdown()
+{
+  delete sWebIDLGlobalNames;
+}
+
+/* static */
+void
+WebIDLGlobalNameHash::Register(uint16_t aNameOffset, uint16_t aNameLength,
+                               DefineGlobalName aDefine,
+                               ConstructorEnabled* aEnabled)
+{
+  const char* name = sNames + aNameOffset;
+  WebIDLNameTableKey key(name, aNameLength);
+  WebIDLNameTableEntry* entry = sWebIDLGlobalNames->PutEntry(key);
+  entry->mNameOffset = aNameOffset;
+  entry->mNameLength = aNameLength;
+  entry->mDefine = aDefine;
+  entry->mEnabled = aEnabled;
+}
+
+/* static */
+void
+WebIDLGlobalNameHash::Remove(const char* aName, uint32_t aLength)
+{
+  WebIDLNameTableKey key(aName, aLength);
+  sWebIDLGlobalNames->RemoveEntry(key);
+}
+
+/* static */
+bool
+WebIDLGlobalNameHash::DefineIfEnabled(JSContext* aCx,
+                                      JS::Handle<JSObject*> aObj,
+                                      JS::Handle<jsid> aId,
+                                      JS::MutableHandle<JS::PropertyDescriptor> aDesc,
+                                      bool* aFound)
+{
+  MOZ_ASSERT(JSID_IS_STRING(aId), "Check for string id before calling this!");
+
+  const WebIDLNameTableEntry* entry;
+  {
+    WebIDLNameTableKey key(JSID_TO_FLAT_STRING(aId));
+    // Rooting analysis thinks nsTHashtable<...>::GetEntry may GC because it
+    // ends up calling through PLDHashTableOps' matchEntry function pointer, but
+    // we know WebIDLNameTableEntry::KeyEquals can't cause a GC.
+    JS::AutoSuppressGCAnalysis suppress;
+    entry = sWebIDLGlobalNames->GetEntry(key);
+  }
+
+  if (!entry) {
+    *aFound = false;
+    return true;
+  }
+
+  *aFound = true;
+
+  ConstructorEnabled* checkEnabledForScope = entry->mEnabled;
+  // We do the enabled check on the current compartment of aCx, but for the
+  // actual object we pass in the underlying object in the Xray case.  That
+  // way the callee can decide whether to allow access based on the caller
+  // or the window being touched.
+  JS::Rooted<JSObject*> global(aCx,
+    js::CheckedUnwrap(aObj, /* stopAtWindowProxy = */ false));
+  if (!global) {
+    return Throw(aCx, NS_ERROR_DOM_SECURITY_ERR);
+  }
+
+  {
+    // It's safe to pass "&global" here, because we've already unwrapped it, but
+    // for general sanity better to not have debug code even having the
+    // appearance of mutating things that opt code uses.
+#ifdef DEBUG
+    JS::Rooted<JSObject*> temp(aCx, global);
+    DebugOnly<nsGlobalWindow*> win;
+    MOZ_ASSERT(NS_SUCCEEDED(UNWRAP_OBJECT(Window, &temp, win)));
+#endif
+  }
+
+  if (checkEnabledForScope && !checkEnabledForScope(aCx, global)) {
+    return true;
+  }
+
+  // The DOM constructor resolve machinery interacts with Xrays in tricky
+  // ways, and there are some asymmetries that are important to understand.
+  //
+  // In the regular (non-Xray) case, we only want to resolve constructors
+  // once (so that if they're deleted, they don't reappear). We do this by
+  // stashing the constructor in a slot on the global, such that we can see
+  // during resolve whether we've created it already. This is rather
+  // memory-intensive, so we don't try to maintain these semantics when
+  // manipulating a global over Xray (so the properties just re-resolve if
+  // they've been deleted).
+  //
+  // Unfortunately, there's a bit of an impedance-mismatch between the Xray
+  // and non-Xray machinery. The Xray machinery wants an API that returns a
+  // JS::PropertyDescriptor, so that the resolve hook doesn't have to get
+  // snared up with trying to define a property on the Xray holder. At the
+  // same time, the DefineInterface callbacks are set up to define things
+  // directly on the global.  And re-jiggering them to return property
+  // descriptors is tricky, because some DefineInterface callbacks define
+  // multiple things (like the Image() alias for HTMLImageElement).
+  //
+  // So the setup is as-follows:
+  //
+  // * The resolve function takes a JS::PropertyDescriptor, but in the
+  //   non-Xray case, callees may define things directly on the global, and
+  //   set the value on the property descriptor to |undefined| to indicate
+  //   that there's nothing more for the caller to do. We assert against
+  //   this behavior in the Xray case.
+  //
+  // * We make sure that we do a non-Xray resolve first, so that all the
+  //   slots are set up. In the Xray case, this means unwrapping and doing
+  //   a non-Xray resolve before doing the Xray resolve.
+  //
+  // This all could use some grand refactoring, but for now we just limp
+  // along.
+  if (xpc::WrapperFactory::IsXrayWrapper(aObj)) {
+    JS::Rooted<JSObject*> interfaceObject(aCx);
+    {
+      JSAutoCompartment ac(aCx, global);
+      interfaceObject = entry->mDefine(aCx, global, aId, false);
+    }
+    if (NS_WARN_IF(!interfaceObject)) {
+      return Throw(aCx, NS_ERROR_FAILURE);
+    }
+    if (!JS_WrapObject(aCx, &interfaceObject)) {
+      return Throw(aCx, NS_ERROR_FAILURE);
+    }
+
+    FillPropertyDescriptor(aDesc, aObj, 0, JS::ObjectValue(*interfaceObject));
+    return true;
+  }
+
+  JS::Rooted<JSObject*> interfaceObject(aCx,
+                                        entry->mDefine(aCx, aObj, aId, true));
+  if (NS_WARN_IF(!interfaceObject)) {
+    return Throw(aCx, NS_ERROR_FAILURE);
+  }
+
+  // We've already defined the property.  We indicate this to the caller
+  // by filling a property descriptor with JS::UndefinedValue() as the
+  // value.  We still have to fill in a property descriptor, though, so
+  // that the caller knows the property is in fact on this object.  It
+  // doesn't matter what we pass for the "readonly" argument here.
+  FillPropertyDescriptor(aDesc, aObj, JS::UndefinedValue(), false);
+
+  return true;
+}
+
+/* static */
+bool
+WebIDLGlobalNameHash::MayResolve(jsid aId)
+{
+  WebIDLNameTableKey key(JSID_TO_FLAT_STRING(aId));
+  // Rooting analysis thinks nsTHashtable<...>::Contains may GC because it ends
+  // up calling through PLDHashTableOps' matchEntry function pointer, but we
+  // know WebIDLNameTableEntry::KeyEquals can't cause a GC.
+  JS::AutoSuppressGCAnalysis suppress;
+  return sWebIDLGlobalNames->Contains(key);
+}
+
+/* static */
+void
+WebIDLGlobalNameHash::GetNames(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                               nsTArray<nsString>& aNames)
+{
+  for (auto iter = sWebIDLGlobalNames->Iter(); !iter.Done(); iter.Next()) {
+    const WebIDLNameTableEntry* entry = iter.Get();
+    if (!entry->mEnabled || entry->mEnabled(aCx, aObj)) {
+      AppendASCIItoUTF16(nsDependentCString(sNames + entry->mNameOffset,
+                                            entry->mNameLength),
+                         *aNames.AppendElement());
+    }
+  }
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/WebIDLGlobalNameHash.h b/dom/bindings/WebIDLGlobalNameHash.h
new file mode 100644
index 000000000..bbe015395
--- /dev/null
+++ b/dom/bindings/WebIDLGlobalNameHash.h
@@ -0,0 +1,70 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_WebIDLGlobalNameHash_h__
+#define mozilla_dom_WebIDLGlobalNameHash_h__
+
+#include "js/RootingAPI.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace dom {
+
+struct WebIDLNameTableEntry;
+
+class WebIDLGlobalNameHash
+{
+public:
+  static void Init();
+  static void Shutdown();
+
+  typedef JSObject*
+  (*DefineGlobalName)(JSContext* cx, JS::Handle<JSObject*> global,
+                      JS::Handle<jsid> id, bool defineOnGlobal);
+
+  // Check whether a constructor should be enabled for the given object.
+  // Note that the object should NOT be an Xray, since Xrays will end up
+  // defining constructors on the underlying object.
+  // This is a typedef for the function type itself, not the function
+  // pointer, so it's more obvious that pointers to a ConstructorEnabled
+  // can be null.
+  typedef bool
+  (ConstructorEnabled)(JSContext* cx, JS::Handle<JSObject*> obj);
+
+  static void Register(uint16_t aNameOffset, uint16_t aNameLength,
+                       DefineGlobalName aDefine, ConstructorEnabled* aEnabled);
+
+  static void Remove(const char* aName, uint32_t aLength);
+
+  // Returns false if something failed. aFound is set to true if the name is in
+  // the hash, whether it's enabled or not.
+  static bool DefineIfEnabled(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                              JS::Handle<jsid> aId,
+                              JS::MutableHandle<JS::PropertyDescriptor> aDesc,
+                              bool* aFound);
+
+  static bool MayResolve(jsid aId);
+
+  static void GetNames(JSContext* aCx, JS::Handle<JSObject*> aObj,
+                       nsTArray<nsString>& aNames);
+
+private:
+  friend struct WebIDLNameTableEntry;
+
+  // The total number of names that we will add to the hash.
+  // The value of sCount is generated by Codegen.py in RegisterBindings.cpp.
+  static const uint32_t sCount;
+
+  // The names that will be registered in the hash, concatenated as one big
+  // string with \0 as a separator between names.
+  // The value of sNames is generated by Codegen.py in RegisterBindings.cpp.
+  static const char sNames[];
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_WebIDLGlobalNameHash_h__
diff --git a/dom/bindings/XrayExpandoClass.h b/dom/bindings/XrayExpandoClass.h
new file mode 100644
index 000000000..af5c1e9ba
--- /dev/null
+++ b/dom/bindings/XrayExpandoClass.h
@@ -0,0 +1,41 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This file declares a macro for defining Xray expando classes and declares the
+ * default Xray expando class.  The actual definition of that default class
+ * lives elsewhere.
+ */
+#ifndef mozilla_dom_XrayExpandoClass_h
+#define mozilla_dom_XrayExpandoClass_h
+
+/*
+ * maybeStatic_ Should be either `static` or nothing (because some Xray expando
+ * classes are not static).
+ *
+ * name_ should be the name of the variable.
+ *
+ * extraSlots_ should be how many extra slots to give the class, in addition to
+ * the ones Xray expandos want.
+ */
+#define DEFINE_XRAY_EXPANDO_CLASS(maybeStatic_, name_, extraSlots_)	\
+  maybeStatic_ const JSClass name_ = {					\
+    "XrayExpandoObject",						\
+    JSCLASS_HAS_RESERVED_SLOTS(xpc::JSSLOT_EXPANDO_COUNT +		\
+			       (extraSlots_)) |				\
+    JSCLASS_FOREGROUND_FINALIZE,					\
+    &xpc::XrayExpandoObjectClassOps					\
+  }
+
+namespace mozilla {
+namespace dom {
+
+extern const JSClass DefaultXrayExpandoObjectClass;
+
+} // namespace mozilla
+} // namespace dom
+
+#endif /* mozilla_dom_XrayExpandoClass_h */
diff --git a/dom/bindings/crashtests/1010658-1.html b/dom/bindings/crashtests/1010658-1.html
new file mode 100644
index 000000000..af46069c7
--- /dev/null
+++ b/dom/bindings/crashtests/1010658-1.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>

+<html>

+<head>

+<script>

+function boom()

+{

+    window.__proto__ = null;

+    for (var i = 0; i < 10000; ++i) {

+        self.document;

+    }

+}

+

+</script></head>

+

+<body onload="boom();"></body>

+</html>

diff --git a/dom/bindings/crashtests/1010658-2.html b/dom/bindings/crashtests/1010658-2.html
new file mode 100644
index 000000000..4b80242ec
--- /dev/null
+++ b/dom/bindings/crashtests/1010658-2.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>

+<html>

+<head>

+<script>

+function boom()

+{

+    window.__proto__ = function(){};

+    for (var i = 0; i < 10000; ++i) {

+        self.document;

+    }

+}

+

+</script></head>

+

+<body onload="boom();"></body>

+</html>

diff --git a/dom/bindings/crashtests/769464.html b/dom/bindings/crashtests/769464.html
new file mode 100644
index 000000000..84d6dbc08
--- /dev/null
+++ b/dom/bindings/crashtests/769464.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<script>
+
+function boom()
+{
+    window.getComputedStyle(new Worker("404.js"));
+}
+
+window.addEventListener("load", boom, false);
+
+</script>
diff --git a/dom/bindings/crashtests/822340-1.html b/dom/bindings/crashtests/822340-1.html
new file mode 100644
index 000000000..4c8f6ae46
--- /dev/null
+++ b/dom/bindings/crashtests/822340-1.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<script>
+  var xhr = new XMLHttpRequest;
+  function f() {
+    var x = xhr.getResponseHeader;
+    x("abc");
+  }
+  for (var i = 0; i < 20000; ++i) {
+    try { f(); } catch (e) {}
+  }
+</script>
diff --git a/dom/bindings/crashtests/822340-2.html b/dom/bindings/crashtests/822340-2.html
new file mode 100644
index 000000000..e938c91aa
--- /dev/null
+++ b/dom/bindings/crashtests/822340-2.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<script>
+  var l = document.getElementsByTagName("*");
+  var count = 20000;
+  for (var i = 0; i < count; ++i) {
+    l.item(0);
+  }
+</script>
diff --git a/dom/bindings/crashtests/832899.html b/dom/bindings/crashtests/832899.html
new file mode 100644
index 000000000..c565ad00f
--- /dev/null
+++ b/dom/bindings/crashtests/832899.html
@@ -0,0 +1,5 @@
+<!DOCTYPE html>
+<script>
+  var ev = document.createEvent("Events");
+  EventTarget.prototype.dispatchEvent.call(navigator.connection, ev);
+</script>
diff --git a/dom/bindings/crashtests/860551.html b/dom/bindings/crashtests/860551.html
new file mode 100644
index 000000000..5008e5739
--- /dev/null
+++ b/dom/bindings/crashtests/860551.html
@@ -0,0 +1,4 @@
+<!DOCTYPE html>
+<script>
+SVGZoomAndPan instanceof SVGZoomAndPan
+</script>
diff --git a/dom/bindings/crashtests/860591.html b/dom/bindings/crashtests/860591.html
new file mode 100644
index 000000000..565a729c4
--- /dev/null
+++ b/dom/bindings/crashtests/860591.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html>
+<head>
+<script>
+    var timeEvent = document.createEvent('TimeEvent');
+    var mutationEvent = document.createEvent('MutationEvents');
+    mutationEvent.__proto__ = timeEvent;
+    mutationEvent.target;
+
+    var mouseScrollEvent = document.createEvent("MouseScrollEvents");
+    var mouseEvent = document.createEvent("MouseEvents");
+    mouseEvent.__proto__ = mouseScrollEvent;
+    mouseEvent.relatedTarget;
+
+    var uiEvent = document.createEvent("UIEvents");
+    uiEvent.__proto__ = mouseScrollEvent;
+    uiEvent.rangeParent;
+</script>
+</head>
+</html>
diff --git a/dom/bindings/crashtests/862092.html b/dom/bindings/crashtests/862092.html
new file mode 100644
index 000000000..1b31775a9
--- /dev/null
+++ b/dom/bindings/crashtests/862092.html
@@ -0,0 +1,19 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+
+function boom()
+{
+  var frameDoc = document.getElementById("f").contentDocument;
+  frameDoc.adoptNode(document.createElement("select"));
+}
+
+</script>
+</head>
+
+<body onload="boom();">
+<iframe id="f"></iframe>
+</body>
+</html>
diff --git a/dom/bindings/crashtests/862610.html b/dom/bindings/crashtests/862610.html
new file mode 100644
index 000000000..768871ad9
--- /dev/null
+++ b/dom/bindings/crashtests/862610.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+  HTMLElement.prototype.__proto__ = new Proxy({}, {});
+  try {
+    window.Image;
+  } finally {
+    // Restore our prototype so the test harnesses can deal with us
+    // We can't just assign to __proto__ because it lives on our proto chain
+    // and we messed that up.
+    var desc = Object.getOwnPropertyDescriptor(Object.prototype, "__proto__");
+    desc.set.call(HTMLElement.prototype, Element.prototype);
+  }
+</script>
+</head>
+
+<body></body>
+</html>
diff --git a/dom/bindings/crashtests/869038.html b/dom/bindings/crashtests/869038.html
new file mode 100644
index 000000000..dedb4dd4d
--- /dev/null
+++ b/dom/bindings/crashtests/869038.html
@@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+
+function boom()
+{
+  var frame = document.createElementNS("http://www.w3.org/1999/xhtml", "iframe");
+  document.body.appendChild(frame);
+  var frameDoc = frame.contentDocument;
+  frameDoc.contentEditable = "true";
+  document.body.removeChild(frame);
+  SpecialPowers.gc();
+  frameDoc.focus();
+}
+
+</script>
+</head>
+
+<body onload="boom();"></body>
+</html>
diff --git a/dom/bindings/crashtests/949940.html b/dom/bindings/crashtests/949940.html
new file mode 100644
index 000000000..7f20085fe
--- /dev/null
+++ b/dom/bindings/crashtests/949940.html
@@ -0,0 +1,16 @@
+<!DOCTYPE html>
+<html>
+<head>
+<meta charset="UTF-8">
+<script>
+function boom()
+{
+  var frameWin =  document.getElementById("f").contentWindow;
+  Object.create(frameWin).self;
+}
+</script>
+</head>
+<body onload="boom()">
+<iframe id="f" src="data:text/html,3"></iframe>
+</body>
+</html>
diff --git a/dom/bindings/crashtests/crashtests.list b/dom/bindings/crashtests/crashtests.list
new file mode 100644
index 000000000..3b517dd88
--- /dev/null
+++ b/dom/bindings/crashtests/crashtests.list
@@ -0,0 +1,12 @@
+skip load 769464.html # bug 823822 - assert often leaks into other tests
+load 822340-1.html
+load 822340-2.html
+load 832899.html
+load 860551.html
+load 860591.html
+load 862092.html
+load 862610.html
+load 869038.html
+load 949940.html
+load 1010658-1.html
+load 1010658-2.html
diff --git a/dom/bindings/docs/index.rst b/dom/bindings/docs/index.rst
new file mode 100644
index 000000000..f6fedbd16
--- /dev/null
+++ b/dom/bindings/docs/index.rst
@@ -0,0 +1,123 @@
+.. _webidl:
+
+======
+WebIDL
+======
+
+WebIDL describes interfaces web browsers are supposed to implement.
+
+The interaction between WebIDL and the build system is somewhat complex.
+This document will attempt to explain how it all works.
+
+Overview
+========
+
+``.webidl`` files throughout the tree define interfaces the browser
+implements. Since Gecko/Firefox is implemented in C++, there is a
+mechanism to convert these interfaces and associated metadata to
+C++ code. That's where the build system comes into play.
+
+All the code for interacting with ``.webidl`` files lives under
+``dom/bindings``. There is code in the build system to deal with
+WebIDLs explicitly.
+
+WebIDL source file flavors
+==========================
+
+Not all ``.webidl`` files are created equal! There are several flavors,
+each represented by a separate symbol from :ref:`mozbuild_symbols`.
+
+WEBIDL_FILES
+   Refers to regular/static ``.webidl`` files. Most WebIDL interfaces
+   are defined this way.
+
+GENERATED_EVENTS_WEBIDL_FILES
+   In addition to generating a binding, these ``.webidl`` files also
+   generate a source file implementing the event object in C++
+
+PREPROCESSED_WEBIDL_FILES
+   The ``.webidl`` files are generated by preprocessing an input file.
+   They otherwise behave like *WEBIDL_FILES*.
+
+TEST_WEBIDL_FILES
+   Like *WEBIDL_FILES* but the interfaces are for testing only and
+   aren't shipped with the browser.
+
+PREPROCESSED_TEST_WEBIDL_FILES
+   Like *TEST_WEBIDL_FILES* except the ``.webidl`` is obtained via
+   preprocessing, much like *PREPROCESSED_WEBIDL_FILES*.
+
+GENERATED_WEBIDL_FILES
+   The ``.webidl`` for these is obtained through an *external*
+   mechanism. Typically there are custom build rules for producing these
+   files.
+
+Producing C++ code
+==================
+
+The most complicated part about WebIDLs is the process by which
+``.webidl`` files are converted into C++.
+
+This process is handled by code in the :py:mod:`mozwebidlcodegen`
+package. :py:class:`mozwebidlcodegen.WebIDLCodegenManager` is
+specifically where you want to look for how code generation is
+performed. This includes complex dependency management.
+
+Requirements
+============
+
+This section aims to document the build and developer workflow requirements
+for WebIDL.
+
+Parser unit tests
+   There are parser tests provided by ``dom/bindings/parser/runtests.py``
+   that should run as part of ``make check``. There must be a mechanism
+   to run the tests in *human* mode so they output friendly error
+   messages.
+
+   The current mechanism for this is ``mach webidl-parser-test``.
+
+Mochitests
+   There are various mochitests under ``dom/bindings/test``. They should
+   be runnable through the standard mechanisms.
+
+Working with test interfaces
+   ``TestExampleGenBinding.cpp`` calls into methods from the
+   ``TestExampleInterface``, ``TestExampleProxyInterface``,
+   and ``TestExampleWorkerInterface`` interfaces.
+   These interfaces need to be generated as part of the build. These
+   interfaces should not be exported or packaged.
+
+   There is a ``compiletests`` make target in ``dom/bindings`` that
+   isn't part of the build that facilitates turnkey code generation
+   and test file compilation.
+
+Minimal rebuilds
+   Reprocessing every output for every change is expensive. So we don't
+   inconvenience people changing ``.webidl`` files, the build system
+   should only perform a minimal rebuild when sources change.
+
+   This logic is mostly all handled in
+   :py:class:`mozwebidlcodegen.WebIDLCodegenManager`. The unit tests for
+   that Python code should adequately test typical rebuild scenarios.
+
+   Bug 940469 tracks making the existing implementation better.
+
+Explicit method for performing codegen
+   There needs to be an explicit method for invoking code generation.
+   It needs to cover regular and test files.
+
+   This is implemented via ``make export`` in ``dom/bindings``.
+
+No-op binding generation should be fast
+   So developers touching ``.webidl`` files are not inconvenienced,
+   no-op binding generation should be fast. Watch out for the build system
+   processing large dependency files it doesn't need in order to perform
+   code generation.
+
+Ability to generate example files
+   *Any* interface can have example ``.h``/``.cpp`` files generated.
+   There must be a mechanism to facilitate this.
+
+   This is currently facilitated through ``mach webidl-example``. e.g.
+   ``mach webidl-example HTMLStyleElement``.
diff --git a/dom/bindings/mach_commands.py b/dom/bindings/mach_commands.py
new file mode 100644
index 000000000..eec68c907
--- /dev/null
+++ b/dom/bindings/mach_commands.py
@@ -0,0 +1,55 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, # You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import absolute_import, unicode_literals
+
+import os
+import sys
+
+from mach.decorators import (
+    CommandArgument,
+    CommandProvider,
+    Command,
+)
+
+from mozbuild.base import MachCommandBase
+
+def get_test_parser():
+    import runtests
+    return runtests.get_parser
+
+@CommandProvider
+class WebIDLProvider(MachCommandBase):
+    @Command('webidl-example', category='misc',
+             description='Generate example files for a WebIDL interface.')
+    @CommandArgument('interface', nargs='+',
+                     help='Interface(s) whose examples to generate.')
+    def webidl_example(self, interface):
+        from mozwebidlcodegen import BuildSystemWebIDL
+
+        manager = self._spawn(BuildSystemWebIDL).manager
+        for i in interface:
+            manager.generate_example_files(i)
+
+    @Command('webidl-parser-test', category='testing', parser=get_test_parser,
+             description='Run WebIDL tests (Interface Browser parser).')
+    def webidl_test(self, **kwargs):
+        sys.path.insert(0, os.path.join(self.topsrcdir, 'other-licenses',
+                        'ply'))
+
+        # Make sure we drop our cached grammar bits in the objdir, not
+        # wherever we happen to be running from.
+        os.chdir(self.topobjdir)
+
+        if kwargs["verbose"] is None:
+            kwargs["verbose"] = False
+
+        # Now we're going to create the cached grammar file in the
+        # objdir.  But we're going to try loading it as a python
+        # module, so we need to make sure the objdir is in our search
+        # path.
+        sys.path.insert(0, self.topobjdir)
+
+        import runtests
+        return runtests.run_tests(kwargs["tests"], verbose=kwargs["verbose"])
diff --git a/dom/bindings/moz.build b/dom/bindings/moz.build
new file mode 100644
index 000000000..fadaac69b
--- /dev/null
+++ b/dom/bindings/moz.build
@@ -0,0 +1,161 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+TEST_DIRS += ['test']
+
+EXPORTS.ipc += [
+    'ErrorIPCUtils.h',
+]
+
+EXPORTS.mozilla += [
+    'ErrorResult.h',
+    'RootedOwningNonNull.h',
+    'RootedRefPtr.h',
+]
+
+EXPORTS.mozilla.dom += [
+    'AtomList.h',
+    'BindingDeclarations.h',
+    'BindingUtils.h',
+    'CallbackFunction.h',
+    'CallbackInterface.h',
+    'CallbackObject.h',
+    'Date.h',
+    'DOMJSClass.h',
+    'DOMJSProxyHandler.h',
+    'DOMString.h',
+    'Errors.msg',
+    'Exceptions.h',
+    'FakeString.h',
+    'IterableIterator.h',
+    'JSSlots.h',
+    'MozMap.h',
+    'NonRefcountedDOMObject.h',
+    'Nullable.h',
+    'PrimitiveConversions.h',
+    'RootedDictionary.h',
+    'SimpleGlobalObject.h',
+    'StructuredClone.h',
+    'ToJSValue.h',
+    'TypedArray.h',
+    'UnionMember.h',
+    'WebIDLGlobalNameHash.h',
+    'XrayExpandoClass.h',
+]
+
+# Generated bindings reference *Binding.h, not mozilla/dom/*Binding.h. And,
+# since we generate exported bindings directly to $(DIST)/include, we need
+# to add that path to the search list.
+#
+# Ideally, binding generation uses the prefixed header file names.
+# Bug 932082 tracks.
+LOCAL_INCLUDES += [
+    '!/dist/include/mozilla/dom',
+]
+
+LOCAL_INCLUDES += [
+    '/dom/base',
+    '/dom/battery',
+    '/dom/canvas',
+    '/dom/geolocation',
+    '/dom/html',
+    '/dom/indexedDB',
+    '/dom/media/webaudio',
+    '/dom/media/webspeech/recognition',
+    '/dom/svg',
+    '/dom/workers',
+    '/dom/xbl',
+    '/dom/xml',
+    '/dom/xslt/base',
+    '/dom/xslt/xpath',
+    '/dom/xul',
+    '/js/xpconnect/src',
+    '/js/xpconnect/wrappers',
+    '/layout/generic',
+    '/layout/style',
+    '/layout/xul/tree',
+    '/media/mtransport',
+    '/media/webrtc/',
+    '/media/webrtc/signaling/src/common/time_profiling',
+    '/media/webrtc/signaling/src/peerconnection',
+]
+
+UNIFIED_SOURCES += [
+    'BindingUtils.cpp',
+    'CallbackInterface.cpp',
+    'CallbackObject.cpp',
+    'Date.cpp',
+    'DOMJSProxyHandler.cpp',
+    'Exceptions.cpp',
+    'IterableIterator.cpp',
+    'SimpleGlobalObject.cpp',
+    'ToJSValue.cpp',
+    'WebIDLGlobalNameHash.cpp',
+]
+
+SOURCES += [
+    'StructuredClone.cpp',
+]
+
+# Tests for maplike and setlike require bindings to be built, which means they
+# must be included in libxul. This breaks the "no test classes are exported"
+# rule stated in the test/ directory, but it's the only way this will work.
+# Test classes are only built in debug mode, and all tests requiring use of
+# them are only run in debug mode.
+if CONFIG['MOZ_DEBUG']:
+    EXPORTS.mozilla.dom += [
+        "test/TestFunctions.h",
+        "test/TestInterfaceIterableDouble.h",
+        "test/TestInterfaceIterableDoubleUnion.h",
+        "test/TestInterfaceIterableSingle.h",
+        "test/TestInterfaceMaplike.h",
+        "test/TestInterfaceMaplikeObject.h",
+        "test/TestInterfaceSetlike.h",
+        "test/TestInterfaceSetlikeNode.h"
+        ]
+    UNIFIED_SOURCES += [
+        "test/TestFunctions.cpp",
+        "test/TestInterfaceIterableDouble.cpp",
+        "test/TestInterfaceIterableDoubleUnion.cpp",
+        "test/TestInterfaceIterableSingle.cpp",
+        "test/TestInterfaceMaplike.cpp",
+        "test/TestInterfaceMaplikeObject.cpp",
+        "test/TestInterfaceSetlike.cpp",
+        "test/TestInterfaceSetlikeNode.cpp",
+        ]
+
+include('/ipc/chromium/chromium-config.mozbuild')
+
+if CONFIG['MOZ_AUDIO_CHANNEL_MANAGER']:
+    LOCAL_INCLUDES += [
+        '/dom/system/gonk',
+    ]
+
+FINAL_LIBRARY = 'xul'
+
+SPHINX_TREES['webidl'] = 'docs'
+SPHINX_PYTHON_PACKAGE_DIRS += ['mozwebidlcodegen']
+
+if CONFIG['MOZ_BUILD_APP'] in ['browser', 'mobile/android', 'xulrunner']:
+    # This is needed for Window.webidl
+    DEFINES['HAVE_SIDEBAR'] = True
+
+
+PYTHON_UNIT_TESTS += [
+    'mozwebidlcodegen/test/test_mozwebidlcodegen.py',
+]
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
+
+if CONFIG['COMPILE_ENVIRONMENT']:
+    GENERATED_FILES += ['CSS2Properties.webidl']
+    css_props = GENERATED_FILES['CSS2Properties.webidl']
+    css_props.script = 'GenerateCSS2PropertiesWebIDL.py:generate'
+    css_props.inputs = [
+        '/dom/webidl/CSS2Properties.webidl.in',
+        '/layout/style/PythonCSSProps.h',
+    ]
diff --git a/dom/bindings/mozwebidlcodegen/__init__.py b/dom/bindings/mozwebidlcodegen/__init__.py
new file mode 100644
index 000000000..b6e351e52
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/__init__.py
@@ -0,0 +1,583 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+# This module contains code for managing WebIDL files and bindings for
+# the build system.
+
+from __future__ import unicode_literals
+
+import errno
+import hashlib
+import json
+import logging
+import os
+
+from copy import deepcopy
+
+from mach.mixin.logging import LoggingMixin
+
+from mozbuild.base import MozbuildObject
+from mozbuild.makeutil import Makefile
+from mozbuild.pythonutil import iter_modules_in_path
+from mozbuild.util import FileAvoidWrite
+
+import mozpack.path as mozpath
+
+# There are various imports in this file in functions to avoid adding
+# dependencies to config.status. See bug 949875.
+
+
+class BuildResult(object):
+    """Represents the result of processing WebIDL files.
+
+    This holds a summary of output file generation during code generation.
+    """
+
+    def __init__(self):
+        # The .webidl files that had their outputs regenerated.
+        self.inputs = set()
+
+        # The output files that were created.
+        self.created = set()
+
+        # The output files that changed.
+        self.updated = set()
+
+        # The output files that didn't change.
+        self.unchanged = set()
+
+
+class WebIDLCodegenManagerState(dict):
+    """Holds state for the WebIDL code generation manager.
+
+    State is currently just an extended dict. The internal implementation of
+    state should be considered a black box to everyone except
+    WebIDLCodegenManager. But we'll still document it.
+
+    Fields:
+
+    version
+       The integer version of the format. This is to detect incompatible
+       changes between state. It should be bumped whenever the format
+       changes or semantics change.
+
+    webidls
+       A dictionary holding information about every known WebIDL input.
+       Keys are the basenames of input WebIDL files. Values are dicts of
+       metadata. Keys in those dicts are:
+
+       * filename - The full path to the input filename.
+       * inputs - A set of full paths to other webidl files this webidl
+         depends on.
+       * outputs - Set of full output paths that are created/derived from
+         this file.
+       * sha1 - The hexidecimal SHA-1 of the input filename from the last
+         processing time.
+
+    global_inputs
+       A dictionary defining files that influence all processing. Keys
+       are full filenames. Values are hexidecimal SHA-1 from the last
+       processing time.
+    """
+
+    VERSION = 1
+
+    def __init__(self, fh=None):
+        self['version'] = self.VERSION
+        self['webidls'] = {}
+        self['global_depends'] = {}
+
+        if not fh:
+            return
+
+        state = json.load(fh)
+        if state['version'] != self.VERSION:
+            raise Exception('Unknown state version: %s' % state['version'])
+
+        self['version'] = state['version']
+        self['global_depends'] = state['global_depends']
+
+        for k, v in state['webidls'].items():
+            self['webidls'][k] = v
+
+            # Sets are converted to lists for serialization because JSON
+            # doesn't support sets.
+            self['webidls'][k]['inputs'] = set(v['inputs'])
+            self['webidls'][k]['outputs'] = set(v['outputs'])
+
+    def dump(self, fh):
+        """Dump serialized state to a file handle."""
+        normalized = deepcopy(self)
+
+        for k, v in self['webidls'].items():
+            # Convert sets to lists because JSON doesn't support sets.
+            normalized['webidls'][k]['outputs'] = sorted(v['outputs'])
+            normalized['webidls'][k]['inputs'] = sorted(v['inputs'])
+
+        json.dump(normalized, fh, sort_keys=True)
+
+
+class WebIDLCodegenManager(LoggingMixin):
+    """Manages all code generation around WebIDL.
+
+    To facilitate testing, this object is meant to be generic and reusable.
+    Paths, etc should be parameters and not hardcoded.
+    """
+
+    # Global parser derived declaration files.
+    GLOBAL_DECLARE_FILES = {
+        'GeneratedAtomList.h',
+        'GeneratedEventList.h',
+        'PrototypeList.h',
+        'RegisterBindings.h',
+        'RegisterWorkerBindings.h',
+        'RegisterWorkerDebuggerBindings.h',
+        'RegisterWorkletBindings.h',
+        'ResolveSystemBinding.h',
+        'UnionConversions.h',
+        'UnionTypes.h',
+    }
+
+    # Global parser derived definition files.
+    GLOBAL_DEFINE_FILES = {
+        'RegisterBindings.cpp',
+        'RegisterWorkerBindings.cpp',
+        'RegisterWorkerDebuggerBindings.cpp',
+        'RegisterWorkletBindings.cpp',
+        'ResolveSystemBinding.cpp',
+        'UnionTypes.cpp',
+        'PrototypeList.cpp',
+    }
+
+    def __init__(self, config_path, inputs, exported_header_dir,
+                 codegen_dir, state_path, cache_dir=None, make_deps_path=None,
+                 make_deps_target=None):
+        """Create an instance that manages WebIDLs in the build system.
+
+        config_path refers to a WebIDL config file (e.g. Bindings.conf).
+        inputs is a 4-tuple describing the input .webidl files and how to
+        process them. Members are:
+            (set(.webidl files), set(basenames of exported files),
+                set(basenames of generated events files),
+                set(example interface names))
+
+        exported_header_dir and codegen_dir are directories where generated
+        files will be written to.
+        state_path is the path to a file that will receive JSON state from our
+        actions.
+        make_deps_path is the path to a make dependency file that we can
+        optionally write.
+        make_deps_target is the target that receives the make dependencies. It
+        must be defined if using make_deps_path.
+        """
+        self.populate_logger()
+
+        input_paths, exported_stems, generated_events_stems, example_interfaces = inputs
+
+        self._config_path = config_path
+        self._input_paths = set(input_paths)
+        self._exported_stems = set(exported_stems)
+        self._generated_events_stems = set(generated_events_stems)
+        self._generated_events_stems_as_array = generated_events_stems
+        self._example_interfaces = set(example_interfaces)
+        self._exported_header_dir = exported_header_dir
+        self._codegen_dir = codegen_dir
+        self._state_path = state_path
+        self._cache_dir = cache_dir
+        self._make_deps_path = make_deps_path
+        self._make_deps_target = make_deps_target
+
+        if ((make_deps_path and not make_deps_target) or
+                (not make_deps_path and make_deps_target)):
+            raise Exception('Must define both make_deps_path and make_deps_target '
+                            'if one is defined.')
+
+        self._parser_results = None
+        self._config = None
+        self._state = WebIDLCodegenManagerState()
+
+        if os.path.exists(state_path):
+            with open(state_path, 'rb') as fh:
+                try:
+                    self._state = WebIDLCodegenManagerState(fh=fh)
+                except Exception as e:
+                    self.log(logging.WARN, 'webidl_bad_state', {'msg': str(e)},
+                                           'Bad WebIDL state: {msg}')
+
+    @property
+    def config(self):
+        if not self._config:
+            self._parse_webidl()
+
+        return self._config
+
+    def generate_build_files(self):
+        """Generate files required for the build.
+
+        This function is in charge of generating all the .h/.cpp files derived
+        from input .webidl files. Please note that there are build actions
+        required to produce .webidl files and these build actions are
+        explicitly not captured here: this function assumes all .webidl files
+        are present and up to date.
+
+        This routine is called as part of the build to ensure files that need
+        to exist are present and up to date. This routine may not be called if
+        the build dependencies (generated as a result of calling this the first
+        time) say everything is up to date.
+
+        Because reprocessing outputs for every .webidl on every invocation
+        is expensive, we only regenerate the minimal set of files on every
+        invocation. The rules for deciding what needs done are roughly as
+        follows:
+
+        1. If any .webidl changes, reparse all .webidl files and regenerate
+           the global derived files. Only regenerate output files (.h/.cpp)
+           impacted by the modified .webidl files.
+        2. If an non-.webidl dependency (Python files, config file) changes,
+           assume everything is out of date and regenerate the world. This
+           is because changes in those could globally impact every output
+           file.
+        3. If an output file is missing, ensure it is present by performing
+           necessary regeneration.
+        """
+        # Despite #1 above, we assume the build system is smart enough to not
+        # invoke us if nothing has changed. Therefore, any invocation means
+        # something has changed. And, if anything has changed, we need to
+        # parse the WebIDL.
+        self._parse_webidl()
+
+        result = BuildResult()
+
+        # If we parse, we always update globals - they are cheap and it is
+        # easier that way.
+        created, updated, unchanged = self._write_global_derived()
+        result.created |= created
+        result.updated |= updated
+        result.unchanged |= unchanged
+
+        # If any of the extra dependencies changed, regenerate the world.
+        global_changed, global_hashes = self._global_dependencies_changed()
+        if global_changed:
+            # Make a copy because we may modify.
+            changed_inputs = set(self._input_paths)
+        else:
+            changed_inputs = self._compute_changed_inputs()
+
+        self._state['global_depends'] = global_hashes
+
+        # Generate bindings from .webidl files.
+        for filename in sorted(changed_inputs):
+            basename = mozpath.basename(filename)
+            result.inputs.add(filename)
+            written, deps = self._generate_build_files_for_webidl(filename)
+            result.created |= written[0]
+            result.updated |= written[1]
+            result.unchanged |= written[2]
+
+            self._state['webidls'][basename] = dict(
+                filename=filename,
+                outputs=written[0] | written[1] | written[2],
+                inputs=set(deps),
+                sha1=self._input_hashes[filename],
+            )
+
+        # Process some special interfaces required for testing.
+        for interface in self._example_interfaces:
+            written = self.generate_example_files(interface)
+            result.created |= written[0]
+            result.updated |= written[1]
+            result.unchanged |= written[2]
+
+        # Generate a make dependency file.
+        if self._make_deps_path:
+            mk = Makefile()
+            codegen_rule = mk.create_rule([self._make_deps_target])
+            codegen_rule.add_dependencies(global_hashes.keys())
+            codegen_rule.add_dependencies(self._input_paths)
+
+            with FileAvoidWrite(self._make_deps_path) as fh:
+                mk.dump(fh)
+
+        self._save_state()
+
+        return result
+
+    def generate_example_files(self, interface):
+        """Generates example files for a given interface."""
+        from Codegen import CGExampleRoot
+
+        root = CGExampleRoot(self.config, interface)
+
+        example_paths = self._example_paths(interface)
+        for path in example_paths:
+            print "Generating %s" % path
+
+        return self._maybe_write_codegen(root, *example_paths)
+
+    def _parse_webidl(self):
+        import WebIDL
+        from Configuration import Configuration
+
+        self.log(logging.INFO, 'webidl_parse',
+                 {'count': len(self._input_paths)},
+                 'Parsing {count} WebIDL files.')
+
+        hashes = {}
+        parser = WebIDL.Parser(self._cache_dir)
+
+        for path in sorted(self._input_paths):
+            with open(path, 'rb') as fh:
+                data = fh.read()
+                hashes[path] = hashlib.sha1(data).hexdigest()
+                parser.parse(data, path)
+
+        self._parser_results = parser.finish()
+        self._config = Configuration(self._config_path, self._parser_results,
+                                     self._generated_events_stems_as_array)
+        self._input_hashes = hashes
+
+    def _write_global_derived(self):
+        from Codegen import GlobalGenRoots
+
+        things = [('declare', f) for f in self.GLOBAL_DECLARE_FILES]
+        things.extend(('define', f) for f in self.GLOBAL_DEFINE_FILES)
+
+        result = (set(), set(), set())
+
+        for what, filename in things:
+            stem = mozpath.splitext(filename)[0]
+            root = getattr(GlobalGenRoots, stem)(self._config)
+
+            if what == 'declare':
+                code = root.declare()
+                output_root = self._exported_header_dir
+            elif what == 'define':
+                code = root.define()
+                output_root = self._codegen_dir
+            else:
+                raise Exception('Unknown global gen type: %s' % what)
+
+            output_path = mozpath.join(output_root, filename)
+            self._maybe_write_file(output_path, code, result)
+
+        return result
+
+    def _compute_changed_inputs(self):
+        """Compute the set of input files that need to be regenerated."""
+        changed_inputs = set()
+        expected_outputs = self.expected_build_output_files()
+
+        # Look for missing output files.
+        if any(not os.path.exists(f) for f in expected_outputs):
+            # FUTURE Bug 940469 Only regenerate minimum set.
+            changed_inputs |= self._input_paths
+
+        # That's it for examining output files. We /could/ examine SHA-1's of
+        # output files from a previous run to detect modifications. But that's
+        # a lot of extra work and most build systems don't do that anyway.
+
+        # Now we move on to the input files.
+        old_hashes = {v['filename']: v['sha1']
+                      for v in self._state['webidls'].values()}
+
+        old_filenames = set(old_hashes.keys())
+        new_filenames = self._input_paths
+
+        # If an old file has disappeared or a new file has arrived, mark
+        # it.
+        changed_inputs |= old_filenames ^ new_filenames
+
+        # For the files in common between runs, compare content. If the file
+        # has changed, mark it. We don't need to perform mtime comparisons
+        # because content is a stronger validator.
+        for filename in old_filenames & new_filenames:
+            if old_hashes[filename] != self._input_hashes[filename]:
+                changed_inputs.add(filename)
+
+        # We've now populated the base set of inputs that have changed.
+
+        # Inherit dependencies from previous run. The full set of dependencies
+        # is associated with each record, so we don't need to perform any fancy
+        # graph traversal.
+        for v in self._state['webidls'].values():
+            if any(dep for dep in v['inputs'] if dep in changed_inputs):
+                changed_inputs.add(v['filename'])
+
+        # Only use paths that are known to our current state.
+        # This filters out files that were deleted or changed type (e.g. from
+        # static to preprocessed).
+        return changed_inputs & self._input_paths
+
+    def _binding_info(self, p):
+        """Compute binding metadata for an input path.
+
+        Returns a tuple of:
+
+          (stem, binding_stem, is_event, output_files)
+
+        output_files is itself a tuple. The first two items are the binding
+        header and C++ paths, respectively. The 2nd pair are the event header
+        and C++ paths or None if this isn't an event binding.
+        """
+        basename = mozpath.basename(p)
+        stem = mozpath.splitext(basename)[0]
+        binding_stem = '%sBinding' % stem
+
+        if stem in self._exported_stems:
+            header_dir = self._exported_header_dir
+        else:
+            header_dir = self._codegen_dir
+
+        is_event = stem in self._generated_events_stems
+
+        files = (
+            mozpath.join(header_dir, '%s.h' % binding_stem),
+            mozpath.join(self._codegen_dir, '%s.cpp' % binding_stem),
+            mozpath.join(header_dir, '%s.h' % stem) if is_event else None,
+            mozpath.join(self._codegen_dir, '%s.cpp' % stem) if is_event else None,
+        )
+
+        return stem, binding_stem, is_event, header_dir, files
+
+    def _example_paths(self, interface):
+        return (
+            mozpath.join(self._codegen_dir, '%s-example.h' % interface),
+            mozpath.join(self._codegen_dir, '%s-example.cpp' % interface))
+
+    def expected_build_output_files(self):
+        """Obtain the set of files generate_build_files() should write."""
+        paths = set()
+
+        # Account for global generation.
+        for p in self.GLOBAL_DECLARE_FILES:
+            paths.add(mozpath.join(self._exported_header_dir, p))
+        for p in self.GLOBAL_DEFINE_FILES:
+            paths.add(mozpath.join(self._codegen_dir, p))
+
+        for p in self._input_paths:
+            stem, binding_stem, is_event, header_dir, files = self._binding_info(p)
+            paths |= {f for f in files if f}
+
+        for interface in self._example_interfaces:
+            for p in self._example_paths(interface):
+                paths.add(p)
+
+        return paths
+
+    def _generate_build_files_for_webidl(self, filename):
+        from Codegen import (
+            CGBindingRoot,
+            CGEventRoot,
+        )
+
+        self.log(logging.INFO, 'webidl_generate_build_for_input',
+                 {'filename': filename},
+                 'Generating WebIDL files derived from {filename}')
+
+        stem, binding_stem, is_event, header_dir, files = self._binding_info(filename)
+        root = CGBindingRoot(self._config, binding_stem, filename)
+
+        result = self._maybe_write_codegen(root, files[0], files[1])
+
+        if is_event:
+            generated_event = CGEventRoot(self._config, stem)
+            result = self._maybe_write_codegen(generated_event, files[2],
+                                               files[3], result)
+
+        return result, root.deps()
+
+    def _global_dependencies_changed(self):
+        """Determine whether the global dependencies have changed."""
+        current_files = set(iter_modules_in_path(mozpath.dirname(__file__)))
+
+        # We need to catch other .py files from /dom/bindings. We assume these
+        # are in the same directory as the config file.
+        current_files |= set(iter_modules_in_path(mozpath.dirname(self._config_path)))
+
+        current_files.add(self._config_path)
+
+        current_hashes = {}
+        for f in current_files:
+            # This will fail if the file doesn't exist. If a current global
+            # dependency doesn't exist, something else is wrong.
+            with open(f, 'rb') as fh:
+                current_hashes[f] = hashlib.sha1(fh.read()).hexdigest()
+
+        # The set of files has changed.
+        if current_files ^ set(self._state['global_depends'].keys()):
+            return True, current_hashes
+
+        # Compare hashes.
+        for f, sha1 in current_hashes.items():
+            if sha1 != self._state['global_depends'][f]:
+                return True, current_hashes
+
+        return False, current_hashes
+
+    def _save_state(self):
+        with open(self._state_path, 'wb') as fh:
+            self._state.dump(fh)
+
+    def _maybe_write_codegen(self, obj, declare_path, define_path, result=None):
+        assert declare_path and define_path
+        if not result:
+            result = (set(), set(), set())
+
+        self._maybe_write_file(declare_path, obj.declare(), result)
+        self._maybe_write_file(define_path, obj.define(), result)
+
+        return result
+
+    def _maybe_write_file(self, path, content, result):
+        fh = FileAvoidWrite(path)
+        fh.write(content)
+        existed, updated = fh.close()
+
+        if not existed:
+            result[0].add(path)
+        elif updated:
+            result[1].add(path)
+        else:
+            result[2].add(path)
+
+
+def create_build_system_manager(topsrcdir, topobjdir, dist_dir):
+    """Create a WebIDLCodegenManager for use by the build system."""
+    src_dir = os.path.join(topsrcdir, 'dom', 'bindings')
+    obj_dir = os.path.join(topobjdir, 'dom', 'bindings')
+
+    with open(os.path.join(obj_dir, 'file-lists.json'), 'rb') as fh:
+        files = json.load(fh)
+
+    inputs = (files['webidls'], files['exported_stems'],
+              files['generated_events_stems'], files['example_interfaces'])
+
+    cache_dir = os.path.join(obj_dir, '_cache')
+    try:
+        os.makedirs(cache_dir)
+    except OSError as e:
+        if e.errno != errno.EEXIST:
+            raise
+
+    return WebIDLCodegenManager(
+        os.path.join(src_dir, 'Bindings.conf'),
+        inputs,
+        os.path.join(dist_dir, 'include', 'mozilla', 'dom'),
+        obj_dir,
+        os.path.join(obj_dir, 'codegen.json'),
+        cache_dir=cache_dir,
+        # The make rules include a codegen.pp file containing dependencies.
+        make_deps_path=os.path.join(obj_dir, 'codegen.pp'),
+        make_deps_target='codegen.pp',
+    )
+
+
+class BuildSystemWebIDL(MozbuildObject):
+    @property
+    def manager(self):
+        if not hasattr(self, '_webidl_manager'):
+            self._webidl_manager = create_build_system_manager(
+                self.topsrcdir, self.topobjdir, self.distdir)
+
+        return self._webidl_manager
diff --git a/dom/bindings/mozwebidlcodegen/test/Child.webidl b/dom/bindings/mozwebidlcodegen/test/Child.webidl
new file mode 100644
index 000000000..f7d0a76c9
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/test/Child.webidl
@@ -0,0 +1,3 @@
+interface Child : Parent {
+  void ChildBaz();
+};
diff --git a/dom/bindings/mozwebidlcodegen/test/ExampleBinding.webidl b/dom/bindings/mozwebidlcodegen/test/ExampleBinding.webidl
new file mode 100644
index 000000000..34794993f
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/test/ExampleBinding.webidl
@@ -0,0 +1,3 @@
+/* These interfaces are hard-coded and need to be defined. */
+interface TestExampleInterface {};
+interface TestExampleProxyInterface {};
diff --git a/dom/bindings/mozwebidlcodegen/test/Parent.webidl b/dom/bindings/mozwebidlcodegen/test/Parent.webidl
new file mode 100644
index 000000000..423f364ae
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/test/Parent.webidl
@@ -0,0 +1,3 @@
+interface Parent {
+  void MethodFoo();
+};
diff --git a/dom/bindings/mozwebidlcodegen/test/TestEvent.webidl b/dom/bindings/mozwebidlcodegen/test/TestEvent.webidl
new file mode 100644
index 000000000..db0856291
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/test/TestEvent.webidl
@@ -0,0 +1,13 @@
+interface EventTarget {
+  void addEventListener();
+};
+
+interface Event {};
+
+callback EventHandlerNonNull = any (Event event);
+typedef EventHandlerNonNull? EventHandler;
+
+[NoInterfaceObject]
+interface TestEvent : EventTarget {
+  attribute EventHandler onfoo;
+};
diff --git a/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py b/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py
new file mode 100644
index 000000000..ce3315e88
--- /dev/null
+++ b/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py
@@ -0,0 +1,298 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+from __future__ import unicode_literals
+
+import imp
+import json
+import os
+import shutil
+import sys
+import tempfile
+import unittest
+
+import mozpack.path as mozpath
+
+from mozwebidlcodegen import (
+    WebIDLCodegenManager,
+    WebIDLCodegenManagerState,
+)
+
+from mozfile import NamedTemporaryFile
+
+from mozunit import (
+    MockedOpen,
+    main,
+)
+
+
+OUR_DIR = mozpath.abspath(mozpath.dirname(__file__))
+TOPSRCDIR = mozpath.normpath(mozpath.join(OUR_DIR, '..', '..', '..', '..'))
+
+
+class TestWebIDLCodegenManager(unittest.TestCase):
+    TEST_STEMS = {
+        'Child',
+        'Parent',
+        'ExampleBinding',
+        'TestEvent',
+    }
+
+    @property
+    def _static_input_paths(self):
+        s = {mozpath.join(OUR_DIR, p) for p in os.listdir(OUR_DIR)
+             if p.endswith('.webidl')}
+
+        return s
+
+    @property
+    def _config_path(self):
+        config = mozpath.join(TOPSRCDIR, 'dom', 'bindings', 'Bindings.conf')
+        self.assertTrue(os.path.exists(config))
+
+        return config
+
+    def _get_manager_args(self):
+        tmp = tempfile.mkdtemp()
+        self.addCleanup(shutil.rmtree, tmp)
+
+        cache_dir = mozpath.join(tmp, 'cache')
+        os.mkdir(cache_dir)
+
+        ip = self._static_input_paths
+
+        inputs = (
+            ip,
+            {mozpath.splitext(mozpath.basename(p))[0] for p in ip},
+            set(),
+            set(),
+        )
+
+        return dict(
+            config_path=self._config_path,
+            inputs=inputs,
+            exported_header_dir=mozpath.join(tmp, 'exports'),
+            codegen_dir=mozpath.join(tmp, 'codegen'),
+            state_path=mozpath.join(tmp, 'state.json'),
+            make_deps_path=mozpath.join(tmp, 'codegen.pp'),
+            make_deps_target='codegen.pp',
+            cache_dir=cache_dir,
+        )
+
+    def _get_manager(self):
+        return WebIDLCodegenManager(**self._get_manager_args())
+
+    def test_unknown_state_version(self):
+        """Loading a state file with a too new version resets state."""
+        args = self._get_manager_args()
+
+        p = args['state_path']
+
+        with open(p, 'wb') as fh:
+            json.dump({
+                'version': WebIDLCodegenManagerState.VERSION + 1,
+                'foobar': '1',
+            }, fh)
+
+        manager = WebIDLCodegenManager(**args)
+
+        self.assertEqual(manager._state['version'],
+                         WebIDLCodegenManagerState.VERSION)
+        self.assertNotIn('foobar', manager._state)
+
+    def test_generate_build_files(self):
+        """generate_build_files() does the right thing from empty."""
+        manager = self._get_manager()
+        result = manager.generate_build_files()
+        self.assertEqual(len(result.inputs), 4)
+
+        output = manager.expected_build_output_files()
+        self.assertEqual(result.created, output)
+        self.assertEqual(len(result.updated), 0)
+        self.assertEqual(len(result.unchanged), 0)
+
+        for f in output:
+            self.assertTrue(os.path.isfile(f))
+
+        for f in manager.GLOBAL_DECLARE_FILES:
+            self.assertIn(mozpath.join(manager._exported_header_dir, f), output)
+
+        for f in manager.GLOBAL_DEFINE_FILES:
+            self.assertIn(mozpath.join(manager._codegen_dir, f), output)
+
+        for s in self.TEST_STEMS:
+            self.assertTrue(os.path.isfile(mozpath.join(
+                manager._exported_header_dir, '%sBinding.h' % s)))
+            self.assertTrue(os.path.isfile(mozpath.join(
+                manager._codegen_dir, '%sBinding.cpp' % s)))
+
+        self.assertTrue(os.path.isfile(manager._state_path))
+
+        with open(manager._state_path, 'rb') as fh:
+            state = json.load(fh)
+            self.assertEqual(state['version'], 1)
+            self.assertIn('webidls', state)
+
+            child = state['webidls']['Child.webidl']
+            self.assertEqual(len(child['inputs']), 2)
+            self.assertEqual(len(child['outputs']), 2)
+            self.assertEqual(child['sha1'], 'c41527cad3bc161fa6e7909e48fa11f9eca0468b')
+
+    def test_generate_build_files_load_state(self):
+        """State should be equivalent when instantiating a new instance."""
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        self.assertEqual(len(m1._state['webidls']), 0)
+        m1.generate_build_files()
+
+        m2 = WebIDLCodegenManager(**args)
+        self.assertGreater(len(m2._state['webidls']), 2)
+        self.assertEqual(m1._state, m2._state)
+
+    def test_no_change_no_writes(self):
+        """If nothing changes, no files should be updated."""
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        m1.generate_build_files()
+
+        m2 = WebIDLCodegenManager(**args)
+        result = m2.generate_build_files()
+
+        self.assertEqual(len(result.inputs), 0)
+        self.assertEqual(len(result.created), 0)
+        self.assertEqual(len(result.updated), 0)
+
+    def test_output_file_regenerated(self):
+        """If an output file disappears, it is regenerated."""
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        m1.generate_build_files()
+
+        rm_count = 0
+        for p in m1._state['webidls']['Child.webidl']['outputs']:
+            rm_count += 1
+            os.unlink(p)
+
+        for p in m1.GLOBAL_DECLARE_FILES:
+            rm_count += 1
+            os.unlink(mozpath.join(m1._exported_header_dir, p))
+
+        m2 = WebIDLCodegenManager(**args)
+        result = m2.generate_build_files()
+        self.assertEqual(len(result.created), rm_count)
+
+    def test_only_rebuild_self(self):
+        """If an input file changes, only rebuild that one file."""
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        m1.generate_build_files()
+
+        child_path = None
+        for p in m1._input_paths:
+            if p.endswith('Child.webidl'):
+                child_path = p
+                break
+
+        self.assertIsNotNone(child_path)
+        child_content = open(child_path, 'rb').read()
+
+        with MockedOpen({child_path: child_content + '\n/* */'}):
+            m2 = WebIDLCodegenManager(**args)
+            result = m2.generate_build_files()
+            self.assertEqual(result.inputs, set([child_path]))
+            self.assertEqual(len(result.updated), 0)
+            self.assertEqual(len(result.created), 0)
+
+    def test_rebuild_dependencies(self):
+        """Ensure an input file used by others results in others rebuilding."""
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        m1.generate_build_files()
+
+        parent_path = None
+        child_path = None
+        for p in m1._input_paths:
+            if p.endswith('Parent.webidl'):
+                parent_path = p
+            elif p.endswith('Child.webidl'):
+                child_path = p
+
+        self.assertIsNotNone(parent_path)
+        parent_content = open(parent_path, 'rb').read()
+
+        with MockedOpen({parent_path: parent_content + '\n/* */'}):
+            m2 = WebIDLCodegenManager(**args)
+            result = m2.generate_build_files()
+            self.assertEqual(result.inputs, {child_path, parent_path})
+            self.assertEqual(len(result.updated), 0)
+            self.assertEqual(len(result.created), 0)
+
+    def test_python_change_regenerate_everything(self):
+        """If a Python file changes, we should attempt to rebuild everything."""
+
+        # We don't want to mutate files in the source directory because we want
+        # to be able to build from a read-only filesystem. So, we install a
+        # dummy module and rewrite the metadata to say it comes from the source
+        # directory.
+        #
+        # Hacking imp to accept a MockedFile doesn't appear possible. So for
+        # the first iteration we read from a temp file. The second iteration
+        # doesn't need to import, so we are fine with a mocked file.
+        fake_path = mozpath.join(OUR_DIR, 'fakemodule.py')
+        with NamedTemporaryFile('wt') as fh:
+            fh.write('# Original content')
+            fh.flush()
+            mod = imp.load_source('mozwebidlcodegen.fakemodule', fh.name)
+            mod.__file__ = fake_path
+
+            args = self._get_manager_args()
+            m1 = WebIDLCodegenManager(**args)
+            with MockedOpen({fake_path: '# Original content'}):
+                try:
+                    result = m1.generate_build_files()
+                    l = len(result.inputs)
+
+                    with open(fake_path, 'wt') as fh:
+                        fh.write('# Modified content')
+
+                    m2 = WebIDLCodegenManager(**args)
+                    result = m2.generate_build_files()
+                    self.assertEqual(len(result.inputs), l)
+
+                    result = m2.generate_build_files()
+                    self.assertEqual(len(result.inputs), 0)
+                finally:
+                    del sys.modules['mozwebidlcodegen.fakemodule']
+
+    def test_copy_input(self):
+        """Ensure a copied .webidl file is handled properly."""
+
+        # This test simulates changing the type of a WebIDL from static to
+        # preprocessed. In that scenario, the original file still exists but
+        # it should no longer be consulted during codegen.
+
+        args = self._get_manager_args()
+        m1 = WebIDLCodegenManager(**args)
+        m1.generate_build_files()
+
+        old_path = None
+        for p in args['inputs'][0]:
+            if p.endswith('Parent.webidl'):
+                old_path = p
+                break
+        self.assertIsNotNone(old_path)
+
+        new_path = mozpath.join(args['cache_dir'], 'Parent.webidl')
+        shutil.copy2(old_path, new_path)
+
+        args['inputs'][0].remove(old_path)
+        args['inputs'][0].add(new_path)
+
+        m2 = WebIDLCodegenManager(**args)
+        result = m2.generate_build_files()
+        self.assertEqual(len(result.updated), 0)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/dom/bindings/parser/README b/dom/bindings/parser/README
new file mode 100644
index 000000000..94b64b884
--- /dev/null
+++ b/dom/bindings/parser/README
@@ -0,0 +1 @@
+A WebIDL parser written in Python to be used in Mozilla.
\ No newline at end of file
diff --git a/dom/bindings/parser/UPSTREAM b/dom/bindings/parser/UPSTREAM
new file mode 100644
index 000000000..7ac589937
--- /dev/null
+++ b/dom/bindings/parser/UPSTREAM
@@ -0,0 +1 @@
+http://dev.w3.org/cvsweb/~checkout~/2006/webapi/WebIDL/Overview.html?rev=1.409;content-type=text%2Fhtml%3b+charset=utf-8
\ No newline at end of file
diff --git a/dom/bindings/parser/WebIDL.py b/dom/bindings/parser/WebIDL.py
new file mode 100644
index 000000000..f668d7d62
--- /dev/null
+++ b/dom/bindings/parser/WebIDL.py
@@ -0,0 +1,6874 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+""" A WebIDL parser. """
+
+from ply import lex, yacc
+import re
+import os
+import traceback
+import math
+import string
+from collections import defaultdict
+
+# Machinery
+
+
+def parseInt(literal):
+    string = literal
+    sign = 0
+    base = 0
+
+    if string[0] == '-':
+        sign = -1
+        string = string[1:]
+    else:
+        sign = 1
+
+    if string[0] == '0' and len(string) > 1:
+        if string[1] == 'x' or string[1] == 'X':
+            base = 16
+            string = string[2:]
+        else:
+            base = 8
+            string = string[1:]
+    else:
+        base = 10
+
+    value = int(string, base)
+    return value * sign
+
+
+# Magic for creating enums
+def M_add_class_attribs(attribs, start):
+    def foo(name, bases, dict_):
+        for v, k in enumerate(attribs):
+            dict_[k] = start + v
+        assert 'length' not in dict_
+        dict_['length'] = start + len(attribs)
+        return type(name, bases, dict_)
+    return foo
+
+
+def enum(*names, **kw):
+    if len(kw) == 1:
+        base = kw['base'].__class__
+        start = base.length
+    else:
+        assert len(kw) == 0
+        base = object
+        start = 0
+
+    class Foo(base):
+        __metaclass__ = M_add_class_attribs(names, start)
+
+        def __setattr__(self, name, value):  # this makes it read-only
+            raise NotImplementedError
+    return Foo()
+
+
+class WebIDLError(Exception):
+    def __init__(self, message, locations, warning=False):
+        self.message = message
+        self.locations = [str(loc) for loc in locations]
+        self.warning = warning
+
+    def __str__(self):
+        return "%s: %s%s%s" % (self.warning and 'warning' or 'error',
+                               self.message,
+                               ", " if len(self.locations) != 0 else "",
+                               "\n".join(self.locations))
+
+
+class Location(object):
+    def __init__(self, lexer, lineno, lexpos, filename):
+        self._line = None
+        self._lineno = lineno
+        self._lexpos = lexpos
+        self._lexdata = lexer.lexdata
+        self._file = filename if filename else "<unknown>"
+
+    def __eq__(self, other):
+        return (self._lexpos == other._lexpos and
+                self._file == other._file)
+
+    def filename(self):
+        return self._file
+
+    def resolve(self):
+        if self._line:
+            return
+
+        startofline = self._lexdata.rfind('\n', 0, self._lexpos) + 1
+        endofline = self._lexdata.find('\n', self._lexpos, self._lexpos + 80)
+        if endofline != -1:
+            self._line = self._lexdata[startofline:endofline]
+        else:
+            self._line = self._lexdata[startofline:]
+        self._colno = self._lexpos - startofline
+
+        # Our line number seems to point to the start of self._lexdata
+        self._lineno += self._lexdata.count('\n', 0, startofline)
+
+    def get(self):
+        self.resolve()
+        return "%s line %s:%s" % (self._file, self._lineno, self._colno)
+
+    def _pointerline(self):
+        return " " * self._colno + "^"
+
+    def __str__(self):
+        self.resolve()
+        return "%s line %s:%s\n%s\n%s" % (self._file, self._lineno, self._colno,
+                                          self._line, self._pointerline())
+
+
+class BuiltinLocation(object):
+    def __init__(self, text):
+        self.msg = text + "\n"
+
+    def __eq__(self, other):
+        return (isinstance(other, BuiltinLocation) and
+                self.msg == other.msg)
+
+    def filename(self):
+        return '<builtin>'
+
+    def resolve(self):
+        pass
+
+    def get(self):
+        return self.msg
+
+    def __str__(self):
+        return self.get()
+
+
+# Data Model
+
+
+class IDLObject(object):
+    def __init__(self, location):
+        self.location = location
+        self.userData = dict()
+
+    def filename(self):
+        return self.location.filename()
+
+    def isInterface(self):
+        return False
+
+    def isNamespace(self):
+        return False
+
+    def isEnum(self):
+        return False
+
+    def isCallback(self):
+        return False
+
+    def isType(self):
+        return False
+
+    def isDictionary(self):
+        return False
+
+    def isUnion(self):
+        return False
+
+    def isTypedef(self):
+        return False
+
+    def getUserData(self, key, default):
+        return self.userData.get(key, default)
+
+    def setUserData(self, key, value):
+        self.userData[key] = value
+
+    def addExtendedAttributes(self, attrs):
+        assert False  # Override me!
+
+    def handleExtendedAttribute(self, attr):
+        assert False  # Override me!
+
+    def _getDependentObjects(self):
+        assert False  # Override me!
+
+    def getDeps(self, visited=None):
+        """ Return a set of files that this object depends on.  If any of
+            these files are changed the parser needs to be rerun to regenerate
+            a new IDLObject.
+
+            The visited argument is a set of all the objects already visited.
+            We must test to see if we are in it, and if so, do nothing.  This
+            prevents infinite recursion."""
+
+        # NB: We can't use visited=set() above because the default value is
+        # evaluated when the def statement is evaluated, not when the function
+        # is executed, so there would be one set for all invocations.
+        if visited is None:
+            visited = set()
+
+        if self in visited:
+            return set()
+
+        visited.add(self)
+
+        deps = set()
+        if self.filename() != "<builtin>":
+            deps.add(self.filename())
+
+        for d in self._getDependentObjects():
+            deps.update(d.getDeps(visited))
+
+        return deps
+
+
+class IDLScope(IDLObject):
+    def __init__(self, location, parentScope, identifier):
+        IDLObject.__init__(self, location)
+
+        self.parentScope = parentScope
+        if identifier:
+            assert isinstance(identifier, IDLIdentifier)
+            self._name = identifier
+        else:
+            self._name = None
+
+        self._dict = {}
+        self.globalNames = set()
+        # A mapping from global name to the set of global interfaces
+        # that have that global name.
+        self.globalNameMapping = defaultdict(set)
+        self.primaryGlobalAttr = None
+        self.primaryGlobalName = None
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        if self._name:
+            return self._name.QName() + "::"
+        return "::"
+
+    def ensureUnique(self, identifier, object):
+        """
+            Ensure that there is at most one 'identifier' in scope ('self').
+            Note that object can be None.  This occurs if we end up here for an
+            interface type we haven't seen yet.
+        """
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        assert not object or isinstance(object, IDLObjectWithIdentifier)
+        assert not object or object.identifier == identifier
+
+        if identifier.name in self._dict:
+            if not object:
+                return
+
+            # ensureUnique twice with the same object is not allowed
+            assert id(object) != id(self._dict[identifier.name])
+
+            replacement = self.resolveIdentifierConflict(self, identifier,
+                                                         self._dict[identifier.name],
+                                                         object)
+            self._dict[identifier.name] = replacement
+            return
+
+        assert object
+
+        self._dict[identifier.name] = object
+
+    def resolveIdentifierConflict(self, scope, identifier, originalObject, newObject):
+        if (isinstance(originalObject, IDLExternalInterface) and
+            isinstance(newObject, IDLExternalInterface) and
+            originalObject.identifier.name == newObject.identifier.name):
+            return originalObject
+
+        if (isinstance(originalObject, IDLExternalInterface) or
+            isinstance(newObject, IDLExternalInterface)):
+            raise WebIDLError(
+                "Name collision between "
+                "interface declarations for identifier '%s' at '%s' and '%s'"
+                % (identifier.name,
+                    originalObject.location, newObject.location), [])
+
+        if (isinstance(originalObject, IDLDictionary) or
+            isinstance(newObject, IDLDictionary)):
+            raise WebIDLError(
+                "Name collision between dictionary declarations for "
+                "identifier '%s'.\n%s\n%s"
+                % (identifier.name,
+                   originalObject.location, newObject.location), [])
+
+        # We do the merging of overloads here as opposed to in IDLInterface
+        # because we need to merge overloads of NamedConstructors and we need to
+        # detect conflicts in those across interfaces. See also the comment in
+        # IDLInterface.addExtendedAttributes for "NamedConstructor".
+        if (isinstance(originalObject, IDLMethod) and
+            isinstance(newObject, IDLMethod)):
+            return originalObject.addOverload(newObject)
+
+        # Default to throwing, derived classes can override.
+        conflictdesc = "\n\t%s at %s\n\t%s at %s" % (originalObject,
+                                                     originalObject.location,
+                                                     newObject,
+                                                     newObject.location)
+
+        raise WebIDLError(
+            "Multiple unresolvable definitions of identifier '%s' in scope '%s%s"
+            % (identifier.name, str(self), conflictdesc), [])
+
+    def _lookupIdentifier(self, identifier):
+        return self._dict[identifier.name]
+
+    def lookupIdentifier(self, identifier):
+        assert isinstance(identifier, IDLIdentifier)
+        assert identifier.scope == self
+        return self._lookupIdentifier(identifier)
+
+
+class IDLIdentifier(IDLObject):
+    def __init__(self, location, scope, name):
+        IDLObject.__init__(self, location)
+
+        self.name = name
+        assert isinstance(scope, IDLScope)
+        self.scope = scope
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        return self.scope.QName() + self.name
+
+    def __hash__(self):
+        return self.QName().__hash__()
+
+    def __eq__(self, other):
+        return self.QName() == other.QName()
+
+    def object(self):
+        return self.scope.lookupIdentifier(self)
+
+
+class IDLUnresolvedIdentifier(IDLObject):
+    def __init__(self, location, name, allowDoubleUnderscore=False,
+                 allowForbidden=False):
+        IDLObject.__init__(self, location)
+
+        assert len(name) > 0
+
+        if name == "__noSuchMethod__":
+            raise WebIDLError("__noSuchMethod__ is deprecated", [location])
+
+        if name[:2] == "__" and name != "__content" and not allowDoubleUnderscore:
+            raise WebIDLError("Identifiers beginning with __ are reserved",
+                              [location])
+        if name[0] == '_' and not allowDoubleUnderscore:
+            name = name[1:]
+        # TODO: Bug 872377, Restore "toJSON" to below list.
+        # We sometimes need custom serialization, so allow toJSON for now.
+        if (name in ["constructor", "toString"] and
+            not allowForbidden):
+            raise WebIDLError("Cannot use reserved identifier '%s'" % (name),
+                              [location])
+
+        self.name = name
+
+    def __str__(self):
+        return self.QName()
+
+    def QName(self):
+        return "<unresolved scope>::" + self.name
+
+    def resolve(self, scope, object):
+        assert isinstance(scope, IDLScope)
+        assert not object or isinstance(object, IDLObjectWithIdentifier)
+        assert not object or object.identifier == self
+
+        scope.ensureUnique(self, object)
+
+        identifier = IDLIdentifier(self.location, scope, self.name)
+        if object:
+            object.identifier = identifier
+        return identifier
+
+    def finish(self):
+        assert False  # Should replace with a resolved identifier first.
+
+
+class IDLObjectWithIdentifier(IDLObject):
+    def __init__(self, location, parentScope, identifier):
+        IDLObject.__init__(self, location)
+
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+
+        self.identifier = identifier
+
+        if parentScope:
+            self.resolve(parentScope)
+
+        self.treatNullAs = "Default"
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(self.identifier, IDLUnresolvedIdentifier)
+        self.identifier.resolve(parentScope, self)
+
+    def checkForStringHandlingExtendedAttributes(self, attrs,
+                                                 isDictionaryMember=False,
+                                                 isOptional=False):
+        """
+        A helper function to deal with TreatNullAs.  Returns the list
+        of attrs it didn't handle itself.
+        """
+        assert isinstance(self, IDLArgument) or isinstance(self, IDLAttribute)
+        unhandledAttrs = list()
+        for attr in attrs:
+            if not attr.hasValue():
+                unhandledAttrs.append(attr)
+                continue
+
+            identifier = attr.identifier()
+            value = attr.value()
+            if identifier == "TreatNullAs":
+                if not self.type.isDOMString() or self.type.nullable():
+                    raise WebIDLError("[TreatNullAs] is only allowed on "
+                                      "arguments or attributes whose type is "
+                                      "DOMString",
+                                      [self.location])
+                if isDictionaryMember:
+                    raise WebIDLError("[TreatNullAs] is not allowed for "
+                                      "dictionary members", [self.location])
+                if value != 'EmptyString':
+                    raise WebIDLError("[TreatNullAs] must take the identifier "
+                                      "'EmptyString', not '%s'" % value,
+                                      [self.location])
+                self.treatNullAs = value
+            else:
+                unhandledAttrs.append(attr)
+
+        return unhandledAttrs
+
+
+class IDLObjectWithScope(IDLObjectWithIdentifier, IDLScope):
+    def __init__(self, location, parentScope, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+        IDLScope.__init__(self, location, parentScope, self.identifier)
+
+
+class IDLIdentifierPlaceholder(IDLObjectWithIdentifier):
+    def __init__(self, location, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+
+    def finish(self, scope):
+        try:
+            scope._lookupIdentifier(self.identifier)
+        except:
+            raise WebIDLError("Unresolved type '%s'." % self.identifier,
+                              [self.location])
+
+        obj = self.identifier.resolve(scope, None)
+        return scope.lookupIdentifier(obj)
+
+
+class IDLExposureMixins():
+    def __init__(self, location):
+        # _exposureGlobalNames are the global names listed in our [Exposed]
+        # extended attribute.  exposureSet is the exposure set as defined in the
+        # Web IDL spec: it contains interface names.
+        self._exposureGlobalNames = set()
+        self.exposureSet = set()
+        self._location = location
+        self._globalScope = None
+
+    def finish(self, scope):
+        assert scope.parentScope is None
+        self._globalScope = scope
+
+        # Verify that our [Exposed] value, if any, makes sense.
+        for globalName in self._exposureGlobalNames:
+            if globalName not in scope.globalNames:
+                raise WebIDLError("Unknown [Exposed] value %s" % globalName,
+                                  [self._location])
+
+        if len(self._exposureGlobalNames) == 0:
+            self._exposureGlobalNames.add(scope.primaryGlobalName)
+
+        globalNameSetToExposureSet(scope, self._exposureGlobalNames,
+                                   self.exposureSet)
+
+    def isExposedInWindow(self):
+        return 'Window' in self.exposureSet
+
+    def isExposedOnMainThread(self):
+        return (self.isExposedInWindow() or
+                self.isExposedInSystemGlobals())
+
+    def isExposedInAnyWorker(self):
+        return len(self.getWorkerExposureSet()) > 0
+
+    def isExposedInWorkerDebugger(self):
+        return len(self.getWorkerDebuggerExposureSet()) > 0
+
+    def isExposedInAnyWorklet(self):
+        return len(self.getWorkletExposureSet()) > 0
+
+    def isExposedInSystemGlobals(self):
+        return 'BackstagePass' in self.exposureSet
+
+    def isExposedInSomeButNotAllWorkers(self):
+        """
+        Returns true if the Exposed extended attribute for this interface
+        exposes it in some worker globals but not others.  The return value does
+        not depend on whether the interface is exposed in Window or System
+        globals.
+        """
+        if not self.isExposedInAnyWorker():
+            return False
+        workerScopes = self.parentScope.globalNameMapping["Worker"]
+        return len(workerScopes.difference(self.exposureSet)) > 0
+
+    def getWorkerExposureSet(self):
+        workerScopes = self._globalScope.globalNameMapping["Worker"]
+        return workerScopes.intersection(self.exposureSet)
+
+    def getWorkletExposureSet(self):
+        workletScopes = self._globalScope.globalNameMapping["Worklet"]
+        return workletScopes.intersection(self.exposureSet)
+
+    def getWorkerDebuggerExposureSet(self):
+        workerDebuggerScopes = self._globalScope.globalNameMapping["WorkerDebugger"]
+        return workerDebuggerScopes.intersection(self.exposureSet)
+
+
+class IDLExternalInterface(IDLObjectWithIdentifier, IDLExposureMixins):
+    def __init__(self, location, parentScope, identifier):
+        assert isinstance(identifier, IDLUnresolvedIdentifier)
+        assert isinstance(parentScope, IDLScope)
+        self.parent = None
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+        IDLExposureMixins.__init__(self, location)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+
+    def finish(self, scope):
+        IDLExposureMixins.finish(self, scope)
+        pass
+
+    def validate(self):
+        pass
+
+    def isIteratorInterface(self):
+        return False
+
+    def isExternal(self):
+        return True
+
+    def isInterface(self):
+        return True
+
+    def isConsequential(self):
+        return False
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def resolve(self, parentScope):
+        pass
+
+    def getJSImplementation(self):
+        return None
+
+    def isJSImplemented(self):
+        return False
+
+    def isProbablyShortLivingObject(self):
+        return False
+
+    def isNavigatorProperty(self):
+        return False
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLPartialInterfaceOrNamespace(IDLObject):
+    def __init__(self, location, name, members, nonPartialInterfaceOrNamespace):
+        assert isinstance(name, IDLUnresolvedIdentifier)
+
+        IDLObject.__init__(self, location)
+        self.identifier = name
+        self.members = members
+        # propagatedExtendedAttrs are the ones that should get
+        # propagated to our non-partial interface.
+        self.propagatedExtendedAttrs = []
+        self._haveSecureContextExtendedAttribute = False
+        self._nonPartialInterfaceOrNamespace = nonPartialInterfaceOrNamespace
+        self._finished = False
+        nonPartialInterfaceOrNamespace.addPartialInterface(self)
+
+    def addExtendedAttributes(self, attrs):
+        for attr in attrs:
+            identifier = attr.identifier()
+
+            if identifier in ["Constructor", "NamedConstructor"]:
+                self.propagatedExtendedAttrs.append(attr)
+            elif identifier == "SecureContext":
+                self._haveSecureContextExtendedAttribute = True
+                # This gets propagated to all our members.
+                for member in self.members:
+                    if member.getExtendedAttribute("SecureContext"):
+                        raise WebIDLError("[SecureContext] specified on both a "
+                                          "partial interface member and on the "
+                                          "partial interface itself",
+                                          [member.location, attr.location])
+                    member.addExtendedAttributes([attr])
+            elif identifier == "Exposed":
+                # This just gets propagated to all our members.
+                for member in self.members:
+                    if len(member._exposureGlobalNames) != 0:
+                        raise WebIDLError("[Exposed] specified on both a "
+                                          "partial interface member and on the "
+                                          "partial interface itself",
+                                          [member.location, attr.location])
+                    member.addExtendedAttributes([attr])
+            else:
+                raise WebIDLError("Unknown extended attribute %s on partial "
+                                  "interface" % identifier,
+                                  [attr.location])
+
+    def finish(self, scope):
+        if self._finished:
+            return
+        self._finished = True
+        if (not self._haveSecureContextExtendedAttribute and
+            self._nonPartialInterfaceOrNamespace.getExtendedAttribute("SecureContext")):
+            # This gets propagated to all our members.
+            for member in self.members:
+                if member.getExtendedAttribute("SecureContext"):
+                    raise WebIDLError("[SecureContext] specified on both a "
+                                      "partial interface member and on the "
+                                      "non-partial interface",
+                                      [member.location,
+                                       self._nonPartialInterfaceOrNamespace.location])
+                member.addExtendedAttributes(
+                    [IDLExtendedAttribute(self._nonPartialInterfaceOrNamespace.location,
+                                          ("SecureContext",))])
+        # Need to make sure our non-partial interface or namespace gets
+        # finished so it can report cases when we only have partial
+        # interfaces/namespaces.
+        self._nonPartialInterfaceOrNamespace.finish(scope)
+
+    def validate(self):
+        pass
+
+
+def convertExposedAttrToGlobalNameSet(exposedAttr, targetSet):
+    assert len(targetSet) == 0
+    if exposedAttr.hasValue():
+        targetSet.add(exposedAttr.value())
+    else:
+        assert exposedAttr.hasArgs()
+        targetSet.update(exposedAttr.args())
+
+
+def globalNameSetToExposureSet(globalScope, nameSet, exposureSet):
+    for name in nameSet:
+        exposureSet.update(globalScope.globalNameMapping[name])
+
+
+class IDLInterfaceOrNamespace(IDLObjectWithScope, IDLExposureMixins):
+    def __init__(self, location, parentScope, name, parent, members,
+                 isKnownNonPartial):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+        assert isKnownNonPartial or not parent
+        assert isKnownNonPartial or len(members) == 0
+
+        self.parent = None
+        self._callback = False
+        self._finished = False
+        self.members = []
+        self.maplikeOrSetlikeOrIterable = None
+        self._partialInterfaces = []
+        self._extendedAttrDict = {}
+        # namedConstructors needs deterministic ordering because bindings code
+        # outputs the constructs in the order that namedConstructors enumerates
+        # them.
+        self.namedConstructors = list()
+        self.implementedInterfaces = set()
+        self._consequential = False
+        self._isKnownNonPartial = False
+        # self.interfacesBasedOnSelf is the set of interfaces that inherit from
+        # self or have self as a consequential interface, including self itself.
+        # Used for distinguishability checking.
+        self.interfacesBasedOnSelf = set([self])
+        # self.interfacesImplementingSelf is the set of interfaces that directly
+        # have self as a consequential interface
+        self.interfacesImplementingSelf = set()
+        self._hasChildInterfaces = False
+        self._isOnGlobalProtoChain = False
+        # Tracking of the number of reserved slots we need for our
+        # members and those of ancestor interfaces.
+        self.totalMembersInSlots = 0
+        # Tracking of the number of own own members we have in slots
+        self._ownMembersInSlots = 0
+        # If this is an iterator interface, we need to know what iterable
+        # interface we're iterating for in order to get its nativeType.
+        self.iterableInterface = None
+
+        IDLObjectWithScope.__init__(self, location, parentScope, name)
+        IDLExposureMixins.__init__(self, location)
+
+        if isKnownNonPartial:
+            self.setNonPartial(location, parent, members)
+
+    def ctor(self):
+        identifier = IDLUnresolvedIdentifier(self.location, "constructor",
+                                             allowForbidden=True)
+        try:
+            return self._lookupIdentifier(identifier)
+        except:
+            return None
+
+    def isIterable(self):
+        return (self.maplikeOrSetlikeOrIterable and
+                self.maplikeOrSetlikeOrIterable.isIterable())
+
+    def isIteratorInterface(self):
+        return self.iterableInterface is not None
+
+    def resolveIdentifierConflict(self, scope, identifier, originalObject, newObject):
+        assert isinstance(scope, IDLScope)
+        assert isinstance(originalObject, IDLInterfaceMember)
+        assert isinstance(newObject, IDLInterfaceMember)
+
+        retval = IDLScope.resolveIdentifierConflict(self, scope, identifier,
+                                                    originalObject, newObject)
+
+        # Might be a ctor, which isn't in self.members
+        if newObject in self.members:
+            self.members.remove(newObject)
+        return retval
+
+    def finish(self, scope):
+        if self._finished:
+            return
+
+        self._finished = True
+
+        if not self._isKnownNonPartial:
+            raise WebIDLError("Interface %s does not have a non-partial "
+                              "declaration" % self.identifier.name,
+                              [self.location])
+
+        IDLExposureMixins.finish(self, scope)
+
+        # Now go ahead and merge in our partial interfaces.
+        for partial in self._partialInterfaces:
+            partial.finish(scope)
+            self.addExtendedAttributes(partial.propagatedExtendedAttrs)
+            self.members.extend(partial.members)
+
+        # Generate maplike/setlike interface members. Since generated members
+        # need to be treated like regular interface members, do this before
+        # things like exposure setting.
+        for member in self.members:
+            if member.isMaplikeOrSetlikeOrIterable():
+                # Check that we only have one interface declaration (currently
+                # there can only be one maplike/setlike declaration per
+                # interface)
+                if self.maplikeOrSetlikeOrIterable:
+                    raise WebIDLError("%s declaration used on "
+                                      "interface that already has %s "
+                                      "declaration" %
+                                      (member.maplikeOrSetlikeOrIterableType,
+                                       self.maplikeOrSetlikeOrIterable.maplikeOrSetlikeOrIterableType),
+                                      [self.maplikeOrSetlikeOrIterable.location,
+                                       member.location])
+                self.maplikeOrSetlikeOrIterable = member
+                # If we've got a maplike or setlike declaration, we'll be building all of
+                # our required methods in Codegen. Generate members now.
+                self.maplikeOrSetlikeOrIterable.expand(self.members, self.isJSImplemented())
+
+        # Now that we've merged in our partial interfaces, set the
+        # _exposureGlobalNames on any members that don't have it set yet.  Note
+        # that any partial interfaces that had [Exposed] set have already set up
+        # _exposureGlobalNames on all the members coming from them, so this is
+        # just implementing the "members default to interface that defined them"
+        # and "partial interfaces default to interface they're a partial for"
+        # rules from the spec.
+        for m in self.members:
+            # If m, or the partial interface m came from, had [Exposed]
+            # specified, it already has a nonempty exposure global names set.
+            if len(m._exposureGlobalNames) == 0:
+                m._exposureGlobalNames.update(self._exposureGlobalNames)
+
+        assert not self.parent or isinstance(self.parent, IDLIdentifierPlaceholder)
+        parent = self.parent.finish(scope) if self.parent else None
+        if parent and isinstance(parent, IDLExternalInterface):
+            raise WebIDLError("%s inherits from %s which does not have "
+                              "a definition" %
+                              (self.identifier.name,
+                               self.parent.identifier.name),
+                              [self.location])
+        assert not parent or isinstance(parent, IDLInterface)
+
+        self.parent = parent
+
+        assert iter(self.members)
+
+        if self.isNamespace():
+            assert not self.parent
+            for m in self.members:
+                if m.isAttr() or m.isMethod():
+                    if m.isStatic():
+                        raise WebIDLError("Don't mark things explicitly static "
+                                          "in namespaces",
+                                          [self.location, m.location])
+                    # Just mark all our methods/attributes as static.  The other
+                    # option is to duplicate the relevant InterfaceMembers
+                    # production bits but modified to produce static stuff to
+                    # start with, but that sounds annoying.
+                    m.forceStatic()
+
+        if self.parent:
+            self.parent.finish(scope)
+            self.parent._hasChildInterfaces = True
+
+            self.totalMembersInSlots = self.parent.totalMembersInSlots
+
+            # Interfaces with [Global] or [PrimaryGlobal] must not
+            # have anything inherit from them
+            if (self.parent.getExtendedAttribute("Global") or
+                self.parent.getExtendedAttribute("PrimaryGlobal")):
+                # Note: This is not a self.parent.isOnGlobalProtoChain() check
+                # because ancestors of a [Global] interface can have other
+                # descendants.
+                raise WebIDLError("[Global] interface has another interface "
+                                  "inheriting from it",
+                                  [self.location, self.parent.location])
+
+            # Make sure that we're not exposed in places where our parent is not
+            if not self.exposureSet.issubset(self.parent.exposureSet):
+                raise WebIDLError("Interface %s is exposed in globals where its "
+                                  "parent interface %s is not exposed." %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
+            # Callbacks must not inherit from non-callbacks or inherit from
+            # anything that has consequential interfaces.
+            # XXXbz Can non-callbacks inherit from callbacks?  Spec issue pending.
+            # XXXbz Can callbacks have consequential interfaces?  Spec issue pending
+            if self.isCallback():
+                if not self.parent.isCallback():
+                    raise WebIDLError("Callback interface %s inheriting from "
+                                      "non-callback interface %s" %
+                                      (self.identifier.name,
+                                       self.parent.identifier.name),
+                                      [self.location, self.parent.location])
+            elif self.parent.isCallback():
+                raise WebIDLError("Non-callback interface %s inheriting from "
+                                  "callback interface %s" %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
+            # Interfaces which have interface objects can't inherit
+            # from [NoInterfaceObject] interfaces.
+            if (self.parent.getExtendedAttribute("NoInterfaceObject") and
+                not self.getExtendedAttribute("NoInterfaceObject")):
+                raise WebIDLError("Interface %s does not have "
+                                  "[NoInterfaceObject] but inherits from "
+                                  "interface %s which does" %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
+            # Interfaces that are not [SecureContext] can't inherit
+            # from [SecureContext] interfaces.
+            if (self.parent.getExtendedAttribute("SecureContext") and
+                not self.getExtendedAttribute("SecureContext")):
+                raise WebIDLError("Interface %s does not have "
+                                  "[SecureContext] but inherits from "
+                                  "interface %s which does" %
+                                  (self.identifier.name,
+                                   self.parent.identifier.name),
+                                  [self.location, self.parent.location])
+
+        for iface in self.implementedInterfaces:
+            iface.finish(scope)
+
+        cycleInGraph = self.findInterfaceLoopPoint(self)
+        if cycleInGraph:
+            raise WebIDLError("Interface %s has itself as ancestor or "
+                              "implemented interface" % self.identifier.name,
+                              [self.location, cycleInGraph.location])
+
+        if self.isCallback():
+            # "implements" should have made sure we have no
+            # consequential interfaces.
+            assert len(self.getConsequentialInterfaces()) == 0
+            # And that we're not consequential.
+            assert not self.isConsequential()
+
+        # Now resolve() and finish() our members before importing the
+        # ones from our implemented interfaces.
+
+        # resolve() will modify self.members, so we need to iterate
+        # over a copy of the member list here.
+        for member in list(self.members):
+            member.resolve(self)
+
+        for member in self.members:
+            member.finish(scope)
+
+        # Now that we've finished our members, which has updated their exposure
+        # sets, make sure they aren't exposed in places where we are not.
+        for member in self.members:
+            if not member.exposureSet.issubset(self.exposureSet):
+                raise WebIDLError("Interface member has larger exposure set "
+                                  "than the interface itself",
+                                  [member.location, self.location])
+
+        ctor = self.ctor()
+        if ctor is not None:
+            assert len(ctor._exposureGlobalNames) == 0
+            ctor._exposureGlobalNames.update(self._exposureGlobalNames)
+            ctor.finish(scope)
+
+        for ctor in self.namedConstructors:
+            assert len(ctor._exposureGlobalNames) == 0
+            ctor._exposureGlobalNames.update(self._exposureGlobalNames)
+            ctor.finish(scope)
+
+        # Make a copy of our member list, so things that implement us
+        # can get those without all the stuff we implement ourselves
+        # admixed.
+        self.originalMembers = list(self.members)
+
+        # Import everything from our consequential interfaces into
+        # self.members.  Sort our consequential interfaces by name
+        # just so we have a consistent order.
+        for iface in sorted(self.getConsequentialInterfaces(),
+                            cmp=cmp,
+                            key=lambda x: x.identifier.name):
+            # Flag the interface as being someone's consequential interface
+            iface.setIsConsequentialInterfaceOf(self)
+            # Verify that we're not exposed somewhere where iface is not exposed
+            if not self.exposureSet.issubset(iface.exposureSet):
+                raise WebIDLError("Interface %s is exposed in globals where its "
+                                  "consequential interface %s is not exposed." %
+                                  (self.identifier.name, iface.identifier.name),
+                                  [self.location, iface.location])
+
+            # If we have a maplike or setlike, and the consequential interface
+            # also does, throw an error.
+            if iface.maplikeOrSetlikeOrIterable and self.maplikeOrSetlikeOrIterable:
+                raise WebIDLError("Maplike/setlike/iterable interface %s cannot have "
+                                  "maplike/setlike/iterable interface %s as a "
+                                  "consequential interface" %
+                                  (self.identifier.name,
+                                   iface.identifier.name),
+                                  [self.maplikeOrSetlikeOrIterable.location,
+                                   iface.maplikeOrSetlikeOrIterable.location])
+            additionalMembers = iface.originalMembers
+            for additionalMember in additionalMembers:
+                for member in self.members:
+                    if additionalMember.identifier.name == member.identifier.name:
+                        raise WebIDLError(
+                            "Multiple definitions of %s on %s coming from 'implements' statements" %
+                            (member.identifier.name, self),
+                            [additionalMember.location, member.location])
+            self.members.extend(additionalMembers)
+            iface.interfacesImplementingSelf.add(self)
+
+        for ancestor in self.getInheritedInterfaces():
+            ancestor.interfacesBasedOnSelf.add(self)
+            if (ancestor.maplikeOrSetlikeOrIterable is not None and
+                self.maplikeOrSetlikeOrIterable is not None):
+                raise WebIDLError("Cannot have maplike/setlike on %s that "
+                                  "inherits %s, which is already "
+                                  "maplike/setlike" %
+                                  (self.identifier.name,
+                                   ancestor.identifier.name),
+                                  [self.maplikeOrSetlikeOrIterable.location,
+                                   ancestor.maplikeOrSetlikeOrIterable.location])
+            for ancestorConsequential in ancestor.getConsequentialInterfaces():
+                ancestorConsequential.interfacesBasedOnSelf.add(self)
+
+        # Deal with interfaces marked [Unforgeable], now that we have our full
+        # member list, except unforgeables pulled in from parents.  We want to
+        # do this before we set "originatingInterface" on our unforgeable
+        # members.
+        if self.getExtendedAttribute("Unforgeable"):
+            # Check that the interface already has all the things the
+            # spec would otherwise require us to synthesize and is
+            # missing the ones we plan to synthesize.
+            if not any(m.isMethod() and m.isStringifier() for m in self.members):
+                raise WebIDLError("Unforgeable interface %s does not have a "
+                                  "stringifier" % self.identifier.name,
+                                  [self.location])
+
+            for m in self.members:
+                if ((m.isMethod() and m.isJsonifier()) or
+                    m.identifier.name == "toJSON"):
+                    raise WebIDLError("Unforgeable interface %s has a "
+                                      "jsonifier so we won't be able to add "
+                                      "one ourselves" % self.identifier.name,
+                                      [self.location, m.location])
+
+                if m.identifier.name == "valueOf" and not m.isStatic():
+                    raise WebIDLError("Unforgeable interface %s has a valueOf "
+                                      "member so we won't be able to add one "
+                                      "ourselves" % self.identifier.name,
+                                      [self.location, m.location])
+
+        for member in self.members:
+            if ((member.isAttr() or member.isMethod()) and
+                member.isUnforgeable() and
+                not hasattr(member, "originatingInterface")):
+                member.originatingInterface = self
+
+        # Compute slot indices for our members before we pull in unforgeable
+        # members from our parent. Also, maplike/setlike declarations get a
+        # slot to hold their backing object.
+        for member in self.members:
+            if ((member.isAttr() and
+                 (member.getExtendedAttribute("StoreInSlot") or
+                  member.getExtendedAttribute("Cached"))) or
+                member.isMaplikeOrSetlike()):
+                if member.slotIndices is None:
+                    member.slotIndices = dict()
+                member.slotIndices[self.identifier.name] = self.totalMembersInSlots
+                self.totalMembersInSlots += 1
+                if member.getExtendedAttribute("StoreInSlot"):
+                    self._ownMembersInSlots += 1
+
+        if self.parent:
+            # Make sure we don't shadow any of the [Unforgeable] attributes on
+            # our ancestor interfaces.  We don't have to worry about
+            # consequential interfaces here, because those have already been
+            # imported into the relevant .members lists.  And we don't have to
+            # worry about anything other than our parent, because it has already
+            # imported its ancestors unforgeable attributes into its member
+            # list.
+            for unforgeableMember in (member for member in self.parent.members if
+                                      (member.isAttr() or member.isMethod()) and
+                                      member.isUnforgeable()):
+                shadows = [m for m in self.members if
+                           (m.isAttr() or m.isMethod()) and
+                           not m.isStatic() and
+                           m.identifier.name == unforgeableMember.identifier.name]
+                if len(shadows) != 0:
+                    locs = [unforgeableMember.location] + [s.location for s
+                                                           in shadows]
+                    raise WebIDLError("Interface %s shadows [Unforgeable] "
+                                      "members of %s" %
+                                      (self.identifier.name,
+                                       ancestor.identifier.name),
+                                      locs)
+                # And now just stick it in our members, since we won't be
+                # inheriting this down the proto chain.  If we really cared we
+                # could try to do something where we set up the unforgeable
+                # attributes/methods of ancestor interfaces, with their
+                # corresponding getters, on our interface, but that gets pretty
+                # complicated and seems unnecessary.
+                self.members.append(unforgeableMember)
+
+        # At this point, we have all of our members. If the current interface
+        # uses maplike/setlike, check for collisions anywhere in the current
+        # interface or higher in the inheritance chain.
+        if self.maplikeOrSetlikeOrIterable:
+            testInterface = self
+            isAncestor = False
+            while testInterface:
+                self.maplikeOrSetlikeOrIterable.checkCollisions(testInterface.members,
+                                                                isAncestor)
+                isAncestor = True
+                testInterface = testInterface.parent
+
+        # Ensure that there's at most one of each {named,indexed}
+        # {getter,setter,creator,deleter}, at most one stringifier,
+        # and at most one legacycaller.  Note that this last is not
+        # quite per spec, but in practice no one overloads
+        # legacycallers.  Also note that in practice we disallow
+        # indexed deleters, but it simplifies some other code to
+        # treat deleter analogously to getter/setter/creator by
+        # prefixing it with "named".
+        specialMembersSeen = {}
+        for member in self.members:
+            if not member.isMethod():
+                continue
+
+            if member.isGetter():
+                memberType = "getters"
+            elif member.isSetter():
+                memberType = "setters"
+            elif member.isCreator():
+                memberType = "creators"
+            elif member.isDeleter():
+                memberType = "deleters"
+            elif member.isStringifier():
+                memberType = "stringifiers"
+            elif member.isJsonifier():
+                memberType = "jsonifiers"
+            elif member.isLegacycaller():
+                memberType = "legacycallers"
+            else:
+                continue
+
+            if (memberType != "stringifiers" and memberType != "legacycallers" and
+                memberType != "jsonifiers"):
+                if member.isNamed():
+                    memberType = "named " + memberType
+                else:
+                    assert member.isIndexed()
+                    memberType = "indexed " + memberType
+
+            if memberType in specialMembersSeen:
+                raise WebIDLError("Multiple " + memberType + " on %s" % (self),
+                                  [self.location,
+                                   specialMembersSeen[memberType].location,
+                                   member.location])
+
+            specialMembersSeen[memberType] = member
+
+        if self.getExtendedAttribute("LegacyUnenumerableNamedProperties"):
+            # Check that we have a named getter.
+            if "named getters" not in specialMembersSeen:
+                raise WebIDLError(
+                    "Interface with [LegacyUnenumerableNamedProperties] does "
+                    "not have a named getter",
+                    [self.location])
+            ancestor = self.parent
+            while ancestor:
+                if ancestor.getExtendedAttribute("LegacyUnenumerableNamedProperties"):
+                    raise WebIDLError(
+                        "Interface with [LegacyUnenumerableNamedProperties] "
+                        "inherits from another interface with "
+                        "[LegacyUnenumerableNamedProperties]",
+                        [self.location, ancestor.location])
+                ancestor = ancestor.parent
+
+        if self._isOnGlobalProtoChain:
+            # Make sure we have no named setters, creators, or deleters
+            for memberType in ["setter", "creator", "deleter"]:
+                memberId = "named " + memberType + "s"
+                if memberId in specialMembersSeen:
+                    raise WebIDLError("Interface with [Global] has a named %s" %
+                                      memberType,
+                                      [self.location,
+                                       specialMembersSeen[memberId].location])
+            # Make sure we're not [OverrideBuiltins]
+            if self.getExtendedAttribute("OverrideBuiltins"):
+                raise WebIDLError("Interface with [Global] also has "
+                                  "[OverrideBuiltins]",
+                                  [self.location])
+            # Mark all of our ancestors as being on the global's proto chain too
+            parent = self.parent
+            while parent:
+                # Must not inherit from an interface with [OverrideBuiltins]
+                if parent.getExtendedAttribute("OverrideBuiltins"):
+                    raise WebIDLError("Interface with [Global] inherits from "
+                                      "interface with [OverrideBuiltins]",
+                                      [self.location, parent.location])
+                parent._isOnGlobalProtoChain = True
+                parent = parent.parent
+
+    def validate(self):
+        # We don't support consequential unforgeable interfaces.  Need to check
+        # this here, because in finish() an interface might not know yet that
+        # it's consequential.
+        if self.getExtendedAttribute("Unforgeable") and self.isConsequential():
+            raise WebIDLError(
+                "%s is an unforgeable consequential interface" %
+                self.identifier.name,
+                [self.location] +
+                list(i.location for i in
+                     (self.interfacesBasedOnSelf - {self})))
+
+        # We also don't support inheriting from unforgeable interfaces.
+        if self.getExtendedAttribute("Unforgeable") and self.hasChildInterfaces():
+            locations = ([self.location] +
+                         list(i.location for i in
+                              self.interfacesBasedOnSelf if i.parent == self))
+            raise WebIDLError("%s is an unforgeable ancestor interface" %
+                              self.identifier.name,
+                              locations)
+
+        indexedGetter = None
+        hasLengthAttribute = False
+        for member in self.members:
+            member.validate()
+
+            if self.isCallback() and member.getExtendedAttribute("Replaceable"):
+                raise WebIDLError("[Replaceable] used on an attribute on "
+                                  "interface %s which is a callback interface" %
+                                  self.identifier.name,
+                                  [self.location, member.location])
+
+            # Check that PutForwards refers to another attribute and that no
+            # cycles exist in forwarded assignments.  Also check for a
+            # integer-typed "length" attribute.
+            if member.isAttr():
+                if (member.identifier.name == "length" and
+                    member.type.isInteger()):
+                    hasLengthAttribute = True
+
+                iface = self
+                attr = member
+                putForwards = attr.getExtendedAttribute("PutForwards")
+                if putForwards and self.isCallback():
+                    raise WebIDLError("[PutForwards] used on an attribute "
+                                      "on interface %s which is a callback "
+                                      "interface" % self.identifier.name,
+                                      [self.location, member.location])
+
+                while putForwards is not None:
+                    forwardIface = attr.type.unroll().inner
+                    fowardAttr = None
+
+                    for forwardedMember in forwardIface.members:
+                        if (not forwardedMember.isAttr() or
+                            forwardedMember.identifier.name != putForwards[0]):
+                            continue
+                        if forwardedMember == member:
+                            raise WebIDLError("Cycle detected in forwarded "
+                                              "assignments for attribute %s on "
+                                              "%s" %
+                                              (member.identifier.name, self),
+                                              [member.location])
+                        fowardAttr = forwardedMember
+                        break
+
+                    if fowardAttr is None:
+                        raise WebIDLError("Attribute %s on %s forwards to "
+                                          "missing attribute %s" %
+                                          (attr.identifier.name, iface, putForwards),
+                                          [attr.location])
+
+                    iface = forwardIface
+                    attr = fowardAttr
+                    putForwards = attr.getExtendedAttribute("PutForwards")
+
+            # Check that the name of an [Alias] doesn't conflict with an
+            # interface member and whether we support indexed properties.
+            if member.isMethod():
+                if member.isGetter() and member.isIndexed():
+                    indexedGetter = member
+
+                for alias in member.aliases:
+                    if self.isOnGlobalProtoChain():
+                        raise WebIDLError("[Alias] must not be used on a "
+                                          "[Global] interface operation",
+                                          [member.location])
+                    if (member.getExtendedAttribute("Exposed") or
+                        member.getExtendedAttribute("ChromeOnly") or
+                        member.getExtendedAttribute("Pref") or
+                        member.getExtendedAttribute("Func") or
+                        member.getExtendedAttribute("SecureContext")):
+                        raise WebIDLError("[Alias] must not be used on a "
+                                          "conditionally exposed operation",
+                                          [member.location])
+                    if member.isStatic():
+                        raise WebIDLError("[Alias] must not be used on a "
+                                          "static operation",
+                                          [member.location])
+                    if member.isIdentifierLess():
+                        raise WebIDLError("[Alias] must not be used on an "
+                                          "identifierless operation",
+                                          [member.location])
+                    if member.isUnforgeable():
+                        raise WebIDLError("[Alias] must not be used on an "
+                                          "[Unforgeable] operation",
+                                          [member.location])
+                    for m in self.members:
+                        if m.identifier.name == alias:
+                            raise WebIDLError("[Alias=%s] has same name as "
+                                              "interface member" % alias,
+                                              [member.location, m.location])
+                        if m.isMethod() and m != member and alias in m.aliases:
+                            raise WebIDLError("duplicate [Alias=%s] definitions" %
+                                              alias,
+                                              [member.location, m.location])
+
+        if (self.getExtendedAttribute("Pref") and
+            self._exposureGlobalNames != set([self.parentScope.primaryGlobalName])):
+            raise WebIDLError("[Pref] used on an interface that is not %s-only" %
+                              self.parentScope.primaryGlobalName,
+                              [self.location])
+
+        # Conditional exposure makes no sense for interfaces with no
+        # interface object, unless they're navigator properties.
+        # And SecureContext makes sense for interfaces with no interface object,
+        # since it is also propagated to interface members.
+        if (self.isExposedConditionally(exclusions=["SecureContext"]) and
+            not self.hasInterfaceObject() and
+            not self.isNavigatorProperty()):
+            raise WebIDLError("Interface with no interface object is "
+                              "exposed conditionally",
+                              [self.location])
+
+        # Value iterators are only allowed on interfaces with indexed getters,
+        # and pair iterators are only allowed on interfaces without indexed
+        # getters.
+        if self.isIterable():
+            iterableDecl = self.maplikeOrSetlikeOrIterable
+            if iterableDecl.isValueIterator():
+                if not indexedGetter:
+                    raise WebIDLError("Interface with value iterator does not "
+                                      "support indexed properties",
+                                      [self.location])
+
+                if iterableDecl.valueType != indexedGetter.signatures()[0][0]:
+                    raise WebIDLError("Iterable type does not match indexed "
+                                      "getter type",
+                                      [iterableDecl.location,
+                                       indexedGetter.location])
+
+                if not hasLengthAttribute:
+                    raise WebIDLError('Interface with value iterator does not '
+                                      'have an integer-typed "length" attribute',
+                                      [self.location])
+            else:
+                assert iterableDecl.isPairIterator()
+                if indexedGetter:
+                    raise WebIDLError("Interface with pair iterator supports "
+                                      "indexed properties",
+                                      [self.location, iterableDecl.location,
+                                       indexedGetter.location])
+
+    def isExternal(self):
+        return False
+
+    def setIsConsequentialInterfaceOf(self, other):
+        self._consequential = True
+        self.interfacesBasedOnSelf.add(other)
+
+    def isConsequential(self):
+        return self._consequential
+
+    def setCallback(self, value):
+        self._callback = value
+
+    def isCallback(self):
+        return self._callback
+
+    def isSingleOperationInterface(self):
+        assert self.isCallback() or self.isJSImplemented()
+        return (
+            # JS-implemented things should never need the
+            # this-handling weirdness of single-operation interfaces.
+            not self.isJSImplemented() and
+            # Not inheriting from another interface
+            not self.parent and
+            # No consequential interfaces
+            len(self.getConsequentialInterfaces()) == 0 and
+            # No attributes of any kinds
+            not any(m.isAttr() for m in self.members) and
+            # There is at least one regular operation, and all regular
+            # operations have the same identifier
+            len(set(m.identifier.name for m in self.members if
+                    m.isMethod() and not m.isStatic())) == 1)
+
+    def inheritanceDepth(self):
+        depth = 0
+        parent = self.parent
+        while parent:
+            depth = depth + 1
+            parent = parent.parent
+        return depth
+
+    def hasConstants(self):
+        return any(m.isConst() for m in self.members)
+
+    def hasInterfaceObject(self):
+        if self.isCallback():
+            return self.hasConstants()
+        return not hasattr(self, "_noInterfaceObject")
+
+    def hasInterfacePrototypeObject(self):
+        return (not self.isCallback() and not self.isNamespace()
+                and self.getUserData('hasConcreteDescendant', False))
+
+    def addImplementedInterface(self, implementedInterface):
+        assert(isinstance(implementedInterface, IDLInterface))
+        self.implementedInterfaces.add(implementedInterface)
+
+    def getInheritedInterfaces(self):
+        """
+        Returns a list of the interfaces this interface inherits from
+        (not including this interface itself).  The list is in order
+        from most derived to least derived.
+        """
+        assert(self._finished)
+        if not self.parent:
+            return []
+        parentInterfaces = self.parent.getInheritedInterfaces()
+        parentInterfaces.insert(0, self.parent)
+        return parentInterfaces
+
+    def getConsequentialInterfaces(self):
+        assert(self._finished)
+        # The interfaces we implement directly
+        consequentialInterfaces = set(self.implementedInterfaces)
+
+        # And their inherited interfaces
+        for iface in self.implementedInterfaces:
+            consequentialInterfaces |= set(iface.getInheritedInterfaces())
+
+        # And now collect up the consequential interfaces of all of those
+        temp = set()
+        for iface in consequentialInterfaces:
+            temp |= iface.getConsequentialInterfaces()
+
+        return consequentialInterfaces | temp
+
+    def findInterfaceLoopPoint(self, otherInterface):
+        """
+        Finds an interface, amongst our ancestors and consequential interfaces,
+        that inherits from otherInterface or implements otherInterface
+        directly.  If there is no such interface, returns None.
+        """
+        if self.parent:
+            if self.parent == otherInterface:
+                return self
+            loopPoint = self.parent.findInterfaceLoopPoint(otherInterface)
+            if loopPoint:
+                return loopPoint
+        if otherInterface in self.implementedInterfaces:
+            return self
+        for iface in self.implementedInterfaces:
+            loopPoint = iface.findInterfaceLoopPoint(otherInterface)
+            if loopPoint:
+                return loopPoint
+        return None
+
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
+    def setNonPartial(self, location, parent, members):
+        assert not parent or isinstance(parent, IDLIdentifierPlaceholder)
+        if self._isKnownNonPartial:
+            raise WebIDLError("Two non-partial definitions for the "
+                              "same %s" %
+                              ("interface" if self.isInterface()
+                               else "namespace"),
+                              [location, self.location])
+        self._isKnownNonPartial = True
+        # Now make it look like we were parsed at this new location, since
+        # that's the place where the interface is "really" defined
+        self.location = location
+        assert not self.parent
+        self.parent = parent
+        # Put the new members at the beginning
+        self.members = members + self.members
+
+    def addPartialInterface(self, partial):
+        assert self.identifier.name == partial.identifier.name
+        self._partialInterfaces.append(partial)
+
+    def getJSImplementation(self):
+        classId = self.getExtendedAttribute("JSImplementation")
+        if not classId:
+            return classId
+        assert isinstance(classId, list)
+        assert len(classId) == 1
+        return classId[0]
+
+    def isJSImplemented(self):
+        return bool(self.getJSImplementation())
+
+    def isProbablyShortLivingObject(self):
+        current = self
+        while current:
+            if current.getExtendedAttribute("ProbablyShortLivingObject"):
+                return True
+            current = current.parent
+        return False
+
+    def isNavigatorProperty(self):
+        naviProp = self.getExtendedAttribute("NavigatorProperty")
+        if not naviProp:
+            return False
+        assert len(naviProp) == 1
+        assert isinstance(naviProp, list)
+        assert len(naviProp[0]) != 0
+        return True
+
+    def getNavigatorProperty(self):
+        naviProp = self.getExtendedAttribute("NavigatorProperty")
+        if not naviProp:
+            return None
+        assert len(naviProp) == 1
+        assert isinstance(naviProp, list)
+        assert len(naviProp[0]) != 0
+        conditionExtendedAttributes = self._extendedAttrDict.viewkeys() & IDLInterfaceOrNamespace.conditionExtendedAttributes
+        attr = IDLAttribute(self.location,
+                            IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"), naviProp[0]),
+                            IDLUnresolvedType(self.location, IDLUnresolvedIdentifier(self.location, self.identifier.name)),
+                            True,
+                            extendedAttrDict={ a: self._extendedAttrDict[a] for a in conditionExtendedAttributes },
+                            navigatorObjectGetter=True)
+        attr._exposureGlobalNames = self._exposureGlobalNames
+        # We're abusing Constant a little bit here, because we need Cached. The
+        # getter will create a new object every time, but we're never going to
+        # clear the cached value.
+        extendedAttrs = [ IDLExtendedAttribute(self.location, ("Throws", )),
+                          IDLExtendedAttribute(self.location, ("Cached", )),
+                          IDLExtendedAttribute(self.location, ("Constant", )) ]
+        attr.addExtendedAttributes(extendedAttrs)
+        return attr
+
+    def hasChildInterfaces(self):
+        return self._hasChildInterfaces
+
+    def isOnGlobalProtoChain(self):
+        return self._isOnGlobalProtoChain
+
+    def _getDependentObjects(self):
+        deps = set(self.members)
+        deps.update(self.implementedInterfaces)
+        if self.parent:
+            deps.add(self.parent)
+        return deps
+
+    def hasMembersInSlots(self):
+        return self._ownMembersInSlots != 0
+
+    conditionExtendedAttributes = [ "Pref", "ChromeOnly", "Func", "AvailableIn",
+                                    "SecureContext",
+                                    "CheckAnyPermissions",
+                                    "CheckAllPermissions" ]
+    def isExposedConditionally(self, exclusions=[]):
+        return any(((not a in exclusions) and self.getExtendedAttribute(a)) for a in self.conditionExtendedAttributes)
+
+class IDLInterface(IDLInterfaceOrNamespace):
+    def __init__(self, location, parentScope, name, parent, members,
+                 isKnownNonPartial):
+        IDLInterfaceOrNamespace.__init__(self, location, parentScope, name,
+                                         parent, members, isKnownNonPartial)
+
+    def __str__(self):
+        return "Interface '%s'" % self.identifier.name
+
+    def isInterface(self):
+        return True
+
+    def addExtendedAttributes(self, attrs):
+        for attr in attrs:
+            identifier = attr.identifier()
+
+            # Special cased attrs
+            if identifier == "TreatNonCallableAsNull":
+                raise WebIDLError("TreatNonCallableAsNull cannot be specified on interfaces",
+                                  [attr.location, self.location])
+            if identifier == "TreatNonObjectAsNull":
+                raise WebIDLError("TreatNonObjectAsNull cannot be specified on interfaces",
+                                  [attr.location, self.location])
+            elif identifier == "NoInterfaceObject":
+                if not attr.noArguments():
+                    raise WebIDLError("[NoInterfaceObject] must take no arguments",
+                                      [attr.location])
+
+                if self.ctor():
+                    raise WebIDLError("Constructor and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                self._noInterfaceObject = True
+            elif identifier == "Constructor" or identifier == "NamedConstructor" or identifier == "ChromeConstructor":
+                if identifier == "Constructor" and not self.hasInterfaceObject():
+                    raise WebIDLError(str(identifier) + " and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                if identifier == "NamedConstructor" and not attr.hasValue():
+                    raise WebIDLError("NamedConstructor must either take an identifier or take a named argument list",
+                                      [attr.location])
+
+                if identifier == "ChromeConstructor" and not self.hasInterfaceObject():
+                    raise WebIDLError(str(identifier) + " and NoInterfaceObject are incompatible",
+                                      [self.location])
+
+                args = attr.args() if attr.hasArgs() else []
+
+                if self.identifier.name == "Promise":
+                    promiseType = BuiltinTypes[IDLBuiltinType.Types.any]
+                else:
+                    promiseType = None
+                retType = IDLWrapperType(self.location, self, promiseType)
+
+                if identifier == "Constructor" or identifier == "ChromeConstructor":
+                    name = "constructor"
+                    allowForbidden = True
+                else:
+                    name = attr.value()
+                    allowForbidden = False
+
+                methodIdentifier = IDLUnresolvedIdentifier(self.location, name,
+                                                           allowForbidden=allowForbidden)
+
+                method = IDLMethod(self.location, methodIdentifier, retType,
+                                   args, static=True)
+                # Constructors are always NewObject and are always
+                # assumed to be able to throw (since there's no way to
+                # indicate otherwise) and never have any other
+                # extended attributes.
+                method.addExtendedAttributes(
+                    [IDLExtendedAttribute(self.location, ("NewObject",)),
+                     IDLExtendedAttribute(self.location, ("Throws",))])
+                if identifier == "ChromeConstructor":
+                    method.addExtendedAttributes(
+                        [IDLExtendedAttribute(self.location, ("ChromeOnly",))])
+
+                if identifier == "Constructor" or identifier == "ChromeConstructor":
+                    method.resolve(self)
+                else:
+                    # We need to detect conflicts for NamedConstructors across
+                    # interfaces. We first call resolve on the parentScope,
+                    # which will merge all NamedConstructors with the same
+                    # identifier accross interfaces as overloads.
+                    method.resolve(self.parentScope)
+
+                    # Then we look up the identifier on the parentScope. If the
+                    # result is the same as the method we're adding then it
+                    # hasn't been added as an overload and it's the first time
+                    # we've encountered a NamedConstructor with that identifier.
+                    # If the result is not the same as the method we're adding
+                    # then it has been added as an overload and we need to check
+                    # whether the result is actually one of our existing
+                    # NamedConstructors.
+                    newMethod = self.parentScope.lookupIdentifier(method.identifier)
+                    if newMethod == method:
+                        self.namedConstructors.append(method)
+                    elif newMethod not in self.namedConstructors:
+                        raise WebIDLError("NamedConstructor conflicts with a NamedConstructor of a different interface",
+                                          [method.location, newMethod.location])
+            elif (identifier == "ArrayClass"):
+                if not attr.noArguments():
+                    raise WebIDLError("[ArrayClass] must take no arguments",
+                                      [attr.location])
+                if self.parent:
+                    raise WebIDLError("[ArrayClass] must not be specified on "
+                                      "an interface with inherited interfaces",
+                                      [attr.location, self.location])
+            elif (identifier == "ExceptionClass"):
+                if not attr.noArguments():
+                    raise WebIDLError("[ExceptionClass] must take no arguments",
+                                      [attr.location])
+                if self.parent:
+                    raise WebIDLError("[ExceptionClass] must not be specified on "
+                                      "an interface with inherited interfaces",
+                                      [attr.location, self.location])
+            elif identifier == "Global":
+                if attr.hasValue():
+                    self.globalNames = [attr.value()]
+                elif attr.hasArgs():
+                    self.globalNames = attr.args()
+                else:
+                    self.globalNames = [self.identifier.name]
+                self.parentScope.globalNames.update(self.globalNames)
+                for globalName in self.globalNames:
+                    self.parentScope.globalNameMapping[globalName].add(self.identifier.name)
+                self._isOnGlobalProtoChain = True
+            elif identifier == "PrimaryGlobal":
+                if not attr.noArguments():
+                    raise WebIDLError("[PrimaryGlobal] must take no arguments",
+                                      [attr.location])
+                if self.parentScope.primaryGlobalAttr is not None:
+                    raise WebIDLError(
+                        "[PrimaryGlobal] specified twice",
+                        [attr.location,
+                         self.parentScope.primaryGlobalAttr.location])
+                self.parentScope.primaryGlobalAttr = attr
+                self.parentScope.primaryGlobalName = self.identifier.name
+                self.parentScope.globalNames.add(self.identifier.name)
+                self.parentScope.globalNameMapping[self.identifier.name].add(self.identifier.name)
+                self._isOnGlobalProtoChain = True
+            elif identifier == "SecureContext":
+                if not attr.noArguments():
+                    raise WebIDLError("[%s] must take no arguments" % identifier,
+                                      [attr.location])
+                # This gets propagated to all our members.
+                for member in self.members:
+                    if member.getExtendedAttribute("SecureContext"):
+                        raise WebIDLError("[SecureContext] specified on both "
+                                          "an interface member and on the "
+                                          "interface itself",
+                                          [member.location, attr.location])
+                    member.addExtendedAttributes([attr])
+            elif (identifier == "NeedResolve" or
+                  identifier == "OverrideBuiltins" or
+                  identifier == "ChromeOnly" or
+                  identifier == "Unforgeable" or
+                  identifier == "UnsafeInPrerendering" or
+                  identifier == "LegacyEventInit" or
+                  identifier == "ProbablyShortLivingObject" or
+                  identifier == "LegacyUnenumerableNamedProperties" or
+                  identifier == "NonOrdinaryGetPrototypeOf"):
+                # Known extended attributes that do not take values
+                if not attr.noArguments():
+                    raise WebIDLError("[%s] must take no arguments" % identifier,
+                                      [attr.location])
+            elif identifier == "Exposed":
+                convertExposedAttrToGlobalNameSet(attr,
+                                                  self._exposureGlobalNames)
+            elif (identifier == "Pref" or
+                  identifier == "JSImplementation" or
+                  identifier == "HeaderFile" or
+                  identifier == "NavigatorProperty" or
+                  identifier == "Func" or
+                  identifier == "Deprecated"):
+                # Known extended attributes that take a string value
+                if not attr.hasValue():
+                    raise WebIDLError("[%s] must have a value" % identifier,
+                                      [attr.location])
+            else:
+                raise WebIDLError("Unknown extended attribute %s on interface" % identifier,
+                                  [attr.location])
+
+            attrlist = attr.listValue()
+            self._extendedAttrDict[identifier] = attrlist if len(attrlist) else True
+
+
+class IDLNamespace(IDLInterfaceOrNamespace):
+    def __init__(self, location, parentScope, name, members, isKnownNonPartial):
+        IDLInterfaceOrNamespace.__init__(self, location, parentScope, name,
+                                         None, members, isKnownNonPartial)
+
+    def __str__(self):
+        return "Namespace '%s'" % self.identifier.name
+
+    def isNamespace(self):
+        return True
+
+    def addExtendedAttributes(self, attrs):
+        # The set of things namespaces support is small enough it's simpler
+        # to factor out into a separate method than it is to sprinkle
+        # isNamespace() checks all through
+        # IDLInterfaceOrNamespace.addExtendedAttributes.
+        for attr in attrs:
+            identifier = attr.identifier()
+
+            if identifier == "Exposed":
+                convertExposedAttrToGlobalNameSet(attr,
+                                                  self._exposureGlobalNames)
+            elif identifier == "ClassString":
+                # Takes a string value to override the default "Object" if
+                # desired.
+                if not attr.hasValue():
+                    raise WebIDLError("[%s] must have a value" % identifier,
+                                      [attr.location])
+            elif identifier == "ProtoObjectHack":
+                if not attr.noArguments():
+                    raise WebIDLError("[%s] must not have arguments" % identifier,
+                                      [attr.location])
+            else:
+                raise WebIDLError("Unknown extended attribute %s on namespace" %
+                                  identifier,
+                                  [attr.location])
+
+            attrlist = attr.listValue()
+            self._extendedAttrDict[identifier] = attrlist if len(attrlist) else True
+
+
+class IDLDictionary(IDLObjectWithScope):
+    def __init__(self, location, parentScope, name, parent, members):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+        assert not parent or isinstance(parent, IDLIdentifierPlaceholder)
+
+        self.parent = parent
+        self._finished = False
+        self.members = list(members)
+
+        IDLObjectWithScope.__init__(self, location, parentScope, name)
+
+    def __str__(self):
+        return "Dictionary '%s'" % self.identifier.name
+
+    def isDictionary(self):
+        return True
+
+    def canBeEmpty(self):
+        """
+        Returns true if this dictionary can be empty (that is, it has no
+        required members and neither do any of its ancestors).
+        """
+        return (all(member.optional for member in self.members) and
+                (not self.parent or self.parent.canBeEmpty()))
+
+    def finish(self, scope):
+        if self._finished:
+            return
+
+        self._finished = True
+
+        if self.parent:
+            assert isinstance(self.parent, IDLIdentifierPlaceholder)
+            oldParent = self.parent
+            self.parent = self.parent.finish(scope)
+            if not isinstance(self.parent, IDLDictionary):
+                raise WebIDLError("Dictionary %s has parent that is not a dictionary" %
+                                  self.identifier.name,
+                                  [oldParent.location, self.parent.location])
+
+            # Make sure the parent resolves all its members before we start
+            # looking at them.
+            self.parent.finish(scope)
+
+        for member in self.members:
+            member.resolve(self)
+            if not member.isComplete():
+                member.complete(scope)
+                assert member.type.isComplete()
+
+        # Members of a dictionary are sorted in lexicographic order
+        self.members.sort(cmp=cmp, key=lambda x: x.identifier.name)
+
+        inheritedMembers = []
+        ancestor = self.parent
+        while ancestor:
+            if ancestor == self:
+                raise WebIDLError("Dictionary %s has itself as an ancestor" %
+                                  self.identifier.name,
+                                  [self.identifier.location])
+            inheritedMembers.extend(ancestor.members)
+            ancestor = ancestor.parent
+
+        # Catch name duplication
+        for inheritedMember in inheritedMembers:
+            for member in self.members:
+                if member.identifier.name == inheritedMember.identifier.name:
+                    raise WebIDLError("Dictionary %s has two members with name %s" %
+                                      (self.identifier.name, member.identifier.name),
+                                      [member.location, inheritedMember.location])
+
+    def validate(self):
+        def typeContainsDictionary(memberType, dictionary):
+            """
+            Returns a tuple whose:
+
+                - First element is a Boolean value indicating whether
+                  memberType contains dictionary.
+
+                - Second element is:
+                    A list of locations that leads from the type that was passed in
+                    the memberType argument, to the dictionary being validated,
+                    if the boolean value in the first element is True.
+
+                    None, if the boolean value in the first element is False.
+            """
+
+            if (memberType.nullable() or
+                memberType.isSequence() or
+                memberType.isMozMap()):
+                return typeContainsDictionary(memberType.inner, dictionary)
+
+            if memberType.isDictionary():
+                if memberType.inner == dictionary:
+                    return (True, [memberType.location])
+
+                (contains, locations) = dictionaryContainsDictionary(memberType.inner,
+                                                                     dictionary)
+                if contains:
+                    return (True, [memberType.location] + locations)
+
+            if memberType.isUnion():
+                for member in memberType.flatMemberTypes:
+                    (contains, locations) = typeContainsDictionary(member, dictionary)
+                    if contains:
+                        return (True, locations)
+
+            return (False, None)
+
+        def dictionaryContainsDictionary(dictMember, dictionary):
+            for member in dictMember.members:
+                (contains, locations) = typeContainsDictionary(member.type, dictionary)
+                if contains:
+                    return (True, [member.location] + locations)
+
+            if dictMember.parent:
+                if dictMember.parent == dictionary:
+                    return (True, [dictMember.location])
+                else:
+                    (contains, locations) = dictionaryContainsDictionary(dictMember.parent, dictionary)
+                    if contains:
+                        return (True, [dictMember.location] + locations)
+
+            return (False, None)
+
+        for member in self.members:
+            if member.type.isDictionary() and member.type.nullable():
+                raise WebIDLError("Dictionary %s has member with nullable "
+                                  "dictionary type" % self.identifier.name,
+                                  [member.location])
+            (contains, locations) = typeContainsDictionary(member.type, self)
+            if contains:
+                raise WebIDLError("Dictionary %s has member with itself as type." %
+                                  self.identifier.name,
+                                  [member.location] + locations)
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def _getDependentObjects(self):
+        deps = set(self.members)
+        if (self.parent):
+            deps.add(self.parent)
+        return deps
+
+
+class IDLEnum(IDLObjectWithIdentifier):
+    def __init__(self, location, parentScope, name, values):
+        assert isinstance(parentScope, IDLScope)
+        assert isinstance(name, IDLUnresolvedIdentifier)
+
+        if len(values) != len(set(values)):
+            raise WebIDLError("Enum %s has multiple identical strings" % name.name,
+                              [location])
+
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, name)
+        self._values = values
+
+    def values(self):
+        return self._values
+
+    def finish(self, scope):
+        pass
+
+    def validate(self):
+        pass
+
+    def isEnum(self):
+        return True
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLType(IDLObject):
+    Tags = enum(
+        # The integer types
+        'int8',
+        'uint8',
+        'int16',
+        'uint16',
+        'int32',
+        'uint32',
+        'int64',
+        'uint64',
+        # Additional primitive types
+        'bool',
+        'unrestricted_float',
+        'float',
+        'unrestricted_double',
+        # "double" last primitive type to match IDLBuiltinType
+        'double',
+        # Other types
+        'any',
+        'domstring',
+        'bytestring',
+        'usvstring',
+        'object',
+        'date',
+        'void',
+        # Funny stuff
+        'interface',
+        'dictionary',
+        'enum',
+        'callback',
+        'union',
+        'sequence',
+        'mozmap'
+        )
+
+    def __init__(self, location, name):
+        IDLObject.__init__(self, location)
+        self.name = name
+        self.builtin = False
+
+    def __eq__(self, other):
+        return other and self.builtin == other.builtin and self.name == other.name
+
+    def __ne__(self, other):
+        return not self == other
+
+    def __str__(self):
+        return str(self.name)
+
+    def isType(self):
+        return True
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isBoolean(self):
+        return False
+
+    def isNumeric(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isUSVString(self):
+        return False
+
+    def isVoid(self):
+        return self.name == "Void"
+
+    def isSequence(self):
+        return False
+
+    def isMozMap(self):
+        return False
+
+    def isArrayBuffer(self):
+        return False
+
+    def isArrayBufferView(self):
+        return False
+
+    def isSharedArrayBuffer(self):
+        return False
+
+    def isTypedArray(self):
+        return False
+
+    def isCallbackInterface(self):
+        return False
+
+    def isNonCallbackInterface(self):
+        return False
+
+    def isGeckoInterface(self):
+        """ Returns a boolean indicating whether this type is an 'interface'
+            type that is implemented in Gecko. At the moment, this returns
+            true for all interface types that are not types from the TypedArray
+            spec."""
+        return self.isInterface() and not self.isSpiderMonkeyInterface()
+
+    def isSpiderMonkeyInterface(self):
+        """ Returns a boolean indicating whether this type is an 'interface'
+            type that is implemented in Spidermonkey.  At the moment, this
+            only returns true for the types from the TypedArray spec. """
+        return self.isInterface() and (self.isArrayBuffer() or
+                                       self.isArrayBufferView() or
+                                       self.isSharedArrayBuffer() or
+                                       self.isTypedArray())
+
+    def isDictionary(self):
+        return False
+
+    def isInterface(self):
+        return False
+
+    def isAny(self):
+        return self.tag() == IDLType.Tags.any
+
+    def isDate(self):
+        return self.tag() == IDLType.Tags.date
+
+    def isObject(self):
+        return self.tag() == IDLType.Tags.object
+
+    def isPromise(self):
+        return False
+
+    def isComplete(self):
+        return True
+
+    def includesRestrictedFloat(self):
+        return False
+
+    def isFloat(self):
+        return False
+
+    def isUnrestricted(self):
+        # Should only call this on float types
+        assert self.isFloat()
+
+    def isSerializable(self):
+        return False
+
+    def tag(self):
+        assert False  # Override me!
+
+    def treatNonCallableAsNull(self):
+        assert self.tag() == IDLType.Tags.callback
+        return self.nullable() and self.inner.callback._treatNonCallableAsNull
+
+    def treatNonObjectAsNull(self):
+        assert self.tag() == IDLType.Tags.callback
+        return self.nullable() and self.inner.callback._treatNonObjectAsNull
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def resolveType(self, parentScope):
+        pass
+
+    def unroll(self):
+        return self
+
+    def isDistinguishableFrom(self, other):
+        raise TypeError("Can't tell whether a generic type is or is not "
+                        "distinguishable from other things")
+
+    def isExposedInAllOf(self, exposureSet):
+        return True
+
+
+class IDLUnresolvedType(IDLType):
+    """
+        Unresolved types are interface types
+    """
+
+    def __init__(self, location, name, promiseInnerType=None):
+        IDLType.__init__(self, location, name)
+        self._promiseInnerType = promiseInnerType
+
+    def isComplete(self):
+        return False
+
+    def complete(self, scope):
+        obj = None
+        try:
+            obj = scope._lookupIdentifier(self.name)
+        except:
+            raise WebIDLError("Unresolved type '%s'." % self.name,
+                              [self.location])
+
+        assert obj
+        if obj.isType():
+            print obj
+        assert not obj.isType()
+        if obj.isTypedef():
+            assert self.name.name == obj.identifier.name
+            typedefType = IDLTypedefType(self.location, obj.innerType,
+                                         obj.identifier)
+            assert not typedefType.isComplete()
+            return typedefType.complete(scope)
+        elif obj.isCallback() and not obj.isInterface():
+            assert self.name.name == obj.identifier.name
+            return IDLCallbackType(self.location, obj)
+
+        if self._promiseInnerType and not self._promiseInnerType.isComplete():
+            self._promiseInnerType = self._promiseInnerType.complete(scope)
+
+        name = self.name.resolve(scope, None)
+        return IDLWrapperType(self.location, obj, self._promiseInnerType)
+
+    def isDistinguishableFrom(self, other):
+        raise TypeError("Can't tell whether an unresolved type is or is not "
+                        "distinguishable from other things")
+
+
+class IDLParameterizedType(IDLType):
+    def __init__(self, location, name, innerType):
+        IDLType.__init__(self, location, name)
+        self.builtin = False
+        self.inner = innerType
+
+    def includesRestrictedFloat(self):
+        return self.inner.includesRestrictedFloat()
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.inner.isComplete()
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+
+class IDLNullableType(IDLParameterizedType):
+    def __init__(self, location, innerType):
+        assert not innerType.isVoid()
+        assert not innerType == BuiltinTypes[IDLBuiltinType.Types.any]
+
+        name = innerType.name
+        if innerType.isComplete():
+            name += "OrNull"
+        IDLParameterizedType.__init__(self, location, name, innerType)
+
+    def __eq__(self, other):
+        return isinstance(other, IDLNullableType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "OrNull"
+
+    def nullable(self):
+        return True
+
+    def isCallback(self):
+        return self.inner.isCallback()
+
+    def isPrimitive(self):
+        return self.inner.isPrimitive()
+
+    def isBoolean(self):
+        return self.inner.isBoolean()
+
+    def isNumeric(self):
+        return self.inner.isNumeric()
+
+    def isString(self):
+        return self.inner.isString()
+
+    def isByteString(self):
+        return self.inner.isByteString()
+
+    def isDOMString(self):
+        return self.inner.isDOMString()
+
+    def isUSVString(self):
+        return self.inner.isUSVString()
+
+    def isFloat(self):
+        return self.inner.isFloat()
+
+    def isUnrestricted(self):
+        return self.inner.isUnrestricted()
+
+    def isInteger(self):
+        return self.inner.isInteger()
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return self.inner.isSequence()
+
+    def isMozMap(self):
+        return self.inner.isMozMap()
+
+    def isArrayBuffer(self):
+        return self.inner.isArrayBuffer()
+
+    def isArrayBufferView(self):
+        return self.inner.isArrayBufferView()
+
+    def isSharedArrayBuffer(self):
+        return self.inner.isSharedArrayBuffer()
+
+    def isTypedArray(self):
+        return self.inner.isTypedArray()
+
+    def isDictionary(self):
+        return self.inner.isDictionary()
+
+    def isInterface(self):
+        return self.inner.isInterface()
+
+    def isPromise(self):
+        return self.inner.isPromise()
+
+    def isCallbackInterface(self):
+        return self.inner.isCallbackInterface()
+
+    def isNonCallbackInterface(self):
+        return self.inner.isNonCallbackInterface()
+
+    def isEnum(self):
+        return self.inner.isEnum()
+
+    def isUnion(self):
+        return self.inner.isUnion()
+
+    def isSerializable(self):
+        return self.inner.isSerializable()
+
+    def tag(self):
+        return self.inner.tag()
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        if self.inner.nullable():
+            raise WebIDLError("The inner type of a nullable type must not be "
+                              "a nullable type",
+                              [self.location, self.inner.location])
+        if self.inner.isUnion():
+            if self.inner.hasNullableType:
+                raise WebIDLError("The inner type of a nullable type must not "
+                                  "be a union type that itself has a nullable "
+                                  "type as a member type", [self.location])
+
+        self.name = self.inner.name + "OrNull"
+        return self
+
+    def isDistinguishableFrom(self, other):
+        if (other.nullable() or (other.isUnion() and other.hasNullableType) or
+            other.isDictionary()):
+            # Can't tell which type null should become
+            return False
+        return self.inner.isDistinguishableFrom(other)
+
+
+class IDLSequenceType(IDLParameterizedType):
+    def __init__(self, location, parameterType):
+        assert not parameterType.isVoid()
+
+        IDLParameterizedType.__init__(self, location, parameterType.name, parameterType)
+        # Need to set self.name up front if our inner type is already complete,
+        # since in that case our .complete() won't be called.
+        if self.inner.isComplete():
+            self.name = self.inner.name + "Sequence"
+
+    def __eq__(self, other):
+        return isinstance(other, IDLSequenceType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "Sequence"
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isUSVString(self):
+        return False
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return True
+
+    def isDictionary(self):
+        return False
+
+    def isInterface(self):
+        return False
+
+    def isEnum(self):
+        return False
+
+    def isSerializable(self):
+        return self.inner.isSerializable()
+
+    def tag(self):
+        return IDLType.Tags.sequence
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        self.name = self.inner.name + "Sequence"
+        return self
+
+    def isDistinguishableFrom(self, other):
+        if other.isPromise():
+            return False
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isDate() or other.isInterface() or
+                other.isDictionary() or
+                other.isCallback() or other.isMozMap())
+
+
+class IDLMozMapType(IDLParameterizedType):
+    def __init__(self, location, parameterType):
+        assert not parameterType.isVoid()
+
+        IDLParameterizedType.__init__(self, location, parameterType.name, parameterType)
+        # Need to set self.name up front if our inner type is already complete,
+        # since in that case our .complete() won't be called.
+        if self.inner.isComplete():
+            self.name = self.inner.name + "MozMap"
+
+    def __eq__(self, other):
+        return isinstance(other, IDLMozMapType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.inner.__str__() + "MozMap"
+
+    def isMozMap(self):
+        return True
+
+    def tag(self):
+        return IDLType.Tags.mozmap
+
+    def complete(self, scope):
+        self.inner = self.inner.complete(scope)
+        self.name = self.inner.name + "MozMap"
+        return self
+
+    def unroll(self):
+        # We do not unroll our inner.  Just stop at ourselves.  That
+        # lets us add headers for both ourselves and our inner as
+        # needed.
+        return self
+
+    def isDistinguishableFrom(self, other):
+        if other.isPromise():
+            return False
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isDate() or other.isNonCallbackInterface() or other.isSequence())
+
+    def isExposedInAllOf(self, exposureSet):
+        return self.inner.unroll().isExposedInAllOf(exposureSet)
+
+
+class IDLUnionType(IDLType):
+    def __init__(self, location, memberTypes):
+        IDLType.__init__(self, location, "")
+        self.memberTypes = memberTypes
+        self.hasNullableType = False
+        self._dictionaryType = None
+        self.flatMemberTypes = None
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLUnionType) and self.memberTypes == other.memberTypes
+
+    def __hash__(self):
+        assert self.isComplete()
+        return self.name.__hash__()
+
+    def isVoid(self):
+        return False
+
+    def isUnion(self):
+        return True
+
+    def isSerializable(self):
+        return all(m.isSerializable() for m in self.memberTypes)
+
+    def includesRestrictedFloat(self):
+        return any(t.includesRestrictedFloat() for t in self.memberTypes)
+
+    def tag(self):
+        return IDLType.Tags.union
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        for t in self.memberTypes:
+            t.resolveType(parentScope)
+
+    def isComplete(self):
+        return self.flatMemberTypes is not None
+
+    def complete(self, scope):
+        def typeName(type):
+            if isinstance(type, IDLNullableType):
+                return typeName(type.inner) + "OrNull"
+            if isinstance(type, IDLWrapperType):
+                return typeName(type._identifier.object())
+            if isinstance(type, IDLObjectWithIdentifier):
+                return typeName(type.identifier)
+            return type.name
+
+        for (i, type) in enumerate(self.memberTypes):
+            if not type.isComplete():
+                self.memberTypes[i] = type.complete(scope)
+
+        self.name = "Or".join(typeName(type) for type in self.memberTypes)
+        self.flatMemberTypes = list(self.memberTypes)
+        i = 0
+        while i < len(self.flatMemberTypes):
+            if self.flatMemberTypes[i].nullable():
+                if self.hasNullableType:
+                    raise WebIDLError("Can't have more than one nullable types in a union",
+                                      [nullableType.location, self.flatMemberTypes[i].location])
+                if self.hasDictionaryType():
+                    raise WebIDLError("Can't have a nullable type and a "
+                                      "dictionary type in a union",
+                                      [self._dictionaryType.location,
+                                       self.flatMemberTypes[i].location])
+                self.hasNullableType = True
+                nullableType = self.flatMemberTypes[i]
+                self.flatMemberTypes[i] = self.flatMemberTypes[i].inner
+                continue
+            if self.flatMemberTypes[i].isDictionary():
+                if self.hasNullableType:
+                    raise WebIDLError("Can't have a nullable type and a "
+                                      "dictionary type in a union",
+                                      [nullableType.location,
+                                       self.flatMemberTypes[i].location])
+                self._dictionaryType = self.flatMemberTypes[i]
+            elif self.flatMemberTypes[i].isUnion():
+                self.flatMemberTypes[i:i + 1] = self.flatMemberTypes[i].memberTypes
+                continue
+            i += 1
+
+        for (i, t) in enumerate(self.flatMemberTypes[:-1]):
+            for u in self.flatMemberTypes[i + 1:]:
+                if not t.isDistinguishableFrom(u):
+                    raise WebIDLError("Flat member types of a union should be "
+                                      "distinguishable, " + str(t) + " is not "
+                                      "distinguishable from " + str(u),
+                                      [self.location, t.location, u.location])
+
+        return self
+
+    def isDistinguishableFrom(self, other):
+        if self.hasNullableType and other.nullable():
+            # Can't tell which type null should become
+            return False
+        if other.isUnion():
+            otherTypes = other.unroll().memberTypes
+        else:
+            otherTypes = [other]
+        # For every type in otherTypes, check that it's distinguishable from
+        # every type in our types
+        for u in otherTypes:
+            if any(not t.isDistinguishableFrom(u) for t in self.memberTypes):
+                return False
+        return True
+
+    def isExposedInAllOf(self, exposureSet):
+        # We could have different member types in different globals.  Just make sure that each thing in exposureSet has one of our member types exposed in it.
+        for globalName in exposureSet:
+            if not any(t.unroll().isExposedInAllOf(set([globalName])) for t
+                       in self.flatMemberTypes):
+                return False
+        return True
+
+    def hasDictionaryType(self):
+        return self._dictionaryType is not None
+
+    def hasPossiblyEmptyDictionaryType(self):
+        return (self._dictionaryType is not None and
+                self._dictionaryType.inner.canBeEmpty())
+
+    def _getDependentObjects(self):
+        return set(self.memberTypes)
+
+
+class IDLTypedefType(IDLType):
+    def __init__(self, location, innerType, name):
+        IDLType.__init__(self, location, name)
+        self.inner = innerType
+        self.builtin = False
+
+    def __eq__(self, other):
+        return isinstance(other, IDLTypedefType) and self.inner == other.inner
+
+    def __str__(self):
+        return self.name
+
+    def nullable(self):
+        return self.inner.nullable()
+
+    def isPrimitive(self):
+        return self.inner.isPrimitive()
+
+    def isBoolean(self):
+        return self.inner.isBoolean()
+
+    def isNumeric(self):
+        return self.inner.isNumeric()
+
+    def isString(self):
+        return self.inner.isString()
+
+    def isByteString(self):
+        return self.inner.isByteString()
+
+    def isDOMString(self):
+        return self.inner.isDOMString()
+
+    def isUSVString(self):
+        return self.inner.isUSVString()
+
+    def isVoid(self):
+        return self.inner.isVoid()
+
+    def isSequence(self):
+        return self.inner.isSequence()
+
+    def isMozMap(self):
+        return self.inner.isMozMap()
+
+    def isDictionary(self):
+        return self.inner.isDictionary()
+
+    def isArrayBuffer(self):
+        return self.inner.isArrayBuffer()
+
+    def isArrayBufferView(self):
+        return self.inner.isArrayBufferView()
+
+    def isSharedArrayBuffer(self):
+        return self.inner.isSharedArrayBuffer()
+
+    def isTypedArray(self):
+        return self.inner.isTypedArray()
+
+    def isInterface(self):
+        return self.inner.isInterface()
+
+    def isCallbackInterface(self):
+        return self.inner.isCallbackInterface()
+
+    def isNonCallbackInterface(self):
+        return self.inner.isNonCallbackInterface()
+
+    def isComplete(self):
+        return False
+
+    def complete(self, parentScope):
+        if not self.inner.isComplete():
+            self.inner = self.inner.complete(parentScope)
+        assert self.inner.isComplete()
+        return self.inner
+
+    # Do we need a resolveType impl?  I don't think it's particularly useful....
+
+    def tag(self):
+        return self.inner.tag()
+
+    def unroll(self):
+        return self.inner.unroll()
+
+    def isDistinguishableFrom(self, other):
+        return self.inner.isDistinguishableFrom(other)
+
+    def _getDependentObjects(self):
+        return self.inner._getDependentObjects()
+
+
+class IDLTypedef(IDLObjectWithIdentifier):
+    def __init__(self, location, parentScope, innerType, name):
+        identifier = IDLUnresolvedIdentifier(location, name)
+        IDLObjectWithIdentifier.__init__(self, location, parentScope, identifier)
+        self.innerType = innerType
+
+    def __str__(self):
+        return "Typedef %s %s" % (self.identifier.name, self.innerType)
+
+    def finish(self, parentScope):
+        if not self.innerType.isComplete():
+            self.innerType = self.innerType.complete(parentScope)
+
+    def validate(self):
+        pass
+
+    def isTypedef(self):
+        return True
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+    def _getDependentObjects(self):
+        return self.innerType._getDependentObjects()
+
+
+class IDLWrapperType(IDLType):
+    def __init__(self, location, inner, promiseInnerType=None):
+        IDLType.__init__(self, location, inner.identifier.name)
+        self.inner = inner
+        self._identifier = inner.identifier
+        self.builtin = False
+        assert not promiseInnerType or inner.identifier.name == "Promise"
+        self._promiseInnerType = promiseInnerType
+
+    def __eq__(self, other):
+        return (isinstance(other, IDLWrapperType) and
+                self._identifier == other._identifier and
+                self.builtin == other.builtin)
+
+    def __str__(self):
+        return str(self.name) + " (Wrapper)"
+
+    def nullable(self):
+        return False
+
+    def isPrimitive(self):
+        return False
+
+    def isString(self):
+        return False
+
+    def isByteString(self):
+        return False
+
+    def isDOMString(self):
+        return False
+
+    def isUSVString(self):
+        return False
+
+    def isVoid(self):
+        return False
+
+    def isSequence(self):
+        return False
+
+    def isDictionary(self):
+        return isinstance(self.inner, IDLDictionary)
+
+    def isInterface(self):
+        return (isinstance(self.inner, IDLInterface) or
+                isinstance(self.inner, IDLExternalInterface))
+
+    def isCallbackInterface(self):
+        return self.isInterface() and self.inner.isCallback()
+
+    def isNonCallbackInterface(self):
+        return self.isInterface() and not self.inner.isCallback()
+
+    def isEnum(self):
+        return isinstance(self.inner, IDLEnum)
+
+    def isPromise(self):
+        return (isinstance(self.inner, IDLInterface) and
+                self.inner.identifier.name == "Promise")
+
+    def promiseInnerType(self):
+        assert self.isPromise()
+        return self._promiseInnerType
+
+    def isSerializable(self):
+        if self.isInterface():
+            if self.inner.isExternal():
+                return False
+            return any(m.isMethod() and m.isJsonifier() for m in self.inner.members)
+        elif self.isEnum():
+            return True
+        elif self.isDictionary():
+            return all(m.type.isSerializable() for m in self.inner.members)
+        else:
+            raise WebIDLError("IDLWrapperType wraps type %s that we don't know if "
+                              "is serializable" % type(self.inner), [self.location])
+
+    def resolveType(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.inner.resolve(parentScope)
+
+    def isComplete(self):
+        return True
+
+    def tag(self):
+        if self.isInterface():
+            return IDLType.Tags.interface
+        elif self.isEnum():
+            return IDLType.Tags.enum
+        elif self.isDictionary():
+            return IDLType.Tags.dictionary
+        else:
+            assert False
+
+    def isDistinguishableFrom(self, other):
+        if self.isPromise():
+            return False
+        if other.isPromise():
+            return False
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        assert self.isInterface() or self.isEnum() or self.isDictionary()
+        if self.isEnum():
+            return (other.isPrimitive() or other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isMozMap() or other.isDate())
+        if self.isDictionary() and other.nullable():
+            return False
+        if (other.isPrimitive() or other.isString() or other.isEnum() or
+            other.isDate() or other.isSequence()):
+            return True
+        if self.isDictionary():
+            return other.isNonCallbackInterface()
+
+        assert self.isInterface()
+        if other.isInterface():
+            if other.isSpiderMonkeyInterface():
+                # Just let |other| handle things
+                return other.isDistinguishableFrom(self)
+            assert self.isGeckoInterface() and other.isGeckoInterface()
+            if self.inner.isExternal() or other.unroll().inner.isExternal():
+                return self != other
+            return (len(self.inner.interfacesBasedOnSelf &
+                        other.unroll().inner.interfacesBasedOnSelf) == 0 and
+                    (self.isNonCallbackInterface() or
+                     other.isNonCallbackInterface()))
+        if (other.isDictionary() or other.isCallback() or
+            other.isMozMap()):
+            return self.isNonCallbackInterface()
+
+        # Not much else |other| can be
+        assert other.isObject()
+        return False
+
+    def isExposedInAllOf(self, exposureSet):
+        if not self.isInterface():
+            return True
+        iface = self.inner
+        if iface.isExternal():
+            # Let's say true, though ideally we'd only do this when
+            # exposureSet contains the primary global's name.
+            return True
+        if (self.isPromise() and
+            # Check the internal type
+            not self.promiseInnerType().unroll().isExposedInAllOf(exposureSet)):
+            return False
+        return iface.exposureSet.issuperset(exposureSet)
+
+    def _getDependentObjects(self):
+        # NB: The codegen for an interface type depends on
+        #  a) That the identifier is in fact an interface (as opposed to
+        #     a dictionary or something else).
+        #  b) The native type of the interface.
+        #  If we depend on the interface object we will also depend on
+        #  anything the interface depends on which is undesirable.  We
+        #  considered implementing a dependency just on the interface type
+        #  file, but then every modification to an interface would cause this
+        #  to be regenerated which is still undesirable.  We decided not to
+        #  depend on anything, reasoning that:
+        #  1) Changing the concrete type of the interface requires modifying
+        #     Bindings.conf, which is still a global dependency.
+        #  2) Changing an interface to a dictionary (or vice versa) with the
+        #     same identifier should be incredibly rare.
+        #
+        # On the other hand, if our type is a dictionary, we should
+        # depend on it, because the member types of a dictionary
+        # affect whether a method taking the dictionary as an argument
+        # takes a JSContext* argument or not.
+        if self.isDictionary():
+            return set([self.inner])
+        return set()
+
+
+class IDLBuiltinType(IDLType):
+
+    Types = enum(
+        # The integer types
+        'byte',
+        'octet',
+        'short',
+        'unsigned_short',
+        'long',
+        'unsigned_long',
+        'long_long',
+        'unsigned_long_long',
+        # Additional primitive types
+        'boolean',
+        'unrestricted_float',
+        'float',
+        'unrestricted_double',
+        # IMPORTANT: "double" must be the last primitive type listed
+        'double',
+        # Other types
+        'any',
+        'domstring',
+        'bytestring',
+        'usvstring',
+        'object',
+        'date',
+        'void',
+        # Funny stuff
+        'ArrayBuffer',
+        'ArrayBufferView',
+        'SharedArrayBuffer',
+        'Int8Array',
+        'Uint8Array',
+        'Uint8ClampedArray',
+        'Int16Array',
+        'Uint16Array',
+        'Int32Array',
+        'Uint32Array',
+        'Float32Array',
+        'Float64Array'
+        )
+
+    TagLookup = {
+        Types.byte: IDLType.Tags.int8,
+        Types.octet: IDLType.Tags.uint8,
+        Types.short: IDLType.Tags.int16,
+        Types.unsigned_short: IDLType.Tags.uint16,
+        Types.long: IDLType.Tags.int32,
+        Types.unsigned_long: IDLType.Tags.uint32,
+        Types.long_long: IDLType.Tags.int64,
+        Types.unsigned_long_long: IDLType.Tags.uint64,
+        Types.boolean: IDLType.Tags.bool,
+        Types.unrestricted_float: IDLType.Tags.unrestricted_float,
+        Types.float: IDLType.Tags.float,
+        Types.unrestricted_double: IDLType.Tags.unrestricted_double,
+        Types.double: IDLType.Tags.double,
+        Types.any: IDLType.Tags.any,
+        Types.domstring: IDLType.Tags.domstring,
+        Types.bytestring: IDLType.Tags.bytestring,
+        Types.usvstring: IDLType.Tags.usvstring,
+        Types.object: IDLType.Tags.object,
+        Types.date: IDLType.Tags.date,
+        Types.void: IDLType.Tags.void,
+        Types.ArrayBuffer: IDLType.Tags.interface,
+        Types.ArrayBufferView: IDLType.Tags.interface,
+        Types.SharedArrayBuffer: IDLType.Tags.interface,
+        Types.Int8Array: IDLType.Tags.interface,
+        Types.Uint8Array: IDLType.Tags.interface,
+        Types.Uint8ClampedArray: IDLType.Tags.interface,
+        Types.Int16Array: IDLType.Tags.interface,
+        Types.Uint16Array: IDLType.Tags.interface,
+        Types.Int32Array: IDLType.Tags.interface,
+        Types.Uint32Array: IDLType.Tags.interface,
+        Types.Float32Array: IDLType.Tags.interface,
+        Types.Float64Array: IDLType.Tags.interface
+    }
+
+    def __init__(self, location, name, type):
+        IDLType.__init__(self, location, name)
+        self.builtin = True
+        self._typeTag = type
+
+    def isPrimitive(self):
+        return self._typeTag <= IDLBuiltinType.Types.double
+
+    def isBoolean(self):
+        return self._typeTag == IDLBuiltinType.Types.boolean
+
+    def isNumeric(self):
+        return self.isPrimitive() and not self.isBoolean()
+
+    def isString(self):
+        return (self._typeTag == IDLBuiltinType.Types.domstring or
+                self._typeTag == IDLBuiltinType.Types.bytestring or
+                self._typeTag == IDLBuiltinType.Types.usvstring)
+
+    def isByteString(self):
+        return self._typeTag == IDLBuiltinType.Types.bytestring
+
+    def isDOMString(self):
+        return self._typeTag == IDLBuiltinType.Types.domstring
+
+    def isUSVString(self):
+        return self._typeTag == IDLBuiltinType.Types.usvstring
+
+    def isInteger(self):
+        return self._typeTag <= IDLBuiltinType.Types.unsigned_long_long
+
+    def isArrayBuffer(self):
+        return self._typeTag == IDLBuiltinType.Types.ArrayBuffer
+
+    def isArrayBufferView(self):
+        return self._typeTag == IDLBuiltinType.Types.ArrayBufferView
+
+    def isSharedArrayBuffer(self):
+        return self._typeTag == IDLBuiltinType.Types.SharedArrayBuffer
+
+    def isTypedArray(self):
+        return (self._typeTag >= IDLBuiltinType.Types.Int8Array and
+                self._typeTag <= IDLBuiltinType.Types.Float64Array)
+
+    def isInterface(self):
+        # TypedArray things are interface types per the TypedArray spec,
+        # but we handle them as builtins because SpiderMonkey implements
+        # all of it internally.
+        return (self.isArrayBuffer() or
+                self.isArrayBufferView() or
+                self.isSharedArrayBuffer() or
+                self.isTypedArray())
+
+    def isNonCallbackInterface(self):
+        # All the interfaces we can be are non-callback
+        return self.isInterface()
+
+    def isFloat(self):
+        return (self._typeTag == IDLBuiltinType.Types.float or
+                self._typeTag == IDLBuiltinType.Types.double or
+                self._typeTag == IDLBuiltinType.Types.unrestricted_float or
+                self._typeTag == IDLBuiltinType.Types.unrestricted_double)
+
+    def isUnrestricted(self):
+        assert self.isFloat()
+        return (self._typeTag == IDLBuiltinType.Types.unrestricted_float or
+                self._typeTag == IDLBuiltinType.Types.unrestricted_double)
+
+    def isSerializable(self):
+        return self.isPrimitive() or self.isString() or self.isDate()
+
+    def includesRestrictedFloat(self):
+        return self.isFloat() and not self.isUnrestricted()
+
+    def tag(self):
+        return IDLBuiltinType.TagLookup[self._typeTag]
+
+    def isDistinguishableFrom(self, other):
+        if other.isPromise():
+            return False
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        if self.isBoolean():
+            return (other.isNumeric() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isMozMap() or other.isDate())
+        if self.isNumeric():
+            return (other.isBoolean() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isMozMap() or other.isDate())
+        if self.isString():
+            return (other.isPrimitive() or other.isInterface() or
+                    other.isObject() or
+                    other.isCallback() or other.isDictionary() or
+                    other.isSequence() or other.isMozMap() or other.isDate())
+        if self.isAny():
+            # Can't tell "any" apart from anything
+            return False
+        if self.isObject():
+            return other.isPrimitive() or other.isString() or other.isEnum()
+        if self.isDate():
+            return (other.isPrimitive() or other.isString() or other.isEnum() or
+                    other.isInterface() or other.isCallback() or
+                    other.isDictionary() or other.isSequence() or
+                    other.isMozMap())
+        if self.isVoid():
+            return not other.isVoid()
+        # Not much else we could be!
+        assert self.isSpiderMonkeyInterface()
+        # Like interfaces, but we know we're not a callback
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isCallback() or other.isDictionary() or
+                other.isSequence() or other.isMozMap() or other.isDate() or
+                (other.isInterface() and (
+                 # ArrayBuffer is distinguishable from everything
+                 # that's not an ArrayBuffer or a callback interface
+                 (self.isArrayBuffer() and not other.isArrayBuffer()) or
+                 (self.isSharedArrayBuffer() and not other.isSharedArrayBuffer()) or
+                 # ArrayBufferView is distinguishable from everything
+                 # that's not an ArrayBufferView or typed array.
+                 (self.isArrayBufferView() and not other.isArrayBufferView() and
+                  not other.isTypedArray()) or
+                 # Typed arrays are distinguishable from everything
+                 # except ArrayBufferView and the same type of typed
+                 # array
+                 (self.isTypedArray() and not other.isArrayBufferView() and not
+                  (other.isTypedArray() and other.name == self.name)))))
+
+    def _getDependentObjects(self):
+        return set()
+
+BuiltinTypes = {
+    IDLBuiltinType.Types.byte:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Byte",
+                       IDLBuiltinType.Types.byte),
+    IDLBuiltinType.Types.octet:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Octet",
+                       IDLBuiltinType.Types.octet),
+    IDLBuiltinType.Types.short:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Short",
+                       IDLBuiltinType.Types.short),
+    IDLBuiltinType.Types.unsigned_short:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedShort",
+                       IDLBuiltinType.Types.unsigned_short),
+    IDLBuiltinType.Types.long:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Long",
+                       IDLBuiltinType.Types.long),
+    IDLBuiltinType.Types.unsigned_long:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedLong",
+                       IDLBuiltinType.Types.unsigned_long),
+    IDLBuiltinType.Types.long_long:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "LongLong",
+                       IDLBuiltinType.Types.long_long),
+    IDLBuiltinType.Types.unsigned_long_long:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnsignedLongLong",
+                       IDLBuiltinType.Types.unsigned_long_long),
+    IDLBuiltinType.Types.boolean:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Boolean",
+                       IDLBuiltinType.Types.boolean),
+    IDLBuiltinType.Types.float:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float",
+                       IDLBuiltinType.Types.float),
+    IDLBuiltinType.Types.unrestricted_float:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnrestrictedFloat",
+                       IDLBuiltinType.Types.unrestricted_float),
+    IDLBuiltinType.Types.double:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Double",
+                       IDLBuiltinType.Types.double),
+    IDLBuiltinType.Types.unrestricted_double:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "UnrestrictedDouble",
+                       IDLBuiltinType.Types.unrestricted_double),
+    IDLBuiltinType.Types.any:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Any",
+                       IDLBuiltinType.Types.any),
+    IDLBuiltinType.Types.domstring:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "String",
+                       IDLBuiltinType.Types.domstring),
+    IDLBuiltinType.Types.bytestring:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "ByteString",
+                       IDLBuiltinType.Types.bytestring),
+    IDLBuiltinType.Types.usvstring:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "USVString",
+                       IDLBuiltinType.Types.usvstring),
+    IDLBuiltinType.Types.object:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Object",
+                       IDLBuiltinType.Types.object),
+    IDLBuiltinType.Types.date:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Date",
+                       IDLBuiltinType.Types.date),
+    IDLBuiltinType.Types.void:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Void",
+                       IDLBuiltinType.Types.void),
+    IDLBuiltinType.Types.ArrayBuffer:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "ArrayBuffer",
+                       IDLBuiltinType.Types.ArrayBuffer),
+    IDLBuiltinType.Types.ArrayBufferView:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "ArrayBufferView",
+                       IDLBuiltinType.Types.ArrayBufferView),
+    IDLBuiltinType.Types.SharedArrayBuffer:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "SharedArrayBuffer",
+                       IDLBuiltinType.Types.SharedArrayBuffer),
+    IDLBuiltinType.Types.Int8Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int8Array",
+                       IDLBuiltinType.Types.Int8Array),
+    IDLBuiltinType.Types.Uint8Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint8Array",
+                       IDLBuiltinType.Types.Uint8Array),
+    IDLBuiltinType.Types.Uint8ClampedArray:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint8ClampedArray",
+                       IDLBuiltinType.Types.Uint8ClampedArray),
+    IDLBuiltinType.Types.Int16Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int16Array",
+                       IDLBuiltinType.Types.Int16Array),
+    IDLBuiltinType.Types.Uint16Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint16Array",
+                       IDLBuiltinType.Types.Uint16Array),
+    IDLBuiltinType.Types.Int32Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Int32Array",
+                       IDLBuiltinType.Types.Int32Array),
+    IDLBuiltinType.Types.Uint32Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Uint32Array",
+                       IDLBuiltinType.Types.Uint32Array),
+    IDLBuiltinType.Types.Float32Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float32Array",
+                       IDLBuiltinType.Types.Float32Array),
+    IDLBuiltinType.Types.Float64Array:
+        IDLBuiltinType(BuiltinLocation("<builtin type>"), "Float64Array",
+                       IDLBuiltinType.Types.Float64Array)
+}
+
+
+integerTypeSizes = {
+    IDLBuiltinType.Types.byte: (-128, 127),
+    IDLBuiltinType.Types.octet:  (0, 255),
+    IDLBuiltinType.Types.short: (-32768, 32767),
+    IDLBuiltinType.Types.unsigned_short: (0, 65535),
+    IDLBuiltinType.Types.long: (-2147483648, 2147483647),
+    IDLBuiltinType.Types.unsigned_long: (0, 4294967295),
+    IDLBuiltinType.Types.long_long: (-9223372036854775808, 9223372036854775807),
+    IDLBuiltinType.Types.unsigned_long_long: (0, 18446744073709551615)
+}
+
+
+def matchIntegerValueToType(value):
+    for type, extremes in integerTypeSizes.items():
+        (min, max) = extremes
+        if value <= max and value >= min:
+            return BuiltinTypes[type]
+
+    return None
+
+class NoCoercionFoundError(WebIDLError):
+    """
+    A class we use to indicate generic coercion failures because none of the
+    types worked out in IDLValue.coerceToType.
+    """
+
+class IDLValue(IDLObject):
+    def __init__(self, location, type, value):
+        IDLObject.__init__(self, location)
+        self.type = type
+        assert isinstance(type, IDLType)
+
+        self.value = value
+
+    def coerceToType(self, type, location):
+        if type == self.type:
+            return self  # Nothing to do
+
+        # We first check for unions to ensure that even if the union is nullable
+        # we end up with the right flat member type, not the union's type.
+        if type.isUnion():
+            # We use the flat member types here, because if we have a nullable
+            # member type, or a nested union, we want the type the value
+            # actually coerces to, not the nullable or nested union type.
+            for subtype in type.unroll().flatMemberTypes:
+                try:
+                    coercedValue = self.coerceToType(subtype, location)
+                    # Create a new IDLValue to make sure that we have the
+                    # correct float/double type.  This is necessary because we
+                    # use the value's type when it is a default value of a
+                    # union, and the union cares about the exact float type.
+                    return IDLValue(self.location, subtype, coercedValue.value)
+                except Exception as e:
+                    # Make sure to propagate out WebIDLErrors that are not the
+                    # generic "hey, we could not coerce to this type at all"
+                    # exception, because those are specific "coercion failed for
+                    # reason X" exceptions.  Note that we want to swallow
+                    # non-WebIDLErrors here, because those can just happen if
+                    # "type" is not something that can have a default value at
+                    # all.
+                    if (isinstance(e, WebIDLError) and
+                        not isinstance(e, NoCoercionFoundError)):
+                        raise e
+
+        # If the type allows null, rerun this matching on the inner type, except
+        # nullable enums.  We handle those specially, because we want our
+        # default string values to stay strings even when assigned to a nullable
+        # enum.
+        elif type.nullable() and not type.isEnum():
+            innerValue = self.coerceToType(type.inner, location)
+            return IDLValue(self.location, type, innerValue.value)
+
+        elif self.type.isInteger() and type.isInteger():
+            # We're both integer types.  See if we fit.
+
+            (min, max) = integerTypeSizes[type._typeTag]
+            if self.value <= max and self.value >= min:
+                # Promote
+                return IDLValue(self.location, type, self.value)
+            else:
+                raise WebIDLError("Value %s is out of range for type %s." %
+                                  (self.value, type), [location])
+        elif self.type.isInteger() and type.isFloat():
+            # Convert an integer literal into float
+            if -2**24 <= self.value <= 2**24:
+                return IDLValue(self.location, type, float(self.value))
+            else:
+                raise WebIDLError("Converting value %s to %s will lose precision." %
+                                  (self.value, type), [location])
+        elif self.type.isString() and type.isEnum():
+            # Just keep our string, but make sure it's a valid value for this enum
+            enum = type.unroll().inner
+            if self.value not in enum.values():
+                raise WebIDLError("'%s' is not a valid default value for enum %s"
+                                  % (self.value, enum.identifier.name),
+                                  [location, enum.location])
+            return self
+        elif self.type.isFloat() and type.isFloat():
+            if (not type.isUnrestricted() and
+                (self.value == float("inf") or self.value == float("-inf") or
+                 math.isnan(self.value))):
+                raise WebIDLError("Trying to convert unrestricted value %s to non-unrestricted"
+                                  % self.value, [location])
+            return IDLValue(self.location, type, self.value)
+        elif self.type.isString() and type.isUSVString():
+            # Allow USVStrings to use default value just like
+            # DOMString.  No coercion is required in this case as Codegen.py
+            # treats USVString just like DOMString, but with an
+            # extra normalization step.
+            assert self.type.isDOMString()
+            return self
+        elif self.type.isString() and type.isByteString():
+            # Allow ByteStrings to use a default value like DOMString.
+            # No coercion is required as Codegen.py will handle the
+            # extra steps. We want to make sure that our string contains
+            # only valid characters, so we check that here.
+            valid_ascii_lit = " " + string.ascii_letters + string.digits + string.punctuation
+            for idx, c in enumerate(self.value):
+                if c not in valid_ascii_lit:
+                    raise WebIDLError("Coercing this string literal %s to a ByteString is not supported yet. "
+                                      "Coercion failed due to an unsupported byte %d at index %d."
+                                      % (self.value.__repr__(), ord(c), idx), [location])
+
+            return IDLValue(self.location, type, self.value)
+
+        raise NoCoercionFoundError("Cannot coerce type %s to type %s." %
+                                   (self.type, type), [location])
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLNullValue(IDLObject):
+    def __init__(self, location):
+        IDLObject.__init__(self, location)
+        self.type = None
+        self.value = None
+
+    def coerceToType(self, type, location):
+        if (not isinstance(type, IDLNullableType) and
+            not (type.isUnion() and type.hasNullableType) and
+            not (type.isUnion() and type.hasDictionaryType()) and
+            not type.isDictionary() and
+            not type.isAny()):
+            raise WebIDLError("Cannot coerce null value to type %s." % type,
+                              [location])
+
+        nullValue = IDLNullValue(self.location)
+        if type.isUnion() and not type.nullable() and type.hasDictionaryType():
+            # We're actually a default value for the union's dictionary member.
+            # Use its type.
+            for t in type.flatMemberTypes:
+                if t.isDictionary():
+                    nullValue.type = t
+                    return nullValue
+        nullValue.type = type
+        return nullValue
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLEmptySequenceValue(IDLObject):
+    def __init__(self, location):
+        IDLObject.__init__(self, location)
+        self.type = None
+        self.value = None
+
+    def coerceToType(self, type, location):
+        if type.isUnion():
+            # We use the flat member types here, because if we have a nullable
+            # member type, or a nested union, we want the type the value
+            # actually coerces to, not the nullable or nested union type.
+            for subtype in type.unroll().flatMemberTypes:
+                try:
+                    return self.coerceToType(subtype, location)
+                except:
+                    pass
+
+        if not type.isSequence():
+            raise WebIDLError("Cannot coerce empty sequence value to type %s." % type,
+                              [location])
+
+        emptySequenceValue = IDLEmptySequenceValue(self.location)
+        emptySequenceValue.type = type
+        return emptySequenceValue
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLUndefinedValue(IDLObject):
+    def __init__(self, location):
+        IDLObject.__init__(self, location)
+        self.type = None
+        self.value = None
+
+    def coerceToType(self, type, location):
+        if not type.isAny():
+            raise WebIDLError("Cannot coerce undefined value to type %s." % type,
+                              [location])
+
+        undefinedValue = IDLUndefinedValue(self.location)
+        undefinedValue.type = type
+        return undefinedValue
+
+    def _getDependentObjects(self):
+        return set()
+
+
+class IDLInterfaceMember(IDLObjectWithIdentifier, IDLExposureMixins):
+
+    Tags = enum(
+        'Const',
+        'Attr',
+        'Method',
+        'MaplikeOrSetlike',
+        'Iterable'
+    )
+
+    Special = enum(
+        'Static',
+        'Stringifier'
+    )
+
+    AffectsValues = ("Nothing", "Everything")
+    DependsOnValues = ("Nothing", "DOMState", "DeviceState", "Everything")
+
+    def __init__(self, location, identifier, tag, extendedAttrDict=None):
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+        IDLExposureMixins.__init__(self, location)
+        self.tag = tag
+        if extendedAttrDict is None:
+            self._extendedAttrDict = {}
+        else:
+            self._extendedAttrDict = extendedAttrDict
+
+    def isMethod(self):
+        return self.tag == IDLInterfaceMember.Tags.Method
+
+    def isAttr(self):
+        return self.tag == IDLInterfaceMember.Tags.Attr
+
+    def isConst(self):
+        return self.tag == IDLInterfaceMember.Tags.Const
+
+    def isMaplikeOrSetlikeOrIterable(self):
+        return (self.tag == IDLInterfaceMember.Tags.MaplikeOrSetlike or
+                self.tag == IDLInterfaceMember.Tags.Iterable)
+
+    def isMaplikeOrSetlike(self):
+        return self.tag == IDLInterfaceMember.Tags.MaplikeOrSetlike
+
+    def addExtendedAttributes(self, attrs):
+        for attr in attrs:
+            self.handleExtendedAttribute(attr)
+            attrlist = attr.listValue()
+            self._extendedAttrDict[attr.identifier()] = attrlist if len(attrlist) else True
+
+    def handleExtendedAttribute(self, attr):
+        pass
+
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
+    def finish(self, scope):
+        # We better be exposed _somewhere_.
+        if (len(self._exposureGlobalNames) == 0):
+            print self.identifier.name
+        assert len(self._exposureGlobalNames) != 0
+        IDLExposureMixins.finish(self, scope)
+
+    def validate(self):
+        if (self.getExtendedAttribute("Pref") and
+            self.exposureSet != set([self._globalScope.primaryGlobalName])):
+            raise WebIDLError("[Pref] used on an interface member that is not "
+                              "%s-only" % self._globalScope.primaryGlobalName,
+                              [self.location])
+
+        if self.isAttr() or self.isMethod():
+            if self.affects == "Everything" and self.dependsOn != "Everything":
+                raise WebIDLError("Interface member is flagged as affecting "
+                                  "everything but not depending on everything. "
+                                  "That seems rather unlikely.",
+                                  [self.location])
+
+        if self.getExtendedAttribute("NewObject"):
+            if self.dependsOn == "Nothing" or self.dependsOn == "DOMState":
+                raise WebIDLError("A [NewObject] method is not idempotent, "
+                                  "so it has to depend on something other than DOM state.",
+                                  [self.location])
+            if (self.getExtendedAttribute("Cached") or
+                self.getExtendedAttribute("StoreInSlot")):
+                raise WebIDLError("A [NewObject] attribute shouldnt be "
+                                  "[Cached] or [StoreInSlot], since the point "
+                                  "of those is to keep returning the same "
+                                  "thing across multiple calls, which is not "
+                                  "what [NewObject] does.",
+                                  [self.location])
+
+    def _setDependsOn(self, dependsOn):
+        if self.dependsOn != "Everything":
+            raise WebIDLError("Trying to specify multiple different DependsOn, "
+                              "Pure, or Constant extended attributes for "
+                              "attribute", [self.location])
+        if dependsOn not in IDLInterfaceMember.DependsOnValues:
+            raise WebIDLError("Invalid [DependsOn=%s] on attribute" % dependsOn,
+                              [self.location])
+        self.dependsOn = dependsOn
+
+    def _setAffects(self, affects):
+        if self.affects != "Everything":
+            raise WebIDLError("Trying to specify multiple different Affects, "
+                              "Pure, or Constant extended attributes for "
+                              "attribute", [self.location])
+        if affects not in IDLInterfaceMember.AffectsValues:
+            raise WebIDLError("Invalid [Affects=%s] on attribute" % dependsOn,
+                              [self.location])
+        self.affects = affects
+
+    def _addAlias(self, alias):
+        if alias in self.aliases:
+            raise WebIDLError("Duplicate [Alias=%s] on attribute" % alias,
+                              [self.location])
+        self.aliases.append(alias)
+
+
+class IDLMaplikeOrSetlikeOrIterableBase(IDLInterfaceMember):
+
+    def __init__(self, location, identifier, ifaceType, keyType, valueType, ifaceKind):
+        IDLInterfaceMember.__init__(self, location, identifier, ifaceKind)
+        if keyType is not None:
+            assert isinstance(keyType, IDLType)
+        else:
+            assert valueType is not None
+        assert ifaceType in ['maplike', 'setlike', 'iterable']
+        if valueType is not None:
+            assert isinstance(valueType, IDLType)
+        self.keyType = keyType
+        self.valueType = valueType
+        self.maplikeOrSetlikeOrIterableType = ifaceType
+        self.disallowedMemberNames = []
+        self.disallowedNonMethodNames = []
+
+    def isMaplike(self):
+        return self.maplikeOrSetlikeOrIterableType == "maplike"
+
+    def isSetlike(self):
+        return self.maplikeOrSetlikeOrIterableType == "setlike"
+
+    def isIterable(self):
+        return self.maplikeOrSetlikeOrIterableType == "iterable"
+
+    def hasKeyType(self):
+        return self.keyType is not None
+
+    def hasValueType(self):
+        return self.valueType is not None
+
+    def checkCollisions(self, members, isAncestor):
+        for member in members:
+            # Check that there are no disallowed members
+            if (member.identifier.name in self.disallowedMemberNames and
+                not ((member.isMethod() and member.isMaplikeOrSetlikeOrIterableMethod()) or
+                     (member.isAttr() and member.isMaplikeOrSetlikeAttr()))):
+                raise WebIDLError("Member '%s' conflicts "
+                                  "with reserved %s name." %
+                                  (member.identifier.name,
+                                   self.maplikeOrSetlikeOrIterableType),
+                                  [self.location, member.location])
+            # Check that there are no disallowed non-method members.
+            # Ancestor members are always disallowed here; own members
+            # are disallowed only if they're non-methods.
+            if ((isAncestor or member.isAttr() or member.isConst()) and
+                member.identifier.name in self.disallowedNonMethodNames):
+                raise WebIDLError("Member '%s' conflicts "
+                                  "with reserved %s method." %
+                                  (member.identifier.name,
+                                   self.maplikeOrSetlikeOrIterableType),
+                                  [self.location, member.location])
+
+    def addMethod(self, name, members, allowExistingOperations, returnType, args=[],
+                  chromeOnly=False, isPure=False, affectsNothing=False, newObject=False,
+                  isIteratorAlias=False):
+        """
+        Create an IDLMethod based on the parameters passed in.
+
+        - members is the member list to add this function to, since this is
+          called during the member expansion portion of interface object
+          building.
+
+        - chromeOnly is only True for read-only js implemented classes, to
+        implement underscore prefixed convenience functions which would
+        otherwise not be available, unlike the case of C++ bindings.
+
+        - isPure is only True for idempotent functions, so it is not valid for
+        things like keys, values, etc. that return a new object every time.
+
+        - affectsNothing means that nothing changes due to this method, which
+          affects JIT optimization behavior
+
+        - newObject means the method creates and returns a new object.
+
+        """
+        # Only add name to lists for collision checks if it's not chrome
+        # only.
+        if chromeOnly:
+            name = "__" + name
+        else:
+            if not allowExistingOperations:
+                self.disallowedMemberNames.append(name)
+            else:
+                self.disallowedNonMethodNames.append(name)
+        # If allowExistingOperations is True, and another operation exists
+        # with the same name as the one we're trying to add, don't add the
+        # maplike/setlike operation. However, if the operation is static,
+        # then fail by way of creating the function, which will cause a
+        # naming conflict, per the spec.
+        if allowExistingOperations:
+            for m in members:
+                if m.identifier.name == name and m.isMethod() and not m.isStatic():
+                    return
+        method = IDLMethod(self.location,
+                           IDLUnresolvedIdentifier(self.location, name, allowDoubleUnderscore=chromeOnly),
+                           returnType, args, maplikeOrSetlikeOrIterable=self)
+        # We need to be able to throw from declaration methods
+        method.addExtendedAttributes(
+            [IDLExtendedAttribute(self.location, ("Throws",))])
+        if chromeOnly:
+            method.addExtendedAttributes(
+                [IDLExtendedAttribute(self.location, ("ChromeOnly",))])
+        if isPure:
+            method.addExtendedAttributes(
+                [IDLExtendedAttribute(self.location, ("Pure",))])
+        # Following attributes are used for keys/values/entries. Can't mark
+        # them pure, since they return a new object each time they are run.
+        if affectsNothing:
+            method.addExtendedAttributes(
+                [IDLExtendedAttribute(self.location, ("DependsOn", "Everything")),
+                 IDLExtendedAttribute(self.location, ("Affects", "Nothing"))])
+        if newObject:
+            method.addExtendedAttributes(
+                [IDLExtendedAttribute(self.location, ("NewObject",))])
+        if isIteratorAlias:
+            method.addExtendedAttributes(
+                [IDLExtendedAttribute(self.location, ("Alias", "@@iterator"))])
+        members.append(method)
+
+    def resolve(self, parentScope):
+        if self.keyType:
+            self.keyType.resolveType(parentScope)
+        if self.valueType:
+            self.valueType.resolveType(parentScope)
+
+    def finish(self, scope):
+        IDLInterfaceMember.finish(self, scope)
+        if self.keyType and not self.keyType.isComplete():
+            t = self.keyType.complete(scope)
+
+            assert not isinstance(t, IDLUnresolvedType)
+            assert not isinstance(t, IDLTypedefType)
+            assert not isinstance(t.name, IDLUnresolvedIdentifier)
+            self.keyType = t
+        if self.valueType and not self.valueType.isComplete():
+            t = self.valueType.complete(scope)
+
+            assert not isinstance(t, IDLUnresolvedType)
+            assert not isinstance(t, IDLTypedefType)
+            assert not isinstance(t.name, IDLUnresolvedIdentifier)
+            self.valueType = t
+
+    def validate(self):
+        IDLInterfaceMember.validate(self)
+
+    def handleExtendedAttribute(self, attr):
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def _getDependentObjects(self):
+        deps = set()
+        if self.keyType:
+            deps.add(self.keyType)
+        if self.valueType:
+            deps.add(self.valueType)
+        return deps
+
+    def getForEachArguments(self):
+        return [IDLArgument(self.location,
+                            IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                                    "callback"),
+                            BuiltinTypes[IDLBuiltinType.Types.object]),
+                IDLArgument(self.location,
+                            IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                                    "thisArg"),
+                            BuiltinTypes[IDLBuiltinType.Types.any],
+                            optional=True)]
+
+# Iterable adds ES6 iterator style functions and traits
+# (keys/values/entries/@@iterator) to an interface.
+class IDLIterable(IDLMaplikeOrSetlikeOrIterableBase):
+
+    def __init__(self, location, identifier, keyType, valueType=None, scope=None):
+        IDLMaplikeOrSetlikeOrIterableBase.__init__(self, location, identifier,
+                                                   "iterable", keyType, valueType,
+                                                   IDLInterfaceMember.Tags.Iterable)
+        self.iteratorType = None
+
+    def __str__(self):
+        return "declared iterable with key '%s' and value '%s'" % (self.keyType, self.valueType)
+
+    def expand(self, members, isJSImplemented):
+        """
+        In order to take advantage of all of the method machinery in Codegen,
+        we generate our functions as if they were part of the interface
+        specification during parsing.
+        """
+        # We only need to add entries/keys/values here if we're a pair iterator.
+        # Value iterators just copy these from %ArrayPrototype% instead.
+        if not self.isPairIterator():
+            return
+
+        # object entries()
+        self.addMethod("entries", members, False, self.iteratorType,
+                       affectsNothing=True, newObject=True,
+                       isIteratorAlias=True)
+        # object keys()
+        self.addMethod("keys", members, False, self.iteratorType,
+                       affectsNothing=True, newObject=True)
+        # object values()
+        self.addMethod("values", members, False, self.iteratorType,
+                       affectsNothing=True, newObject=True)
+
+        # void forEach(callback(valueType, keyType), optional any thisArg)
+        self.addMethod("forEach", members, False,
+                       BuiltinTypes[IDLBuiltinType.Types.void],
+                       self.getForEachArguments())
+
+    def isValueIterator(self):
+        return not self.isPairIterator()
+
+    def isPairIterator(self):
+        return self.hasKeyType()
+
+# MaplikeOrSetlike adds ES6 map-or-set-like traits to an interface.
+class IDLMaplikeOrSetlike(IDLMaplikeOrSetlikeOrIterableBase):
+
+    def __init__(self, location, identifier, maplikeOrSetlikeType,
+                 readonly, keyType, valueType):
+        IDLMaplikeOrSetlikeOrIterableBase.__init__(self, location, identifier, maplikeOrSetlikeType,
+                                                   keyType, valueType, IDLInterfaceMember.Tags.MaplikeOrSetlike)
+        self.readonly = readonly
+        self.slotIndices = None
+
+        # When generating JSAPI access code, we need to know the backing object
+        # type prefix to create the correct function. Generate here for reuse.
+        if self.isMaplike():
+            self.prefix = 'Map'
+        elif self.isSetlike():
+            self.prefix = 'Set'
+
+    def __str__(self):
+        return "declared '%s' with key '%s'" % (self.maplikeOrSetlikeOrIterableType, self.keyType)
+
+    def expand(self, members, isJSImplemented):
+        """
+        In order to take advantage of all of the method machinery in Codegen,
+        we generate our functions as if they were part of the interface
+        specification during parsing.
+        """
+        # Both maplike and setlike have a size attribute
+        members.append(IDLAttribute(self.location,
+                                    IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"), "size"),
+                                    BuiltinTypes[IDLBuiltinType.Types.unsigned_long],
+                                    True,
+                                    maplikeOrSetlike=self))
+        self.reserved_ro_names = ["size"]
+        self.disallowedMemberNames.append("size")
+
+        # object entries()
+        self.addMethod("entries", members, False, BuiltinTypes[IDLBuiltinType.Types.object],
+                       affectsNothing=True, isIteratorAlias=self.isMaplike())
+        # object keys()
+        self.addMethod("keys", members, False, BuiltinTypes[IDLBuiltinType.Types.object],
+                       affectsNothing=True)
+        # object values()
+        self.addMethod("values", members, False, BuiltinTypes[IDLBuiltinType.Types.object],
+                       affectsNothing=True, isIteratorAlias=self.isSetlike())
+
+        # void forEach(callback(valueType, keyType), thisVal)
+        self.addMethod("forEach", members, False, BuiltinTypes[IDLBuiltinType.Types.void],
+                       self.getForEachArguments())
+
+        def getKeyArg():
+            return IDLArgument(self.location,
+                               IDLUnresolvedIdentifier(self.location, "key"),
+                               self.keyType)
+
+        # boolean has(keyType key)
+        self.addMethod("has", members, False, BuiltinTypes[IDLBuiltinType.Types.boolean],
+                       [getKeyArg()], isPure=True)
+
+        if not self.readonly:
+            # void clear()
+            self.addMethod("clear", members, True, BuiltinTypes[IDLBuiltinType.Types.void],
+                           [])
+            # boolean delete(keyType key)
+            self.addMethod("delete", members, True,
+                           BuiltinTypes[IDLBuiltinType.Types.boolean], [getKeyArg()])
+
+        # Always generate underscored functions (e.g. __add, __clear) for js
+        # implemented interfaces as convenience functions.
+        if isJSImplemented:
+            # void clear()
+            self.addMethod("clear", members, True, BuiltinTypes[IDLBuiltinType.Types.void],
+                           [], chromeOnly=True)
+            # boolean delete(keyType key)
+            self.addMethod("delete", members, True,
+                           BuiltinTypes[IDLBuiltinType.Types.boolean], [getKeyArg()],
+                           chromeOnly=True)
+
+        if self.isSetlike():
+            if not self.readonly:
+                # Add returns the set object it just added to.
+                # object add(keyType key)
+
+                self.addMethod("add", members, True,
+                               BuiltinTypes[IDLBuiltinType.Types.object], [getKeyArg()])
+            if isJSImplemented:
+                self.addMethod("add", members, True,
+                               BuiltinTypes[IDLBuiltinType.Types.object], [getKeyArg()],
+                               chromeOnly=True)
+            return
+
+        # If we get this far, we're a maplike declaration.
+
+        # valueType get(keyType key)
+        #
+        # Note that instead of the value type, we're using any here. The
+        # validity checks should happen as things are inserted into the map,
+        # and using any as the return type makes code generation much simpler.
+        #
+        # TODO: Bug 1155340 may change this to use specific type to provide
+        # more info to JIT.
+        self.addMethod("get", members, False, BuiltinTypes[IDLBuiltinType.Types.any],
+                       [getKeyArg()], isPure=True)
+
+        def getValueArg():
+            return IDLArgument(self.location,
+                               IDLUnresolvedIdentifier(self.location, "value"),
+                               self.valueType)
+
+        if not self.readonly:
+            self.addMethod("set", members, True, BuiltinTypes[IDLBuiltinType.Types.object],
+                           [getKeyArg(), getValueArg()])
+        if isJSImplemented:
+            self.addMethod("set", members, True, BuiltinTypes[IDLBuiltinType.Types.object],
+                           [getKeyArg(), getValueArg()], chromeOnly=True)
+
+class IDLConst(IDLInterfaceMember):
+    def __init__(self, location, identifier, type, value):
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Const)
+
+        assert isinstance(type, IDLType)
+        if type.isDictionary():
+            raise WebIDLError("A constant cannot be of a dictionary type",
+                              [self.location])
+        self.type = type
+        self.value = value
+
+        if identifier.name == "prototype":
+            raise WebIDLError("The identifier of a constant must not be 'prototype'",
+                              [location])
+
+    def __str__(self):
+        return "'%s' const '%s'" % (self.type, self.identifier)
+
+    def finish(self, scope):
+        IDLInterfaceMember.finish(self, scope)
+
+        if not self.type.isComplete():
+            type = self.type.complete(scope)
+            if not type.isPrimitive() and not type.isString():
+                locations = [self.type.location, type.location]
+                try:
+                    locations.append(type.inner.location)
+                except:
+                    pass
+                raise WebIDLError("Incorrect type for constant", locations)
+            self.type = type
+
+        # The value might not match the type
+        coercedValue = self.value.coerceToType(self.type, self.location)
+        assert coercedValue
+
+        self.value = coercedValue
+
+    def validate(self):
+        IDLInterfaceMember.validate(self)
+
+    def handleExtendedAttribute(self, attr):
+        identifier = attr.identifier()
+        if identifier == "Exposed":
+            convertExposedAttrToGlobalNameSet(attr, self._exposureGlobalNames)
+        elif (identifier == "Pref" or
+              identifier == "ChromeOnly" or
+              identifier == "Func" or
+              identifier == "SecureContext"):
+            # Known attributes that we don't need to do anything with here
+            pass
+        else:
+            raise WebIDLError("Unknown extended attribute %s on constant" % identifier,
+                              [attr.location])
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def _getDependentObjects(self):
+        return set([self.type, self.value])
+
+
+class IDLAttribute(IDLInterfaceMember):
+    def __init__(self, location, identifier, type, readonly, inherit=False,
+                 static=False, stringifier=False, maplikeOrSetlike=None,
+                 extendedAttrDict=None, navigatorObjectGetter=False):
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Attr,
+                                    extendedAttrDict=extendedAttrDict)
+
+        assert isinstance(type, IDLType)
+        self.type = type
+        self.readonly = readonly
+        self.inherit = inherit
+        self._static = static
+        self.lenientThis = False
+        self._unforgeable = False
+        self.stringifier = stringifier
+        self.enforceRange = False
+        self.clamp = False
+        self.slotIndices = None
+        assert maplikeOrSetlike is None or isinstance(maplikeOrSetlike, IDLMaplikeOrSetlike)
+        self.maplikeOrSetlike = maplikeOrSetlike
+        self.dependsOn = "Everything"
+        self.affects = "Everything"
+        self.navigatorObjectGetter = navigatorObjectGetter
+
+        if static and identifier.name == "prototype":
+            raise WebIDLError("The identifier of a static attribute must not be 'prototype'",
+                              [location])
+
+        if readonly and inherit:
+            raise WebIDLError("An attribute cannot be both 'readonly' and 'inherit'",
+                              [self.location])
+
+    def isStatic(self):
+        return self._static
+
+    def forceStatic(self):
+        self._static = True
+
+    def __str__(self):
+        return "'%s' attribute '%s'" % (self.type, self.identifier)
+
+    def finish(self, scope):
+        IDLInterfaceMember.finish(self, scope)
+
+        if not self.type.isComplete():
+            t = self.type.complete(scope)
+
+            assert not isinstance(t, IDLUnresolvedType)
+            assert not isinstance(t, IDLTypedefType)
+            assert not isinstance(t.name, IDLUnresolvedIdentifier)
+            self.type = t
+
+        if self.type.isDictionary() and not self.getExtendedAttribute("Cached"):
+            raise WebIDLError("An attribute cannot be of a dictionary type",
+                              [self.location])
+        if self.type.isSequence() and not self.getExtendedAttribute("Cached"):
+            raise WebIDLError("A non-cached attribute cannot be of a sequence "
+                              "type", [self.location])
+        if self.type.isMozMap() and not self.getExtendedAttribute("Cached"):
+            raise WebIDLError("A non-cached attribute cannot be of a MozMap "
+                              "type", [self.location])
+        if self.type.isUnion():
+            for f in self.type.unroll().flatMemberTypes:
+                if f.isDictionary():
+                    raise WebIDLError("An attribute cannot be of a union "
+                                      "type if one of its member types (or "
+                                      "one of its member types's member "
+                                      "types, and so on) is a dictionary "
+                                      "type", [self.location, f.location])
+                if f.isSequence():
+                    raise WebIDLError("An attribute cannot be of a union "
+                                      "type if one of its member types (or "
+                                      "one of its member types's member "
+                                      "types, and so on) is a sequence "
+                                      "type", [self.location, f.location])
+                if f.isMozMap():
+                    raise WebIDLError("An attribute cannot be of a union "
+                                      "type if one of its member types (or "
+                                      "one of its member types's member "
+                                      "types, and so on) is a MozMap "
+                                      "type", [self.location, f.location])
+        if not self.type.isInterface() and self.getExtendedAttribute("PutForwards"):
+            raise WebIDLError("An attribute with [PutForwards] must have an "
+                              "interface type as its type", [self.location])
+
+        if not self.type.isInterface() and self.getExtendedAttribute("SameObject"):
+            raise WebIDLError("An attribute with [SameObject] must have an "
+                              "interface type as its type", [self.location])
+
+    def validate(self):
+        def typeContainsChromeOnlyDictionaryMember(type):
+            if (type.nullable() or
+                type.isSequence() or
+                type.isMozMap()):
+                return typeContainsChromeOnlyDictionaryMember(type.inner)
+
+            if type.isUnion():
+                for memberType in type.flatMemberTypes:
+                    (contains, location) = typeContainsChromeOnlyDictionaryMember(memberType)
+                    if contains:
+                        return (True, location)
+
+            if type.isDictionary():
+                dictionary = type.inner
+                while dictionary:
+                    (contains, location) = dictionaryContainsChromeOnlyMember(dictionary)
+                    if contains:
+                        return (True, location)
+                    dictionary = dictionary.parent
+
+            return (False, None)
+
+        def dictionaryContainsChromeOnlyMember(dictionary):
+            for member in dictionary.members:
+                if member.getExtendedAttribute("ChromeOnly"):
+                    return (True, member.location)
+                (contains, location) = typeContainsChromeOnlyDictionaryMember(member.type)
+                if contains:
+                    return (True, location)
+            return (False, None)
+
+        IDLInterfaceMember.validate(self)
+
+        if (self.getExtendedAttribute("Cached") or
+            self.getExtendedAttribute("StoreInSlot")):
+            if not self.affects == "Nothing":
+                raise WebIDLError("Cached attributes and attributes stored in "
+                                  "slots must be Constant or Pure or "
+                                  "Affects=Nothing, since the getter won't always "
+                                  "be called.",
+                                  [self.location])
+            (contains, location) = typeContainsChromeOnlyDictionaryMember(self.type)
+            if contains:
+                raise WebIDLError("[Cached] and [StoreInSlot] must not be used "
+                                  "on an attribute whose type contains a "
+                                  "[ChromeOnly] dictionary member",
+                                  [self.location, location])
+        if self.getExtendedAttribute("Frozen"):
+            if (not self.type.isSequence() and not self.type.isDictionary() and
+                not self.type.isMozMap()):
+                raise WebIDLError("[Frozen] is only allowed on "
+                                  "sequence-valued, dictionary-valued, and "
+                                  "MozMap-valued attributes",
+                                  [self.location])
+        if not self.type.unroll().isExposedInAllOf(self.exposureSet):
+            raise WebIDLError("Attribute returns a type that is not exposed "
+                              "everywhere where the attribute is exposed",
+                              [self.location])
+
+    def handleExtendedAttribute(self, attr):
+        identifier = attr.identifier()
+        if identifier == "SetterThrows" and self.readonly:
+            raise WebIDLError("Readonly attributes must not be flagged as "
+                              "[SetterThrows]",
+                              [self.location])
+        elif (((identifier == "Throws" or identifier == "GetterThrows") and
+               self.getExtendedAttribute("StoreInSlot")) or
+              (identifier == "StoreInSlot" and
+               (self.getExtendedAttribute("Throws") or
+                self.getExtendedAttribute("GetterThrows")))):
+            raise WebIDLError("Throwing things can't be [StoreInSlot]",
+                              [attr.location])
+        elif identifier == "LenientThis":
+            if not attr.noArguments():
+                raise WebIDLError("[LenientThis] must take no arguments",
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[LenientThis] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("CrossOriginReadable"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [CrossOriginReadable]",
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("CrossOriginWritable"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [CrossOriginWritable]",
+                                  [attr.location, self.location])
+            self.lenientThis = True
+        elif identifier == "Unforgeable":
+            if self.isStatic():
+                raise WebIDLError("[Unforgeable] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            self._unforgeable = True
+        elif identifier == "SameObject" and not self.readonly:
+            raise WebIDLError("[SameObject] only allowed on readonly attributes",
+                              [attr.location, self.location])
+        elif identifier == "Constant" and not self.readonly:
+            raise WebIDLError("[Constant] only allowed on readonly attributes",
+                              [attr.location, self.location])
+        elif identifier == "PutForwards":
+            if not self.readonly:
+                raise WebIDLError("[PutForwards] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[PutForwards] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("Replaceable") is not None:
+                raise WebIDLError("[PutForwards] and [Replaceable] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+            if not attr.hasValue():
+                raise WebIDLError("[PutForwards] takes an identifier",
+                                  [attr.location, self.location])
+        elif identifier == "Replaceable":
+            if not attr.noArguments():
+                raise WebIDLError("[Replaceable] must take no arguments",
+                                  [attr.location])
+            if not self.readonly:
+                raise WebIDLError("[Replaceable] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[Replaceable] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("PutForwards") is not None:
+                raise WebIDLError("[PutForwards] and [Replaceable] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+        elif identifier == "LenientSetter":
+            if not attr.noArguments():
+                raise WebIDLError("[LenientSetter] must take no arguments",
+                                  [attr.location])
+            if not self.readonly:
+                raise WebIDLError("[LenientSetter] is only allowed on readonly "
+                                  "attributes", [attr.location, self.location])
+            if self.isStatic():
+                raise WebIDLError("[LenientSetter] is only allowed on non-static "
+                                  "attributes", [attr.location, self.location])
+            if self.getExtendedAttribute("PutForwards") is not None:
+                raise WebIDLError("[LenientSetter] and [PutForwards] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("Replaceable") is not None:
+                raise WebIDLError("[LenientSetter] and [Replaceable] can't both "
+                                  "appear on the same attribute",
+                                  [attr.location, self.location])
+        elif identifier == "LenientFloat":
+            if self.readonly:
+                raise WebIDLError("[LenientFloat] used on a readonly attribute",
+                                  [attr.location, self.location])
+            if not self.type.includesRestrictedFloat():
+                raise WebIDLError("[LenientFloat] used on an attribute with a "
+                                  "non-restricted-float type",
+                                  [attr.location, self.location])
+        elif identifier == "EnforceRange":
+            if self.readonly:
+                raise WebIDLError("[EnforceRange] used on a readonly attribute",
+                                  [attr.location, self.location])
+            self.enforceRange = True
+        elif identifier == "Clamp":
+            if self.readonly:
+                raise WebIDLError("[Clamp] used on a readonly attribute",
+                                  [attr.location, self.location])
+            self.clamp = True
+        elif identifier == "StoreInSlot":
+            if self.getExtendedAttribute("Cached"):
+                raise WebIDLError("[StoreInSlot] and [Cached] must not be "
+                                  "specified on the same attribute",
+                                  [attr.location, self.location])
+        elif identifier == "Cached":
+            if self.getExtendedAttribute("StoreInSlot"):
+                raise WebIDLError("[Cached] and [StoreInSlot] must not be "
+                                  "specified on the same attribute",
+                                  [attr.location, self.location])
+        elif (identifier == "CrossOriginReadable" or
+              identifier == "CrossOriginWritable"):
+            if not attr.noArguments() and identifier == "CrossOriginReadable":
+                raise WebIDLError("[%s] must take no arguments" % identifier,
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[%s] is only allowed on non-static "
+                                  "attributes" % identifier,
+                                  [attr.location, self.location])
+            if self.getExtendedAttribute("LenientThis"):
+                raise WebIDLError("[LenientThis] is not allowed in combination "
+                                  "with [%s]" % identifier,
+                                  [attr.location, self.location])
+        elif identifier == "Exposed":
+            convertExposedAttrToGlobalNameSet(attr, self._exposureGlobalNames)
+        elif identifier == "Pure":
+            if not attr.noArguments():
+                raise WebIDLError("[Pure] must take no arguments",
+                                  [attr.location])
+            self._setDependsOn("DOMState")
+            self._setAffects("Nothing")
+        elif identifier == "Constant" or identifier == "SameObject":
+            if not attr.noArguments():
+                raise WebIDLError("[%s] must take no arguments" % identifier,
+                                  [attr.location])
+            self._setDependsOn("Nothing")
+            self._setAffects("Nothing")
+        elif identifier == "Affects":
+            if not attr.hasValue():
+                raise WebIDLError("[Affects] takes an identifier",
+                                  [attr.location])
+            self._setAffects(attr.value())
+        elif identifier == "DependsOn":
+            if not attr.hasValue():
+                raise WebIDLError("[DependsOn] takes an identifier",
+                                  [attr.location])
+            if (attr.value() != "Everything" and attr.value() != "DOMState" and
+                not self.readonly):
+                raise WebIDLError("[DependsOn=%s] only allowed on "
+                                  "readonly attributes" % attr.value(),
+                                  [attr.location, self.location])
+            self._setDependsOn(attr.value())
+        elif identifier == "UseCounter":
+            if self.stringifier:
+                raise WebIDLError("[UseCounter] must not be used on a "
+                                  "stringifier attribute",
+                                  [attr.location, self.location])
+        elif identifier == "Unscopable":
+            if not attr.noArguments():
+                raise WebIDLError("[Unscopable] must take no arguments",
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[Unscopable] is only allowed on non-static "
+                                  "attributes and operations",
+                                  [attr.location, self.location])
+        elif (identifier == "Pref" or
+              identifier == "Deprecated" or
+              identifier == "SetterThrows" or
+              identifier == "Throws" or
+              identifier == "GetterThrows" or
+              identifier == "ChromeOnly" or
+              identifier == "Func" or
+              identifier == "SecureContext" or
+              identifier == "Frozen" or
+              identifier == "NewObject" or
+              identifier == "UnsafeInPrerendering" or
+              identifier == "NeedsSubjectPrincipal" or
+              identifier == "NeedsCallerType" or
+              identifier == "ReturnValueNeedsContainsHack" or
+              identifier == "BinaryName"):
+            # Known attributes that we don't need to do anything with here
+            pass
+        else:
+            raise WebIDLError("Unknown extended attribute %s on attribute" % identifier,
+                              [attr.location])
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        self.type.resolveType(parentScope)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+
+    def addExtendedAttributes(self, attrs):
+        attrs = self.checkForStringHandlingExtendedAttributes(attrs)
+        IDLInterfaceMember.addExtendedAttributes(self, attrs)
+
+    def hasLenientThis(self):
+        return self.lenientThis
+
+    def isMaplikeOrSetlikeAttr(self):
+        """
+        True if this attribute was generated from an interface with
+        maplike/setlike (e.g. this is the size attribute for
+        maplike/setlike)
+        """
+        return self.maplikeOrSetlike is not None
+
+    def isUnforgeable(self):
+        return self._unforgeable
+
+    def _getDependentObjects(self):
+        return set([self.type])
+
+
+class IDLArgument(IDLObjectWithIdentifier):
+    def __init__(self, location, identifier, type, optional=False, defaultValue=None, variadic=False, dictionaryMember=False):
+        IDLObjectWithIdentifier.__init__(self, location, None, identifier)
+
+        assert isinstance(type, IDLType)
+        self.type = type
+
+        self.optional = optional
+        self.defaultValue = defaultValue
+        self.variadic = variadic
+        self.dictionaryMember = dictionaryMember
+        self._isComplete = False
+        self.enforceRange = False
+        self.clamp = False
+        self._allowTreatNonCallableAsNull = False
+        self._extendedAttrDict = {}
+
+        assert not variadic or optional
+        assert not variadic or not defaultValue
+
+    def addExtendedAttributes(self, attrs):
+        attrs = self.checkForStringHandlingExtendedAttributes(
+            attrs,
+            isDictionaryMember=self.dictionaryMember,
+            isOptional=self.optional)
+        for attribute in attrs:
+            identifier = attribute.identifier()
+            if identifier == "Clamp":
+                if not attribute.noArguments():
+                    raise WebIDLError("[Clamp] must take no arguments",
+                                      [attribute.location])
+                if self.enforceRange:
+                    raise WebIDLError("[EnforceRange] and [Clamp] are mutually exclusive",
+                                      [self.location])
+                self.clamp = True
+            elif identifier == "EnforceRange":
+                if not attribute.noArguments():
+                    raise WebIDLError("[EnforceRange] must take no arguments",
+                                      [attribute.location])
+                if self.clamp:
+                    raise WebIDLError("[EnforceRange] and [Clamp] are mutually exclusive",
+                                      [self.location])
+                self.enforceRange = True
+            elif identifier == "TreatNonCallableAsNull":
+                self._allowTreatNonCallableAsNull = True
+            elif (self.dictionaryMember and
+                  (identifier == "ChromeOnly" or identifier == "Func")):
+                if not self.optional:
+                    raise WebIDLError("[%s] must not be used on a required "
+                                      "dictionary member" % identifier,
+                                      [attribute.location])
+            else:
+                raise WebIDLError("Unhandled extended attribute on %s" %
+                                  ("a dictionary member" if self.dictionaryMember else
+                                   "an argument"),
+                                  [attribute.location])
+            attrlist = attribute.listValue()
+            self._extendedAttrDict[identifier] = attrlist if len(attrlist) else True
+
+    def getExtendedAttribute(self, name):
+        return self._extendedAttrDict.get(name, None)
+
+    def isComplete(self):
+        return self._isComplete
+
+    def complete(self, scope):
+        if self._isComplete:
+            return
+
+        self._isComplete = True
+
+        if not self.type.isComplete():
+            type = self.type.complete(scope)
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            self.type = type
+
+        if ((self.type.isDictionary() or
+             self.type.isUnion() and self.type.unroll().hasDictionaryType()) and
+            self.optional and not self.defaultValue and not self.variadic):
+            # Default optional non-variadic dictionaries to null,
+            # for simplicity, so the codegen doesn't have to special-case this.
+            self.defaultValue = IDLNullValue(self.location)
+        elif self.type.isAny():
+            assert (self.defaultValue is None or
+                    isinstance(self.defaultValue, IDLNullValue))
+            # optional 'any' values always have a default value
+            if self.optional and not self.defaultValue and not self.variadic:
+                # Set the default value to undefined, for simplicity, so the
+                # codegen doesn't have to special-case this.
+                self.defaultValue = IDLUndefinedValue(self.location)
+
+        # Now do the coercing thing; this needs to happen after the
+        # above creation of a default value.
+        if self.defaultValue:
+            self.defaultValue = self.defaultValue.coerceToType(self.type,
+                                                               self.location)
+            assert self.defaultValue
+
+    def allowTreatNonCallableAsNull(self):
+        return self._allowTreatNonCallableAsNull
+
+    def _getDependentObjects(self):
+        deps = set([self.type])
+        if self.defaultValue:
+            deps.add(self.defaultValue)
+        return deps
+
+    def canHaveMissingValue(self):
+        return self.optional and not self.defaultValue
+
+
+class IDLCallback(IDLObjectWithScope):
+    def __init__(self, location, parentScope, identifier, returnType, arguments):
+        assert isinstance(returnType, IDLType)
+
+        self._returnType = returnType
+        # Clone the list
+        self._arguments = list(arguments)
+
+        IDLObjectWithScope.__init__(self, location, parentScope, identifier)
+
+        for (returnType, arguments) in self.signatures():
+            for argument in arguments:
+                argument.resolve(self)
+
+        self._treatNonCallableAsNull = False
+        self._treatNonObjectAsNull = False
+
+    def isCallback(self):
+        return True
+
+    def signatures(self):
+        return [(self._returnType, self._arguments)]
+
+    def finish(self, scope):
+        if not self._returnType.isComplete():
+            type = self._returnType.complete(scope)
+
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            self._returnType = type
+
+        for argument in self._arguments:
+            if argument.type.isComplete():
+                continue
+
+            type = argument.type.complete(scope)
+
+            assert not isinstance(type, IDLUnresolvedType)
+            assert not isinstance(type, IDLTypedefType)
+            assert not isinstance(type.name, IDLUnresolvedIdentifier)
+            argument.type = type
+
+    def validate(self):
+        pass
+
+    def addExtendedAttributes(self, attrs):
+        unhandledAttrs = []
+        for attr in attrs:
+            if attr.identifier() == "TreatNonCallableAsNull":
+                self._treatNonCallableAsNull = True
+            elif attr.identifier() == "TreatNonObjectAsNull":
+                self._treatNonObjectAsNull = True
+            else:
+                unhandledAttrs.append(attr)
+        if self._treatNonCallableAsNull and self._treatNonObjectAsNull:
+            raise WebIDLError("Cannot specify both [TreatNonCallableAsNull] "
+                              "and [TreatNonObjectAsNull]", [self.location])
+        if len(unhandledAttrs) != 0:
+            IDLType.addExtendedAttributes(self, unhandledAttrs)
+
+    def _getDependentObjects(self):
+        return set([self._returnType] + self._arguments)
+
+
+class IDLCallbackType(IDLType):
+    def __init__(self, location, callback):
+        IDLType.__init__(self, location, callback.identifier.name)
+        self.callback = callback
+
+    def isCallback(self):
+        return True
+
+    def tag(self):
+        return IDLType.Tags.callback
+
+    def isDistinguishableFrom(self, other):
+        if other.isPromise():
+            return False
+        if other.isUnion():
+            # Just forward to the union; it'll deal
+            return other.isDistinguishableFrom(self)
+        return (other.isPrimitive() or other.isString() or other.isEnum() or
+                other.isNonCallbackInterface() or other.isDate() or
+                other.isSequence())
+
+    def _getDependentObjects(self):
+        return self.callback._getDependentObjects()
+
+
+class IDLMethodOverload:
+    """
+    A class that represents a single overload of a WebIDL method.  This is not
+    quite the same as an element of the "effective overload set" in the spec,
+    because separate IDLMethodOverloads are not created based on arguments being
+    optional.  Rather, when multiple methods have the same name, there is an
+    IDLMethodOverload for each one, all hanging off an IDLMethod representing
+    the full set of overloads.
+    """
+    def __init__(self, returnType, arguments, location):
+        self.returnType = returnType
+        # Clone the list of arguments, just in case
+        self.arguments = list(arguments)
+        self.location = location
+
+    def _getDependentObjects(self):
+        deps = set(self.arguments)
+        deps.add(self.returnType)
+        return deps
+
+
+class IDLMethod(IDLInterfaceMember, IDLScope):
+
+    Special = enum(
+        'Getter',
+        'Setter',
+        'Creator',
+        'Deleter',
+        'LegacyCaller',
+        base=IDLInterfaceMember.Special
+    )
+
+    NamedOrIndexed = enum(
+        'Neither',
+        'Named',
+        'Indexed'
+    )
+
+    def __init__(self, location, identifier, returnType, arguments,
+                 static=False, getter=False, setter=False, creator=False,
+                 deleter=False, specialType=NamedOrIndexed.Neither,
+                 legacycaller=False, stringifier=False, jsonifier=False,
+                 maplikeOrSetlikeOrIterable=None):
+        # REVIEW: specialType is NamedOrIndexed -- wow, this is messed up.
+        IDLInterfaceMember.__init__(self, location, identifier,
+                                    IDLInterfaceMember.Tags.Method)
+
+        self._hasOverloads = False
+
+        assert isinstance(returnType, IDLType)
+
+        # self._overloads is a list of IDLMethodOverloads
+        self._overloads = [IDLMethodOverload(returnType, arguments, location)]
+
+        assert isinstance(static, bool)
+        self._static = static
+        assert isinstance(getter, bool)
+        self._getter = getter
+        assert isinstance(setter, bool)
+        self._setter = setter
+        assert isinstance(creator, bool)
+        self._creator = creator
+        assert isinstance(deleter, bool)
+        self._deleter = deleter
+        assert isinstance(legacycaller, bool)
+        self._legacycaller = legacycaller
+        assert isinstance(stringifier, bool)
+        self._stringifier = stringifier
+        assert isinstance(jsonifier, bool)
+        self._jsonifier = jsonifier
+        assert maplikeOrSetlikeOrIterable is None or isinstance(maplikeOrSetlikeOrIterable, IDLMaplikeOrSetlikeOrIterableBase)
+        self.maplikeOrSetlikeOrIterable = maplikeOrSetlikeOrIterable
+        self._specialType = specialType
+        self._unforgeable = False
+        self.dependsOn = "Everything"
+        self.affects = "Everything"
+        self.aliases = []
+
+        if static and identifier.name == "prototype":
+            raise WebIDLError("The identifier of a static operation must not be 'prototype'",
+                              [location])
+
+        self.assertSignatureConstraints()
+
+    def __str__(self):
+        return "Method '%s'" % self.identifier
+
+    def assertSignatureConstraints(self):
+        if self._getter or self._deleter:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            arguments = overload.arguments
+            assert len(arguments) == 1
+            assert (arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.domstring] or
+                    arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.unsigned_long])
+            assert not arguments[0].optional and not arguments[0].variadic
+            assert not self._getter or not overload.returnType.isVoid()
+
+        if self._setter or self._creator:
+            assert len(self._overloads) == 1
+            arguments = self._overloads[0].arguments
+            assert len(arguments) == 2
+            assert (arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.domstring] or
+                    arguments[0].type == BuiltinTypes[IDLBuiltinType.Types.unsigned_long])
+            assert not arguments[0].optional and not arguments[0].variadic
+            assert not arguments[1].optional and not arguments[1].variadic
+
+        if self._stringifier:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            assert len(overload.arguments) == 0
+            assert overload.returnType == BuiltinTypes[IDLBuiltinType.Types.domstring]
+
+        if self._jsonifier:
+            assert len(self._overloads) == 1
+            overload = self._overloads[0]
+            assert len(overload.arguments) == 0
+            assert overload.returnType == BuiltinTypes[IDLBuiltinType.Types.object]
+
+    def isStatic(self):
+        return self._static
+
+    def forceStatic(self):
+        self._static = True
+
+    def isGetter(self):
+        return self._getter
+
+    def isSetter(self):
+        return self._setter
+
+    def isCreator(self):
+        return self._creator
+
+    def isDeleter(self):
+        return self._deleter
+
+    def isNamed(self):
+        assert (self._specialType == IDLMethod.NamedOrIndexed.Named or
+                self._specialType == IDLMethod.NamedOrIndexed.Indexed)
+        return self._specialType == IDLMethod.NamedOrIndexed.Named
+
+    def isIndexed(self):
+        assert (self._specialType == IDLMethod.NamedOrIndexed.Named or
+                self._specialType == IDLMethod.NamedOrIndexed.Indexed)
+        return self._specialType == IDLMethod.NamedOrIndexed.Indexed
+
+    def isLegacycaller(self):
+        return self._legacycaller
+
+    def isStringifier(self):
+        return self._stringifier
+
+    def isJsonifier(self):
+        return self._jsonifier
+
+    def isMaplikeOrSetlikeOrIterableMethod(self):
+        """
+        True if this method was generated as part of a
+        maplike/setlike/etc interface (e.g. has/get methods)
+        """
+        return self.maplikeOrSetlikeOrIterable is not None
+
+    def isSpecial(self):
+        return (self.isGetter() or
+                self.isSetter() or
+                self.isCreator() or
+                self.isDeleter() or
+                self.isLegacycaller() or
+                self.isStringifier() or
+                self.isJsonifier())
+
+    def hasOverloads(self):
+        return self._hasOverloads
+
+    def isIdentifierLess(self):
+        """
+        True if the method name started with __, and if the method is not a
+        maplike/setlike method. Interfaces with maplike/setlike will generate
+        methods starting with __ for chrome only backing object access in JS
+        implemented interfaces, so while these functions use what is considered
+        an non-identifier name, they actually DO have an identifier.
+        """
+        return (self.identifier.name[:2] == "__" and
+                not self.isMaplikeOrSetlikeOrIterableMethod())
+
+    def resolve(self, parentScope):
+        assert isinstance(parentScope, IDLScope)
+        IDLObjectWithIdentifier.resolve(self, parentScope)
+        IDLScope.__init__(self, self.location, parentScope, self.identifier)
+        for (returnType, arguments) in self.signatures():
+            for argument in arguments:
+                argument.resolve(self)
+
+    def addOverload(self, method):
+        assert len(method._overloads) == 1
+
+        if self._extendedAttrDict != method ._extendedAttrDict:
+            raise WebIDLError("Extended attributes differ on different "
+                              "overloads of %s" % method.identifier,
+                              [self.location, method.location])
+
+        self._overloads.extend(method._overloads)
+
+        self._hasOverloads = True
+
+        if self.isStatic() != method.isStatic():
+            raise WebIDLError("Overloaded identifier %s appears with different values of the 'static' attribute" % method.identifier,
+                              [method.location])
+
+        if self.isLegacycaller() != method.isLegacycaller():
+            raise WebIDLError("Overloaded identifier %s appears with different values of the 'legacycaller' attribute" % method.identifier,
+                              [method.location])
+
+        # Can't overload special things!
+        assert not self.isGetter()
+        assert not method.isGetter()
+        assert not self.isSetter()
+        assert not method.isSetter()
+        assert not self.isCreator()
+        assert not method.isCreator()
+        assert not self.isDeleter()
+        assert not method.isDeleter()
+        assert not self.isStringifier()
+        assert not method.isStringifier()
+        assert not self.isJsonifier()
+        assert not method.isJsonifier()
+
+        return self
+
+    def signatures(self):
+        return [(overload.returnType, overload.arguments) for overload in
+                self._overloads]
+
+    def finish(self, scope):
+        IDLInterfaceMember.finish(self, scope)
+
+        for overload in self._overloads:
+            returnType = overload.returnType
+            if not returnType.isComplete():
+                returnType = returnType.complete(scope)
+                assert not isinstance(returnType, IDLUnresolvedType)
+                assert not isinstance(returnType, IDLTypedefType)
+                assert not isinstance(returnType.name, IDLUnresolvedIdentifier)
+                overload.returnType = returnType
+
+            for argument in overload.arguments:
+                if not argument.isComplete():
+                    argument.complete(scope)
+                assert argument.type.isComplete()
+
+        # Now compute various information that will be used by the
+        # WebIDL overload resolution algorithm.
+        self.maxArgCount = max(len(s[1]) for s in self.signatures())
+        self.allowedArgCounts = [i for i in range(self.maxArgCount+1)
+                                 if len(self.signaturesForArgCount(i)) != 0]
+
+    def validate(self):
+        IDLInterfaceMember.validate(self)
+
+        # Make sure our overloads are properly distinguishable and don't have
+        # different argument types before the distinguishing args.
+        for argCount in self.allowedArgCounts:
+            possibleOverloads = self.overloadsForArgCount(argCount)
+            if len(possibleOverloads) == 1:
+                continue
+            distinguishingIndex = self.distinguishingIndexForArgCount(argCount)
+            for idx in range(distinguishingIndex):
+                firstSigType = possibleOverloads[0].arguments[idx].type
+                for overload in possibleOverloads[1:]:
+                    if overload.arguments[idx].type != firstSigType:
+                        raise WebIDLError(
+                            "Signatures for method '%s' with %d arguments have "
+                            "different types of arguments at index %d, which "
+                            "is before distinguishing index %d" %
+                            (self.identifier.name, argCount, idx,
+                             distinguishingIndex),
+                            [self.location, overload.location])
+
+        overloadWithPromiseReturnType = None
+        overloadWithoutPromiseReturnType = None
+        for overload in self._overloads:
+            returnType = overload.returnType
+            if not returnType.unroll().isExposedInAllOf(self.exposureSet):
+                raise WebIDLError("Overload returns a type that is not exposed "
+                                  "everywhere where the method is exposed",
+                                  [overload.location])
+
+            variadicArgument = None
+
+            arguments = overload.arguments
+            for (idx, argument) in enumerate(arguments):
+                assert argument.type.isComplete()
+
+                if ((argument.type.isDictionary() and
+                     argument.type.inner.canBeEmpty())or
+                    (argument.type.isUnion() and
+                     argument.type.unroll().hasPossiblyEmptyDictionaryType())):
+                    # Optional dictionaries and unions containing optional
+                    # dictionaries at the end of the list or followed by
+                    # optional arguments must be optional.
+                    if (not argument.optional and
+                        all(arg.optional for arg in arguments[idx+1:])):
+                        raise WebIDLError("Dictionary argument or union "
+                                          "argument containing a dictionary "
+                                          "not followed by a required argument "
+                                          "must be optional",
+                                          [argument.location])
+
+                    # An argument cannot be a Nullable Dictionary
+                    if argument.type.nullable():
+                        raise WebIDLError("An argument cannot be a nullable "
+                                          "dictionary or nullable union "
+                                          "containing a dictionary",
+                                          [argument.location])
+
+                # Only the last argument can be variadic
+                if variadicArgument:
+                    raise WebIDLError("Variadic argument is not last argument",
+                                      [variadicArgument.location])
+                if argument.variadic:
+                    variadicArgument = argument
+
+            if returnType.isPromise():
+                overloadWithPromiseReturnType = overload
+            else:
+                overloadWithoutPromiseReturnType = overload
+
+        # Make sure either all our overloads return Promises or none do
+        if overloadWithPromiseReturnType and overloadWithoutPromiseReturnType:
+            raise WebIDLError("We have overloads with both Promise and "
+                              "non-Promise return types",
+                              [overloadWithPromiseReturnType.location,
+                               overloadWithoutPromiseReturnType.location])
+
+        if overloadWithPromiseReturnType and self._legacycaller:
+            raise WebIDLError("May not have a Promise return type for a "
+                              "legacycaller.",
+                              [overloadWithPromiseReturnType.location])
+
+        if self.getExtendedAttribute("StaticClassOverride") and not \
+           (self.identifier.scope.isJSImplemented() and self.isStatic()):
+            raise WebIDLError("StaticClassOverride can be applied to static"
+                              " methods on JS-implemented classes only.",
+                              [self.location])
+
+    def overloadsForArgCount(self, argc):
+        return [overload for overload in self._overloads if
+                len(overload.arguments) == argc or
+                (len(overload.arguments) > argc and
+                 all(arg.optional for arg in overload.arguments[argc:])) or
+                (len(overload.arguments) < argc and
+                 len(overload.arguments) > 0 and
+                 overload.arguments[-1].variadic)]
+
+    def signaturesForArgCount(self, argc):
+        return [(overload.returnType, overload.arguments) for overload
+                in self.overloadsForArgCount(argc)]
+
+    def locationsForArgCount(self, argc):
+        return [overload.location for overload in self.overloadsForArgCount(argc)]
+
+    def distinguishingIndexForArgCount(self, argc):
+        def isValidDistinguishingIndex(idx, signatures):
+            for (firstSigIndex, (firstRetval, firstArgs)) in enumerate(signatures[:-1]):
+                for (secondRetval, secondArgs) in signatures[firstSigIndex+1:]:
+                    if idx < len(firstArgs):
+                        firstType = firstArgs[idx].type
+                    else:
+                        assert(firstArgs[-1].variadic)
+                        firstType = firstArgs[-1].type
+                    if idx < len(secondArgs):
+                        secondType = secondArgs[idx].type
+                    else:
+                        assert(secondArgs[-1].variadic)
+                        secondType = secondArgs[-1].type
+                    if not firstType.isDistinguishableFrom(secondType):
+                        return False
+            return True
+        signatures = self.signaturesForArgCount(argc)
+        for idx in range(argc):
+            if isValidDistinguishingIndex(idx, signatures):
+                return idx
+        # No valid distinguishing index.  Time to throw
+        locations = self.locationsForArgCount(argc)
+        raise WebIDLError("Signatures with %d arguments for method '%s' are not "
+                          "distinguishable" % (argc, self.identifier.name),
+                          locations)
+
+    def handleExtendedAttribute(self, attr):
+        identifier = attr.identifier()
+        if identifier == "GetterThrows":
+            raise WebIDLError("Methods must not be flagged as "
+                              "[GetterThrows]",
+                              [attr.location, self.location])
+        elif identifier == "SetterThrows":
+            raise WebIDLError("Methods must not be flagged as "
+                              "[SetterThrows]",
+                              [attr.location, self.location])
+        elif identifier == "Unforgeable":
+            if self.isStatic():
+                raise WebIDLError("[Unforgeable] is only allowed on non-static "
+                                  "methods", [attr.location, self.location])
+            self._unforgeable = True
+        elif identifier == "SameObject":
+            raise WebIDLError("Methods must not be flagged as [SameObject]",
+                              [attr.location, self.location])
+        elif identifier == "Constant":
+            raise WebIDLError("Methods must not be flagged as [Constant]",
+                              [attr.location, self.location])
+        elif identifier == "PutForwards":
+            raise WebIDLError("Only attributes support [PutForwards]",
+                              [attr.location, self.location])
+        elif identifier == "LenientSetter":
+            raise WebIDLError("Only attributes support [LenientSetter]",
+                              [attr.location, self.location])
+        elif identifier == "LenientFloat":
+            # This is called before we've done overload resolution
+            assert len(self.signatures()) == 1
+            sig = self.signatures()[0]
+            if not sig[0].isVoid():
+                raise WebIDLError("[LenientFloat] used on a non-void method",
+                                  [attr.location, self.location])
+            if not any(arg.type.includesRestrictedFloat() for arg in sig[1]):
+                raise WebIDLError("[LenientFloat] used on an operation with no "
+                                  "restricted float type arguments",
+                                  [attr.location, self.location])
+        elif identifier == "Exposed":
+            convertExposedAttrToGlobalNameSet(attr, self._exposureGlobalNames)
+        elif (identifier == "CrossOriginCallable" or
+              identifier == "WebGLHandlesContextLoss"):
+            # Known no-argument attributes.
+            if not attr.noArguments():
+                raise WebIDLError("[%s] must take no arguments" % identifier,
+                                  [attr.location])
+        elif identifier == "Pure":
+            if not attr.noArguments():
+                raise WebIDLError("[Pure] must take no arguments",
+                                  [attr.location])
+            self._setDependsOn("DOMState")
+            self._setAffects("Nothing")
+        elif identifier == "Affects":
+            if not attr.hasValue():
+                raise WebIDLError("[Affects] takes an identifier",
+                                  [attr.location])
+            self._setAffects(attr.value())
+        elif identifier == "DependsOn":
+            if not attr.hasValue():
+                raise WebIDLError("[DependsOn] takes an identifier",
+                                  [attr.location])
+            self._setDependsOn(attr.value())
+        elif identifier == "Alias":
+            if not attr.hasValue():
+                raise WebIDLError("[Alias] takes an identifier or string",
+                                  [attr.location])
+            self._addAlias(attr.value())
+        elif identifier == "UseCounter":
+            if self.isSpecial():
+                raise WebIDLError("[UseCounter] must not be used on a special "
+                                  "operation",
+                                  [attr.location, self.location])
+        elif identifier == "Unscopable":
+            if not attr.noArguments():
+                raise WebIDLError("[Unscopable] must take no arguments",
+                                  [attr.location])
+            if self.isStatic():
+                raise WebIDLError("[Unscopable] is only allowed on non-static "
+                                  "attributes and operations",
+                                  [attr.location, self.location])
+        elif (identifier == "Throws" or
+              identifier == "NewObject" or
+              identifier == "ChromeOnly" or
+              identifier == "UnsafeInPrerendering" or
+              identifier == "Pref" or
+              identifier == "Deprecated" or
+              identifier == "Func" or
+              identifier == "SecureContext" or
+              identifier == "BinaryName" or
+              identifier == "NeedsSubjectPrincipal" or
+              identifier == "NeedsCallerType" or
+              identifier == "StaticClassOverride"):
+            # Known attributes that we don't need to do anything with here
+            pass
+        else:
+            raise WebIDLError("Unknown extended attribute %s on method" % identifier,
+                              [attr.location])
+        IDLInterfaceMember.handleExtendedAttribute(self, attr)
+
+    def returnsPromise(self):
+        return self._overloads[0].returnType.isPromise()
+
+    def isUnforgeable(self):
+        return self._unforgeable
+
+    def _getDependentObjects(self):
+        deps = set()
+        for overload in self._overloads:
+            deps.update(overload._getDependentObjects())
+        return deps
+
+
+class IDLImplementsStatement(IDLObject):
+    def __init__(self, location, implementor, implementee):
+        IDLObject.__init__(self, location)
+        self.implementor = implementor
+        self.implementee = implementee
+        self._finished = False
+
+    def finish(self, scope):
+        if self._finished:
+            return
+        assert(isinstance(self.implementor, IDLIdentifierPlaceholder))
+        assert(isinstance(self.implementee, IDLIdentifierPlaceholder))
+        implementor = self.implementor.finish(scope)
+        implementee = self.implementee.finish(scope)
+        # NOTE: we depend on not setting self.implementor and
+        # self.implementee here to keep track of the original
+        # locations.
+        if not isinstance(implementor, IDLInterface):
+            raise WebIDLError("Left-hand side of 'implements' is not an "
+                              "interface",
+                              [self.implementor.location])
+        if implementor.isCallback():
+            raise WebIDLError("Left-hand side of 'implements' is a callback "
+                              "interface",
+                              [self.implementor.location])
+        if not isinstance(implementee, IDLInterface):
+            raise WebIDLError("Right-hand side of 'implements' is not an "
+                              "interface",
+                              [self.implementee.location])
+        if implementee.isCallback():
+            raise WebIDLError("Right-hand side of 'implements' is a callback "
+                              "interface",
+                              [self.implementee.location])
+        implementor.addImplementedInterface(implementee)
+        self.implementor = implementor
+        self.implementee = implementee
+
+    def validate(self):
+        pass
+
+    def addExtendedAttributes(self, attrs):
+        assert len(attrs) == 0
+
+
+class IDLExtendedAttribute(IDLObject):
+    """
+    A class to represent IDL extended attributes so we can give them locations
+    """
+    def __init__(self, location, tuple):
+        IDLObject.__init__(self, location)
+        self._tuple = tuple
+
+    def identifier(self):
+        return self._tuple[0]
+
+    def noArguments(self):
+        return len(self._tuple) == 1
+
+    def hasValue(self):
+        return len(self._tuple) >= 2 and isinstance(self._tuple[1], str)
+
+    def value(self):
+        assert(self.hasValue())
+        return self._tuple[1]
+
+    def hasArgs(self):
+        return (len(self._tuple) == 2 and isinstance(self._tuple[1], list) or
+                len(self._tuple) == 3)
+
+    def args(self):
+        assert(self.hasArgs())
+        # Our args are our last element
+        return self._tuple[-1]
+
+    def listValue(self):
+        """
+        Backdoor for storing random data in _extendedAttrDict
+        """
+        return list(self._tuple)[1:]
+
+# Parser
+
+
+class Tokenizer(object):
+    tokens = [
+        "INTEGER",
+        "FLOATLITERAL",
+        "IDENTIFIER",
+        "STRING",
+        "WHITESPACE",
+        "OTHER"
+        ]
+
+    def t_FLOATLITERAL(self, t):
+        r'(-?(([0-9]+\.[0-9]*|[0-9]*\.[0-9]+)([Ee][+-]?[0-9]+)?|[0-9]+[Ee][+-]?[0-9]+|Infinity))|NaN'
+        t.value = float(t.value)
+        return t
+
+    def t_INTEGER(self, t):
+        r'-?(0([0-7]+|[Xx][0-9A-Fa-f]+)?|[1-9][0-9]*)'
+        try:
+            # Can't use int(), because that doesn't handle octal properly.
+            t.value = parseInt(t.value)
+        except:
+            raise WebIDLError("Invalid integer literal",
+                              [Location(lexer=self.lexer,
+                                        lineno=self.lexer.lineno,
+                                        lexpos=self.lexer.lexpos,
+                                        filename=self._filename)])
+        return t
+
+    def t_IDENTIFIER(self, t):
+        r'[A-Z_a-z][0-9A-Z_a-z-]*'
+        t.type = self.keywords.get(t.value, 'IDENTIFIER')
+        return t
+
+    def t_STRING(self, t):
+        r'"[^"]*"'
+        t.value = t.value[1:-1]
+        return t
+
+    def t_WHITESPACE(self, t):
+        r'[\t\n\r ]+|[\t\n\r ]*((//[^\n]*|/\*.*?\*/)[\t\n\r ]*)+'
+        pass
+
+    def t_ELLIPSIS(self, t):
+        r'\.\.\.'
+        t.type = self.keywords.get(t.value)
+        return t
+
+    def t_OTHER(self, t):
+        r'[^\t\n\r 0-9A-Z_a-z]'
+        t.type = self.keywords.get(t.value, 'OTHER')
+        return t
+
+    keywords = {
+        "module": "MODULE",
+        "interface": "INTERFACE",
+        "partial": "PARTIAL",
+        "dictionary": "DICTIONARY",
+        "exception": "EXCEPTION",
+        "enum": "ENUM",
+        "callback": "CALLBACK",
+        "typedef": "TYPEDEF",
+        "implements": "IMPLEMENTS",
+        "const": "CONST",
+        "null": "NULL",
+        "true": "TRUE",
+        "false": "FALSE",
+        "serializer": "SERIALIZER",
+        "stringifier": "STRINGIFIER",
+        "jsonifier": "JSONIFIER",
+        "unrestricted": "UNRESTRICTED",
+        "attribute": "ATTRIBUTE",
+        "readonly": "READONLY",
+        "inherit": "INHERIT",
+        "static": "STATIC",
+        "getter": "GETTER",
+        "setter": "SETTER",
+        "creator": "CREATOR",
+        "deleter": "DELETER",
+        "legacycaller": "LEGACYCALLER",
+        "optional": "OPTIONAL",
+        "...": "ELLIPSIS",
+        "::": "SCOPE",
+        "Date": "DATE",
+        "DOMString": "DOMSTRING",
+        "ByteString": "BYTESTRING",
+        "USVString": "USVSTRING",
+        "any": "ANY",
+        "boolean": "BOOLEAN",
+        "byte": "BYTE",
+        "double": "DOUBLE",
+        "float": "FLOAT",
+        "long": "LONG",
+        "object": "OBJECT",
+        "octet": "OCTET",
+        "Promise": "PROMISE",
+        "required": "REQUIRED",
+        "sequence": "SEQUENCE",
+        "MozMap": "MOZMAP",
+        "short": "SHORT",
+        "unsigned": "UNSIGNED",
+        "void": "VOID",
+        ":": "COLON",
+        ";": "SEMICOLON",
+        "{": "LBRACE",
+        "}": "RBRACE",
+        "(": "LPAREN",
+        ")": "RPAREN",
+        "[": "LBRACKET",
+        "]": "RBRACKET",
+        "?": "QUESTIONMARK",
+        ",": "COMMA",
+        "=": "EQUALS",
+        "<": "LT",
+        ">": "GT",
+        "ArrayBuffer": "ARRAYBUFFER",
+        "SharedArrayBuffer": "SHAREDARRAYBUFFER",
+        "or": "OR",
+        "maplike": "MAPLIKE",
+        "setlike": "SETLIKE",
+        "iterable": "ITERABLE",
+        "namespace": "NAMESPACE"
+        }
+
+    tokens.extend(keywords.values())
+
+    def t_error(self, t):
+        raise WebIDLError("Unrecognized Input",
+                          [Location(lexer=self.lexer,
+                                    lineno=self.lexer.lineno,
+                                    lexpos=self.lexer.lexpos,
+                                    filename=self.filename)])
+
+    def __init__(self, outputdir, lexer=None):
+        if lexer:
+            self.lexer = lexer
+        else:
+            self.lexer = lex.lex(object=self,
+                                 outputdir=outputdir,
+                                 lextab='webidllex',
+                                 reflags=re.DOTALL)
+
+
+class SqueakyCleanLogger(object):
+    errorWhitelist = [
+        # Web IDL defines the WHITESPACE token, but doesn't actually
+        # use it ... so far.
+        "Token 'WHITESPACE' defined, but not used",
+        # And that means we have an unused token
+        "There is 1 unused token",
+        # Web IDL defines a OtherOrComma rule that's only used in
+        # ExtendedAttributeInner, which we don't use yet.
+        "Rule 'OtherOrComma' defined, but not used",
+        # And an unused rule
+        "There is 1 unused rule",
+        # And the OtherOrComma grammar symbol is unreachable.
+        "Symbol 'OtherOrComma' is unreachable",
+        # Which means the Other symbol is unreachable.
+        "Symbol 'Other' is unreachable",
+        ]
+
+    def __init__(self):
+        self.errors = []
+
+    def debug(self, msg, *args, **kwargs):
+        pass
+    info = debug
+
+    def warning(self, msg, *args, **kwargs):
+        if msg == "%s:%d: Rule %r defined, but not used" or \
+           msg == "%s:%d: Rule '%s' defined, but not used":
+            # Munge things so we don't have to hardcode filenames and
+            # line numbers in our whitelist.
+            whitelistmsg = "Rule %r defined, but not used"
+            whitelistargs = args[2:]
+        else:
+            whitelistmsg = msg
+            whitelistargs = args
+        if (whitelistmsg % whitelistargs) not in SqueakyCleanLogger.errorWhitelist:
+            self.errors.append(msg % args)
+    error = warning
+
+    def reportGrammarErrors(self):
+        if self.errors:
+            raise WebIDLError("\n".join(self.errors), [])
+
+
+class Parser(Tokenizer):
+    def getLocation(self, p, i):
+        return Location(self.lexer, p.lineno(i), p.lexpos(i), self._filename)
+
+    def globalScope(self):
+        return self._globalScope
+
+    # The p_Foo functions here must match the WebIDL spec's grammar.
+    # It's acceptable to split things at '|' boundaries.
+    def p_Definitions(self, p):
+        """
+            Definitions : ExtendedAttributeList Definition Definitions
+        """
+        if p[2]:
+            p[0] = [p[2]]
+            p[2].addExtendedAttributes(p[1])
+        else:
+            assert not p[1]
+            p[0] = []
+
+        p[0].extend(p[3])
+
+    def p_DefinitionsEmpty(self, p):
+        """
+            Definitions :
+        """
+        p[0] = []
+
+    def p_Definition(self, p):
+        """
+            Definition : CallbackOrInterface
+                       | Namespace
+                       | Partial
+                       | Dictionary
+                       | Exception
+                       | Enum
+                       | Typedef
+                       | ImplementsStatement
+        """
+        p[0] = p[1]
+        assert p[1]  # We might not have implemented something ...
+
+    def p_CallbackOrInterfaceCallback(self, p):
+        """
+            CallbackOrInterface : CALLBACK CallbackRestOrInterface
+        """
+        if p[2].isInterface():
+            assert isinstance(p[2], IDLInterface)
+            p[2].setCallback(True)
+
+        p[0] = p[2]
+
+    def p_CallbackOrInterfaceInterface(self, p):
+        """
+            CallbackOrInterface : Interface
+        """
+        p[0] = p[1]
+
+    def p_CallbackRestOrInterface(self, p):
+        """
+            CallbackRestOrInterface : CallbackRest
+                                    | Interface
+        """
+        assert p[1]
+        p[0] = p[1]
+
+    def handleNonPartialObject(self, location, identifier, constructor,
+                               constructorArgs, nonPartialArgs):
+        """
+        This handles non-partial objects (interfaces and namespaces) by
+        checking for an existing partial object, and promoting it to
+        non-partial as needed.  The return value is the non-partial object.
+
+        constructorArgs are all the args for the constructor except the last
+        one: isKnownNonPartial.
+
+        nonPartialArgs are the args for the setNonPartial call.
+        """
+        # The name of the class starts with "IDL", so strip that off.
+        # Also, starts with a capital letter after that, so nix that
+        # as well.
+        prettyname = constructor.__name__[3:].lower()
+
+        try:
+            existingObj = self.globalScope()._lookupIdentifier(identifier)
+            if existingObj:
+                if not isinstance(existingObj, constructor):
+                    raise WebIDLError("%s has the same name as "
+                                      "non-%s object" %
+                                      (prettyname.capitalize(), prettyname),
+                                      [location, existingObj.location])
+                existingObj.setNonPartial(*nonPartialArgs)
+                return existingObj
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        # True for isKnownNonPartial
+        return constructor(*(constructorArgs + [True]))
+
+    def p_Interface(self, p):
+        """
+            Interface : INTERFACE IDENTIFIER Inheritance LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[5]
+        parent = p[3]
+
+        p[0] = self.handleNonPartialObject(
+            location, identifier, IDLInterface,
+            [location, self.globalScope(), identifier, parent, members],
+            [location, parent, members])
+
+    def p_InterfaceForwardDecl(self, p):
+        """
+            Interface : INTERFACE IDENTIFIER SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+
+        try:
+            if self.globalScope()._lookupIdentifier(identifier):
+                p[0] = self.globalScope()._lookupIdentifier(identifier)
+                if not isinstance(p[0], IDLExternalInterface):
+                    raise WebIDLError("Name collision between external "
+                                      "interface declaration for identifier "
+                                      "%s and %s" % (identifier.name, p[0]),
+                                      [location, p[0].location])
+                return
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        p[0] = IDLExternalInterface(location, self.globalScope(), identifier)
+
+    def p_Namespace(self, p):
+        """
+            Namespace : NAMESPACE IDENTIFIER LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[4]
+
+        p[0] = self.handleNonPartialObject(
+            location, identifier, IDLNamespace,
+            [location, self.globalScope(), identifier, members],
+            [location, None, members])
+
+    def p_Partial(self, p):
+        """
+            Partial : PARTIAL PartialDefinition
+        """
+        p[0] = p[2]
+
+    def p_PartialDefinition(self, p):
+        """
+            PartialDefinition : PartialInterface
+                              | PartialNamespace
+        """
+        p[0] = p[1]
+
+    def handlePartialObject(self, location, identifier, nonPartialConstructor,
+                            nonPartialConstructorArgs,
+                            partialConstructorArgs):
+        """
+        This handles partial objects (interfaces and namespaces) by checking for
+        an existing non-partial object, and adding ourselves to it as needed.
+        The return value is our partial object.  For now we just use
+        IDLPartialInterfaceOrNamespace for partial objects.
+
+        nonPartialConstructorArgs are all the args for the non-partial
+        constructor except the last two: members and isKnownNonPartial.
+
+        partialConstructorArgs are the arguments for the
+        IDLPartialInterfaceOrNamespace constructor, except the last one (the
+        non-partial object).
+        """
+        # The name of the class starts with "IDL", so strip that off.
+        # Also, starts with a capital letter after that, so nix that
+        # as well.
+        prettyname = nonPartialConstructor.__name__[3:].lower()
+
+        nonPartialObject = None
+        try:
+            nonPartialObject = self.globalScope()._lookupIdentifier(identifier)
+            if nonPartialObject:
+                if not isinstance(nonPartialObject, nonPartialConstructor):
+                    raise WebIDLError("Partial %s has the same name as "
+                                      "non-%s object" %
+                                      (prettyname, prettyname),
+                                      [location, nonPartialObject.location])
+        except Exception, ex:
+            if isinstance(ex, WebIDLError):
+                raise ex
+            pass
+
+        if not nonPartialObject:
+            nonPartialObject = nonPartialConstructor(
+                # No members, False for isKnownNonPartial
+                *(nonPartialConstructorArgs + [[], False]))
+        partialInterface = IDLPartialInterfaceOrNamespace(
+            *(partialConstructorArgs + [nonPartialObject]))
+        return partialInterface
+
+    def p_PartialInterface(self, p):
+        """
+            PartialInterface : INTERFACE IDENTIFIER LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[4]
+
+        p[0] = self.handlePartialObject(
+            location, identifier, IDLInterface,
+            [location, self.globalScope(), identifier, None],
+            [location, identifier, members])
+
+    def p_PartialNamespace(self, p):
+        """
+            PartialNamespace : NAMESPACE IDENTIFIER LBRACE InterfaceMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[4]
+
+        p[0] = self.handlePartialObject(
+            location, identifier, IDLNamespace,
+            [location, self.globalScope(), identifier],
+            [location, identifier, members])
+
+    def p_Inheritance(self, p):
+        """
+            Inheritance : COLON ScopedName
+        """
+        p[0] = IDLIdentifierPlaceholder(self.getLocation(p, 2), p[2])
+
+    def p_InheritanceEmpty(self, p):
+        """
+            Inheritance :
+        """
+        pass
+
+    def p_InterfaceMembers(self, p):
+        """
+            InterfaceMembers : ExtendedAttributeList InterfaceMember InterfaceMembers
+        """
+        p[0] = [p[2]] if p[2] else []
+
+        assert not p[1] or p[2]
+        p[2].addExtendedAttributes(p[1])
+
+        p[0].extend(p[3])
+
+    def p_InterfaceMembersEmpty(self, p):
+        """
+            InterfaceMembers :
+        """
+        p[0] = []
+
+    def p_InterfaceMember(self, p):
+        """
+            InterfaceMember : Const
+                            | AttributeOrOperationOrMaplikeOrSetlikeOrIterable
+        """
+        p[0] = p[1]
+
+    def p_Dictionary(self, p):
+        """
+            Dictionary : DICTIONARY IDENTIFIER Inheritance LBRACE DictionaryMembers RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+        members = p[5]
+        p[0] = IDLDictionary(location, self.globalScope(), identifier, p[3], members)
+
+    def p_DictionaryMembers(self, p):
+        """
+            DictionaryMembers : ExtendedAttributeList DictionaryMember DictionaryMembers
+                             |
+        """
+        if len(p) == 1:
+            # We're at the end of the list
+            p[0] = []
+            return
+        # Add our extended attributes
+        p[2].addExtendedAttributes(p[1])
+        p[0] = [p[2]]
+        p[0].extend(p[3])
+
+    def p_DictionaryMember(self, p):
+        """
+            DictionaryMember : Required Type IDENTIFIER Default SEMICOLON
+        """
+        # These quack a lot like optional arguments, so just treat them that way.
+        t = p[2]
+        assert isinstance(t, IDLType)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 3), p[3])
+        defaultValue = p[4]
+        optional = not p[1]
+
+        if not optional and defaultValue:
+            raise WebIDLError("Required dictionary members can't have a default value.",
+                              [self.getLocation(p, 4)])
+
+        p[0] = IDLArgument(self.getLocation(p, 3), identifier, t,
+                           optional=optional,
+                           defaultValue=defaultValue, variadic=False,
+                           dictionaryMember=True)
+
+    def p_Default(self, p):
+        """
+            Default : EQUALS DefaultValue
+                    |
+        """
+        if len(p) > 1:
+            p[0] = p[2]
+        else:
+            p[0] = None
+
+    def p_DefaultValue(self, p):
+        """
+            DefaultValue : ConstValue
+                         | LBRACKET RBRACKET
+        """
+        if len(p) == 2:
+            p[0] = p[1]
+        else:
+            assert len(p) == 3  # Must be []
+            p[0] = IDLEmptySequenceValue(self.getLocation(p, 1))
+
+    def p_Exception(self, p):
+        """
+            Exception : EXCEPTION IDENTIFIER Inheritance LBRACE ExceptionMembers RBRACE SEMICOLON
+        """
+        pass
+
+    def p_Enum(self, p):
+        """
+            Enum : ENUM IDENTIFIER LBRACE EnumValueList RBRACE SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 2), p[2])
+
+        values = p[4]
+        assert values
+        p[0] = IDLEnum(location, self.globalScope(), identifier, values)
+
+    def p_EnumValueList(self, p):
+        """
+            EnumValueList : STRING EnumValueListComma
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_EnumValueListComma(self, p):
+        """
+            EnumValueListComma : COMMA EnumValueListString
+        """
+        p[0] = p[2]
+
+    def p_EnumValueListCommaEmpty(self, p):
+        """
+            EnumValueListComma :
+        """
+        p[0] = []
+
+    def p_EnumValueListString(self, p):
+        """
+            EnumValueListString : STRING EnumValueListComma
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_EnumValueListStringEmpty(self, p):
+        """
+            EnumValueListString :
+        """
+        p[0] = []
+
+    def p_CallbackRest(self, p):
+        """
+            CallbackRest : IDENTIFIER EQUALS ReturnType LPAREN ArgumentList RPAREN SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+        p[0] = IDLCallback(self.getLocation(p, 1), self.globalScope(),
+                           identifier, p[3], p[5])
+
+    def p_ExceptionMembers(self, p):
+        """
+            ExceptionMembers : ExtendedAttributeList ExceptionMember ExceptionMembers
+                             |
+        """
+        pass
+
+    def p_Typedef(self, p):
+        """
+            Typedef : TYPEDEF Type IDENTIFIER SEMICOLON
+        """
+        typedef = IDLTypedef(self.getLocation(p, 1), self.globalScope(),
+                             p[2], p[3])
+        p[0] = typedef
+
+    def p_ImplementsStatement(self, p):
+        """
+            ImplementsStatement : ScopedName IMPLEMENTS ScopedName SEMICOLON
+        """
+        assert(p[2] == "implements")
+        implementor = IDLIdentifierPlaceholder(self.getLocation(p, 1), p[1])
+        implementee = IDLIdentifierPlaceholder(self.getLocation(p, 3), p[3])
+        p[0] = IDLImplementsStatement(self.getLocation(p, 1), implementor,
+                                      implementee)
+
+    def p_Const(self, p):
+        """
+            Const : CONST ConstType IDENTIFIER EQUALS ConstValue SEMICOLON
+        """
+        location = self.getLocation(p, 1)
+        type = p[2]
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 3), p[3])
+        value = p[5]
+        p[0] = IDLConst(location, identifier, type, value)
+
+    def p_ConstValueBoolean(self, p):
+        """
+            ConstValue : BooleanLiteral
+        """
+        location = self.getLocation(p, 1)
+        booleanType = BuiltinTypes[IDLBuiltinType.Types.boolean]
+        p[0] = IDLValue(location, booleanType, p[1])
+
+    def p_ConstValueInteger(self, p):
+        """
+            ConstValue : INTEGER
+        """
+        location = self.getLocation(p, 1)
+
+        # We don't know ahead of time what type the integer literal is.
+        # Determine the smallest type it could possibly fit in and use that.
+        integerType = matchIntegerValueToType(p[1])
+        if integerType is None:
+            raise WebIDLError("Integer literal out of range", [location])
+
+        p[0] = IDLValue(location, integerType, p[1])
+
+    def p_ConstValueFloat(self, p):
+        """
+            ConstValue : FLOATLITERAL
+        """
+        location = self.getLocation(p, 1)
+        p[0] = IDLValue(location, BuiltinTypes[IDLBuiltinType.Types.unrestricted_float], p[1])
+
+    def p_ConstValueString(self, p):
+        """
+            ConstValue : STRING
+        """
+        location = self.getLocation(p, 1)
+        stringType = BuiltinTypes[IDLBuiltinType.Types.domstring]
+        p[0] = IDLValue(location, stringType, p[1])
+
+    def p_ConstValueNull(self, p):
+        """
+            ConstValue : NULL
+        """
+        p[0] = IDLNullValue(self.getLocation(p, 1))
+
+    def p_BooleanLiteralTrue(self, p):
+        """
+            BooleanLiteral : TRUE
+        """
+        p[0] = True
+
+    def p_BooleanLiteralFalse(self, p):
+        """
+            BooleanLiteral : FALSE
+        """
+        p[0] = False
+
+    def p_AttributeOrOperationOrMaplikeOrSetlikeOrIterable(self, p):
+        """
+            AttributeOrOperationOrMaplikeOrSetlikeOrIterable : Attribute
+                                                             | Maplike
+                                                             | Setlike
+                                                             | Iterable
+                                                             | Operation
+        """
+        p[0] = p[1]
+
+    def p_Iterable(self, p):
+        """
+            Iterable : ITERABLE LT Type GT SEMICOLON
+                     | ITERABLE LT Type COMMA Type GT SEMICOLON
+        """
+        location = self.getLocation(p, 2)
+        identifier = IDLUnresolvedIdentifier(location, "__iterable",
+                                             allowDoubleUnderscore=True)
+        if (len(p) > 6):
+            keyType = p[3]
+            valueType = p[5]
+        else:
+            keyType = None
+            valueType = p[3]
+
+        p[0] = IDLIterable(location, identifier, keyType, valueType, self.globalScope())
+
+    def p_Setlike(self, p):
+        """
+            Setlike : ReadOnly SETLIKE LT Type GT SEMICOLON
+        """
+        readonly = p[1]
+        maplikeOrSetlikeType = p[2]
+        location = self.getLocation(p, 2)
+        identifier = IDLUnresolvedIdentifier(location, "__setlike",
+                                             allowDoubleUnderscore=True)
+        keyType = p[4]
+        valueType = keyType
+        p[0] = IDLMaplikeOrSetlike(location, identifier, maplikeOrSetlikeType,
+                                   readonly, keyType, valueType)
+
+    def p_Maplike(self, p):
+        """
+            Maplike : ReadOnly MAPLIKE LT Type COMMA Type GT SEMICOLON
+        """
+        readonly = p[1]
+        maplikeOrSetlikeType = p[2]
+        location = self.getLocation(p, 2)
+        identifier = IDLUnresolvedIdentifier(location, "__maplike",
+                                             allowDoubleUnderscore=True)
+        keyType = p[4]
+        valueType = p[6]
+        p[0] = IDLMaplikeOrSetlike(location, identifier, maplikeOrSetlikeType,
+                                   readonly, keyType, valueType)
+
+    def p_AttributeWithQualifier(self, p):
+        """
+            Attribute : Qualifier AttributeRest
+        """
+        static = IDLInterfaceMember.Special.Static in p[1]
+        stringifier = IDLInterfaceMember.Special.Stringifier in p[1]
+        (location, identifier, type, readonly) = p[2]
+        p[0] = IDLAttribute(location, identifier, type, readonly,
+                            static=static, stringifier=stringifier)
+
+    def p_AttributeInherited(self, p):
+        """
+            Attribute : INHERIT AttributeRest
+        """
+        (location, identifier, type, readonly) = p[2]
+        p[0] = IDLAttribute(location, identifier, type, readonly, inherit=True)
+
+    def p_Attribute(self, p):
+        """
+            Attribute : AttributeRest
+        """
+        (location, identifier, type, readonly) = p[1]
+        p[0] = IDLAttribute(location, identifier, type, readonly, inherit=False)
+
+    def p_AttributeRest(self, p):
+        """
+            AttributeRest : ReadOnly ATTRIBUTE Type AttributeName SEMICOLON
+        """
+        location = self.getLocation(p, 2)
+        readonly = p[1]
+        t = p[3]
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 4), p[4])
+        p[0] = (location, identifier, t, readonly)
+
+    def p_ReadOnly(self, p):
+        """
+            ReadOnly : READONLY
+        """
+        p[0] = True
+
+    def p_ReadOnlyEmpty(self, p):
+        """
+            ReadOnly :
+        """
+        p[0] = False
+
+    def p_Operation(self, p):
+        """
+            Operation : Qualifiers OperationRest
+        """
+        qualifiers = p[1]
+
+        # Disallow duplicates in the qualifier set
+        if not len(set(qualifiers)) == len(qualifiers):
+            raise WebIDLError("Duplicate qualifiers are not allowed",
+                              [self.getLocation(p, 1)])
+
+        static = IDLInterfaceMember.Special.Static in p[1]
+        # If static is there that's all that's allowed.  This is disallowed
+        # by the parser, so we can assert here.
+        assert not static or len(qualifiers) == 1
+
+        stringifier = IDLInterfaceMember.Special.Stringifier in p[1]
+        # If stringifier is there that's all that's allowed.  This is disallowed
+        # by the parser, so we can assert here.
+        assert not stringifier or len(qualifiers) == 1
+
+        getter = True if IDLMethod.Special.Getter in p[1] else False
+        setter = True if IDLMethod.Special.Setter in p[1] else False
+        creator = True if IDLMethod.Special.Creator in p[1] else False
+        deleter = True if IDLMethod.Special.Deleter in p[1] else False
+        legacycaller = True if IDLMethod.Special.LegacyCaller in p[1] else False
+
+        if getter or deleter:
+            if setter or creator:
+                raise WebIDLError("getter and deleter are incompatible with setter and creator",
+                                  [self.getLocation(p, 1)])
+
+        (returnType, identifier, arguments) = p[2]
+
+        assert isinstance(returnType, IDLType)
+
+        specialType = IDLMethod.NamedOrIndexed.Neither
+
+        if getter or deleter:
+            if len(arguments) != 1:
+                raise WebIDLError("%s has wrong number of arguments" %
+                                  ("getter" if getter else "deleter"),
+                                  [self.getLocation(p, 2)])
+            argType = arguments[0].type
+            if argType == BuiltinTypes[IDLBuiltinType.Types.domstring]:
+                specialType = IDLMethod.NamedOrIndexed.Named
+            elif argType == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]:
+                specialType = IDLMethod.NamedOrIndexed.Indexed
+                if deleter:
+                    raise WebIDLError("There is no such thing as an indexed deleter.",
+                                      [self.getLocation(p, 1)])
+            else:
+                raise WebIDLError("%s has wrong argument type (must be DOMString or UnsignedLong)" %
+                                  ("getter" if getter else "deleter"),
+                                  [arguments[0].location])
+            if arguments[0].optional or arguments[0].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("getter" if getter else "deleter",
+                                   "optional" if arguments[0].optional else "variadic"),
+                                  [arguments[0].location])
+        if getter:
+            if returnType.isVoid():
+                raise WebIDLError("getter cannot have void return type",
+                                  [self.getLocation(p, 2)])
+        if setter or creator:
+            if len(arguments) != 2:
+                raise WebIDLError("%s has wrong number of arguments" %
+                                  ("setter" if setter else "creator"),
+                                  [self.getLocation(p, 2)])
+            argType = arguments[0].type
+            if argType == BuiltinTypes[IDLBuiltinType.Types.domstring]:
+                specialType = IDLMethod.NamedOrIndexed.Named
+            elif argType == BuiltinTypes[IDLBuiltinType.Types.unsigned_long]:
+                specialType = IDLMethod.NamedOrIndexed.Indexed
+            else:
+                raise WebIDLError("%s has wrong argument type (must be DOMString or UnsignedLong)" %
+                                  ("setter" if setter else "creator"),
+                                  [arguments[0].location])
+            if arguments[0].optional or arguments[0].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("setter" if setter else "creator",
+                                   "optional" if arguments[0].optional else "variadic"),
+                                  [arguments[0].location])
+            if arguments[1].optional or arguments[1].variadic:
+                raise WebIDLError("%s cannot have %s argument" %
+                                  ("setter" if setter else "creator",
+                                   "optional" if arguments[1].optional else "variadic"),
+                                  [arguments[1].location])
+
+        if stringifier:
+            if len(arguments) != 0:
+                raise WebIDLError("stringifier has wrong number of arguments",
+                                  [self.getLocation(p, 2)])
+            if not returnType.isDOMString():
+                raise WebIDLError("stringifier must have DOMString return type",
+                                  [self.getLocation(p, 2)])
+
+        # identifier might be None.  This is only permitted for special methods.
+        if not identifier:
+            if (not getter and not setter and not creator and
+                not deleter and not legacycaller and not stringifier):
+                raise WebIDLError("Identifier required for non-special methods",
+                                  [self.getLocation(p, 2)])
+
+            location = BuiltinLocation("<auto-generated-identifier>")
+            identifier = IDLUnresolvedIdentifier(
+                location,
+                "__%s%s%s%s%s%s%s" %
+                ("named" if specialType == IDLMethod.NamedOrIndexed.Named else
+                 "indexed" if specialType == IDLMethod.NamedOrIndexed.Indexed else "",
+                 "getter" if getter else "",
+                 "setter" if setter else "",
+                 "deleter" if deleter else "",
+                 "creator" if creator else "",
+                 "legacycaller" if legacycaller else "",
+                 "stringifier" if stringifier else ""),
+                allowDoubleUnderscore=True)
+
+        method = IDLMethod(self.getLocation(p, 2), identifier, returnType, arguments,
+                           static=static, getter=getter, setter=setter, creator=creator,
+                           deleter=deleter, specialType=specialType,
+                           legacycaller=legacycaller, stringifier=stringifier)
+        p[0] = method
+
+    def p_Stringifier(self, p):
+        """
+            Operation : STRINGIFIER SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                             "__stringifier",
+                                             allowDoubleUnderscore=True)
+        method = IDLMethod(self.getLocation(p, 1),
+                           identifier,
+                           returnType=BuiltinTypes[IDLBuiltinType.Types.domstring],
+                           arguments=[],
+                           stringifier=True)
+        p[0] = method
+
+    def p_Jsonifier(self, p):
+        """
+            Operation : JSONIFIER SEMICOLON
+        """
+        identifier = IDLUnresolvedIdentifier(BuiltinLocation("<auto-generated-identifier>"),
+                                             "__jsonifier", allowDoubleUnderscore=True)
+        method = IDLMethod(self.getLocation(p, 1),
+                           identifier,
+                           returnType=BuiltinTypes[IDLBuiltinType.Types.object],
+                           arguments=[],
+                           jsonifier=True)
+        p[0] = method
+
+    def p_QualifierStatic(self, p):
+        """
+            Qualifier : STATIC
+        """
+        p[0] = [IDLInterfaceMember.Special.Static]
+
+    def p_QualifierStringifier(self, p):
+        """
+            Qualifier : STRINGIFIER
+        """
+        p[0] = [IDLInterfaceMember.Special.Stringifier]
+
+    def p_Qualifiers(self, p):
+        """
+            Qualifiers : Qualifier
+                       | Specials
+        """
+        p[0] = p[1]
+
+    def p_Specials(self, p):
+        """
+            Specials : Special Specials
+        """
+        p[0] = [p[1]]
+        p[0].extend(p[2])
+
+    def p_SpecialsEmpty(self, p):
+        """
+            Specials :
+        """
+        p[0] = []
+
+    def p_SpecialGetter(self, p):
+        """
+            Special : GETTER
+        """
+        p[0] = IDLMethod.Special.Getter
+
+    def p_SpecialSetter(self, p):
+        """
+            Special : SETTER
+        """
+        p[0] = IDLMethod.Special.Setter
+
+    def p_SpecialCreator(self, p):
+        """
+            Special : CREATOR
+        """
+        p[0] = IDLMethod.Special.Creator
+
+    def p_SpecialDeleter(self, p):
+        """
+            Special : DELETER
+        """
+        p[0] = IDLMethod.Special.Deleter
+
+    def p_SpecialLegacyCaller(self, p):
+        """
+            Special : LEGACYCALLER
+        """
+        p[0] = IDLMethod.Special.LegacyCaller
+
+    def p_OperationRest(self, p):
+        """
+            OperationRest : ReturnType OptionalIdentifier LPAREN ArgumentList RPAREN SEMICOLON
+        """
+        p[0] = (p[1], p[2], p[4])
+
+    def p_OptionalIdentifier(self, p):
+        """
+            OptionalIdentifier : IDENTIFIER
+        """
+        p[0] = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+    def p_OptionalIdentifierEmpty(self, p):
+        """
+            OptionalIdentifier :
+        """
+        pass
+
+    def p_ArgumentList(self, p):
+        """
+            ArgumentList : Argument Arguments
+        """
+        p[0] = [p[1]] if p[1] else []
+        p[0].extend(p[2])
+
+    def p_ArgumentListEmpty(self, p):
+        """
+            ArgumentList :
+        """
+        p[0] = []
+
+    def p_Arguments(self, p):
+        """
+            Arguments : COMMA Argument Arguments
+        """
+        p[0] = [p[2]] if p[2] else []
+        p[0].extend(p[3])
+
+    def p_ArgumentsEmpty(self, p):
+        """
+            Arguments :
+        """
+        p[0] = []
+
+    def p_Argument(self, p):
+        """
+            Argument : ExtendedAttributeList Optional Type Ellipsis ArgumentName Default
+        """
+        t = p[3]
+        assert isinstance(t, IDLType)
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 5), p[5])
+
+        optional = p[2]
+        variadic = p[4]
+        defaultValue = p[6]
+
+        if not optional and defaultValue:
+            raise WebIDLError("Mandatory arguments can't have a default value.",
+                              [self.getLocation(p, 6)])
+
+        # We can't test t.isAny() here and give it a default value as needed,
+        # since at this point t is not a fully resolved type yet (e.g. it might
+        # be a typedef).  We'll handle the 'any' case in IDLArgument.complete.
+
+        if variadic:
+            if optional:
+                raise WebIDLError("Variadic arguments should not be marked optional.",
+                                  [self.getLocation(p, 2)])
+            optional = variadic
+
+        p[0] = IDLArgument(self.getLocation(p, 5), identifier, t, optional, defaultValue, variadic)
+        p[0].addExtendedAttributes(p[1])
+
+    def p_ArgumentName(self, p):
+        """
+            ArgumentName : IDENTIFIER
+                         | ATTRIBUTE
+                         | CALLBACK
+                         | CONST
+                         | CREATOR
+                         | DELETER
+                         | DICTIONARY
+                         | ENUM
+                         | EXCEPTION
+                         | GETTER
+                         | IMPLEMENTS
+                         | INHERIT
+                         | INTERFACE
+                         | ITERABLE
+                         | LEGACYCALLER
+                         | MAPLIKE
+                         | PARTIAL
+                         | REQUIRED
+                         | SERIALIZER
+                         | SETLIKE
+                         | SETTER
+                         | STATIC
+                         | STRINGIFIER
+                         | JSONIFIER
+                         | TYPEDEF
+                         | UNRESTRICTED
+                         | NAMESPACE
+        """
+        p[0] = p[1]
+
+    def p_AttributeName(self, p):
+        """
+            AttributeName : IDENTIFIER
+                          | REQUIRED
+        """
+        p[0] = p[1]
+
+    def p_Optional(self, p):
+        """
+            Optional : OPTIONAL
+        """
+        p[0] = True
+
+    def p_OptionalEmpty(self, p):
+        """
+            Optional :
+        """
+        p[0] = False
+
+    def p_Required(self, p):
+        """
+            Required : REQUIRED
+        """
+        p[0] = True
+
+    def p_RequiredEmpty(self, p):
+        """
+            Required :
+        """
+        p[0] = False
+
+    def p_Ellipsis(self, p):
+        """
+            Ellipsis : ELLIPSIS
+        """
+        p[0] = True
+
+    def p_EllipsisEmpty(self, p):
+        """
+            Ellipsis :
+        """
+        p[0] = False
+
+    def p_ExceptionMember(self, p):
+        """
+            ExceptionMember : Const
+                            | ExceptionField
+        """
+        pass
+
+    def p_ExceptionField(self, p):
+        """
+            ExceptionField : Type IDENTIFIER SEMICOLON
+        """
+        pass
+
+    def p_ExtendedAttributeList(self, p):
+        """
+            ExtendedAttributeList : LBRACKET ExtendedAttribute ExtendedAttributes RBRACKET
+        """
+        p[0] = [p[2]]
+        if p[3]:
+            p[0].extend(p[3])
+
+    def p_ExtendedAttributeListEmpty(self, p):
+        """
+            ExtendedAttributeList :
+        """
+        p[0] = []
+
+    def p_ExtendedAttribute(self, p):
+        """
+            ExtendedAttribute : ExtendedAttributeNoArgs
+                              | ExtendedAttributeArgList
+                              | ExtendedAttributeIdent
+                              | ExtendedAttributeNamedArgList
+                              | ExtendedAttributeIdentList
+        """
+        p[0] = IDLExtendedAttribute(self.getLocation(p, 1), p[1])
+
+    def p_ExtendedAttributeEmpty(self, p):
+        """
+            ExtendedAttribute :
+        """
+        pass
+
+    def p_ExtendedAttributes(self, p):
+        """
+            ExtendedAttributes : COMMA ExtendedAttribute ExtendedAttributes
+        """
+        p[0] = [p[2]] if p[2] else []
+        p[0].extend(p[3])
+
+    def p_ExtendedAttributesEmpty(self, p):
+        """
+            ExtendedAttributes :
+        """
+        p[0] = []
+
+    def p_Other(self, p):
+        """
+            Other : INTEGER
+                  | FLOATLITERAL
+                  | IDENTIFIER
+                  | STRING
+                  | OTHER
+                  | ELLIPSIS
+                  | COLON
+                  | SCOPE
+                  | SEMICOLON
+                  | LT
+                  | EQUALS
+                  | GT
+                  | QUESTIONMARK
+                  | DATE
+                  | DOMSTRING
+                  | BYTESTRING
+                  | USVSTRING
+                  | ANY
+                  | ATTRIBUTE
+                  | BOOLEAN
+                  | BYTE
+                  | LEGACYCALLER
+                  | CONST
+                  | CREATOR
+                  | DELETER
+                  | DOUBLE
+                  | EXCEPTION
+                  | FALSE
+                  | FLOAT
+                  | GETTER
+                  | IMPLEMENTS
+                  | INHERIT
+                  | INTERFACE
+                  | LONG
+                  | MODULE
+                  | NULL
+                  | OBJECT
+                  | OCTET
+                  | OPTIONAL
+                  | SEQUENCE
+                  | MOZMAP
+                  | SETTER
+                  | SHORT
+                  | STATIC
+                  | STRINGIFIER
+                  | JSONIFIER
+                  | TRUE
+                  | TYPEDEF
+                  | UNSIGNED
+                  | VOID
+        """
+        pass
+
+    def p_OtherOrComma(self, p):
+        """
+            OtherOrComma : Other
+                         | COMMA
+        """
+        pass
+
+    def p_TypeSingleType(self, p):
+        """
+            Type : SingleType
+        """
+        p[0] = p[1]
+
+    def p_TypeUnionType(self, p):
+        """
+            Type : UnionType Null
+        """
+        p[0] = self.handleNullable(p[1], p[2])
+
+    def p_SingleTypeNonAnyType(self, p):
+        """
+            SingleType : NonAnyType
+        """
+        p[0] = p[1]
+
+    def p_SingleTypeAnyType(self, p):
+        """
+            SingleType : ANY
+        """
+        p[0] = BuiltinTypes[IDLBuiltinType.Types.any]
+
+    def p_UnionType(self, p):
+        """
+            UnionType : LPAREN UnionMemberType OR UnionMemberType UnionMemberTypes RPAREN
+        """
+        types = [p[2], p[4]]
+        types.extend(p[5])
+        p[0] = IDLUnionType(self.getLocation(p, 1), types)
+
+    def p_UnionMemberTypeNonAnyType(self, p):
+        """
+            UnionMemberType : NonAnyType
+        """
+        p[0] = p[1]
+
+    def p_UnionMemberType(self, p):
+        """
+            UnionMemberType : UnionType Null
+        """
+        p[0] = self.handleNullable(p[1], p[2])
+
+    def p_UnionMemberTypes(self, p):
+        """
+            UnionMemberTypes : OR UnionMemberType UnionMemberTypes
+        """
+        p[0] = [p[2]]
+        p[0].extend(p[3])
+
+    def p_UnionMemberTypesEmpty(self, p):
+        """
+            UnionMemberTypes :
+        """
+        p[0] = []
+
+    def p_NonAnyType(self, p):
+        """
+            NonAnyType : PrimitiveOrStringType Null
+                       | ARRAYBUFFER Null
+                       | SHAREDARRAYBUFFER Null
+                       | OBJECT Null
+        """
+        if p[1] == "object":
+            type = BuiltinTypes[IDLBuiltinType.Types.object]
+        elif p[1] == "ArrayBuffer":
+            type = BuiltinTypes[IDLBuiltinType.Types.ArrayBuffer]
+        elif p[1] == "SharedArrayBuffer":
+            type = BuiltinTypes[IDLBuiltinType.Types.SharedArrayBuffer]
+        else:
+            type = BuiltinTypes[p[1]]
+
+        p[0] = self.handleNullable(type, p[2])
+
+    def p_NonAnyTypeSequenceType(self, p):
+        """
+            NonAnyType : SEQUENCE LT Type GT Null
+        """
+        innerType = p[3]
+        type = IDLSequenceType(self.getLocation(p, 1), innerType)
+        p[0] = self.handleNullable(type, p[5])
+
+    # Note: Promise<void> is allowed, so we want to parametrize on
+    # ReturnType, not Type.  Also, we want this to end up picking up
+    # the Promise interface for now, hence the games with IDLUnresolvedType.
+    def p_NonAnyTypePromiseType(self, p):
+        """
+            NonAnyType : PROMISE LT ReturnType GT Null
+        """
+        innerType = p[3]
+        promiseIdent = IDLUnresolvedIdentifier(self.getLocation(p, 1), "Promise")
+        type = IDLUnresolvedType(self.getLocation(p, 1), promiseIdent, p[3])
+        p[0] = self.handleNullable(type, p[5])
+
+    def p_NonAnyTypeMozMapType(self, p):
+        """
+            NonAnyType : MOZMAP LT Type GT Null
+        """
+        innerType = p[3]
+        type = IDLMozMapType(self.getLocation(p, 1), innerType)
+        p[0] = self.handleNullable(type, p[5])
+
+    def p_NonAnyTypeScopedName(self, p):
+        """
+            NonAnyType : ScopedName Null
+        """
+        assert isinstance(p[1], IDLUnresolvedIdentifier)
+
+        if p[1].name == "Promise":
+            raise WebIDLError("Promise used without saying what it's "
+                              "parametrized over",
+                              [self.getLocation(p, 1)])
+
+        type = None
+
+        try:
+            if self.globalScope()._lookupIdentifier(p[1]):
+                obj = self.globalScope()._lookupIdentifier(p[1])
+                assert not obj.isType()
+                if obj.isTypedef():
+                    type = IDLTypedefType(self.getLocation(p, 1), obj.innerType,
+                                          obj.identifier.name)
+                elif obj.isCallback() and not obj.isInterface():
+                    type = IDLCallbackType(self.getLocation(p, 1), obj)
+                else:
+                    type = IDLWrapperType(self.getLocation(p, 1), p[1])
+                p[0] = self.handleNullable(type, p[2])
+                return
+        except:
+            pass
+
+        type = IDLUnresolvedType(self.getLocation(p, 1), p[1])
+        p[0] = self.handleNullable(type, p[2])
+
+    def p_NonAnyTypeDate(self, p):
+        """
+            NonAnyType : DATE Null
+        """
+        p[0] = self.handleNullable(BuiltinTypes[IDLBuiltinType.Types.date],
+                                   p[2])
+
+    def p_ConstType(self, p):
+        """
+            ConstType : PrimitiveOrStringType Null
+        """
+        type = BuiltinTypes[p[1]]
+        p[0] = self.handleNullable(type, p[2])
+
+    def p_ConstTypeIdentifier(self, p):
+        """
+            ConstType : IDENTIFIER Null
+        """
+        identifier = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+        type = IDLUnresolvedType(self.getLocation(p, 1), identifier)
+        p[0] = self.handleNullable(type, p[2])
+
+    def p_PrimitiveOrStringTypeUint(self, p):
+        """
+            PrimitiveOrStringType : UnsignedIntegerType
+        """
+        p[0] = p[1]
+
+    def p_PrimitiveOrStringTypeBoolean(self, p):
+        """
+            PrimitiveOrStringType : BOOLEAN
+        """
+        p[0] = IDLBuiltinType.Types.boolean
+
+    def p_PrimitiveOrStringTypeByte(self, p):
+        """
+            PrimitiveOrStringType : BYTE
+        """
+        p[0] = IDLBuiltinType.Types.byte
+
+    def p_PrimitiveOrStringTypeOctet(self, p):
+        """
+            PrimitiveOrStringType : OCTET
+        """
+        p[0] = IDLBuiltinType.Types.octet
+
+    def p_PrimitiveOrStringTypeFloat(self, p):
+        """
+            PrimitiveOrStringType : FLOAT
+        """
+        p[0] = IDLBuiltinType.Types.float
+
+    def p_PrimitiveOrStringTypeUnrestictedFloat(self, p):
+        """
+            PrimitiveOrStringType : UNRESTRICTED FLOAT
+        """
+        p[0] = IDLBuiltinType.Types.unrestricted_float
+
+    def p_PrimitiveOrStringTypeDouble(self, p):
+        """
+            PrimitiveOrStringType : DOUBLE
+        """
+        p[0] = IDLBuiltinType.Types.double
+
+    def p_PrimitiveOrStringTypeUnrestictedDouble(self, p):
+        """
+            PrimitiveOrStringType : UNRESTRICTED DOUBLE
+        """
+        p[0] = IDLBuiltinType.Types.unrestricted_double
+
+    def p_PrimitiveOrStringTypeDOMString(self, p):
+        """
+            PrimitiveOrStringType : DOMSTRING
+        """
+        p[0] = IDLBuiltinType.Types.domstring
+
+    def p_PrimitiveOrStringTypeBytestring(self, p):
+        """
+            PrimitiveOrStringType : BYTESTRING
+        """
+        p[0] = IDLBuiltinType.Types.bytestring
+
+    def p_PrimitiveOrStringTypeUSVString(self, p):
+        """
+            PrimitiveOrStringType : USVSTRING
+        """
+        p[0] = IDLBuiltinType.Types.usvstring
+
+    def p_UnsignedIntegerTypeUnsigned(self, p):
+        """
+            UnsignedIntegerType : UNSIGNED IntegerType
+        """
+        # Adding one to a given signed integer type gets you the unsigned type:
+        p[0] = p[2] + 1
+
+    def p_UnsignedIntegerType(self, p):
+        """
+            UnsignedIntegerType : IntegerType
+        """
+        p[0] = p[1]
+
+    def p_IntegerTypeShort(self, p):
+        """
+            IntegerType : SHORT
+        """
+        p[0] = IDLBuiltinType.Types.short
+
+    def p_IntegerTypeLong(self, p):
+        """
+            IntegerType : LONG OptionalLong
+        """
+        if p[2]:
+            p[0] = IDLBuiltinType.Types.long_long
+        else:
+            p[0] = IDLBuiltinType.Types.long
+
+    def p_OptionalLong(self, p):
+        """
+            OptionalLong : LONG
+        """
+        p[0] = True
+
+    def p_OptionalLongEmpty(self, p):
+        """
+            OptionalLong :
+        """
+        p[0] = False
+
+    def p_Null(self, p):
+        """
+            Null : QUESTIONMARK
+                 |
+        """
+        if len(p) > 1:
+            p[0] = self.getLocation(p, 1)
+        else:
+            p[0] = None
+
+    def p_ReturnTypeType(self, p):
+        """
+            ReturnType : Type
+        """
+        p[0] = p[1]
+
+    def p_ReturnTypeVoid(self, p):
+        """
+            ReturnType : VOID
+        """
+        p[0] = BuiltinTypes[IDLBuiltinType.Types.void]
+
+    def p_ScopedName(self, p):
+        """
+            ScopedName : AbsoluteScopedName
+                       | RelativeScopedName
+        """
+        p[0] = p[1]
+
+    def p_AbsoluteScopedName(self, p):
+        """
+            AbsoluteScopedName : SCOPE IDENTIFIER ScopedNameParts
+        """
+        assert False
+        pass
+
+    def p_RelativeScopedName(self, p):
+        """
+            RelativeScopedName : IDENTIFIER ScopedNameParts
+        """
+        assert not p[2]  # Not implemented!
+
+        p[0] = IDLUnresolvedIdentifier(self.getLocation(p, 1), p[1])
+
+    def p_ScopedNameParts(self, p):
+        """
+            ScopedNameParts : SCOPE IDENTIFIER ScopedNameParts
+        """
+        assert False
+        pass
+
+    def p_ScopedNamePartsEmpty(self, p):
+        """
+            ScopedNameParts :
+        """
+        p[0] = None
+
+    def p_ExtendedAttributeNoArgs(self, p):
+        """
+            ExtendedAttributeNoArgs : IDENTIFIER
+        """
+        p[0] = (p[1],)
+
+    def p_ExtendedAttributeArgList(self, p):
+        """
+            ExtendedAttributeArgList : IDENTIFIER LPAREN ArgumentList RPAREN
+        """
+        p[0] = (p[1], p[3])
+
+    def p_ExtendedAttributeIdent(self, p):
+        """
+            ExtendedAttributeIdent : IDENTIFIER EQUALS STRING
+                                   | IDENTIFIER EQUALS IDENTIFIER
+        """
+        p[0] = (p[1], p[3])
+
+    def p_ExtendedAttributeNamedArgList(self, p):
+        """
+            ExtendedAttributeNamedArgList : IDENTIFIER EQUALS IDENTIFIER LPAREN ArgumentList RPAREN
+        """
+        p[0] = (p[1], p[3], p[5])
+
+    def p_ExtendedAttributeIdentList(self, p):
+        """
+            ExtendedAttributeIdentList : IDENTIFIER EQUALS LPAREN IdentifierList RPAREN
+        """
+        p[0] = (p[1], p[4])
+
+    def p_IdentifierList(self, p):
+        """
+            IdentifierList : IDENTIFIER Identifiers
+        """
+        idents = list(p[2])
+        idents.insert(0, p[1])
+        p[0] = idents
+
+    def p_IdentifiersList(self, p):
+        """
+            Identifiers : COMMA IDENTIFIER Identifiers
+        """
+        idents = list(p[3])
+        idents.insert(0, p[2])
+        p[0] = idents
+
+    def p_IdentifiersEmpty(self, p):
+        """
+            Identifiers :
+        """
+        p[0] = []
+
+    def p_error(self, p):
+        if not p:
+            raise WebIDLError("Syntax Error at end of file. Possibly due to missing semicolon(;), braces(}) or both",
+                              [self._filename])
+        else:
+            raise WebIDLError("invalid syntax", [Location(self.lexer, p.lineno, p.lexpos, self._filename)])
+
+    def __init__(self, outputdir='', lexer=None):
+        Tokenizer.__init__(self, outputdir, lexer)
+
+        logger = SqueakyCleanLogger()
+        try:
+            self.parser = yacc.yacc(module=self,
+                                    outputdir=outputdir,
+                                    tabmodule='webidlyacc',
+                                    errorlog=logger
+                                    # Pickling the grammar is a speedup in
+                                    # some cases (older Python?) but a
+                                    # significant slowdown in others.
+                                    # We're not pickling for now, until it
+                                    # becomes a speedup again.
+                                    # , picklefile='WebIDLGrammar.pkl'
+            )
+        finally:
+            logger.reportGrammarErrors()
+
+        self._globalScope = IDLScope(BuiltinLocation("<Global Scope>"), None, None)
+        # To make our test harness work, pretend like we have a primary global already.
+        # Note that we _don't_ set _globalScope.primaryGlobalAttr,
+        # so we'll still be able to detect multiple PrimaryGlobal extended attributes.
+        self._globalScope.primaryGlobalName = "FakeTestPrimaryGlobal"
+        self._globalScope.globalNames.add("FakeTestPrimaryGlobal")
+        self._globalScope.globalNameMapping["FakeTestPrimaryGlobal"].add("FakeTestPrimaryGlobal")
+        # And we add the special-cased "System" global name, which
+        # doesn't have any corresponding interfaces.
+        self._globalScope.globalNames.add("System")
+        self._globalScope.globalNameMapping["System"].add("BackstagePass")
+        self._installBuiltins(self._globalScope)
+        self._productions = []
+
+        self._filename = "<builtin>"
+        self.lexer.input(Parser._builtins)
+        self._filename = None
+
+        self.parser.parse(lexer=self.lexer, tracking=True)
+
+    def _installBuiltins(self, scope):
+        assert isinstance(scope, IDLScope)
+
+        # xrange omits the last value.
+        for x in xrange(IDLBuiltinType.Types.ArrayBuffer, IDLBuiltinType.Types.Float64Array + 1):
+            builtin = BuiltinTypes[x]
+            name = builtin.name
+            typedef = IDLTypedef(BuiltinLocation("<builtin type>"), scope, builtin, name)
+
+    @ staticmethod
+    def handleNullable(type, questionMarkLocation):
+        if questionMarkLocation is not None:
+            type = IDLNullableType(questionMarkLocation, type)
+
+        return type
+
+    def parse(self, t, filename=None):
+        self.lexer.input(t)
+
+        # for tok in iter(self.lexer.token, None):
+        #    print tok
+
+        self._filename = filename
+        self._productions.extend(self.parser.parse(lexer=self.lexer, tracking=True))
+        self._filename = None
+
+    def finish(self):
+        # If we have interfaces that are iterable, create their
+        # iterator interfaces and add them to the productions array.
+        interfaceStatements = []
+        for p in self._productions:
+            if isinstance(p, IDLInterface):
+                interfaceStatements.append(p)
+                if p.identifier.name == "Navigator":
+                    navigatorInterface = p
+
+        iterableIteratorIface = None
+        for iface in interfaceStatements:
+            navigatorProperty = iface.getNavigatorProperty()
+            if navigatorProperty:
+                # We're generating a partial interface to add a readonly
+                # property to the Navigator interface for every interface
+                # annotated with NavigatorProperty.
+                partialInterface = IDLPartialInterfaceOrNamespace(
+                    iface.location,
+                    IDLUnresolvedIdentifier(iface.location, "Navigator"),
+                    [ navigatorProperty ],
+                    navigatorInterface)
+                self._productions.append(partialInterface)
+
+            iterable = None
+            # We haven't run finish() on the interface yet, so we don't know
+            # whether our interface is maplike/setlike/iterable or not. This
+            # means we have to loop through the members to see if we have an
+            # iterable member.
+            for m in iface.members:
+                if isinstance(m, IDLIterable):
+                    iterable = m
+                    break
+            if iterable and iterable.isPairIterator():
+                def simpleExtendedAttr(str):
+                    return IDLExtendedAttribute(iface.location, (str, ))
+                nextMethod = IDLMethod(
+                    iface.location,
+                    IDLUnresolvedIdentifier(iface.location, "next"),
+                    BuiltinTypes[IDLBuiltinType.Types.object], [])
+                nextMethod.addExtendedAttributes([simpleExtendedAttr("Throws")])
+                itr_ident = IDLUnresolvedIdentifier(iface.location,
+                                                    iface.identifier.name + "Iterator")
+                itr_iface = IDLInterface(iface.location, self.globalScope(),
+                                         itr_ident, None, [nextMethod],
+                                         isKnownNonPartial=True)
+                itr_iface.addExtendedAttributes([simpleExtendedAttr("NoInterfaceObject")])
+                # Make sure the exposure set for the iterator interface is the
+                # same as the exposure set for the iterable interface, because
+                # we're going to generate methods on the iterable that return
+                # instances of the iterator.
+                itr_iface._exposureGlobalNames = set(iface._exposureGlobalNames)
+                # Always append generated iterable interfaces after the
+                # interface they're a member of, otherwise nativeType generation
+                # won't work correctly.
+                itr_iface.iterableInterface = iface
+                self._productions.append(itr_iface)
+                iterable.iteratorType = IDLWrapperType(iface.location, itr_iface)
+
+        # Then, finish all the IDLImplementsStatements.  In particular, we
+        # have to make sure we do those before we do the IDLInterfaces.
+        # XXX khuey hates this bit and wants to nuke it from orbit.
+        implementsStatements = [p for p in self._productions if
+                                isinstance(p, IDLImplementsStatement)]
+        otherStatements = [p for p in self._productions if
+                           not isinstance(p, IDLImplementsStatement)]
+        for production in implementsStatements:
+            production.finish(self.globalScope())
+        for production in otherStatements:
+            production.finish(self.globalScope())
+
+        # Do any post-finish validation we need to do
+        for production in self._productions:
+            production.validate()
+
+        # De-duplicate self._productions, without modifying its order.
+        seen = set()
+        result = []
+        for p in self._productions:
+            if p not in seen:
+                seen.add(p)
+                result.append(p)
+        return result
+
+    def reset(self):
+        return Parser(lexer=self.lexer)
+
+    # Builtin IDL defined by WebIDL
+    _builtins = """
+        typedef unsigned long long DOMTimeStamp;
+        typedef (ArrayBufferView or ArrayBuffer) BufferSource;
+    """
+
+
+def main():
+    # Parse arguments.
+    from optparse import OptionParser
+    usageString = "usage: %prog [options] files"
+    o = OptionParser(usage=usageString)
+    o.add_option("--cachedir", dest='cachedir', default=None,
+                 help="Directory in which to cache lex/parse tables.")
+    o.add_option("--verbose-errors", action='store_true', default=False,
+                 help="When an error happens, display the Python traceback.")
+    (options, args) = o.parse_args()
+
+    if len(args) < 1:
+        o.error(usageString)
+
+    fileList = args
+    baseDir = os.getcwd()
+
+    # Parse the WebIDL.
+    parser = Parser(options.cachedir)
+    try:
+        for filename in fileList:
+            fullPath = os.path.normpath(os.path.join(baseDir, filename))
+            f = open(fullPath, 'rb')
+            lines = f.readlines()
+            f.close()
+            print fullPath
+            parser.parse(''.join(lines), fullPath)
+        parser.finish()
+    except WebIDLError, e:
+        if options.verbose_errors:
+            traceback.print_exc()
+        else:
+            print e
+
+if __name__ == '__main__':
+    main()
diff --git a/dom/bindings/parser/runtests.py b/dom/bindings/parser/runtests.py
new file mode 100644
index 000000000..33bb59f8a
--- /dev/null
+++ b/dom/bindings/parser/runtests.py
@@ -0,0 +1,108 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import os, sys
+import glob
+import argparse
+import traceback
+import WebIDL
+
+class TestHarness(object):
+    def __init__(self, test, verbose):
+        self.test = test
+        self.verbose = verbose
+        self.printed_intro = False
+        self.passed = 0
+        self.failures = []
+
+    def start(self):
+        if self.verbose:
+            self.maybe_print_intro()
+
+    def finish(self):
+        if self.verbose or self.printed_intro:
+            print "Finished test %s" % self.test
+
+    def maybe_print_intro(self):
+        if not self.printed_intro:
+            print "Starting test %s" % self.test
+            self.printed_intro = True
+
+    def test_pass(self, msg):
+        self.passed += 1
+        if self.verbose:
+            print "TEST-PASS | %s" % msg
+
+    def test_fail(self, msg):
+        self.maybe_print_intro()
+        self.failures.append(msg)
+        print "TEST-UNEXPECTED-FAIL | %s" % msg
+
+    def ok(self, condition, msg):
+        if condition:
+            self.test_pass(msg)
+        else:
+            self.test_fail(msg)
+
+    def check(self, a, b, msg):
+        if a == b:
+            self.test_pass(msg)
+        else:
+            self.test_fail(msg + " | Got %s expected %s" % (a, b))
+
+def run_tests(tests, verbose):
+    testdir = os.path.join(os.path.dirname(__file__), 'tests')
+    if not tests:
+        tests = glob.iglob(os.path.join(testdir, "*.py"))
+    sys.path.append(testdir)
+
+    all_passed = 0
+    failed_tests = []
+
+    for test in tests:
+        (testpath, ext) = os.path.splitext(os.path.basename(test))
+        _test = __import__(testpath, globals(), locals(), ['WebIDLTest'])
+
+        harness = TestHarness(test, verbose)
+        harness.start()
+        try:
+            _test.WebIDLTest.__call__(WebIDL.Parser(), harness)
+        except Exception, ex:
+            harness.test_fail("Unhandled exception in test %s: %s" %
+                              (testpath, ex))
+            traceback.print_exc()
+        finally:
+            harness.finish()
+        all_passed += harness.passed
+        if harness.failures:
+            failed_tests.append((test, harness.failures))
+
+    if verbose or failed_tests:
+        print
+        print 'Result summary:'
+        print 'Successful: %d' % all_passed
+        print 'Unexpected: %d' % \
+                sum(len(failures) for _, failures in failed_tests)
+        for test, failures in failed_tests:
+            print '%s:' % test
+            for failure in failures:
+                print 'TEST-UNEXPECTED-FAIL | %s' % failure
+
+def get_parser():
+    usage = """%(prog)s [OPTIONS] [TESTS]
+               Where TESTS are relative to the tests directory."""
+    parser = argparse.ArgumentParser(usage=usage)
+    parser.add_argument('-q', '--quiet', action='store_false', dest='verbose',
+                        help="Don't print passing tests.", default=None)
+    parser.add_argument('-v', '--verbose', action='store_true', dest='verbose',
+                        help="Run tests in verbose mode.")
+    parser.add_argument('tests', nargs="*", help="Tests to run")
+    return parser
+
+if __name__ == '__main__':
+    parser = get_parser()
+    args = parser.parse_args()
+    if args.verbose is None:
+        args.verbose = True
+    run_tests(args.tests, verbose=args.verbose)
diff --git a/dom/bindings/parser/tests/test_any_null.py b/dom/bindings/parser/tests/test_any_null.py
new file mode 100644
index 000000000..e3b690bf6
--- /dev/null
+++ b/dom/bindings/parser/tests/test_any_null.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface DoubleNull {
+              attribute any? foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_argument_identifier_conflicts.py b/dom/bindings/parser/tests/test_argument_identifier_conflicts.py
new file mode 100644
index 000000000..eb1f6d3c9
--- /dev/null
+++ b/dom/bindings/parser/tests/test_argument_identifier_conflicts.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface ArgumentIdentifierConflict {
+              void foo(boolean arg1, boolean arg1);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_argument_novoid.py b/dom/bindings/parser/tests/test_argument_novoid.py
new file mode 100644
index 000000000..ef8c2229a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_argument_novoid.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface VoidArgument1 {
+              void foo(void arg2);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_arraybuffer.py b/dom/bindings/parser/tests/test_arraybuffer.py
new file mode 100644
index 000000000..4a96c0ff5
--- /dev/null
+++ b/dom/bindings/parser/tests/test_arraybuffer.py
@@ -0,0 +1,81 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestArrayBuffer {
+          attribute ArrayBuffer bufferAttr;
+          void bufferMethod(ArrayBuffer arg1, ArrayBuffer? arg2, sequence<ArrayBuffer> arg3);
+
+          attribute ArrayBufferView viewAttr;
+          void viewMethod(ArrayBufferView arg1, ArrayBufferView? arg2, sequence<ArrayBufferView> arg3);
+
+          attribute Int8Array int8ArrayAttr;
+          void int8ArrayMethod(Int8Array arg1, Int8Array? arg2, sequence<Int8Array> arg3);
+
+          attribute Uint8Array uint8ArrayAttr;
+          void uint8ArrayMethod(Uint8Array arg1, Uint8Array? arg2, sequence<Uint8Array> arg3);
+
+          attribute Uint8ClampedArray uint8ClampedArrayAttr;
+          void uint8ClampedArrayMethod(Uint8ClampedArray arg1, Uint8ClampedArray? arg2, sequence<Uint8ClampedArray> arg3);
+
+          attribute Int16Array int16ArrayAttr;
+          void int16ArrayMethod(Int16Array arg1, Int16Array? arg2, sequence<Int16Array> arg3);
+
+          attribute Uint16Array uint16ArrayAttr;
+          void uint16ArrayMethod(Uint16Array arg1, Uint16Array? arg2, sequence<Uint16Array> arg3);
+
+          attribute Int32Array int32ArrayAttr;
+          void int32ArrayMethod(Int32Array arg1, Int32Array? arg2, sequence<Int32Array> arg3);
+
+          attribute Uint32Array uint32ArrayAttr;
+          void uint32ArrayMethod(Uint32Array arg1, Uint32Array? arg2, sequence<Uint32Array> arg3);
+
+          attribute Float32Array float32ArrayAttr;
+          void float32ArrayMethod(Float32Array arg1, Float32Array? arg2, sequence<Float32Array> arg3);
+
+          attribute Float64Array float64ArrayAttr;
+          void float64ArrayMethod(Float64Array arg1, Float64Array? arg2, sequence<Float64Array> arg3);
+        };
+    """)
+
+    results = parser.finish()
+
+    iface = results[0]
+
+    harness.ok(True, "TestArrayBuffer interface parsed without error")
+    harness.check(len(iface.members), 22, "Interface should have twenty two members")
+
+    members = iface.members
+
+    def checkStuff(attr, method, t):
+        harness.ok(isinstance(attr, WebIDL.IDLAttribute), "Expect an IDLAttribute")
+        harness.ok(isinstance(method, WebIDL.IDLMethod), "Expect an IDLMethod")
+
+        harness.check(str(attr.type), t, "Expect an ArrayBuffer type")
+        harness.ok(attr.type.isSpiderMonkeyInterface(), "Should test as a js interface")
+
+        (retType, arguments) = method.signatures()[0]
+        harness.ok(retType.isVoid(), "Should have a void return type")
+        harness.check(len(arguments), 3, "Expect 3 arguments")
+
+        harness.check(str(arguments[0].type), t,  "Expect an ArrayBuffer type")
+        harness.ok(arguments[0].type.isSpiderMonkeyInterface(), "Should test as a js interface")
+
+        harness.check(str(arguments[1].type), t + "OrNull",  "Expect an ArrayBuffer type")
+        harness.ok(arguments[1].type.inner.isSpiderMonkeyInterface(), "Should test as a js interface")
+
+        harness.check(str(arguments[2].type), t + "Sequence",  "Expect an ArrayBuffer type")
+        harness.ok(arguments[2].type.inner.isSpiderMonkeyInterface(), "Should test as a js interface")
+
+
+    checkStuff(members[0],  members[1],  "ArrayBuffer")
+    checkStuff(members[2],  members[3],  "ArrayBufferView")
+    checkStuff(members[4],  members[5],  "Int8Array")
+    checkStuff(members[6],  members[7],  "Uint8Array")
+    checkStuff(members[8],  members[9],  "Uint8ClampedArray")
+    checkStuff(members[10], members[11], "Int16Array")
+    checkStuff(members[12], members[13], "Uint16Array")
+    checkStuff(members[14], members[15], "Int32Array")
+    checkStuff(members[16], members[17], "Uint32Array")
+    checkStuff(members[18], members[19], "Float32Array")
+    checkStuff(members[20], members[21], "Float64Array")
diff --git a/dom/bindings/parser/tests/test_attr.py b/dom/bindings/parser/tests/test_attr.py
new file mode 100644
index 000000000..ad7aabc19
--- /dev/null
+++ b/dom/bindings/parser/tests/test_attr.py
@@ -0,0 +1,177 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    testData = [("::TestAttr%s::b", "b", "Byte%s", False),
+                ("::TestAttr%s::rb", "rb", "Byte%s", True),
+                ("::TestAttr%s::o", "o", "Octet%s", False),
+                ("::TestAttr%s::ro", "ro", "Octet%s", True),
+                ("::TestAttr%s::s", "s", "Short%s", False),
+                ("::TestAttr%s::rs", "rs", "Short%s", True),
+                ("::TestAttr%s::us", "us", "UnsignedShort%s", False),
+                ("::TestAttr%s::rus", "rus", "UnsignedShort%s", True),
+                ("::TestAttr%s::l", "l", "Long%s", False),
+                ("::TestAttr%s::rl", "rl", "Long%s", True),
+                ("::TestAttr%s::ul", "ul", "UnsignedLong%s", False),
+                ("::TestAttr%s::rul", "rul", "UnsignedLong%s", True),
+                ("::TestAttr%s::ll", "ll", "LongLong%s", False),
+                ("::TestAttr%s::rll", "rll", "LongLong%s", True),
+                ("::TestAttr%s::ull", "ull", "UnsignedLongLong%s", False),
+                ("::TestAttr%s::rull", "rull", "UnsignedLongLong%s", True),
+                ("::TestAttr%s::str", "str", "String%s", False),
+                ("::TestAttr%s::rstr", "rstr", "String%s", True),
+                ("::TestAttr%s::obj", "obj", "Object%s", False),
+                ("::TestAttr%s::robj", "robj", "Object%s", True),
+                ("::TestAttr%s::object", "object", "Object%s", False),
+                ("::TestAttr%s::f", "f", "Float%s", False),
+                ("::TestAttr%s::rf", "rf", "Float%s", True)]
+
+    parser.parse("""
+        interface TestAttr {
+          attribute byte b;
+          readonly attribute byte rb;
+          attribute octet o;
+          readonly attribute octet ro;
+          attribute short s;
+          readonly attribute short rs;
+          attribute unsigned short us;
+          readonly attribute unsigned short rus;
+          attribute long l;
+          readonly attribute long rl;
+          attribute unsigned long ul;
+          readonly attribute unsigned long rul;
+          attribute long long ll;
+          readonly attribute long long rll;
+          attribute unsigned long long ull;
+          readonly attribute unsigned long long rull;
+          attribute DOMString str;
+          readonly attribute DOMString rstr;
+          attribute object obj;
+          readonly attribute object robj;
+          attribute object _object;
+          attribute float f;
+          readonly attribute float rf;
+        };
+
+        interface TestAttrNullable {
+          attribute byte? b;
+          readonly attribute byte? rb;
+          attribute octet? o;
+          readonly attribute octet? ro;
+          attribute short? s;
+          readonly attribute short? rs;
+          attribute unsigned short? us;
+          readonly attribute unsigned short? rus;
+          attribute long? l;
+          readonly attribute long? rl;
+          attribute unsigned long? ul;
+          readonly attribute unsigned long? rul;
+          attribute long long? ll;
+          readonly attribute long long? rll;
+          attribute unsigned long long? ull;
+          readonly attribute unsigned long long? rull;
+          attribute DOMString? str;
+          readonly attribute DOMString? rstr;
+          attribute object? obj;
+          readonly attribute object? robj;
+          attribute object? _object;
+          attribute float? f;
+          readonly attribute float? rf;
+        };
+    """)
+
+    results = parser.finish()
+
+    def checkAttr(attr, QName, name, type, readonly):
+        harness.ok(isinstance(attr, WebIDL.IDLAttribute),
+                  "Should be an IDLAttribute")
+        harness.ok(attr.isAttr(), "Attr is an Attr")
+        harness.ok(not attr.isMethod(), "Attr is not an method")
+        harness.ok(not attr.isConst(), "Attr is not a const")
+        harness.check(attr.identifier.QName(), QName, "Attr has the right QName")
+        harness.check(attr.identifier.name, name, "Attr has the right name")
+        harness.check(str(attr.type), type, "Attr has the right type")
+        harness.check(attr.readonly, readonly, "Attr's readonly state is correct")
+
+    harness.ok(True, "TestAttr interface parsed without error.")
+    harness.check(len(results), 2, "Should be two productions.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestAttr", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestAttr", "Interface has the right name")
+    harness.check(len(iface.members), len(testData), "Expect %s members" % len(testData))
+
+    attrs = iface.members
+
+    for i in range(len(attrs)):
+        data = testData[i]
+        attr = attrs[i]
+        (QName, name, type, readonly) = data
+        checkAttr(attr, QName % "", name, type % "", readonly)
+
+    iface = results[1]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestAttrNullable", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestAttrNullable", "Interface has the right name")
+    harness.check(len(iface.members), len(testData), "Expect %s members" % len(testData))
+
+    attrs = iface.members
+
+    for i in range(len(attrs)):
+        data = testData[i]
+        attr = attrs[i]
+        (QName, name, type, readonly) = data
+        checkAttr(attr, QName % "Nullable", name, type % "OrNull", readonly)
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [SetterThrows] readonly attribute boolean foo;
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow [SetterThrows] on readonly attributes")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [Throw] readonly attribute boolean foo;
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should spell [Throws] correctly")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [SameObject] readonly attribute boolean foo;
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow [SameObject] on attributes not of interface type")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [SameObject] readonly attribute A foo;
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(not threw, "Should allow [SameObject] on attributes of interface type")
diff --git a/dom/bindings/parser/tests/test_attr_sequence_type.py b/dom/bindings/parser/tests/test_attr_sequence_type.py
new file mode 100644
index 000000000..fb1b97812
--- /dev/null
+++ b/dom/bindings/parser/tests/test_attr_sequence_type.py
@@ -0,0 +1,67 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface AttrSequenceType {
+              attribute sequence<object> foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Attribute type must not be a sequence type")
+
+    parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            interface AttrUnionWithSequenceType {
+              attribute (sequence<object> or DOMString) foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Attribute type must not be a union with a sequence member type")
+
+    parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            interface AttrNullableUnionWithSequenceType {
+              attribute (sequence<object>? or DOMString) foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Attribute type must not be a union with a nullable sequence "
+               "member type")
+
+    parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            interface AttrUnionWithUnionWithSequenceType {
+              attribute ((sequence<object> or DOMString) or AttrUnionWithUnionWithSequenceType) foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Attribute type must not be a union type with a union member "
+               "type that has a sequence member type")
diff --git a/dom/bindings/parser/tests/test_builtin_filename.py b/dom/bindings/parser/tests/test_builtin_filename.py
new file mode 100644
index 000000000..631e52eba
--- /dev/null
+++ b/dom/bindings/parser/tests/test_builtin_filename.py
@@ -0,0 +1,11 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface Test {
+          attribute long b;
+        };
+    """);
+
+    attr = parser.finish()[0].members[0]
+    harness.check(attr.type.filename(), '<builtin>', 'Filename on builtin type')
diff --git a/dom/bindings/parser/tests/test_builtins.py b/dom/bindings/parser/tests/test_builtins.py
new file mode 100644
index 000000000..f8563fc2d
--- /dev/null
+++ b/dom/bindings/parser/tests/test_builtins.py
@@ -0,0 +1,41 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestBuiltins {
+          attribute boolean b;
+          attribute byte s8;
+          attribute octet u8;
+          attribute short s16;
+          attribute unsigned short u16;
+          attribute long s32;
+          attribute unsigned long u32;
+          attribute long long s64;
+          attribute unsigned long long u64;
+          attribute DOMTimeStamp ts;
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestBuiltins interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    iface = results[0]
+    harness.check(iface.identifier.QName(), "::TestBuiltins", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestBuiltins", "Interface has the right name")
+    harness.check(iface.parent, None, "Interface has no parent")
+
+    members = iface.members
+    harness.check(len(members), 10, "Should be one production")
+
+    names = ["b", "s8", "u8", "s16", "u16", "s32", "u32", "s64", "u64", "ts"]
+    types = ["Boolean", "Byte", "Octet", "Short", "UnsignedShort", "Long", "UnsignedLong", "LongLong", "UnsignedLongLong", "UnsignedLongLong"]
+    for i in range(10):
+        attr = members[i]
+        harness.ok(isinstance(attr, WebIDL.IDLAttribute), "Should be an IDLAttribute")
+        harness.check(attr.identifier.QName(), "::TestBuiltins::" + names[i], "Attr has correct QName")
+        harness.check(attr.identifier.name, names[i], "Attr has correct name")
+        harness.check(str(attr.type), types[i], "Attr type is the correct name")
+        harness.ok(attr.type.isPrimitive(), "Should be a primitive type")
diff --git a/dom/bindings/parser/tests/test_bytestring.py b/dom/bindings/parser/tests/test_bytestring.py
new file mode 100644
index 000000000..fa83e9e2d
--- /dev/null
+++ b/dom/bindings/parser/tests/test_bytestring.py
@@ -0,0 +1,99 @@
+# -*- coding: UTF-8 -*-
+
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestByteString {
+          attribute ByteString bs;
+          attribute DOMString ds;
+          };
+    """)
+
+    results = parser.finish();
+
+    harness.ok(True, "TestByteString interface parsed without error.")
+
+    harness.check(len(results), 1, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    iface = results[0]
+    harness.check(iface.identifier.QName(), "::TestByteString", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestByteString", "Interface has the right name")
+    harness.check(iface.parent, None, "Interface has no parent")
+
+    members = iface.members
+    harness.check(len(members), 2, "Should be two productions")
+
+    attr = members[0]
+    harness.ok(isinstance(attr, WebIDL.IDLAttribute), "Should be an IDLAttribute")
+    harness.check(attr.identifier.QName(), "::TestByteString::bs", "Attr has correct QName")
+    harness.check(attr.identifier.name, "bs", "Attr has correct name")
+    harness.check(str(attr.type), "ByteString", "Attr type is the correct name")
+    harness.ok(attr.type.isByteString(), "Should be ByteString type")
+    harness.ok(attr.type.isString(), "Should be String collective type")
+    harness.ok(not attr.type.isDOMString(), "Should be not be DOMString type")
+
+    # now check we haven't broken DOMStrings in the process.
+    attr = members[1]
+    harness.ok(isinstance(attr, WebIDL.IDLAttribute), "Should be an IDLAttribute")
+    harness.check(attr.identifier.QName(), "::TestByteString::ds", "Attr has correct QName")
+    harness.check(attr.identifier.name, "ds", "Attr has correct name")
+    harness.check(str(attr.type), "String", "Attr type is the correct name")
+    harness.ok(attr.type.isDOMString(), "Should be DOMString type")
+    harness.ok(attr.type.isString(), "Should be String collective type")
+    harness.ok(not attr.type.isByteString(), "Should be not be ByteString type")
+
+    # Cannot represent constant ByteString in IDL.
+    threw = False
+    try:
+        parser.parse("""
+            interface ConstByteString {
+              const ByteString foo = "hello"
+              };
+        """)
+    except WebIDL.WebIDLError:
+        threw = True
+    harness.ok(threw, "Should have thrown a WebIDL error for ByteString default in interface")
+
+    # Can have optional ByteStrings with default values
+    try:
+        parser.parse("""
+            interface OptionalByteString {
+              void passByteString(optional ByteString arg = "hello");
+              };
+        """)
+        results2 = parser.finish();
+    except WebIDL.WebIDLError as e:
+        harness.ok(False,
+                   "Should not have thrown a WebIDL error for ByteString "
+                   "default in dictionary. " + str(e))
+
+    # Can have a default ByteString value in a dictionary
+    try:
+        parser.parse("""
+        dictionary OptionalByteStringDict {
+          ByteString item = "some string";
+        };
+        """)
+        results3 = parser.finish();
+    except WebIDL.WebIDLError as e:
+        harness.ok(False,
+                   "Should not have thrown a WebIDL error for ByteString "
+                   "default in dictionary. " + str(e))
+
+    # Don't allow control characters in ByteString literals
+    threw = False
+    try:
+        parser.parse("""
+        dictionary OptionalByteStringDict2 {
+          ByteString item = "\x03";
+        };
+        """)
+        results4 = parser.finish()
+    except WebIDL.WebIDLError as e:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown a WebIDL error for invalid ByteString "
+               "default in dictionary")
diff --git a/dom/bindings/parser/tests/test_callback.py b/dom/bindings/parser/tests/test_callback.py
new file mode 100644
index 000000000..4dfda1c3c
--- /dev/null
+++ b/dom/bindings/parser/tests/test_callback.py
@@ -0,0 +1,34 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestCallback {
+          attribute CallbackType? listener;
+        };
+
+        callback CallbackType = boolean (unsigned long arg);
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestCallback interface parsed without error.")
+    harness.check(len(results), 2, "Should be two productions.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestCallback", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestCallback", "Interface has the right name")
+    harness.check(len(iface.members), 1, "Expect %s members" % 1)
+
+    attr = iface.members[0]
+    harness.ok(isinstance(attr, WebIDL.IDLAttribute),
+               "Should be an IDLAttribute")
+    harness.ok(attr.isAttr(), "Should be an attribute")
+    harness.ok(not attr.isMethod(), "Attr is not an method")
+    harness.ok(not attr.isConst(), "Attr is not a const")
+    harness.check(attr.identifier.QName(), "::TestCallback::listener", "Attr has the right QName")
+    harness.check(attr.identifier.name, "listener", "Attr has the right name")
+    t = attr.type
+    harness.ok(not isinstance(t, WebIDL.IDLWrapperType), "Attr has the right type")
+    harness.ok(isinstance(t, WebIDL.IDLNullableType), "Attr has the right type")
+    harness.ok(t.isCallback(), "Attr has the right type")
diff --git a/dom/bindings/parser/tests/test_callback_interface.py b/dom/bindings/parser/tests/test_callback_interface.py
new file mode 100644
index 000000000..e4789dae1
--- /dev/null
+++ b/dom/bindings/parser/tests/test_callback_interface.py
@@ -0,0 +1,94 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        callback interface TestCallbackInterface {
+          attribute boolean bool;
+        };
+    """)
+
+    results = parser.finish()
+
+    iface = results[0]
+
+    harness.ok(iface.isCallback(), "Interface should be a callback")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface {
+            };
+            callback interface TestCallbackInterface : TestInterface {
+              attribute boolean bool;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow non-callback parent of callback interface")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface : TestCallbackInterface {
+            };
+            callback interface TestCallbackInterface {
+              attribute boolean bool;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow callback parent of non-callback interface")
+
+    parser = parser.reset()
+    parser.parse("""
+        callback interface TestCallbackInterface1 {
+          void foo();
+        };
+        callback interface TestCallbackInterface2 {
+          void foo(DOMString arg);
+          void foo(TestCallbackInterface1 arg);
+        };
+        callback interface TestCallbackInterface3 {
+          void foo(DOMString arg);
+          void foo(TestCallbackInterface1 arg);
+          static void bar();
+        };
+        callback interface TestCallbackInterface4 {
+          void foo(DOMString arg);
+          void foo(TestCallbackInterface1 arg);
+          static void bar();
+          const long baz = 5;
+        };
+        callback interface TestCallbackInterface5 {
+          static attribute boolean bool;
+          void foo();
+        };
+        callback interface TestCallbackInterface6 {
+          void foo(DOMString arg);
+          void foo(TestCallbackInterface1 arg);
+          void bar();
+        };
+        callback interface TestCallbackInterface7 {
+          static attribute boolean bool;
+        };
+        callback interface TestCallbackInterface8 {
+          attribute boolean bool;
+        };
+        callback interface TestCallbackInterface9 : TestCallbackInterface1 {
+          void foo();
+        };
+        callback interface TestCallbackInterface10 : TestCallbackInterface1 {
+          void bar();
+        };
+    """)
+    results = parser.finish()
+    for (i, iface) in enumerate(results):
+      harness.check(iface.isSingleOperationInterface(), i < 4,
+                    "Interface %s should be a single operation interface" %
+                    iface.identifier.name)
diff --git a/dom/bindings/parser/tests/test_conditional_dictionary_member.py b/dom/bindings/parser/tests/test_conditional_dictionary_member.py
new file mode 100644
index 000000000..433b7e501
--- /dev/null
+++ b/dom/bindings/parser/tests/test_conditional_dictionary_member.py
@@ -0,0 +1,110 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      dictionary Dict {
+        any foo;
+        [ChromeOnly] any bar;
+      };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 1, "Should have a dictionary")
+    members = results[0].members;
+    harness.check(len(members), 2, "Should have two members")
+    # Note that members are ordered lexicographically, so "bar" comes
+    # before "foo".
+    harness.ok(members[0].getExtendedAttribute("ChromeOnly"),
+               "First member is not ChromeOnly")
+    harness.ok(not members[1].getExtendedAttribute("ChromeOnly"),
+               "Second member is ChromeOnly")
+
+    parser = parser.reset()
+    parser.parse("""
+      dictionary Dict {
+        any foo;
+        any bar;
+      };
+
+      interface Iface {
+        [Constant, Cached] readonly attribute Dict dict;
+      };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 2, "Should have a dictionary and an interface")
+
+    parser = parser.reset()
+    exception = None
+    try:
+      parser.parse("""
+        dictionary Dict {
+          any foo;
+          [ChromeOnly] any bar;
+        };
+
+        interface Iface {
+          [Constant, Cached] readonly attribute Dict dict;
+        };
+      """)
+      results = parser.finish()
+    except Exception, exception:
+        pass
+
+    harness.ok(exception, "Should have thrown.")
+    harness.check(exception.message,
+                  "[Cached] and [StoreInSlot] must not be used on an attribute "
+                  "whose type contains a [ChromeOnly] dictionary member",
+                  "Should have thrown the right exception")
+
+    parser = parser.reset()
+    exception = None
+    try:
+      parser.parse("""
+        dictionary ParentDict {
+          [ChromeOnly] any bar;
+        };
+
+        dictionary Dict : ParentDict {
+          any foo;
+        };
+
+        interface Iface {
+          [Constant, Cached] readonly attribute Dict dict;
+        };
+      """)
+      results = parser.finish()
+    except Exception, exception:
+        pass
+
+    harness.ok(exception, "Should have thrown (2).")
+    harness.check(exception.message,
+                  "[Cached] and [StoreInSlot] must not be used on an attribute "
+                  "whose type contains a [ChromeOnly] dictionary member",
+                  "Should have thrown the right exception (2)")
+
+    parser = parser.reset()
+    exception = None
+    try:
+      parser.parse("""
+        dictionary GrandParentDict {
+          [ChromeOnly] any baz;
+        };
+
+        dictionary ParentDict : GrandParentDict {
+          any bar;
+        };
+
+        dictionary Dict : ParentDict {
+          any foo;
+        };
+
+        interface Iface {
+          [Constant, Cached] readonly attribute Dict dict;
+        };
+      """)
+      results = parser.finish()
+    except Exception, exception:
+        pass
+
+    harness.ok(exception, "Should have thrown (3).")
+    harness.check(exception.message,
+                  "[Cached] and [StoreInSlot] must not be used on an attribute "
+                  "whose type contains a [ChromeOnly] dictionary member",
+                  "Should have thrown the right exception (3)")
diff --git a/dom/bindings/parser/tests/test_const.py b/dom/bindings/parser/tests/test_const.py
new file mode 100644
index 000000000..80b6fb0e9
--- /dev/null
+++ b/dom/bindings/parser/tests/test_const.py
@@ -0,0 +1,80 @@
+import WebIDL
+
+expected = [
+    ("::TestConsts::zero", "zero", "Byte", 0),
+    ("::TestConsts::b", "b", "Byte", -1),
+    ("::TestConsts::o", "o", "Octet", 2),
+    ("::TestConsts::s", "s", "Short", -3),
+    ("::TestConsts::us", "us", "UnsignedShort", 4),
+    ("::TestConsts::l", "l", "Long", -5),
+    ("::TestConsts::ul", "ul", "UnsignedLong", 6),
+    ("::TestConsts::ull", "ull", "UnsignedLongLong", 7),
+    ("::TestConsts::ll", "ll", "LongLong", -8),
+    ("::TestConsts::t", "t", "Boolean", True),
+    ("::TestConsts::f", "f", "Boolean", False),
+    ("::TestConsts::n", "n", "BooleanOrNull", None),
+    ("::TestConsts::nt", "nt", "BooleanOrNull", True),
+    ("::TestConsts::nf", "nf", "BooleanOrNull", False),
+    ("::TestConsts::fl", "fl", "Float", 0.2),
+    ("::TestConsts::db", "db", "Double", 0.2),
+    ("::TestConsts::ufl", "ufl", "UnrestrictedFloat", 0.2),
+    ("::TestConsts::udb", "udb", "UnrestrictedDouble", 0.2),
+    ("::TestConsts::fli", "fli", "Float", 2),
+    ("::TestConsts::dbi", "dbi", "Double", 2),
+    ("::TestConsts::ufli", "ufli", "UnrestrictedFloat", 2),
+    ("::TestConsts::udbi", "udbi", "UnrestrictedDouble", 2),
+]
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestConsts {
+          const byte zero = 0;
+          const byte b = -1;
+          const octet o = 2;
+          const short s = -3;
+          const unsigned short us = 0x4;
+          const long l = -0X5;
+          const unsigned long ul = 6;
+          const unsigned long long ull = 7;
+          const long long ll = -010;
+          const boolean t = true;
+          const boolean f = false;
+          const boolean? n = null;
+          const boolean? nt = true;
+          const boolean? nf = false;
+          const float fl = 0.2;
+          const double db = 0.2;
+          const unrestricted float ufl = 0.2;
+          const unrestricted double udb = 0.2;
+          const float fli = 2;
+          const double dbi = 2;
+          const unrestricted float ufli = 2;
+          const unrestricted double udbi = 2;
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestConsts interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestConsts", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestConsts", "Interface has the right name")
+    harness.check(len(iface.members), len(expected), "Expect %s members" % len(expected))
+
+    for (const, (QName, name, type, value)) in zip(iface.members, expected):
+        harness.ok(isinstance(const, WebIDL.IDLConst),
+                   "Should be an IDLConst")
+        harness.ok(const.isConst(), "Const is a const")
+        harness.ok(not const.isAttr(), "Const is not an attr")
+        harness.ok(not const.isMethod(), "Const is not a method")
+        harness.check(const.identifier.QName(), QName, "Const has the right QName")
+        harness.check(const.identifier.name, name, "Const has the right name")
+        harness.check(str(const.type), type, "Const has the right type")
+        harness.ok(const.type.isPrimitive(), "All consts should be primitive")
+        harness.check(str(const.value.type), str(const.type),
+                      "Const's value has the same type as the type")
+        harness.check(const.value.value, value, "Const value has the right value.")
+
diff --git a/dom/bindings/parser/tests/test_constructor.py b/dom/bindings/parser/tests/test_constructor.py
new file mode 100644
index 000000000..348204c7d
--- /dev/null
+++ b/dom/bindings/parser/tests/test_constructor.py
@@ -0,0 +1,109 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    def checkArgument(argument, QName, name, type, optional, variadic):
+        harness.ok(isinstance(argument, WebIDL.IDLArgument),
+                   "Should be an IDLArgument")
+        harness.check(argument.identifier.QName(), QName, "Argument has the right QName")
+        harness.check(argument.identifier.name, name, "Argument has the right name")
+        harness.check(str(argument.type), type, "Argument has the right return type")
+        harness.check(argument.optional, optional, "Argument has the right optional value")
+        harness.check(argument.variadic, variadic, "Argument has the right variadic value")
+
+    def checkMethod(method, QName, name, signatures,
+                    static=True, getter=False, setter=False, creator=False,
+                    deleter=False, legacycaller=False, stringifier=False,
+                    chromeOnly=False):
+        harness.ok(isinstance(method, WebIDL.IDLMethod),
+                   "Should be an IDLMethod")
+        harness.ok(method.isMethod(), "Method is a method")
+        harness.ok(not method.isAttr(), "Method is not an attr")
+        harness.ok(not method.isConst(), "Method is not a const")
+        harness.check(method.identifier.QName(), QName, "Method has the right QName")
+        harness.check(method.identifier.name, name, "Method has the right name")
+        harness.check(method.isStatic(), static, "Method has the correct static value")
+        harness.check(method.isGetter(), getter, "Method has the correct getter value")
+        harness.check(method.isSetter(), setter, "Method has the correct setter value")
+        harness.check(method.isCreator(), creator, "Method has the correct creator value")
+        harness.check(method.isDeleter(), deleter, "Method has the correct deleter value")
+        harness.check(method.isLegacycaller(), legacycaller, "Method has the correct legacycaller value")
+        harness.check(method.isStringifier(), stringifier, "Method has the correct stringifier value")
+        harness.check(method.getExtendedAttribute("ChromeOnly") is not None, chromeOnly, "Method has the correct value for ChromeOnly")
+        harness.check(len(method.signatures()), len(signatures), "Method has the correct number of signatures")
+
+        sigpairs = zip(method.signatures(), signatures)
+        for (gotSignature, expectedSignature) in sigpairs:
+            (gotRetType, gotArgs) = gotSignature
+            (expectedRetType, expectedArgs) = expectedSignature
+
+            harness.check(str(gotRetType), expectedRetType,
+                          "Method has the expected return type.")
+
+            for i in range(0, len(gotArgs)):
+                (QName, name, type, optional, variadic) = expectedArgs[i]
+                checkArgument(gotArgs[i], QName, name, type, optional, variadic)
+
+    parser.parse("""
+        [Constructor]
+        interface TestConstructorNoArgs {
+        };
+
+        [Constructor(DOMString name)]
+        interface TestConstructorWithArgs {
+        };
+
+        [Constructor(object foo), Constructor(boolean bar)]
+        interface TestConstructorOverloads {
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 3, "Should be three productions")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.ok(isinstance(results[2], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+
+    checkMethod(results[0].ctor(), "::TestConstructorNoArgs::constructor",
+                "constructor", [("TestConstructorNoArgs (Wrapper)", [])])
+    checkMethod(results[1].ctor(), "::TestConstructorWithArgs::constructor",
+                "constructor",
+                [("TestConstructorWithArgs (Wrapper)",
+                 [("::TestConstructorWithArgs::constructor::name", "name", "String", False, False)])])
+    checkMethod(results[2].ctor(), "::TestConstructorOverloads::constructor",
+                "constructor",
+                [("TestConstructorOverloads (Wrapper)",
+                 [("::TestConstructorOverloads::constructor::foo", "foo", "Object", False, False)]),
+                 ("TestConstructorOverloads (Wrapper)",
+                 [("::TestConstructorOverloads::constructor::bar", "bar", "Boolean", False, False)])])
+
+    parser = parser.reset()
+    parser.parse("""
+        [ChromeConstructor()]
+        interface TestChromeConstructor {
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 1, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+
+    checkMethod(results[0].ctor(), "::TestChromeConstructor::constructor",
+                "constructor", [("TestChromeConstructor (Wrapper)", [])],
+                chromeOnly=True)
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+        [Constructor(),
+         ChromeConstructor(DOMString a)]
+        interface TestChromeConstructor {
+        };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Can't have both a Constructor and a ChromeConstructor")
diff --git a/dom/bindings/parser/tests/test_constructor_no_interface_object.py b/dom/bindings/parser/tests/test_constructor_no_interface_object.py
new file mode 100644
index 000000000..2b09ae71e
--- /dev/null
+++ b/dom/bindings/parser/tests/test_constructor_no_interface_object.py
@@ -0,0 +1,36 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            [Constructor, NoInterfaceObject]
+            interface TestConstructorNoInterfaceObject {
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            [NoInterfaceObject, Constructor]
+            interface TestConstructorNoInterfaceObject {
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+
+    parser.parse("""
+        [NoInterfaceObject, NamedConstructor=FooBar]
+        interface TestNamedConstructorNoInterfaceObject {
+        };
+    """)
diff --git a/dom/bindings/parser/tests/test_date.py b/dom/bindings/parser/tests/test_date.py
new file mode 100644
index 000000000..2bdfc95e1
--- /dev/null
+++ b/dom/bindings/parser/tests/test_date.py
@@ -0,0 +1,15 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface WithDates {
+          attribute Date foo;
+          void bar(Date arg);
+          void baz(sequence<Date> arg);
+        };
+    """)
+
+    results = parser.finish()
+    harness.ok(results[0].members[0].type.isDate(), "Should have Date")
+    harness.ok(results[0].members[1].signatures()[0][1][0].type.isDate(),
+               "Should have Date argument")
+    harness.ok(not results[0].members[2].signatures()[0][1][0].type.isDate(),
+               "Should have non-Date argument")
diff --git a/dom/bindings/parser/tests/test_deduplicate.py b/dom/bindings/parser/tests/test_deduplicate.py
new file mode 100644
index 000000000..6249d36fb
--- /dev/null
+++ b/dom/bindings/parser/tests/test_deduplicate.py
@@ -0,0 +1,15 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface Foo;
+        interface Bar;
+        interface Foo;
+        """);
+
+    results = parser.finish()
+
+    # There should be no duplicate interfaces in the result.
+    expectedNames = sorted(['Foo', 'Bar'])
+    actualNames = sorted(map(lambda iface: iface.identifier.name, results))
+    harness.check(actualNames, expectedNames, "Parser shouldn't output duplicate names.")
diff --git a/dom/bindings/parser/tests/test_dictionary.py b/dom/bindings/parser/tests/test_dictionary.py
new file mode 100644
index 000000000..2c0fa6123
--- /dev/null
+++ b/dom/bindings/parser/tests/test_dictionary.py
@@ -0,0 +1,555 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      dictionary Dict2 : Dict1 {
+        long child = 5;
+        Dict1 aaandAnother;
+      };
+      dictionary Dict1 {
+        long parent;
+        double otherParent;
+      };
+    """)
+    results = parser.finish()
+
+    dict1 = results[1];
+    dict2 = results[0];
+
+    harness.check(len(dict1.members), 2, "Dict1 has two members")
+    harness.check(len(dict2.members), 2, "Dict2 has four members")
+
+    harness.check(dict1.members[0].identifier.name, "otherParent",
+                  "'o' comes before 'p'")
+    harness.check(dict1.members[1].identifier.name, "parent",
+                  "'o' really comes before 'p'")
+    harness.check(dict2.members[0].identifier.name, "aaandAnother",
+                  "'a' comes before 'c'")
+    harness.check(dict2.members[1].identifier.name, "child",
+                  "'a' really comes before 'c'")
+
+    # Now reset our parser
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          dictionary Dict {
+            long prop = 5;
+            long prop;
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow name duplication in a dictionary")
+
+    # Now reset our parser again
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          dictionary Dict1 : Dict2 {
+            long prop = 5;
+          };
+          dictionary Dict2 : Dict3 {
+            long prop2;
+          };
+          dictionary Dict3 {
+            double prop;
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow name duplication in a dictionary and "
+               "its ancestor")
+
+    # More reset
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface Iface {};
+          dictionary Dict : Iface {
+            long prop;
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow non-dictionary parents for dictionaries")
+
+    # Even more reset
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A : B {};
+            dictionary B : A {};
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow cycles in dictionary inheritance chains")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+              [TreatNullAs=EmptyString] DOMString foo;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow [TreatNullAs] on dictionary members");
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(A arg);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Trailing dictionary arg must be optional")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo((A or DOMString) arg);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Trailing union arg containing a dictionary must be optional")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(A arg1, optional long arg2);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Dictionary arg followed by optional arg must be optional")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(A arg1, optional long arg2, long arg3);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(not threw,
+               "Dictionary arg followed by non-optional arg doesn't have to be optional")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo((A or DOMString) arg1, optional long arg2);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Union arg containing dictionary followed by optional arg must "
+               "be optional")
+
+    parser = parser.reset()
+    parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(A arg1, long arg2);
+            };
+        """)
+    results = parser.finish()
+    harness.ok(True, "Dictionary arg followed by required arg can be required")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(optional A? arg1);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Dictionary arg must not be nullable")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(optional (A or long)? arg1);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Dictionary arg must not be in a nullable union")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(optional (A or long?) arg1);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Dictionary must not be in a union with a nullable type")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+            };
+            interface X {
+              void doFoo(optional (long? or A) arg1);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "A nullable type must not be in a union with a dictionary")
+
+    parser = parser.reset()
+    parser.parse("""
+        dictionary A {
+        };
+        interface X {
+          A? doFoo();
+        };
+    """)
+    results = parser.finish()
+    harness.ok(True, "Dictionary return value can be nullable")
+
+    parser = parser.reset()
+    parser.parse("""
+        dictionary A {
+        };
+        interface X {
+          void doFoo(optional A arg);
+        };
+    """)
+    results = parser.finish()
+    harness.ok(True, "Dictionary arg should actually parse")
+
+    parser = parser.reset()
+    parser.parse("""
+        dictionary A {
+        };
+        interface X {
+          void doFoo(optional (A or DOMString) arg);
+        };
+    """)
+    results = parser.finish()
+    harness.ok(True, "Union arg containing a dictionary should actually parse")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              Foo foo;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo3 : Foo {
+              short d;
+            };
+
+            dictionary Foo2 : Foo3 {
+              boolean c;
+            };
+
+            dictionary Foo1 : Foo2 {
+              long a;
+            };
+
+            dictionary Foo {
+              Foo1 b;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a Dictionary that "
+                      "inherits from its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              (Foo or DOMString)[]? b;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a Nullable type "
+                      "whose inner type includes its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              (DOMString or Foo) b;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a Union type, one of "
+                      "whose member types includes its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              sequence<sequence<sequence<Foo>>> c;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a Sequence type "
+                      "whose element type includes its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              (DOMString or Foo)[] d;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be an Array type "
+                      "whose element type includes its Dictionary.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              Foo1 b;
+            };
+
+            dictionary Foo3 {
+              Foo d;
+            };
+
+            dictionary Foo2 : Foo3 {
+              short c;
+            };
+
+            dictionary Foo1 : Foo2 {
+              long a;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a Dictionary, one of whose "
+                      "members or inherited members has a type that includes "
+                      "its Dictionary.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+            };
+
+            dictionary Bar {
+              Foo? d;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Member type must not be a nullable dictionary")
+
+    parser = parser.reset();
+    parser.parse("""
+        dictionary Foo {
+          unrestricted float  urFloat = 0;
+          unrestricted float  urFloat2 = 1.1;
+          unrestricted float  urFloat3 = -1.1;
+          unrestricted float? urFloat4 = null;
+          unrestricted float  infUrFloat = Infinity;
+          unrestricted float  negativeInfUrFloat = -Infinity;
+          unrestricted float  nanUrFloat = NaN;
+
+          unrestricted double  urDouble = 0;
+          unrestricted double  urDouble2 = 1.1;
+          unrestricted double  urDouble3 = -1.1;
+          unrestricted double? urDouble4 = null;
+          unrestricted double  infUrDouble = Infinity;
+          unrestricted double  negativeInfUrDouble = -Infinity;
+          unrestricted double  nanUrDouble = NaN;
+        };
+    """)
+    results = parser.finish()
+    harness.ok(True, "Parsing default values for unrestricted types succeeded.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              double f = Infinity;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to Infinity")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              double f = -Infinity;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to -Infinity")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              double f = NaN;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to NaN")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              float f = Infinity;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to Infinity")
+
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              float f = -Infinity;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to -Infinity")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            dictionary Foo {
+              float f = NaN;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Only unrestricted values can be initialized to NaN")
diff --git a/dom/bindings/parser/tests/test_distinguishability.py b/dom/bindings/parser/tests/test_distinguishability.py
new file mode 100644
index 000000000..d7780c1ff
--- /dev/null
+++ b/dom/bindings/parser/tests/test_distinguishability.py
@@ -0,0 +1,293 @@
+def firstArgType(method):
+    return method.signatures()[0][1][0].type
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      dictionary Dict {
+      };
+      callback interface Foo {
+      };
+      interface Bar {
+        // Bit of a pain to get things that have dictionary types
+        void passDict(optional Dict arg);
+        void passFoo(Foo arg);
+        void passNullableUnion((object? or DOMString) arg);
+        void passNullable(Foo? arg);
+      };
+    """)
+    results = parser.finish()
+
+    iface = results[2]
+    harness.ok(iface.isInterface(), "Should have interface")
+    dictMethod = iface.members[0]
+    ifaceMethod = iface.members[1]
+    nullableUnionMethod = iface.members[2]
+    nullableIfaceMethod = iface.members[3]
+
+    dictType = firstArgType(dictMethod)
+    ifaceType = firstArgType(ifaceMethod)
+
+    harness.ok(dictType.isDictionary(), "Should have dictionary type");
+    harness.ok(ifaceType.isInterface(), "Should have interface type");
+    harness.ok(ifaceType.isCallbackInterface(), "Should have callback interface type");
+
+    harness.ok(not dictType.isDistinguishableFrom(ifaceType),
+               "Dictionary not distinguishable from callback interface")
+    harness.ok(not ifaceType.isDistinguishableFrom(dictType),
+               "Callback interface not distinguishable from dictionary")
+
+    nullableUnionType = firstArgType(nullableUnionMethod)
+    nullableIfaceType = firstArgType(nullableIfaceMethod)
+
+    harness.ok(nullableUnionType.isUnion(), "Should have union type");
+    harness.ok(nullableIfaceType.isInterface(), "Should have interface type");
+    harness.ok(nullableIfaceType.nullable(), "Should have nullable type");
+
+    harness.ok(not nullableUnionType.isDistinguishableFrom(nullableIfaceType),
+               "Nullable type not distinguishable from union with nullable "
+               "member type")
+    harness.ok(not nullableIfaceType.isDistinguishableFrom(nullableUnionType),
+               "Union with nullable member type not distinguishable from "
+               "nullable type")
+
+    parser = parser.reset()
+    parser.parse("""
+      interface TestIface {
+        void passKid(Kid arg);
+        void passParent(Parent arg);
+        void passGrandparent(Grandparent arg);
+        void passImplemented(Implemented arg);
+        void passImplementedParent(ImplementedParent arg);
+        void passUnrelated1(Unrelated1 arg);
+        void passUnrelated2(Unrelated2 arg);
+        void passArrayBuffer(ArrayBuffer arg);
+        void passArrayBuffer(ArrayBufferView arg);
+      };
+
+      interface Kid : Parent {};
+      interface Parent : Grandparent {};
+      interface Grandparent {};
+      interface Implemented : ImplementedParent {};
+      Parent implements Implemented;
+      interface ImplementedParent {};
+      interface Unrelated1 {};
+      interface Unrelated2 {};
+    """)
+    results = parser.finish()
+
+    iface = results[0]
+    harness.ok(iface.isInterface(), "Should have interface")
+    argTypes = [firstArgType(method) for method in iface.members]
+    unrelatedTypes = [firstArgType(method) for method in iface.members[-3:]]
+
+    for type1 in argTypes:
+        for type2 in argTypes:
+            distinguishable = (type1 is not type2 and
+                               (type1 in unrelatedTypes or
+                                type2 in unrelatedTypes))
+
+            harness.check(type1.isDistinguishableFrom(type2),
+                          distinguishable,
+                          "Type %s should %sbe distinguishable from type %s" %
+                          (type1, "" if distinguishable else "not ", type2))
+            harness.check(type2.isDistinguishableFrom(type1),
+                          distinguishable,
+                          "Type %s should %sbe distinguishable from type %s" %
+                          (type2, "" if distinguishable else "not ", type1))
+
+    parser = parser.reset()
+    parser.parse("""
+      interface Dummy {};
+      interface TestIface {
+        void method(long arg1, TestIface arg2);
+        void method(long arg1, long arg2);
+        void method(long arg1, Dummy arg2);
+        void method(DOMString arg1, DOMString arg2, DOMString arg3);
+      };
+    """)
+    results = parser.finish()
+    harness.check(len(results[1].members), 1,
+                  "Should look like we have one method")
+    harness.check(len(results[1].members[0].signatures()), 4,
+                  "Should have four signatures")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface Dummy {};
+          interface TestIface {
+            void method(long arg1, TestIface arg2);
+            void method(long arg1, long arg2);
+            void method(any arg1,  Dummy arg2);
+            void method(DOMString arg1, DOMString arg2, DOMString arg3);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should throw when args before the distinguishing arg are not "
+               "all the same type")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface Dummy {};
+          interface TestIface {
+            void method(long arg1, TestIface arg2);
+            void method(long arg1, long arg2);
+            void method(any arg1,  DOMString arg2);
+            void method(DOMString arg1, DOMString arg2, DOMString arg3);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should throw when there is no distinguishing index")
+
+    # Now let's test our whole distinguishability table
+    argTypes = [ "long", "short", "long?", "short?", "boolean",
+                 "boolean?", "DOMString", "ByteString", "Enum", "Enum2",
+                 "Interface", "Interface?",
+                 "AncestorInterface", "UnrelatedInterface",
+                 "ImplementedInterface", "CallbackInterface",
+                 "CallbackInterface?", "CallbackInterface2",
+                 "object", "Callback", "Callback2", "optional Dict",
+                 "optional Dict2", "sequence<long>", "sequence<short>",
+                 "MozMap<object>", "MozMap<Dict>", "MozMap<long>",
+                 "Date", "Date?", "any",
+                 "Promise<any>", "Promise<any>?",
+                 "USVString", "ArrayBuffer", "ArrayBufferView", "SharedArrayBuffer",
+                 "Uint8Array", "Uint16Array" ]
+    # When we can parse Date and RegExp, we need to add them here.
+
+    # Try to categorize things a bit to keep list lengths down
+    def allBut(list1, list2):
+        return [a for a in list1 if a not in list2 and
+                (a != "any" and a != "Promise<any>" and a != "Promise<any>?")]
+    numerics = [ "long", "short", "long?", "short?" ]
+    booleans = [ "boolean", "boolean?" ]
+    primitives = numerics + booleans
+    nonNumerics = allBut(argTypes, numerics)
+    nonBooleans = allBut(argTypes, booleans)
+    strings = [ "DOMString", "ByteString", "Enum", "Enum2", "USVString" ]
+    nonStrings = allBut(argTypes, strings)
+    nonObjects = primitives + strings
+    objects = allBut(argTypes, nonObjects )
+    bufferSourceTypes = ["ArrayBuffer", "ArrayBufferView", "Uint8Array", "Uint16Array"]
+    sharedBufferSourceTypes = ["SharedArrayBuffer"]
+    interfaces = [ "Interface", "Interface?", "AncestorInterface",
+                   "UnrelatedInterface", "ImplementedInterface" ] + bufferSourceTypes + sharedBufferSourceTypes
+    nullables = ["long?", "short?", "boolean?", "Interface?",
+                 "CallbackInterface?", "optional Dict", "optional Dict2",
+                 "Date?", "any", "Promise<any>?"]
+    dates = [ "Date", "Date?" ]
+    sequences = [ "sequence<long>", "sequence<short>" ]
+    nonUserObjects = nonObjects + interfaces + dates + sequences
+    otherObjects = allBut(argTypes, nonUserObjects + ["object"])
+    notRelatedInterfaces = (nonObjects + ["UnrelatedInterface"] +
+                            otherObjects + dates + sequences + bufferSourceTypes + sharedBufferSourceTypes)
+    mozMaps = [ "MozMap<object>", "MozMap<Dict>", "MozMap<long>" ]
+
+    # Build a representation of the distinguishability table as a dict
+    # of dicts, holding True values where needed, holes elsewhere.
+    data = dict();
+    for type in argTypes:
+        data[type] = dict()
+    def setDistinguishable(type, types):
+        for other in types:
+            data[type][other] = True
+
+    setDistinguishable("long", nonNumerics)
+    setDistinguishable("short", nonNumerics)
+    setDistinguishable("long?", allBut(nonNumerics, nullables))
+    setDistinguishable("short?", allBut(nonNumerics, nullables))
+    setDistinguishable("boolean", nonBooleans)
+    setDistinguishable("boolean?", allBut(nonBooleans, nullables))
+    setDistinguishable("DOMString", nonStrings)
+    setDistinguishable("ByteString", nonStrings)
+    setDistinguishable("USVString", nonStrings)
+    setDistinguishable("Enum", nonStrings)
+    setDistinguishable("Enum2", nonStrings)
+    setDistinguishable("Interface", notRelatedInterfaces)
+    setDistinguishable("Interface?", allBut(notRelatedInterfaces, nullables))
+    setDistinguishable("AncestorInterface", notRelatedInterfaces)
+    setDistinguishable("UnrelatedInterface",
+                       allBut(argTypes, ["object", "UnrelatedInterface"]))
+    setDistinguishable("ImplementedInterface", notRelatedInterfaces)
+    setDistinguishable("CallbackInterface", nonUserObjects)
+    setDistinguishable("CallbackInterface?", allBut(nonUserObjects, nullables))
+    setDistinguishable("CallbackInterface2", nonUserObjects)
+    setDistinguishable("object", nonObjects)
+    setDistinguishable("Callback", nonUserObjects)
+    setDistinguishable("Callback2", nonUserObjects)
+    setDistinguishable("optional Dict", allBut(nonUserObjects, nullables))
+    setDistinguishable("optional Dict2", allBut(nonUserObjects, nullables))
+    setDistinguishable("sequence<long>",
+                       allBut(argTypes, sequences + ["object"]))
+    setDistinguishable("sequence<short>",
+                       allBut(argTypes, sequences + ["object"]))
+    setDistinguishable("MozMap<object>", nonUserObjects)
+    setDistinguishable("MozMap<Dict>", nonUserObjects)
+    setDistinguishable("MozMap<long>", nonUserObjects)
+    setDistinguishable("Date", allBut(argTypes, dates + ["object"]))
+    setDistinguishable("Date?", allBut(argTypes, dates + nullables + ["object"]))
+    setDistinguishable("any", [])
+    setDistinguishable("Promise<any>", [])
+    setDistinguishable("Promise<any>?", [])
+    setDistinguishable("ArrayBuffer", allBut(argTypes, ["ArrayBuffer", "object"]))
+    setDistinguishable("ArrayBufferView", allBut(argTypes, ["ArrayBufferView", "Uint8Array", "Uint16Array", "object"]))
+    setDistinguishable("Uint8Array", allBut(argTypes, ["ArrayBufferView", "Uint8Array", "object"]))
+    setDistinguishable("Uint16Array", allBut(argTypes, ["ArrayBufferView", "Uint16Array", "object"]))
+    setDistinguishable("SharedArrayBuffer", allBut(argTypes, ["SharedArrayBuffer", "object"]))
+
+    def areDistinguishable(type1, type2):
+        return data[type1].get(type2, False)
+
+    def checkDistinguishability(parser, type1, type2):
+        idlTemplate = """
+          enum Enum { "a", "b" };
+          enum Enum2 { "c", "d" };
+          interface Interface : AncestorInterface {};
+          interface AncestorInterface {};
+          interface UnrelatedInterface {};
+          interface ImplementedInterface {};
+          Interface implements ImplementedInterface;
+          callback interface CallbackInterface {};
+          callback interface CallbackInterface2 {};
+          callback Callback = any();
+          callback Callback2 = long(short arg);
+          dictionary Dict {};
+          dictionary Dict2 {};
+          interface _Promise {};
+          interface TestInterface {%s
+          };
+        """
+        methodTemplate = """
+            void myMethod(%s arg);"""
+        methods = (methodTemplate % type1) + (methodTemplate % type2)
+        idl = idlTemplate % methods
+        parser = parser.reset()
+        threw = False
+        try:
+            parser.parse(idl)
+            results = parser.finish()
+        except:
+            threw = True
+
+        if areDistinguishable(type1, type2):
+            harness.ok(not threw,
+                       "Should not throw for '%s' and '%s' because they are distinguishable" % (type1, type2))
+        else:
+            harness.ok(threw,
+                       "Should throw for '%s' and '%s' because they are not distinguishable" % (type1, type2))
+
+    # Enumerate over everything in both orders, since order matters in
+    # terms of our implementation of distinguishability checks
+    for type1 in argTypes:
+        for type2 in argTypes:
+            checkDistinguishability(parser, type1, type2)
diff --git a/dom/bindings/parser/tests/test_double_null.py b/dom/bindings/parser/tests/test_double_null.py
new file mode 100644
index 000000000..700c7eade
--- /dev/null
+++ b/dom/bindings/parser/tests/test_double_null.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface DoubleNull {
+              attribute byte?? foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_duplicate_qualifiers.py b/dom/bindings/parser/tests/test_duplicate_qualifiers.py
new file mode 100644
index 000000000..799f2e0e0
--- /dev/null
+++ b/dom/bindings/parser/tests/test_duplicate_qualifiers.py
@@ -0,0 +1,84 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface DuplicateQualifiers1 {
+              getter getter byte foo(unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface DuplicateQualifiers2 {
+              setter setter byte foo(unsigned long index, byte value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface DuplicateQualifiers3 {
+              creator creator byte foo(unsigned long index, byte value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface DuplicateQualifiers4 {
+              deleter deleter byte foo(unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface DuplicateQualifiers5 {
+              getter deleter getter byte foo(unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        results = parser.parse("""
+            interface DuplicateQualifiers6 {
+              creator setter creator byte foo(unsigned long index, byte value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_empty_enum.py b/dom/bindings/parser/tests/test_empty_enum.py
new file mode 100644
index 000000000..ee0079f06
--- /dev/null
+++ b/dom/bindings/parser/tests/test_empty_enum.py
@@ -0,0 +1,14 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    try:
+        parser.parse("""
+            enum TestEmptyEnum {
+            };
+        """)
+
+        harness.ok(False, "Should have thrown!")
+    except:
+        harness.ok(True, "Parsing TestEmptyEnum enum should fail")
+
+    results = parser.finish()
diff --git a/dom/bindings/parser/tests/test_empty_sequence_default_value.py b/dom/bindings/parser/tests/test_empty_sequence_default_value.py
new file mode 100644
index 000000000..350ae72f0
--- /dev/null
+++ b/dom/bindings/parser/tests/test_empty_sequence_default_value.py
@@ -0,0 +1,45 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface X {
+              const sequence<long> foo = [];
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Constant cannot have [] as a default value")
+
+    parser = parser.reset()
+
+    parser.parse("""
+        interface X {
+          void foo(optional sequence<long> arg = []);
+        };
+    """)
+    results = parser.finish();
+
+    harness.ok(isinstance(
+        results[0].members[0].signatures()[0][1][0].defaultValue,
+        WebIDL.IDLEmptySequenceValue),
+               "Should have IDLEmptySequenceValue as default value of argument")
+
+    parser = parser.reset()
+
+    parser.parse("""
+        dictionary X {
+          sequence<long> foo = [];
+        };
+    """)
+    results = parser.finish();
+
+    harness.ok(isinstance(results[0].members[0].defaultValue,
+                          WebIDL.IDLEmptySequenceValue),
+               "Should have IDLEmptySequenceValue as default value of "
+               "dictionary member")
+
diff --git a/dom/bindings/parser/tests/test_enum.py b/dom/bindings/parser/tests/test_enum.py
new file mode 100644
index 000000000..862289391
--- /dev/null
+++ b/dom/bindings/parser/tests/test_enum.py
@@ -0,0 +1,93 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        enum TestEnum {
+          "",
+          "foo",
+          "bar"
+        };
+
+        interface TestEnumInterface {
+          TestEnum doFoo(boolean arg);
+          readonly attribute TestEnum foo;
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestEnumInterfaces interface parsed without error.")
+    harness.check(len(results), 2, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLEnum),
+               "Should be an IDLEnum")
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+
+    enum = results[0]
+    harness.check(enum.identifier.QName(), "::TestEnum", "Enum has the right QName")
+    harness.check(enum.identifier.name, "TestEnum", "Enum has the right name")
+    harness.check(enum.values(), ["", "foo", "bar"], "Enum has the right values")
+
+    iface = results[1]
+
+    harness.check(iface.identifier.QName(), "::TestEnumInterface", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestEnumInterface", "Interface has the right name")
+    harness.check(iface.parent, None, "Interface has no parent")
+
+    members = iface.members
+    harness.check(len(members), 2, "Should be one production")
+    harness.ok(isinstance(members[0], WebIDL.IDLMethod),
+               "Should be an IDLMethod")
+    method = members[0]
+    harness.check(method.identifier.QName(), "::TestEnumInterface::doFoo",
+                  "Method has correct QName")
+    harness.check(method.identifier.name, "doFoo", "Method has correct name")
+
+    signatures = method.signatures()
+    harness.check(len(signatures), 1, "Expect one signature")
+
+    (returnType, arguments) = signatures[0]
+    harness.check(str(returnType), "TestEnum (Wrapper)", "Method type is the correct name")
+    harness.check(len(arguments), 1, "Method has the right number of arguments")
+    arg = arguments[0]
+    harness.ok(isinstance(arg, WebIDL.IDLArgument), "Should be an IDLArgument")
+    harness.check(str(arg.type), "Boolean", "Argument has the right type")
+
+    attr = members[1]
+    harness.check(attr.identifier.QName(), "::TestEnumInterface::foo",
+                  "Attr has correct QName")
+    harness.check(attr.identifier.name, "foo", "Attr has correct name")
+
+    harness.check(str(attr.type), "TestEnum (Wrapper)", "Attr type is the correct name")
+
+    # Now reset our parser
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          enum Enum {
+            "a",
+            "b",
+            "c"
+          };
+          interface TestInterface {
+            void foo(optional Enum e = "d");
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow a bogus default value for an enum")
+
+    # Now reset our parser
+    parser = parser.reset()
+    parser.parse("""
+      enum Enum {
+        "a",
+        "b",
+        "c",
+      };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 1, "Should allow trailing comma in enum")
diff --git a/dom/bindings/parser/tests/test_enum_duplicate_values.py b/dom/bindings/parser/tests/test_enum_duplicate_values.py
new file mode 100644
index 000000000..51205d209
--- /dev/null
+++ b/dom/bindings/parser/tests/test_enum_duplicate_values.py
@@ -0,0 +1,13 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    try:
+        parser.parse("""
+            enum TestEnumDuplicateValue {
+              "",
+              ""
+            };
+        """)
+        harness.ok(False, "Should have thrown!")
+    except:
+        harness.ok(True, "Enum TestEnumDuplicateValue should throw")
diff --git a/dom/bindings/parser/tests/test_error_colno.py b/dom/bindings/parser/tests/test_error_colno.py
new file mode 100644
index 000000000..ca0674aec
--- /dev/null
+++ b/dom/bindings/parser/tests/test_error_colno.py
@@ -0,0 +1,20 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    # Check that error messages put the '^' in the right place.
+
+    threw = False
+    input = 'interface ?'
+    try:
+        parser.parse(input)
+        results = parser.finish()
+    except WebIDL.WebIDLError, e:
+        threw = True
+        lines = str(e).split('\n')
+
+        harness.check(len(lines), 3, 'Expected number of lines in error message')
+        harness.check(lines[1], input, 'Second line shows error')
+        harness.check(lines[2], ' ' * (len(input) - 1) + '^',
+                      'Correct column pointer in error message')
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_error_lineno.py b/dom/bindings/parser/tests/test_error_lineno.py
new file mode 100644
index 000000000..f11222e7a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_error_lineno.py
@@ -0,0 +1,28 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    # Check that error messages put the '^' in the right place.
+
+    threw = False
+    input = """\
+// This is a comment.
+interface Foo {
+};
+
+/* This is also a comment. */
+interface ?"""
+    try:
+        parser.parse(input)
+        results = parser.finish()
+    except WebIDL.WebIDLError, e:
+        threw = True
+        lines = str(e).split('\n')
+
+        harness.check(len(lines), 3, 'Expected number of lines in error message')
+        harness.ok(lines[0].endswith('line 6:10'), 'First line of error should end with "line 6:10", but was "%s".' % lines[0])
+        harness.check(lines[1], 'interface ?', 'Second line of error message is the line which caused the error.')
+        harness.check(lines[2], ' ' * (len('interface ?') - 1) + '^',
+                      'Correct column pointer in error message.')
+
+    harness.ok(threw, "Should have thrown.")
+
diff --git a/dom/bindings/parser/tests/test_exposed_extended_attribute.py b/dom/bindings/parser/tests/test_exposed_extended_attribute.py
new file mode 100644
index 000000000..48957098b
--- /dev/null
+++ b/dom/bindings/parser/tests/test_exposed_extended_attribute.py
@@ -0,0 +1,222 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      [PrimaryGlobal] interface Foo {};
+      [Global=(Bar1,Bar2)] interface Bar {};
+      [Global=Baz2] interface Baz {};
+
+      [Exposed=(Foo,Bar1)]
+      interface Iface {
+        void method1();
+
+        [Exposed=Bar1]
+        readonly attribute any attr;
+      };
+
+      [Exposed=Foo]
+      partial interface Iface {
+        void method2();
+      };
+    """)
+
+    results = parser.finish()
+
+    harness.check(len(results), 5, "Should know about five things");
+    iface = results[3]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should have an interface here");
+    members = iface.members
+    harness.check(len(members), 3, "Should have three members")
+
+    harness.ok(members[0].exposureSet == set(["Foo", "Bar"]),
+               "method1 should have the right exposure set")
+    harness.ok(members[0]._exposureGlobalNames == set(["Foo", "Bar1"]),
+               "method1 should have the right exposure global names")
+
+    harness.ok(members[1].exposureSet == set(["Bar"]),
+               "attr should have the right exposure set")
+    harness.ok(members[1]._exposureGlobalNames == set(["Bar1"]),
+               "attr should have the right exposure global names")
+
+    harness.ok(members[2].exposureSet == set(["Foo"]),
+               "method2 should have the right exposure set")
+    harness.ok(members[2]._exposureGlobalNames == set(["Foo"]),
+               "method2 should have the right exposure global names")
+
+    harness.ok(iface.exposureSet == set(["Foo", "Bar"]),
+               "Iface should have the right exposure set")
+    harness.ok(iface._exposureGlobalNames == set(["Foo", "Bar1"]),
+               "Iface should have the right exposure global names")
+
+    parser = parser.reset()
+    parser.parse("""
+      [PrimaryGlobal] interface Foo {};
+      [Global=(Bar1,Bar2)] interface Bar {};
+      [Global=Baz2] interface Baz {};
+
+      interface Iface2 {
+        void method3();
+      };
+    """)
+    results = parser.finish()
+
+    harness.check(len(results), 4, "Should know about four things");
+    iface = results[3]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should have an interface here");
+    members = iface.members
+    harness.check(len(members), 1, "Should have one member")
+
+    harness.ok(members[0].exposureSet == set(["Foo"]),
+               "method3 should have the right exposure set")
+    harness.ok(members[0]._exposureGlobalNames == set(["Foo"]),
+               "method3 should have the right exposure global names")
+
+    harness.ok(iface.exposureSet == set(["Foo"]),
+               "Iface2 should have the right exposure set")
+    harness.ok(iface._exposureGlobalNames == set(["Foo"]),
+               "Iface2 should have the right exposure global names")
+
+    parser = parser.reset()
+    parser.parse("""
+      [PrimaryGlobal] interface Foo {};
+      [Global=(Bar1,Bar2)] interface Bar {};
+      [Global=Baz2] interface Baz {};
+
+      [Exposed=Foo]
+      interface Iface3 {
+        void method4();
+      };
+
+      [Exposed=(Foo,Bar1)]
+      interface Mixin {
+        void method5();
+      };
+
+      Iface3 implements Mixin;
+    """)
+    results = parser.finish()
+    harness.check(len(results), 6, "Should know about six things");
+    iface = results[3]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should have an interface here");
+    members = iface.members
+    harness.check(len(members), 2, "Should have two members")
+
+    harness.ok(members[0].exposureSet == set(["Foo"]),
+               "method4 should have the right exposure set")
+    harness.ok(members[0]._exposureGlobalNames == set(["Foo"]),
+               "method4 should have the right exposure global names")
+
+    harness.ok(members[1].exposureSet == set(["Foo", "Bar"]),
+               "method5 should have the right exposure set")
+    harness.ok(members[1]._exposureGlobalNames == set(["Foo", "Bar1"]),
+               "method5 should have the right exposure global names")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [Exposed=Foo]
+            interface Bar {
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on invalid Exposed value on interface.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface Bar {
+              [Exposed=Foo]
+              readonly attribute bool attr;
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on invalid Exposed value on attribute.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface Bar {
+              [Exposed=Foo]
+              void operation();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on invalid Exposed value on operation.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface Bar {
+              [Exposed=Foo]
+              const long constant = 5;
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on invalid Exposed value on constant.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [Global] interface Foo {};
+            [Global] interface Bar {};
+
+            [Exposed=Foo]
+            interface Baz {
+              [Exposed=Bar]
+              void method();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on member exposed where its interface is not.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [Global] interface Foo {};
+            [Global] interface Bar {};
+
+            [Exposed=Foo]
+            interface Baz {
+              void method();
+            };
+
+            [Exposed=Bar]
+            interface Mixin {};
+
+            Baz implements Mixin;
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on LHS of implements being exposed where RHS is not.")
diff --git a/dom/bindings/parser/tests/test_extended_attributes.py b/dom/bindings/parser/tests/test_extended_attributes.py
new file mode 100644
index 000000000..85a70d98f
--- /dev/null
+++ b/dom/bindings/parser/tests/test_extended_attributes.py
@@ -0,0 +1,107 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        [NoInterfaceObject]
+        interface TestExtendedAttr {
+          [Unforgeable] readonly attribute byte b;
+        };
+    """)
+
+    results = parser.finish()
+
+    parser = parser.reset()
+    parser.parse("""
+        [Pref="foo.bar",Pref=flop]
+        interface TestExtendedAttr {
+          [Pref="foo.bar"] attribute byte b;
+        };
+    """)
+
+    results = parser.finish()
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestLenientThis {
+          [LenientThis] attribute byte b;
+        };
+    """)
+
+    results = parser.finish()
+    harness.ok(results[0].members[0].hasLenientThis(),
+               "Should have a lenient this")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestLenientThis2 {
+              [LenientThis=something] attribute byte b;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "[LenientThis] must take no arguments")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestClamp {
+          void testClamp([Clamp] long foo);
+          void testNotClamp(long foo);
+        };
+    """)
+
+    results = parser.finish()
+    # Pull out the first argument out of the arglist of the first (and
+    # only) signature.
+    harness.ok(results[0].members[0].signatures()[0][1][0].clamp,
+               "Should be clamped")
+    harness.ok(not results[0].members[1].signatures()[0][1][0].clamp,
+               "Should not be clamped")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestClamp2 {
+              void testClamp([Clamp=something] long foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "[Clamp] must take no arguments")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestEnforceRange {
+          void testEnforceRange([EnforceRange] long foo);
+          void testNotEnforceRange(long foo);
+        };
+    """)
+
+    results = parser.finish()
+    # Pull out the first argument out of the arglist of the first (and
+    # only) signature.
+    harness.ok(results[0].members[0].signatures()[0][1][0].enforceRange,
+               "Should be enforceRange")
+    harness.ok(not results[0].members[1].signatures()[0][1][0].enforceRange,
+               "Should not be enforceRange")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestEnforceRange2 {
+              void testEnforceRange([EnforceRange=something] long foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "[EnforceRange] must take no arguments")
+    
diff --git a/dom/bindings/parser/tests/test_float_types.py b/dom/bindings/parser/tests/test_float_types.py
new file mode 100644
index 000000000..718f09c11
--- /dev/null
+++ b/dom/bindings/parser/tests/test_float_types.py
@@ -0,0 +1,125 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        typedef float myFloat;
+        typedef unrestricted float myUnrestrictedFloat;
+        interface FloatTypes {
+          attribute float f;
+          attribute unrestricted float uf;
+          attribute double d;
+          attribute unrestricted double ud;
+          [LenientFloat]
+          attribute float lf;
+          [LenientFloat]
+          attribute double ld;
+
+          void m1(float arg1, double arg2, float? arg3, double? arg4,
+                  myFloat arg5, unrestricted float arg6,
+                  unrestricted double arg7, unrestricted float? arg8,
+                  unrestricted double? arg9, myUnrestrictedFloat arg10);
+          [LenientFloat]
+          void m2(float arg1, double arg2, float? arg3, double? arg4,
+                  myFloat arg5, unrestricted float arg6,
+                  unrestricted double arg7, unrestricted float? arg8,
+                  unrestricted double? arg9, myUnrestrictedFloat arg10);
+          [LenientFloat]
+          void m3(float arg);
+          [LenientFloat]
+          void m4(double arg);
+          [LenientFloat]
+          void m5((float or FloatTypes) arg);
+          [LenientFloat]
+          void m6(sequence<float> arg);
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.check(len(results), 3, "Should be two typedefs and one interface.")
+    iface = results[2]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    types = [a.type for a in iface.members if a.isAttr()]
+    harness.ok(types[0].isFloat(), "'float' is a float")
+    harness.ok(not types[0].isUnrestricted(), "'float' is not unrestricted")
+    harness.ok(types[1].isFloat(), "'unrestricted float' is a float")
+    harness.ok(types[1].isUnrestricted(), "'unrestricted float' is unrestricted")
+    harness.ok(types[2].isFloat(), "'double' is a float")
+    harness.ok(not types[2].isUnrestricted(), "'double' is not unrestricted")
+    harness.ok(types[3].isFloat(), "'unrestricted double' is a float")
+    harness.ok(types[3].isUnrestricted(), "'unrestricted double' is unrestricted")
+
+    method = iface.members[6]
+    harness.ok(isinstance(method, WebIDL.IDLMethod), "Should be an IDLMethod")
+    argtypes = [a.type for a in method.signatures()[0][1]]
+    for (idx, type) in enumerate(argtypes):
+        harness.ok(type.isFloat(), "Type %d should be float" % idx)
+        harness.check(type.isUnrestricted(), idx >= 5,
+                      "Type %d should %sbe unrestricted" % (
+                idx, "" if idx >= 4 else "not "))
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface FloatTypes {
+              [LenientFloat]
+              long m(float arg);
+            };
+        """)
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "[LenientFloat] only allowed on void methods")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface FloatTypes {
+              [LenientFloat]
+              void m(unrestricted float arg);
+            };
+        """)
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "[LenientFloat] only allowed on methods with unrestricted float args")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface FloatTypes {
+              [LenientFloat]
+              void m(sequence<unrestricted float> arg);
+            };
+        """)
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "[LenientFloat] only allowed on methods with unrestricted float args (2)")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface FloatTypes {
+              [LenientFloat]
+              void m((unrestricted float or FloatTypes) arg);
+            };
+        """)
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "[LenientFloat] only allowed on methods with unrestricted float args (3)")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface FloatTypes {
+              [LenientFloat]
+              readonly attribute float foo;
+            };
+        """)
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "[LenientFloat] only allowed on writable attributes")
diff --git a/dom/bindings/parser/tests/test_forward_decl.py b/dom/bindings/parser/tests/test_forward_decl.py
new file mode 100644
index 000000000..cac24c832
--- /dev/null
+++ b/dom/bindings/parser/tests/test_forward_decl.py
@@ -0,0 +1,15 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface ForwardDeclared;
+        interface ForwardDeclared;
+
+        interface TestForwardDecl {
+          attribute ForwardDeclared foo;
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestForwardDeclared interface parsed without error.")
diff --git a/dom/bindings/parser/tests/test_global_extended_attr.py b/dom/bindings/parser/tests/test_global_extended_attr.py
new file mode 100644
index 000000000..c752cecd2
--- /dev/null
+++ b/dom/bindings/parser/tests/test_global_extended_attr.py
@@ -0,0 +1,122 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      [Global]
+      interface Foo : Bar {
+        getter any(DOMString name);
+      };
+      interface Bar {};
+    """)
+
+    results = parser.finish()
+
+    harness.ok(results[0].isOnGlobalProtoChain(),
+               "[Global] interface should be on global's proto chain")
+    harness.ok(results[1].isOnGlobalProtoChain(),
+               "[Global] interface should be on global's proto chain")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global]
+          interface Foo {
+            getter any(DOMString name);
+            setter void(DOMString name, any arg);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with a "
+               "named setter")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global]
+          interface Foo {
+            getter any(DOMString name);
+            creator void(DOMString name, any arg);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with a "
+               "named creator")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global]
+          interface Foo {
+            getter any(DOMString name);
+            deleter void(DOMString name);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with a "
+               "named deleter")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global, OverrideBuiltins]
+          interface Foo {
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with a "
+               "[OverrideBuiltins]")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global]
+          interface Foo : Bar {
+          };
+          [OverrideBuiltins]
+          interface Bar {
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with an "
+               "[OverrideBuiltins] ancestor")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          [Global]
+          interface Foo {
+          };
+          interface Bar : Foo {
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown for [Global] used on an interface with a "
+               "descendant")
diff --git a/dom/bindings/parser/tests/test_identifier_conflict.py b/dom/bindings/parser/tests/test_identifier_conflict.py
new file mode 100644
index 000000000..b510a30c0
--- /dev/null
+++ b/dom/bindings/parser/tests/test_identifier_conflict.py
@@ -0,0 +1,39 @@
+# Import the WebIDL module, so we can do isinstance checks and whatnot
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    try:
+        parser.parse("""
+            enum Foo { "a" };
+            interface Foo;
+        """)
+        results = parser.finish()
+        harness.ok(False, "Should fail to parse")
+    except Exception, e:
+        harness.ok("Name collision" in e.message,
+                   "Should have name collision for interface")
+
+    parser = parser.reset()
+    try:
+        parser.parse("""
+            dictionary Foo { long x; };
+            enum Foo { "a" };
+        """)
+        results = parser.finish()
+        harness.ok(False, "Should fail to parse")
+    except Exception, e:
+        harness.ok("Name collision" in e.message,
+                   "Should have name collision for dictionary")
+
+    parser = parser.reset()
+    try:
+        parser.parse("""
+            enum Foo { "a" };
+            enum Foo { "b" };
+        """)
+        results = parser.finish()
+        harness.ok(False, "Should fail to parse")
+    except Exception, e:
+        harness.ok("Multiple unresolvable definitions" in e.message,
+                   "Should have name collision for dictionary")
+
diff --git a/dom/bindings/parser/tests/test_implements.py b/dom/bindings/parser/tests/test_implements.py
new file mode 100644
index 000000000..04c47d92a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_implements.py
@@ -0,0 +1,216 @@
+# Import the WebIDL module, so we can do isinstance checks and whatnot
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    # Basic functionality
+    threw = False
+    try:
+        parser.parse("""
+            A implements B;
+            interface B {
+              attribute long x;
+            };
+            interface A {
+              attribute long y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(not threw, "Should not have thrown on implements statement "
+               "before interfaces")
+    harness.check(len(results), 3, "We have three statements")
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface), "B is an interface")
+    harness.check(len(results[1].members), 1, "B has one member")
+    A = results[2]
+    harness.ok(isinstance(A, WebIDL.IDLInterface), "A is an interface")
+    harness.check(len(A.members), 2, "A has two members")
+    harness.check(A.members[0].identifier.name, "y", "First member is 'y'")
+    harness.check(A.members[1].identifier.name, "x", "Second member is 'x'")
+
+    # Duplicated member names not allowed
+    threw = False
+    try:
+        parser.parse("""
+            C implements D;
+            interface D {
+              attribute long x;
+            };
+            interface C {
+              attribute long x;
+            };
+        """)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on implemented interface duplicating "
+               "a name on base interface")
+
+    # Same, but duplicated across implemented interfaces
+    threw = False
+    try:
+        parser.parse("""
+            E implements F;
+            E implements G;
+            interface F {
+              attribute long x;
+            };
+            interface G {
+              attribute long x;
+            };
+            interface E {};
+        """)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on implemented interfaces "
+               "duplicating each other's member names")
+
+    # Same, but duplicated across indirectly implemented interfaces
+    threw = False
+    try:
+        parser.parse("""
+            H implements I;
+            H implements J;
+            I implements K;
+            interface K {
+              attribute long x;
+            };
+            interface L {
+              attribute long x;
+            };
+            interface I {};
+            interface J : L {};
+            interface H {};
+        """)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on indirectly implemented interfaces "
+               "duplicating each other's member names")
+
+    # Same, but duplicated across an implemented interface and its parent
+    threw = False
+    try:
+        parser.parse("""
+            M implements N;
+            interface O {
+              attribute long x;
+            };
+            interface N : O {
+              attribute long x;
+            };
+            interface M {};
+        """)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on implemented interface and its "
+               "ancestor duplicating member names")
+
+    # Reset the parser so we can actually find things where we expect
+    # them in the list
+    parser = parser.reset()
+
+    # Diamonds should be allowed
+    threw = False
+    try:
+        parser.parse("""
+            P implements Q;
+            P implements R;
+            Q implements S;
+            R implements S;
+            interface Q {};
+            interface R {};
+            interface S {
+              attribute long x;
+            };
+            interface P {};
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(not threw, "Diamond inheritance is fine")
+    harness.check(results[6].identifier.name, "S", "We should be looking at 'S'")
+    harness.check(len(results[6].members), 1, "S should have one member")
+    harness.check(results[6].members[0].identifier.name, "x",
+                  "S's member should be 'x'")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface {
+            };
+            callback interface TestCallbackInterface {
+            };
+            TestInterface implements TestCallbackInterface;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should not allow callback interfaces on the right-hand side "
+               "of 'implements'")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface {
+            };
+            callback interface TestCallbackInterface {
+            };
+            TestCallbackInterface implements TestInterface;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should not allow callback interfaces on the left-hand side of "
+               "'implements'")
+    
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface {
+            };
+            dictionary Dict {
+            };
+            Dict implements TestInterface;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should not allow non-interfaces on the left-hand side "
+               "of 'implements'")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestInterface {
+            };
+            dictionary Dict {
+            };
+            TestInterface implements Dict;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should not allow non-interfaces on the right-hand side "
+               "of 'implements'")
+
diff --git a/dom/bindings/parser/tests/test_incomplete_parent.py b/dom/bindings/parser/tests/test_incomplete_parent.py
new file mode 100644
index 000000000..1f520a28e
--- /dev/null
+++ b/dom/bindings/parser/tests/test_incomplete_parent.py
@@ -0,0 +1,18 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestIncompleteParent : NotYetDefined {
+          void foo();
+        };
+
+        interface NotYetDefined : EvenHigherOnTheChain {
+        };
+
+        interface EvenHigherOnTheChain {
+        };
+    """)
+
+    parser.finish()
+
+    harness.ok(True, "TestIncompleteParent interface parsed without error.")
diff --git a/dom/bindings/parser/tests/test_incomplete_types.py b/dom/bindings/parser/tests/test_incomplete_types.py
new file mode 100644
index 000000000..fdc396040
--- /dev/null
+++ b/dom/bindings/parser/tests/test_incomplete_types.py
@@ -0,0 +1,44 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestIncompleteTypes {
+          attribute FooInterface attr1;
+
+          FooInterface method1(FooInterface arg);
+        };
+
+        interface FooInterface {
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestIncompleteTypes interface parsed without error.")
+    harness.check(len(results), 2, "Should be two productions.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestIncompleteTypes", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestIncompleteTypes", "Interface has the right name")
+    harness.check(len(iface.members), 2, "Expect 2 members")
+
+    attr = iface.members[0]
+    harness.ok(isinstance(attr, WebIDL.IDLAttribute),
+               "Should be an IDLAttribute")
+    method = iface.members[1]
+    harness.ok(isinstance(method, WebIDL.IDLMethod),
+               "Should be an IDLMethod")
+
+    harness.check(attr.identifier.QName(), "::TestIncompleteTypes::attr1",
+                  "Attribute has the right QName")
+    harness.check(attr.type.name, "FooInterface",
+                  "Previously unresolved type has the right name")
+
+    harness.check(method.identifier.QName(), "::TestIncompleteTypes::method1",
+                  "Attribute has the right QName")
+    (returnType, args) = method.signatures()[0]
+    harness.check(returnType.name, "FooInterface",
+                  "Previously unresolved type has the right name")
+    harness.check(args[0].type.name, "FooInterface",
+                  "Previously unresolved type has the right name")
diff --git a/dom/bindings/parser/tests/test_interface.py b/dom/bindings/parser/tests/test_interface.py
new file mode 100644
index 000000000..e8ed67b54
--- /dev/null
+++ b/dom/bindings/parser/tests/test_interface.py
@@ -0,0 +1,405 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("interface Foo { };")
+    results = parser.finish()
+    harness.ok(True, "Empty interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    iface = results[0]
+    harness.check(iface.identifier.QName(), "::Foo", "Interface has the right QName")
+    harness.check(iface.identifier.name, "Foo", "Interface has the right name")
+    harness.check(iface.parent, None, "Interface has no parent")
+
+    parser.parse("interface Bar : Foo { };")
+    results = parser.finish()
+    harness.ok(True, "Empty interface parsed without error.")
+    harness.check(len(results), 2, "Should be two productions")
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    iface = results[1]
+    harness.check(iface.identifier.QName(), "::Bar", "Interface has the right QName")
+    harness.check(iface.identifier.name, "Bar", "Interface has the right name")
+    harness.ok(isinstance(iface.parent, WebIDL.IDLInterface),
+               "Interface has a parent")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface QNameBase {
+          attribute long foo;
+        };
+
+        interface QNameDerived : QNameBase {
+          attribute long long foo;
+          attribute byte bar;          
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results), 2, "Should be two productions")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(results[1].parent, results[0], "Inheritance chain is right")
+    harness.check(len(results[0].members), 1, "Expect 1 productions")
+    harness.check(len(results[1].members), 2, "Expect 2 productions")
+    base = results[0]
+    derived = results[1]
+    harness.check(base.members[0].identifier.QName(), "::QNameBase::foo",
+                  "Member has the right QName")
+    harness.check(derived.members[0].identifier.QName(), "::QNameDerived::foo",
+                  "Member has the right QName")
+    harness.check(derived.members[1].identifier.QName(), "::QNameDerived::bar",
+                  "Member has the right QName")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : B {};
+            interface B : A {};
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow cycles in interface inheritance chains")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : C {};
+            interface C : B {};
+            interface B : A {};
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow indirect cycles in interface inheritance chains")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A {};
+            interface B {};
+            A implements B;
+            B implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow cycles via implements")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A {};
+            interface C {};
+            interface B {};
+            A implements C;
+            C implements B;
+            B implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow indirect cycles via implements")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : B {};
+            interface B {};
+            B implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow inheriting from an interface that implements us")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : B {};
+            interface B {};
+            interface C {};
+            B implements C;
+            C implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow inheriting from an interface that indirectly implements us")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : B {};
+            interface B : C {};
+            interface C {};
+            C implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow indirectly inheriting from an interface that implements us")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A : B {};
+            interface B : C {};
+            interface C {};
+            interface D {};
+            C implements D;
+            D implements A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow indirectly inheriting from an interface that indirectly implements us")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A;
+            interface B : A {};
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow inheriting from an interface that is only forward declared")
+
+    parser = parser.reset()
+    parser.parse("""
+        [Constructor(long arg)]
+        interface A {
+            readonly attribute boolean x;
+            void foo();
+        };
+        [Constructor]
+        partial interface A {
+            readonly attribute boolean y;
+            void foo(long arg);
+        };
+    """);
+    results = parser.finish();
+    harness.check(len(results), 2,
+                  "Should have two results with partial interface")
+    iface = results[0]
+    harness.check(len(iface.members), 3,
+                  "Should have three members with partial interface")
+    harness.check(iface.members[0].identifier.name, "x",
+                  "First member should be x with partial interface")
+    harness.check(iface.members[1].identifier.name, "foo",
+                  "Second member should be foo with partial interface")
+    harness.check(len(iface.members[1].signatures()), 2,
+                  "Should have two foo signatures with partial interface")
+    harness.check(iface.members[2].identifier.name, "y",
+                  "Third member should be y with partial interface")
+    harness.check(len(iface.ctor().signatures()), 2,
+                  "Should have two constructors with partial interface")
+
+    parser = parser.reset()
+    parser.parse("""
+        [Constructor]
+        partial interface A {
+            readonly attribute boolean y;
+            void foo(long arg);
+        };
+        [Constructor(long arg)]
+        interface A {
+            readonly attribute boolean x;
+            void foo();
+        };
+    """);
+    results = parser.finish();
+    harness.check(len(results), 2,
+                  "Should have two results with reversed partial interface")
+    iface = results[1]
+    harness.check(len(iface.members), 3,
+                  "Should have three members with reversed partial interface")
+    harness.check(iface.members[0].identifier.name, "x",
+                  "First member should be x with reversed partial interface")
+    harness.check(iface.members[1].identifier.name, "foo",
+                  "Second member should be foo with reversed partial interface")
+    harness.check(len(iface.members[1].signatures()), 2,
+                  "Should have two foo signatures with reversed partial interface")
+    harness.check(iface.members[2].identifier.name, "y",
+                  "Third member should be y with reversed partial interface")
+    harness.check(len(iface.ctor().signatures()), 2,
+                  "Should have two constructors with reversed partial interface")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A {
+                readonly attribute boolean x;
+            };
+            interface A {
+                readonly attribute boolean y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow two non-partial interfaces with the same name")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            partial interface A {
+                readonly attribute boolean x;
+            };
+            partial interface A {
+                readonly attribute boolean y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Must have a non-partial interface for a given name")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary  A {
+                boolean x;
+            };
+            partial interface A {
+                readonly attribute boolean y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow a name collision between partial interface "
+               "and other object")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+                boolean x;
+            };
+            interface A {
+                readonly attribute boolean y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow a name collision between interface "
+               "and other object")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            dictionary A {
+                boolean x;
+            };
+            interface A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow a name collision between external interface "
+               "and other object")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface A {
+                readonly attribute boolean x;
+            };
+            interface A;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow a name collision between external interface "
+               "and interface")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface A;
+        interface A;
+    """)
+    results = parser.finish()
+    harness.ok(len(results) == 1 and
+               isinstance(results[0], WebIDL.IDLExternalInterface),
+               "Should allow name collisions between external interface "
+               "declarations")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [SomeRandomAnnotation]
+            interface A {
+                readonly attribute boolean y;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow unknown extended attributes on interfaces")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface B {};
+            [ArrayClass]
+            interface A : B {
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow [ArrayClass] on interfaces with parents")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [ArrayClass]
+            interface A {
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(not threw,
+               "Should allow [ArrayClass] on interfaces without parents")
diff --git a/dom/bindings/parser/tests/test_interface_const_identifier_conflicts.py b/dom/bindings/parser/tests/test_interface_const_identifier_conflicts.py
new file mode 100644
index 000000000..db944e7aa
--- /dev/null
+++ b/dom/bindings/parser/tests/test_interface_const_identifier_conflicts.py
@@ -0,0 +1,15 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface IdentifierConflict {
+              const byte thing1 = 1;
+              const unsigned long thing1 = 1;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_interface_identifier_conflicts_across_members.py b/dom/bindings/parser/tests/test_interface_identifier_conflicts_across_members.py
new file mode 100644
index 000000000..1a73fb917
--- /dev/null
+++ b/dom/bindings/parser/tests/test_interface_identifier_conflicts_across_members.py
@@ -0,0 +1,60 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface IdentifierConflictAcrossMembers1 {
+              const byte thing1 = 1;
+              readonly attribute long thing1;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface IdentifierConflictAcrossMembers2 {
+              readonly attribute long thing1;
+              const byte thing1 = 1;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface IdentifierConflictAcrossMembers3 {
+              getter boolean thing1(DOMString name);
+              readonly attribute long thing1;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface IdentifierConflictAcrossMembers1 {
+              const byte thing1 = 1;
+              long thing1();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_interface_maplikesetlikeiterable.py b/dom/bindings/parser/tests/test_interface_maplikesetlikeiterable.py
new file mode 100644
index 000000000..ee5d870c2
--- /dev/null
+++ b/dom/bindings/parser/tests/test_interface_maplikesetlikeiterable.py
@@ -0,0 +1,691 @@
+import WebIDL
+import traceback
+def WebIDLTest(parser, harness):
+
+    def shouldPass(prefix, iface, expectedMembers, numProductions=1):
+        p = parser.reset()
+        p.parse(iface)
+        results = p.finish()
+        harness.check(len(results), numProductions,
+                      "%s - Should have production count %d" % (prefix, numProductions))
+        harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+                   "%s - Should be an IDLInterface" % (prefix))
+        # Make a copy, since we plan to modify it
+        expectedMembers = list(expectedMembers)
+        for m in results[0].members:
+            name = m.identifier.name
+            if (name, type(m)) in expectedMembers:
+                harness.ok(True, "%s - %s - Should be a %s" % (prefix, name,
+                                                               type(m)))
+                expectedMembers.remove((name, type(m)))
+            else:
+                harness.ok(False, "%s - %s - Unknown symbol of type %s" %
+                           (prefix, name, type(m)))
+        # A bit of a hoop because we can't generate the error string if we pass
+        if len(expectedMembers) == 0:
+            harness.ok(True, "Found all the members")
+        else:
+            harness.ok(False,
+                       "Expected member not found: %s of type %s" %
+                       (expectedMembers[0][0], expectedMembers[0][1]))
+        return results
+
+    def shouldFail(prefix, iface):
+        try:
+            p = parser.reset()
+            p.parse(iface)
+            p.finish()
+            harness.ok(False,
+                       prefix + " - Interface passed when should've failed")
+        except WebIDL.WebIDLError, e:
+            harness.ok(True,
+                       prefix + " - Interface failed as expected")
+        except Exception, e:
+            harness.ok(False,
+                       prefix + " - Interface failed but not as a WebIDLError exception: %s" % e)
+
+    iterableMembers = [(x, WebIDL.IDLMethod) for x in ["entries", "keys",
+                                                       "values", "forEach"]]
+    setROMembers = ([(x, WebIDL.IDLMethod) for x in ["has"]] +
+                    [("__setlike", WebIDL.IDLMaplikeOrSetlike)] +
+                    iterableMembers)
+    setROMembers.extend([("size", WebIDL.IDLAttribute)])
+    setRWMembers = ([(x, WebIDL.IDLMethod) for x in ["add",
+                                                     "clear",
+                                                     "delete"]] +
+                    setROMembers)
+    setROChromeMembers = ([(x, WebIDL.IDLMethod) for x in ["__add",
+                                                           "__clear",
+                                                           "__delete"]] +
+                          setROMembers)
+    setRWChromeMembers = ([(x, WebIDL.IDLMethod) for x in ["__add",
+                                                           "__clear",
+                                                           "__delete"]] +
+                          setRWMembers)
+    mapROMembers = ([(x, WebIDL.IDLMethod) for x in ["get", "has"]] +
+                    [("__maplike", WebIDL.IDLMaplikeOrSetlike)] +
+                    iterableMembers)
+    mapROMembers.extend([("size", WebIDL.IDLAttribute)])
+    mapRWMembers = ([(x, WebIDL.IDLMethod) for x in ["set",
+                                                     "clear",
+                                                     "delete"]] + mapROMembers)
+    mapRWChromeMembers = ([(x, WebIDL.IDLMethod) for x in ["__set",
+                                                           "__clear",
+                                                           "__delete"]] +
+                          mapRWMembers)
+
+    # OK, now that we've used iterableMembers to set up the above, append
+    # __iterable to it for the iterable<> case.
+    iterableMembers.append(("__iterable", WebIDL.IDLIterable))
+
+    valueIterableMembers = [("__iterable", WebIDL.IDLIterable)]
+    valueIterableMembers.append(("__indexedgetter", WebIDL.IDLMethod))
+    valueIterableMembers.append(("length", WebIDL.IDLAttribute))
+
+    disallowedIterableNames = ["keys", "entries", "values"]
+    disallowedMemberNames = ["forEach", "has", "size"] + disallowedIterableNames
+    mapDisallowedMemberNames = ["get"] + disallowedMemberNames
+    disallowedNonMethodNames = ["clear", "delete"]
+    mapDisallowedNonMethodNames = ["set"] + disallowedNonMethodNames
+    setDisallowedNonMethodNames = ["add"] + disallowedNonMethodNames
+    unrelatedMembers = [("unrelatedAttribute", WebIDL.IDLAttribute),
+                        ("unrelatedMethod", WebIDL.IDLMethod)]
+
+    #
+    # Simple Usage Tests
+    #
+
+    shouldPass("Iterable (key only)",
+               """
+               interface Foo1 {
+               iterable<long>;
+               readonly attribute unsigned long length;
+               getter long(unsigned long index);
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, valueIterableMembers + unrelatedMembers)
+
+    shouldPass("Iterable (key only) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               iterable<long>;
+               readonly attribute unsigned long length;
+               getter long(unsigned long index);
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, valueIterableMembers, numProductions=2)
+
+    shouldPass("Iterable (key and value)",
+               """
+               interface Foo1 {
+               iterable<long, long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, iterableMembers + unrelatedMembers,
+               # numProductions == 2 because of the generated iterator iface,
+               numProductions=2)
+
+    shouldPass("Iterable (key and value) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               iterable<long, long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, iterableMembers,
+               # numProductions == 3 because of the generated iterator iface,
+               numProductions=3)
+
+    shouldPass("Maplike (readwrite)",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapRWMembers + unrelatedMembers)
+
+    shouldPass("Maplike (readwrite) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldPass("Maplike (readwrite)",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapRWMembers + unrelatedMembers)
+
+    shouldPass("Maplike (readwrite) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldPass("Maplike (readonly)",
+               """
+               interface Foo1 {
+               readonly maplike<long, long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapROMembers + unrelatedMembers)
+
+    shouldPass("Maplike (readonly) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               readonly maplike<long, long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, mapROMembers, numProductions=2)
+
+    shouldPass("Setlike (readwrite)",
+               """
+               interface Foo1 {
+               setlike<long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, setRWMembers + unrelatedMembers)
+
+    shouldPass("Setlike (readwrite) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               setlike<long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, setRWMembers, numProductions=2)
+
+    shouldPass("Setlike (readonly)",
+               """
+               interface Foo1 {
+               readonly setlike<long>;
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, setROMembers + unrelatedMembers)
+
+    shouldPass("Setlike (readonly) inheriting from parent",
+               """
+               interface Foo1 : Foo2 {
+               readonly setlike<long>;
+               };
+               interface Foo2 {
+               attribute long unrelatedAttribute;
+               long unrelatedMethod();
+               };
+               """, setROMembers, numProductions=2)
+
+    shouldPass("Inheritance of maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldPass("Implements with maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               };
+               Foo2 implements Foo1;
+               """, mapRWMembers, numProductions=3)
+
+    shouldPass("JS Implemented maplike interface",
+               """
+               [JSImplementation="@mozilla.org/dom/test-interface-js-maplike;1",
+               Constructor()]
+               interface Foo1 {
+               setlike<long>;
+               };
+               """, setRWChromeMembers)
+
+    shouldPass("JS Implemented maplike interface",
+               """
+               [JSImplementation="@mozilla.org/dom/test-interface-js-maplike;1",
+               Constructor()]
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               """, mapRWChromeMembers)
+
+    #
+    # Multiple maplike/setlike tests
+    #
+
+    shouldFail("Two maplike/setlikes on same interface",
+               """
+               interface Foo1 {
+               setlike<long>;
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Two iterable/setlikes on same interface",
+               """
+               interface Foo1 {
+               iterable<long>;
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Two iterables on same interface",
+               """
+               interface Foo1 {
+               iterable<long>;
+               iterable<long, long>;
+               };
+               """)
+
+    shouldFail("Two maplike/setlikes in partials",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               partial interface Foo1 {
+               setlike<long>;
+               };
+               """)
+
+    shouldFail("Conflicting maplike/setlikes across inheritance",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               setlike<long>;
+               };
+               """)
+
+    shouldFail("Conflicting maplike/iterable across inheritance",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               iterable<long>;
+               };
+               """)
+
+    shouldFail("Conflicting maplike/setlikes across multistep inheritance",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               setlike<long>;
+               };
+               """)
+
+    shouldFail("Consequential interface with conflicting maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               setlike<long>;
+               };
+               Foo2 implements Foo1;
+               """)
+
+    shouldFail("Consequential interfaces with conflicting maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               setlike<long>;
+               };
+               interface Foo3 {
+               };
+               Foo3 implements Foo1;
+               Foo3 implements Foo2;
+               """)
+
+    #
+    # Member name collision tests
+    #
+
+    def testConflictingMembers(likeMember, conflictName, expectedMembers, methodPasses):
+        """
+        Tests for maplike/setlike member generation against conflicting member
+        names. If methodPasses is True, this means we expect the interface to
+        pass in the case of method shadowing, and expectedMembers should be the
+        list of interface members to check against on the passing interface.
+
+        """
+        if methodPasses:
+            shouldPass("Conflicting method: %s and %s" % (likeMember, conflictName),
+                       """
+                       interface Foo1 {
+                       %s;
+                       [Throws]
+                       void %s(long test1, double test2, double test3);
+                       };
+                       """ % (likeMember, conflictName), expectedMembers)
+        else:
+            shouldFail("Conflicting method: %s and %s" % (likeMember, conflictName),
+                       """
+                       interface Foo1 {
+                       %s;
+                       [Throws]
+                       void %s(long test1, double test2, double test3);
+                       };
+                       """ % (likeMember, conflictName))
+        # Inherited conflicting methods should ALWAYS fail
+        shouldFail("Conflicting inherited method: %s and %s" % (likeMember, conflictName),
+                   """
+                   interface Foo1 {
+                   void %s(long test1, double test2, double test3);
+                   };
+                   interface Foo2 : Foo1 {
+                   %s;
+                   };
+                   """ % (conflictName, likeMember))
+        shouldFail("Conflicting static method: %s and %s" % (likeMember, conflictName),
+                   """
+                   interface Foo1 {
+                   %s;
+                   static void %s(long test1, double test2, double test3);
+                   };
+                   """ % (likeMember, conflictName))
+        shouldFail("Conflicting attribute: %s and %s" % (likeMember, conflictName),
+                   """
+                   interface Foo1 {
+                   %s
+                   attribute double %s;
+                   };
+                   """ % (likeMember, conflictName))
+        shouldFail("Conflicting const: %s and %s" % (likeMember, conflictName),
+                   """
+                   interface Foo1 {
+                   %s;
+                   const double %s = 0;
+                   };
+                   """ % (likeMember, conflictName))
+        shouldFail("Conflicting static attribute: %s and %s" % (likeMember, conflictName),
+                   """
+                   interface Foo1 {
+                   %s;
+                   static attribute long %s;
+                   };
+                   """ % (likeMember, conflictName))
+
+    for member in disallowedIterableNames:
+        testConflictingMembers("iterable<long, long>", member, iterableMembers, False)
+    for member in mapDisallowedMemberNames:
+        testConflictingMembers("maplike<long, long>", member, mapRWMembers, False)
+    for member in disallowedMemberNames:
+        testConflictingMembers("setlike<long>", member, setRWMembers, False)
+    for member in mapDisallowedNonMethodNames:
+        testConflictingMembers("maplike<long, long>", member, mapRWMembers, True)
+    for member in setDisallowedNonMethodNames:
+        testConflictingMembers("setlike<long>", member, setRWMembers, True)
+
+    shouldPass("Inheritance of maplike/setlike with child member collision",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               void entries();
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldPass("Inheritance of multi-level maplike/setlike with child member collision",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               void entries();
+               };
+               """, mapRWMembers, numProductions=3)
+
+    shouldFail("Interface with consequential maplike/setlike interface member collision",
+               """
+               interface Foo1 {
+               void entries();
+               };
+               interface Foo2 {
+               maplike<long, long>;
+               };
+               Foo1 implements Foo2;
+               """)
+
+    shouldFail("Maplike interface with consequential interface member collision",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               void entries();
+               };
+               Foo1 implements Foo2;
+               """)
+
+    shouldPass("Consequential Maplike interface with inherited interface member collision",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               void entries();
+               };
+               interface Foo3 : Foo2 {
+               };
+               Foo3 implements Foo1;
+               """, mapRWMembers, numProductions=4)
+
+    shouldPass("Inherited Maplike interface with consequential interface member collision",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 {
+               void entries();
+               };
+               interface Foo3 : Foo1 {
+               };
+               Foo3 implements Foo2;
+               """, mapRWMembers, numProductions=4)
+
+    shouldFail("Inheritance of name collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               void entries();
+               };
+               interface Foo2 : Foo1 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Inheritance of multi-level name collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               void entries();
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldPass("Inheritance of attribute collision with parent maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               attribute double size;
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldPass("Inheritance of multi-level attribute collision with parent maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               attribute double size;
+               };
+               """, mapRWMembers, numProductions=3)
+
+    shouldFail("Inheritance of attribute collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               attribute double size;
+               };
+               interface Foo2 : Foo1 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Inheritance of multi-level attribute collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               attribute double size;
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Inheritance of attribute/rw function collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               attribute double set;
+               };
+               interface Foo2 : Foo1 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Inheritance of const/rw function collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               const double set = 0;
+               };
+               interface Foo2 : Foo1 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldPass("Inheritance of rw function with same name in child maplike/setlike",
+               """
+               interface Foo1 {
+               maplike<long, long>;
+               };
+               interface Foo2 : Foo1 {
+               void clear();
+               };
+               """, mapRWMembers, numProductions=2)
+
+    shouldFail("Inheritance of unforgeable attribute collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               [Unforgeable]
+               attribute double size;
+               };
+               interface Foo2 : Foo1 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldFail("Inheritance of multi-level unforgeable attribute collision with child maplike/setlike",
+               """
+               interface Foo1 {
+               [Unforgeable]
+               attribute double size;
+               };
+               interface Foo2 : Foo1 {
+               };
+               interface Foo3 : Foo2 {
+               maplike<long, long>;
+               };
+               """)
+
+    shouldPass("Implemented interface with readonly allowable overrides",
+               """
+               interface Foo1 {
+               readonly setlike<long>;
+               readonly attribute boolean clear;
+               };
+               """, setROMembers + [("clear", WebIDL.IDLAttribute)])
+
+    shouldPass("JS Implemented read-only interface with readonly allowable overrides",
+               """
+               [JSImplementation="@mozilla.org/dom/test-interface-js-maplike;1",
+               Constructor()]
+               interface Foo1 {
+               readonly setlike<long>;
+               readonly attribute boolean clear;
+               };
+               """, setROChromeMembers + [("clear", WebIDL.IDLAttribute)])
+
+    shouldFail("JS Implemented read-write interface with non-readwrite allowable overrides",
+               """
+               [JSImplementation="@mozilla.org/dom/test-interface-js-maplike;1",
+               Constructor()]
+               interface Foo1 {
+               setlike<long>;
+               readonly attribute boolean clear;
+               };
+               """)
+
+    r = shouldPass("Check proper override of clear/delete/set",
+                   """
+                   interface Foo1 {
+                   maplike<long, long>;
+                   long clear(long a, long b, double c, double d);
+                   long set(long a, long b, double c, double d);
+                   long delete(long a, long b, double c, double d);
+                   };
+                   """, mapRWMembers)
+
+    for m in r[0].members:
+        if m.identifier.name in ["clear", "set", "delete"]:
+            harness.ok(m.isMethod(), "%s should be a method" % m.identifier.name)
+            harness.check(m.maxArgCount, 4, "%s should have 4 arguments" % m.identifier.name)
+            harness.ok(not m.isMaplikeOrSetlikeOrIterableMethod(),
+                       "%s should not be a maplike/setlike function" % m.identifier.name)
diff --git a/dom/bindings/parser/tests/test_lenientSetter.py b/dom/bindings/parser/tests/test_lenientSetter.py
new file mode 100644
index 000000000..78a9ffe9e
--- /dev/null
+++ b/dom/bindings/parser/tests/test_lenientSetter.py
@@ -0,0 +1,58 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+def should_throw(parser, harness, message, code):
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse(code)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown: %s" % message)
+
+
+def WebIDLTest(parser, harness):
+    # The [LenientSetter] extended attribute MUST take no arguments.
+    should_throw(parser, harness, "no arguments", """
+        interface I {
+          [LenientSetter=X] readonly attribute long A;
+        };
+    """)
+
+    # An attribute with the [LenientSetter] extended attribute MUST NOT
+    # also be declared with the [PutForwards] extended attribute.
+    should_throw(parser, harness, "PutForwards", """
+        interface I {
+          [PutForwards=B, LenientSetter] readonly attribute J A;
+        };
+        interface J {
+          attribute long B;
+        };
+    """)
+
+    # An attribute with the [LenientSetter] extended attribute MUST NOT
+    # also be declared with the [Replaceable] extended attribute.
+    should_throw(parser, harness, "Replaceable", """
+        interface I {
+          [Replaceable, LenientSetter] readonly attribute J A;
+        };
+    """)
+
+    # The [LenientSetter] extended attribute MUST NOT be used on an
+    # attribute that is not read only.
+    should_throw(parser, harness, "writable attribute", """
+        interface I {
+          [LenientSetter] attribute long A;
+        };
+    """)
+
+    # The [LenientSetter] extended attribute MUST NOT be used on a
+    # static attribute.
+    should_throw(parser, harness, "static attribute", """
+        interface I {
+          [LenientSetter] static readonly attribute long A;
+        };
+    """)
diff --git a/dom/bindings/parser/tests/test_method.py b/dom/bindings/parser/tests/test_method.py
new file mode 100644
index 000000000..cf7f1b40d
--- /dev/null
+++ b/dom/bindings/parser/tests/test_method.py
@@ -0,0 +1,178 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestMethods {
+          void basic();
+          static void basicStatic();
+          void basicWithSimpleArgs(boolean arg1, byte arg2, unsigned long arg3);
+          boolean basicBoolean();
+          static boolean basicStaticBoolean();
+          boolean basicBooleanWithSimpleArgs(boolean arg1, byte arg2, unsigned long arg3);
+          void optionalArg(optional byte? arg1, optional sequence<byte> arg2);
+          void variadicArg(byte?... arg1);
+          object getObject();
+          void setObject(object arg1);
+          void setAny(any arg1);
+          float doFloats(float arg1);
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestMethods interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestMethods", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestMethods", "Interface has the right name")
+    harness.check(len(iface.members), 12, "Expect 12 members")
+
+    methods = iface.members
+
+    def checkArgument(argument, QName, name, type, optional, variadic):
+        harness.ok(isinstance(argument, WebIDL.IDLArgument),
+                   "Should be an IDLArgument")
+        harness.check(argument.identifier.QName(), QName, "Argument has the right QName")
+        harness.check(argument.identifier.name, name, "Argument has the right name")
+        harness.check(str(argument.type), type, "Argument has the right return type")
+        harness.check(argument.optional, optional, "Argument has the right optional value")
+        harness.check(argument.variadic, variadic, "Argument has the right variadic value")
+
+    def checkMethod(method, QName, name, signatures,
+                    static=False, getter=False, setter=False, creator=False,
+                    deleter=False, legacycaller=False, stringifier=False):
+        harness.ok(isinstance(method, WebIDL.IDLMethod),
+                   "Should be an IDLMethod")
+        harness.ok(method.isMethod(), "Method is a method")
+        harness.ok(not method.isAttr(), "Method is not an attr")
+        harness.ok(not method.isConst(), "Method is not a const")
+        harness.check(method.identifier.QName(), QName, "Method has the right QName")
+        harness.check(method.identifier.name, name, "Method has the right name")
+        harness.check(method.isStatic(), static, "Method has the correct static value")
+        harness.check(method.isGetter(), getter, "Method has the correct getter value")
+        harness.check(method.isSetter(), setter, "Method has the correct setter value")
+        harness.check(method.isCreator(), creator, "Method has the correct creator value")
+        harness.check(method.isDeleter(), deleter, "Method has the correct deleter value")
+        harness.check(method.isLegacycaller(), legacycaller, "Method has the correct legacycaller value")
+        harness.check(method.isStringifier(), stringifier, "Method has the correct stringifier value")
+        harness.check(len(method.signatures()), len(signatures), "Method has the correct number of signatures")
+
+        sigpairs = zip(method.signatures(), signatures)
+        for (gotSignature, expectedSignature) in sigpairs:
+            (gotRetType, gotArgs) = gotSignature
+            (expectedRetType, expectedArgs) = expectedSignature
+
+            harness.check(str(gotRetType), expectedRetType,
+                          "Method has the expected return type.")
+
+            for i in range(0, len(gotArgs)):
+                (QName, name, type, optional, variadic) = expectedArgs[i]
+                checkArgument(gotArgs[i], QName, name, type, optional, variadic)
+
+    checkMethod(methods[0], "::TestMethods::basic", "basic", [("Void", [])])
+    checkMethod(methods[1], "::TestMethods::basicStatic", "basicStatic",
+                [("Void", [])], static=True)
+    checkMethod(methods[2], "::TestMethods::basicWithSimpleArgs",
+                "basicWithSimpleArgs",
+       [("Void",
+        [("::TestMethods::basicWithSimpleArgs::arg1", "arg1", "Boolean", False, False),
+         ("::TestMethods::basicWithSimpleArgs::arg2", "arg2", "Byte", False, False),
+         ("::TestMethods::basicWithSimpleArgs::arg3", "arg3", "UnsignedLong", False, False)])])
+    checkMethod(methods[3], "::TestMethods::basicBoolean", "basicBoolean", [("Boolean", [])])
+    checkMethod(methods[4], "::TestMethods::basicStaticBoolean", "basicStaticBoolean", [("Boolean", [])], static=True)
+    checkMethod(methods[5], "::TestMethods::basicBooleanWithSimpleArgs",
+                "basicBooleanWithSimpleArgs",
+       [("Boolean",
+        [("::TestMethods::basicBooleanWithSimpleArgs::arg1", "arg1", "Boolean", False, False),
+         ("::TestMethods::basicBooleanWithSimpleArgs::arg2", "arg2", "Byte", False, False),
+         ("::TestMethods::basicBooleanWithSimpleArgs::arg3", "arg3", "UnsignedLong", False, False)])])
+    checkMethod(methods[6], "::TestMethods::optionalArg",
+                "optionalArg",
+       [("Void",
+        [("::TestMethods::optionalArg::arg1", "arg1", "ByteOrNull", True, False),
+         ("::TestMethods::optionalArg::arg2", "arg2", "ByteSequence", True, False)])])
+    checkMethod(methods[7], "::TestMethods::variadicArg",
+                "variadicArg",
+       [("Void",
+        [("::TestMethods::variadicArg::arg1", "arg1", "ByteOrNull", True, True)])])
+    checkMethod(methods[8], "::TestMethods::getObject",
+                "getObject", [("Object", [])])
+    checkMethod(methods[9], "::TestMethods::setObject",
+                "setObject",
+       [("Void",
+        [("::TestMethods::setObject::arg1", "arg1", "Object", False, False)])])
+    checkMethod(methods[10], "::TestMethods::setAny",
+                "setAny",
+       [("Void",
+        [("::TestMethods::setAny::arg1", "arg1", "Any", False, False)])])
+    checkMethod(methods[11], "::TestMethods::doFloats",
+                "doFloats",
+       [("Float",
+        [("::TestMethods::doFloats::arg1", "arg1", "Float", False, False)])])
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            void foo(optional float bar = 1);
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(not threw, "Should allow integer to float type corecion")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [GetterThrows] void foo();
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow [GetterThrows] on methods")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [SetterThrows] void foo();
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow [SetterThrows] on methods")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            [Throw] void foo();
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should spell [Throws] correctly on methods")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface A {
+            void __noSuchMethod__();
+          };
+        """)
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should not allow __noSuchMethod__ methods")
diff --git a/dom/bindings/parser/tests/test_mozmap.py b/dom/bindings/parser/tests/test_mozmap.py
new file mode 100644
index 000000000..1a36fdd62
--- /dev/null
+++ b/dom/bindings/parser/tests/test_mozmap.py
@@ -0,0 +1,39 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        dictionary Dict {};
+        interface MozMapArg {
+          void foo(MozMap<Dict> arg);
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.check(len(results), 2, "Should know about two things");
+    harness.ok(isinstance(results[1], WebIDL.IDLInterface),
+               "Should have an interface here");
+    members = results[1].members
+    harness.check(len(members), 1, "Should have one member")
+    harness.ok(members[0].isMethod(), "Should have method")
+    signature = members[0].signatures()[0]
+    args = signature[1]
+    harness.check(len(args), 1, "Should have one arg")
+    harness.ok(args[0].type.isMozMap(), "Should have a MozMap type here")
+    harness.ok(args[0].type.inner.isDictionary(),
+               "Should have a dictionary inner type")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface MozMapVoidArg {
+              void foo(MozMap<void> arg);
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_namespace.py b/dom/bindings/parser/tests/test_namespace.py
new file mode 100644
index 000000000..74533a177
--- /dev/null
+++ b/dom/bindings/parser/tests/test_namespace.py
@@ -0,0 +1,223 @@
+def WebIDLTest(parser, harness):
+    parser.parse(
+        """
+        namespace MyNamespace {
+          attribute any foo;
+          any bar();
+        };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 1, "Should have a thing.")
+    harness.ok(results[0].isNamespace(), "Our thing should be a namespace");
+    harness.check(len(results[0].members), 2,
+                  "Should have two things in our namespace")
+    harness.ok(results[0].members[0].isAttr(), "First member is attribute")
+    harness.ok(results[0].members[0].isStatic(), "Attribute should be static")
+    harness.ok(results[0].members[1].isMethod(), "Second member is method")
+    harness.ok(results[0].members[1].isStatic(), "Operation should be static")
+
+    parser = parser.reset()
+    parser.parse(
+        """
+        namespace MyNamespace {
+          attribute any foo;
+        };
+        partial namespace MyNamespace {
+          any bar();
+        };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2, "Should have things.")
+    harness.ok(results[0].isNamespace(), "Our thing should be a namespace");
+    harness.check(len(results[0].members), 2,
+                  "Should have two things in our namespace")
+    harness.ok(results[0].members[0].isAttr(), "First member is attribute")
+    harness.ok(results[0].members[0].isStatic(), "Attribute should be static");
+    harness.ok(results[0].members[1].isMethod(), "Second member is method")
+    harness.ok(results[0].members[1].isStatic(), "Operation should be static");
+
+    parser = parser.reset()
+    parser.parse(
+        """
+        partial namespace MyNamespace {
+          any bar();
+        };
+        namespace MyNamespace {
+          attribute any foo;
+        };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2, "Should have things.")
+    harness.ok(results[1].isNamespace(), "Our thing should be a namespace");
+    harness.check(len(results[1].members), 2,
+                  "Should have two things in our namespace")
+    harness.ok(results[1].members[0].isAttr(), "First member is attribute")
+    harness.ok(results[1].members[0].isStatic(), "Attribute should be static");
+    harness.ok(results[1].members[1].isMethod(), "Second member is method")
+    harness.ok(results[1].members[1].isStatic(), "Operation should be static");
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            namespace MyNamespace {
+              static attribute any foo;
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            namespace MyNamespace {
+              static any bar();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            namespace MyNamespace {
+              any bar();
+            };
+
+            interface MyNamespace {
+              any baz();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface MyNamespace {
+              any baz();
+            };
+
+            namespace MyNamespace {
+              any bar();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            namespace MyNamespace {
+              any baz();
+            };
+
+            namespace MyNamespace {
+              any bar();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            partial namespace MyNamespace {
+              any baz();
+            };
+
+            interface MyNamespace {
+              any bar();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            namespace MyNamespace {
+              any bar();
+            };
+
+            partial interface MyNamespace {
+              any baz();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            partial interface MyNamespace {
+              any baz();
+            };
+
+            namespace MyNamespace {
+              any bar();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface MyNamespace {
+              any bar();
+            };
+
+            partial namespace MyNamespace {
+              any baz();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_newobject.py b/dom/bindings/parser/tests/test_newobject.py
new file mode 100644
index 000000000..26785c6a2
--- /dev/null
+++ b/dom/bindings/parser/tests/test_newobject.py
@@ -0,0 +1,70 @@
+# Import the WebIDL module, so we can do isinstance checks and whatnot
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    # Basic functionality
+    parser.parse(
+        """
+        interface Iface {
+          [NewObject] readonly attribute Iface attr;
+          [NewObject] Iface method();
+        };
+        """)
+    results = parser.finish()
+    harness.ok(results, "Should not have thrown on basic [NewObject] usage")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface Iface {
+              [Pure, NewObject] readonly attribute Iface attr;
+            };
+            """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[NewObject] attributes must depend on something")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface Iface {
+              [Pure, NewObject] Iface method();
+            };
+            """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[NewObject] methods must depend on something")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface Iface {
+              [Cached, NewObject, Affects=Nothing] readonly attribute Iface attr;
+            };
+            """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[NewObject] attributes must not be [Cached]")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface Iface {
+              [StoreInSlot, NewObject, Affects=Nothing] readonly attribute Iface attr;
+            };
+            """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[NewObject] attributes must not be [StoreInSlot]")
diff --git a/dom/bindings/parser/tests/test_nullable_equivalency.py b/dom/bindings/parser/tests/test_nullable_equivalency.py
new file mode 100644
index 000000000..2b48b615d
--- /dev/null
+++ b/dom/bindings/parser/tests/test_nullable_equivalency.py
@@ -0,0 +1,115 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestNullableEquivalency1 {
+          attribute long  a;
+          attribute long? b;
+        };
+
+        interface TestNullableEquivalency2 {
+          attribute ArrayBuffer  a;
+          attribute ArrayBuffer? b;
+        };
+
+        /* Can't have dictionary-valued attributes, so can't test that here */
+
+        enum TestNullableEquivalency4Enum {
+          "Foo",
+          "Bar"
+        };
+
+        interface TestNullableEquivalency4 {
+          attribute TestNullableEquivalency4Enum  a;
+          attribute TestNullableEquivalency4Enum? b;
+        };
+
+        interface TestNullableEquivalency5 {
+          attribute TestNullableEquivalency4  a;
+          attribute TestNullableEquivalency4? b;
+        };
+
+        interface TestNullableEquivalency6 {
+          attribute boolean  a;
+          attribute boolean? b;
+        };
+
+        interface TestNullableEquivalency7 {
+          attribute DOMString  a;
+          attribute DOMString? b;
+        };
+
+        interface TestNullableEquivalency8 {
+          attribute float  a;
+          attribute float? b;
+        };
+
+        interface TestNullableEquivalency9 {
+          attribute double  a;
+          attribute double? b;
+        };
+
+        interface TestNullableEquivalency10 {
+          attribute object  a;
+          attribute object? b;
+        };
+    """)
+
+    for decl in parser.finish():
+        if decl.isInterface():
+            checkEquivalent(decl, harness)
+
+def checkEquivalent(iface, harness):
+    type1 = iface.members[0].type
+    type2 = iface.members[1].type
+
+    harness.check(type1.nullable(), False, 'attr1 should not be nullable')
+    harness.check(type2.nullable(), True, 'attr2 should be nullable')
+
+    # We don't know about type1, but type2, the nullable type, definitely
+    # shouldn't be builtin.
+    harness.check(type2.builtin, False, 'attr2 should not be builtin')
+
+    # Ensure that all attributes of type2 match those in type1, except for:
+    #  - names on an ignore list,
+    #  - names beginning with '_',
+    #  - functions which throw when called with no args, and
+    #  - class-level non-callables ("static variables").
+    #
+    # Yes, this is an ugly, fragile hack.  But it finds bugs...
+    for attr in dir(type1):
+        if attr.startswith('_') or \
+           attr in ['nullable', 'builtin', 'filename', 'location',
+                    'inner', 'QName', 'getDeps', 'name'] or \
+           (hasattr(type(type1), attr) and not callable(getattr(type1, attr))):
+            continue
+
+        a1 = getattr(type1, attr)
+
+        if callable(a1):
+            try:
+                v1 = a1()
+            except:
+                # Can't call a1 with no args, so skip this attriute.
+                continue
+
+            try:
+                a2 = getattr(type2, attr)
+            except:
+                harness.ok(False, 'Missing %s attribute on type %s in %s' % (attr, type2, iface))
+                continue
+
+            if not callable(a2):
+                harness.ok(False, "%s attribute on type %s in %s wasn't callable" % (attr, type2, iface))
+                continue
+
+            v2 = a2()
+            harness.check(v2, v1, '%s method return value' % attr)
+        else:
+            try:
+                a2 = getattr(type2, attr)
+            except:
+                harness.ok(False, 'Missing %s attribute on type %s in %s' % (attr, type2, iface))
+                continue
+
+            harness.check(a2, a1, '%s attribute should match' % attr)
diff --git a/dom/bindings/parser/tests/test_nullable_void.py b/dom/bindings/parser/tests/test_nullable_void.py
new file mode 100644
index 000000000..961ff825e
--- /dev/null
+++ b/dom/bindings/parser/tests/test_nullable_void.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface NullableVoid {
+              void? foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_optional_constraints.py b/dom/bindings/parser/tests/test_optional_constraints.py
new file mode 100644
index 000000000..6217465ce
--- /dev/null
+++ b/dom/bindings/parser/tests/test_optional_constraints.py
@@ -0,0 +1,30 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface OptionalConstraints1 {
+              void foo(optional byte arg1, byte arg2);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(not threw,
+               "Should not have thrown on non-optional argument following "
+               "optional argument.")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface OptionalConstraints2 {
+          void foo(optional byte arg1 = 1, optional byte arg2 = 2,
+                   optional byte arg3, optional byte arg4 = 4,
+                   optional byte arg5, optional byte arg6 = 9);
+        };
+    """)
+    results = parser.finish()
+    args = results[0].members[0].signatures()[0][1]
+    harness.check(len(args), 6, "Should have 6 arguments")
+    harness.check(args[5].defaultValue.value, 9,
+                  "Should have correct default value")
diff --git a/dom/bindings/parser/tests/test_overload.py b/dom/bindings/parser/tests/test_overload.py
new file mode 100644
index 000000000..3c680ad52
--- /dev/null
+++ b/dom/bindings/parser/tests/test_overload.py
@@ -0,0 +1,60 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestOverloads {
+          void basic();
+          void basic(long arg1);
+          boolean abitharder(TestOverloads foo);
+          boolean abitharder(boolean foo);
+          void abitharder(ArrayBuffer? foo);
+          void withVariadics(long... numbers);
+          void withVariadics(TestOverloads iface);
+          void withVariadics(long num, TestOverloads iface);
+          void optionalTest();
+          void optionalTest(optional long num1, long num2);
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestOverloads interface parsed without error.")
+    harness.check(len(results), 1, "Should be one production.")
+    iface = results[0]
+    harness.ok(isinstance(iface, WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    harness.check(iface.identifier.QName(), "::TestOverloads", "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestOverloads", "Interface has the right name")
+    harness.check(len(iface.members), 4, "Expect %s members" % 4)
+
+    member = iface.members[0]
+    harness.check(member.identifier.QName(), "::TestOverloads::basic", "Method has the right QName")
+    harness.check(member.identifier.name, "basic", "Method has the right name")
+    harness.check(member.hasOverloads(), True, "Method has overloads")
+
+    signatures = member.signatures()
+    harness.check(len(signatures), 2, "Method should have 2 signatures")
+
+    (retval, argumentSet) = signatures[0]
+
+    harness.check(str(retval), "Void", "Expect a void retval")
+    harness.check(len(argumentSet), 0, "Expect an empty argument set")
+
+    (retval, argumentSet) = signatures[1]
+    harness.check(str(retval), "Void", "Expect a void retval")
+    harness.check(len(argumentSet), 1, "Expect an argument set with one argument")
+
+    argument = argumentSet[0]
+    harness.ok(isinstance(argument, WebIDL.IDLArgument),
+               "Should be an IDLArgument")
+    harness.check(argument.identifier.QName(), "::TestOverloads::basic::arg1", "Argument has the right QName")
+    harness.check(argument.identifier.name, "arg1", "Argument has the right name")
+    harness.check(str(argument.type), "Long", "Argument has the right type")
+
+    member = iface.members[3]
+    harness.check(len(member.overloadsForArgCount(0)), 1,
+                  "Only one overload for no args")
+    harness.check(len(member.overloadsForArgCount(1)), 0,
+                  "No overloads for one arg")
+    harness.check(len(member.overloadsForArgCount(2)), 1,
+                  "Only one overload for two args")
diff --git a/dom/bindings/parser/tests/test_promise.py b/dom/bindings/parser/tests/test_promise.py
new file mode 100644
index 000000000..55bc07680
--- /dev/null
+++ b/dom/bindings/parser/tests/test_promise.py
@@ -0,0 +1,63 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface _Promise {};
+            interface A {
+              legacycaller Promise<any> foo();
+            };
+        """)
+        results = parser.finish()
+
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow Promise return values for legacycaller.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface _Promise {};
+            interface A {
+              Promise<any> foo();
+              long foo(long arg);
+            };
+        """)
+        results = parser.finish();
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow overloads which have both Promise and "
+               "non-Promise return types.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface _Promise {};
+            interface A {
+              long foo(long arg);
+              Promise<any> foo();
+            };
+        """)
+        results = parser.finish();
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should not allow overloads which have both Promise and "
+               "non-Promise return types.")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface _Promise {};
+        interface A {
+          Promise<any> foo();
+          Promise<any> foo(long arg);
+        };
+    """)
+    results = parser.finish();
+
+    harness.ok(True,
+               "Should allow overloads which only have Promise and return "
+               "types.")
diff --git a/dom/bindings/parser/tests/test_prototype_ident.py b/dom/bindings/parser/tests/test_prototype_ident.py
new file mode 100644
index 000000000..d3932b54f
--- /dev/null
+++ b/dom/bindings/parser/tests/test_prototype_ident.py
@@ -0,0 +1,80 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface TestIface {
+              static attribute boolean prototype;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "The identifier of a static attribute must not be 'prototype'")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestIface {
+              static boolean prototype();
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "The identifier of a static operation must not be 'prototype'")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestIface {
+              const boolean prototype = true;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "The identifier of a constant must not be 'prototype'")
+
+    # Make sure that we can parse non-static attributes with 'prototype' as identifier.
+    parser = parser.reset()
+    parser.parse("""
+        interface TestIface {
+          attribute boolean prototype;
+        };
+    """)
+    results = parser.finish()
+
+    testIface = results[0];
+    harness.check(testIface.members[0].isStatic(), False, "Attribute should not be static")
+    harness.check(testIface.members[0].identifier.name, "prototype", "Attribute identifier should be 'prototype'")
+
+    # Make sure that we can parse non-static operations with 'prototype' as identifier.
+    parser = parser.reset()
+    parser.parse("""
+        interface TestIface {
+          boolean prototype();
+        };
+    """)
+    results = parser.finish()
+
+    testIface = results[0];
+    harness.check(testIface.members[0].isStatic(), False, "Operation should not be static")
+    harness.check(testIface.members[0].identifier.name, "prototype", "Operation identifier should be 'prototype'")
+
+    # Make sure that we can parse dictionary members with 'prototype' as identifier.
+    parser = parser.reset()
+    parser.parse("""
+        dictionary TestDict {
+          boolean prototype;
+        };
+    """)
+    results = parser.finish()
+
+    testDict = results[0];
+    harness.check(testDict.members[0].identifier.name, "prototype", "Dictionary member should be 'prototype'")
+
diff --git a/dom/bindings/parser/tests/test_putForwards.py b/dom/bindings/parser/tests/test_putForwards.py
new file mode 100644
index 000000000..86a1bf115
--- /dev/null
+++ b/dom/bindings/parser/tests/test_putForwards.py
@@ -0,0 +1,107 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface I {
+              [PutForwards=B] readonly attribute long A;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface I {
+              [PutForwards=B] readonly attribute J A;
+            };
+            interface J {
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface I {
+              [PutForwards=B] attribute J A;
+            };
+            interface J {
+              attribute long B;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface I {
+              [PutForwards=B] static readonly attribute J A;
+            };
+            interface J {
+              attribute long B;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            callback interface I {
+              [PutForwards=B] readonly attribute J A;
+            };
+            interface J {
+              attribute long B;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface I {
+              [PutForwards=C] readonly attribute J A;
+              [PutForwards=C] readonly attribute J B;
+            };
+            interface J {
+              [PutForwards=D] readonly attribute K C;
+            };
+            interface K {
+              [PutForwards=A] readonly attribute I D;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_replaceable.py b/dom/bindings/parser/tests/test_replaceable.py
new file mode 100644
index 000000000..93ee42ed9
--- /dev/null
+++ b/dom/bindings/parser/tests/test_replaceable.py
@@ -0,0 +1,58 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+def should_throw(parser, harness, message, code):
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse(code)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown: %s" % message)
+
+
+def WebIDLTest(parser, harness):
+    # The [Replaceable] extended attribute MUST take no arguments.
+    should_throw(parser, harness, "no arguments", """
+        interface I {
+          [Replaceable=X] readonly attribute long A;
+        };
+    """)
+
+    # An attribute with the [Replaceable] extended attribute MUST NOT also be
+    # declared with the [PutForwards] extended attribute.
+    should_throw(parser, harness, "PutForwards", """
+        interface I {
+          [PutForwards=B, Replaceable] readonly attribute J A;
+        };
+        interface J {
+          attribute long B;
+        };
+    """)
+
+    # The [Replaceable] extended attribute MUST NOT be used on an attribute
+    # that is not read only.
+    should_throw(parser, harness, "writable attribute", """
+        interface I {
+          [Replaceable] attribute long A;
+        };
+    """)
+
+    # The [Replaceable] extended attribute MUST NOT be used on a static
+    # attribute.
+    should_throw(parser, harness, "static attribute", """
+        interface I {
+          [Replaceable] static readonly attribute long A;
+        };
+    """)
+
+    # The [Replaceable] extended attribute MUST NOT be used on an attribute
+    # declared on a callback interface.
+    should_throw(parser, harness, "callback interface", """
+        callback interface I {
+          [Replaceable] readonly attribute long A;
+        };
+    """)
diff --git a/dom/bindings/parser/tests/test_sanity.py b/dom/bindings/parser/tests/test_sanity.py
new file mode 100644
index 000000000..d3184c007
--- /dev/null
+++ b/dom/bindings/parser/tests/test_sanity.py
@@ -0,0 +1,7 @@
+def WebIDLTest(parser, harness):
+    parser.parse("")
+    parser.finish()
+    harness.ok(True, "Parsing nothing doesn't throw.")
+    parser.parse("interface Foo {};")
+    parser.finish()
+    harness.ok(True, "Parsing a silly interface doesn't throw.")
diff --git a/dom/bindings/parser/tests/test_securecontext_extended_attribute.py b/dom/bindings/parser/tests/test_securecontext_extended_attribute.py
new file mode 100644
index 000000000..084f19fa7
--- /dev/null
+++ b/dom/bindings/parser/tests/test_securecontext_extended_attribute.py
@@ -0,0 +1,332 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        [SecureContext]
+        interface TestSecureContextOnInterface {
+          const octet TEST_CONSTANT = 0;
+          readonly attribute byte testAttribute;
+          void testMethod(byte foo);
+        };
+        partial interface TestSecureContextOnInterface {
+          const octet TEST_CONSTANT_2 = 0;
+          readonly attribute byte testAttribute2;
+          void testMethod2(byte foo);
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 6, "TestSecureContextOnInterface should have six members")
+    harness.ok(results[0].getExtendedAttribute("SecureContext"),
+               "Interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to constant members")
+    harness.ok(results[0].members[1].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to attribute members")
+    harness.ok(results[0].members[2].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to method members")
+    harness.ok(results[0].members[3].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to constant members from partial interface")
+    harness.ok(results[0].members[4].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to attribute members from partial interface")
+    harness.ok(results[0].members[5].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to method members from partial interface")
+
+    # Same thing, but with the partial interface specified first:
+    parser = parser.reset()
+    parser.parse("""
+        partial interface TestSecureContextOnInterfaceAfterPartialInterface {
+          const octet TEST_CONSTANT_2 = 0;
+          readonly attribute byte testAttribute2;
+          void testMethod2(byte foo);
+        };
+        [SecureContext]
+        interface TestSecureContextOnInterfaceAfterPartialInterface {
+          const octet TEST_CONSTANT = 0;
+          readonly attribute byte testAttribute;
+          void testMethod(byte foo);
+        };
+     """)
+    results = parser.finish()
+    harness.check(len(results[1].members), 6, "TestSecureContextOnInterfaceAfterPartialInterface should have six members")
+    harness.ok(results[1].getExtendedAttribute("SecureContext"),
+               "Interface should have [SecureContext] extended attribute")
+    harness.ok(results[1].members[0].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to constant members")
+    harness.ok(results[1].members[1].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to attribute members")
+    harness.ok(results[1].members[2].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to method members")
+    harness.ok(results[1].members[3].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to constant members from partial interface")
+    harness.ok(results[1].members[4].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to attribute members from partial interface")
+    harness.ok(results[1].members[5].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to method members from partial interface")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestSecureContextOnPartialInterface {
+          const octet TEST_CONSTANT = 0;
+          readonly attribute byte testAttribute;
+          void testMethod(byte foo);
+        };
+        [SecureContext]
+        partial interface TestSecureContextOnPartialInterface {
+          const octet TEST_CONSTANT_2 = 0;
+          readonly attribute byte testAttribute2;
+          void testMethod2(byte foo);
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 6, "TestSecureContextOnPartialInterface should have six members")
+    harness.ok(results[0].getExtendedAttribute("SecureContext") is None,
+               "[SecureContext] should not propagate from a partial interface to the interface")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext") is None,
+               "[SecureContext] should not propagate from a partial interface to the interface's constant members")
+    harness.ok(results[0].members[1].getExtendedAttribute("SecureContext") is None,
+               "[SecureContext] should not propagate from a partial interface to the interface's attribute members")
+    harness.ok(results[0].members[2].getExtendedAttribute("SecureContext") is None,
+               "[SecureContext] should not propagate from a partial interface to the interface's method members")
+    harness.ok(results[0].members[3].getExtendedAttribute("SecureContext"),
+               "Constant members from [SecureContext] partial interface should be [SecureContext]")
+    harness.ok(results[0].members[4].getExtendedAttribute("SecureContext"),
+               "Attribute members from [SecureContext] partial interface should be [SecureContext]")
+    harness.ok(results[0].members[5].getExtendedAttribute("SecureContext"),
+               "Method members from [SecureContext] partial interface should be [SecureContext]")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestSecureContextOnInterfaceMembers {
+          const octet TEST_NON_SECURE_CONSTANT_1 = 0;
+          [SecureContext]
+          const octet TEST_SECURE_CONSTANT       = 1;
+          const octet TEST_NON_SECURE_CONSTANT_2 = 2;
+          readonly attribute byte testNonSecureAttribute1;
+          [SecureContext]
+          readonly attribute byte testSecureAttribute;
+          readonly attribute byte testNonSecureAttribute2;
+          void testNonSecureMethod1(byte foo);
+          [SecureContext]
+          void testSecureMethod(byte foo);
+          void testNonSecureMethod2(byte foo);
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 9, "TestSecureContextOnInterfaceMembers should have nine members")
+    harness.ok(results[0].getExtendedAttribute("SecureContext") is None,
+               "[SecureContext] on members should not propagate up to the interface")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext") is None,
+               "Constant should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[1].getExtendedAttribute("SecureContext"),
+               "Constant should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[2].getExtendedAttribute("SecureContext") is None,
+               "Constant should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[3].getExtendedAttribute("SecureContext") is None,
+               "Attribute should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[4].getExtendedAttribute("SecureContext"),
+               "Attribute should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[5].getExtendedAttribute("SecureContext") is None,
+               "Attribute should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[6].getExtendedAttribute("SecureContext") is None,
+               "Method should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[7].getExtendedAttribute("SecureContext"),
+               "Method should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[8].getExtendedAttribute("SecureContext") is None,
+               "Method should not have [SecureContext] extended attribute")
+
+    parser = parser.reset()
+    parser.parse("""
+        interface TestSecureContextOnPartialInterfaceMembers {
+        };
+        partial interface TestSecureContextOnPartialInterfaceMembers {
+          const octet TEST_NON_SECURE_CONSTANT_1 = 0;
+          [SecureContext]
+          const octet TEST_SECURE_CONSTANT       = 1;
+          const octet TEST_NON_SECURE_CONSTANT_2 = 2;
+          readonly attribute byte testNonSecureAttribute1;
+          [SecureContext]
+          readonly attribute byte testSecureAttribute;
+          readonly attribute byte testNonSecureAttribute2;
+          void testNonSecureMethod1(byte foo);
+          [SecureContext]
+          void testSecureMethod(byte foo);
+          void testNonSecureMethod2(byte foo);
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 9, "TestSecureContextOnPartialInterfaceMembers should have nine members")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext") is None,
+               "Constant from partial interface should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[1].getExtendedAttribute("SecureContext"),
+               "Constant from partial interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[2].getExtendedAttribute("SecureContext") is None,
+               "Constant from partial interface should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[3].getExtendedAttribute("SecureContext") is None,
+               "Attribute from partial interface should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[4].getExtendedAttribute("SecureContext"),
+               "Attribute from partial interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[5].getExtendedAttribute("SecureContext") is None,
+               "Attribute from partial interface should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[6].getExtendedAttribute("SecureContext") is None,
+               "Method from partial interface should not have [SecureContext] extended attribute")
+    harness.ok(results[0].members[7].getExtendedAttribute("SecureContext"),
+               "Method from partial interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[8].getExtendedAttribute("SecureContext") is None,
+               "Method from partial interface should not have [SecureContext] extended attribute")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [SecureContext=something]
+            interface TestSecureContextTakesNoValue1 {
+              const octet TEST_SECURE_CONSTANT = 0;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[SecureContext] must take no arguments (testing on interface)")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestSecureContextForOverloads1 {
+              [SecureContext]
+              void testSecureMethod(byte foo);
+            };
+            partial interface TestSecureContextForOverloads1 {
+              void testSecureMethod(byte foo, byte bar);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "If [SecureContext] appears on an overloaded operation, then it MUST appear on all overloads")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestSecureContextForOverloads2 {
+              [SecureContext]
+              void testSecureMethod(byte foo);
+            };
+            partial interface TestSecureContextForOverloads2 {
+              [SecureContext]
+              void testSecureMethod(byte foo, byte bar);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(not threw, "[SecureContext] can appear on an overloaded operation if it appears on all overloads")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [SecureContext]
+            interface TestSecureContextOnInterfaceAndMember {
+              [SecureContext]
+              void testSecureMethod(byte foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[SecureContext] must not appear on an interface and interface member")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface TestSecureContextOnPartialInterfaceAndMember {
+            };
+            [SecureContext]
+            partial interface TestSecureContextOnPartialInterfaceAndMember {
+              [SecureContext]
+              void testSecureMethod(byte foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[SecureContext] must not appear on a partial interface and one of the partial interface's member's")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [SecureContext]
+            interface TestSecureContextOnInterfaceAndPartialInterfaceMember {
+            };
+            partial interface TestSecureContextOnInterfaceAndPartialInterfaceMember {
+              [SecureContext]
+              void testSecureMethod(byte foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[SecureContext] must not appear on an interface and one of its partial interface's member's")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [SecureContext]
+            interface TestSecureContextOnInheritedInterface {
+            };
+            interface TestSecureContextNotOnInheritingInterface : TestSecureContextOnInheritedInterface {
+              void testSecureMethod(byte foo);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw, "[SecureContext] must appear on interfaces that inherit from another [SecureContext] interface")
+
+    # Test 'implements'. The behavior tested here may have to change depending
+    # on the resolution of https://github.com/heycam/webidl/issues/118
+    parser = parser.reset()
+    parser.parse("""
+        [SecureContext]
+        interface TestSecureContextInterfaceThatImplementsNonSecureContextInterface {
+          const octet TEST_CONSTANT = 0;
+        };
+        interface TestNonSecureContextInterface {
+          const octet TEST_CONSTANT_2 = 0;
+          readonly attribute byte testAttribute2;
+          void testMethod2(byte foo);
+        };
+        TestSecureContextInterfaceThatImplementsNonSecureContextInterface implements TestNonSecureContextInterface;
+     """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 4, "TestSecureContextInterfaceThatImplementsNonSecureContextInterface should have two members")
+    harness.ok(results[0].getExtendedAttribute("SecureContext"),
+               "Interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext"),
+               "[SecureContext] should propagate from interface to constant members even when other members are copied from a non-[SecureContext] interface")
+    harness.ok(results[0].members[1].getExtendedAttribute("SecureContext") is None,
+               "Constants copied from non-[SecureContext] interface should not be [SecureContext]")
+    harness.ok(results[0].members[2].getExtendedAttribute("SecureContext") is None,
+               "Attributes copied from non-[SecureContext] interface should not be [SecureContext]")
+    harness.ok(results[0].members[3].getExtendedAttribute("SecureContext") is None,
+               "Methods copied from non-[SecureContext] interface should not be [SecureContext]")
+ 
+    # Test SecureContext and NoInterfaceObject
+    parser = parser.reset()
+    parser.parse("""
+        [NoInterfaceObject, SecureContext]
+        interface TestSecureContextNoInterfaceObject {
+          void testSecureMethod(byte foo);
+        };
+    """)
+    results = parser.finish()
+    harness.check(len(results[0].members), 1, "TestSecureContextNoInterfaceObject should have only one member")
+    harness.ok(results[0].getExtendedAttribute("SecureContext"),
+      "Interface should have [SecureContext] extended attribute")
+    harness.ok(results[0].members[0].getExtendedAttribute("SecureContext"),
+      "Interface member should have [SecureContext] extended attribute")
diff --git a/dom/bindings/parser/tests/test_special_method_signature_mismatch.py b/dom/bindings/parser/tests/test_special_method_signature_mismatch.py
new file mode 100644
index 000000000..5ea1743d3
--- /dev/null
+++ b/dom/bindings/parser/tests/test_special_method_signature_mismatch.py
@@ -0,0 +1,294 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch1 {
+              getter long long foo(long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch2 {
+              getter void foo(unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch3 {
+              getter boolean foo(unsigned long index, boolean extraArg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch4 {
+              getter boolean foo(unsigned long... index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch5 {
+              getter boolean foo(optional unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch6 {
+              getter boolean foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch7 {
+              deleter long long foo(long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch9 {
+              deleter boolean foo(unsigned long index, boolean extraArg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch10 {
+              deleter boolean foo(unsigned long... index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch11 {
+              deleter boolean foo(optional unsigned long index);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch12 {
+              deleter boolean foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch13 {
+              setter long long foo(long index, long long value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch15 {
+              setter boolean foo(unsigned long index, boolean value, long long extraArg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch16 {
+              setter boolean foo(unsigned long index, boolean... value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch17 {
+              setter boolean foo(unsigned long index, optional boolean value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch18 {
+              setter boolean foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch20 {
+              creator long long foo(long index, long long value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch22 {
+              creator boolean foo(unsigned long index, boolean value, long long extraArg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch23 {
+              creator boolean foo(unsigned long index, boolean... value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch24 {
+              creator boolean foo(unsigned long index, optional boolean value);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodSignatureMismatch25 {
+              creator boolean foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_special_methods.py b/dom/bindings/parser/tests/test_special_methods.py
new file mode 100644
index 000000000..5b45c3399
--- /dev/null
+++ b/dom/bindings/parser/tests/test_special_methods.py
@@ -0,0 +1,85 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface SpecialMethods {
+          getter long long (unsigned long index);
+          setter long long (unsigned long index, long long value);
+          creator long long (unsigned long index, long long value);
+          getter boolean (DOMString name);
+          setter boolean (DOMString name, boolean value);
+          creator boolean (DOMString name, boolean value);
+          deleter boolean (DOMString name);
+        };
+
+        interface SpecialMethodsCombination {
+          setter creator long long (unsigned long index, long long value);
+          getter deleter boolean (DOMString name);
+          setter creator boolean (DOMString name, boolean value);
+        };
+    """)
+
+    results = parser.finish()
+
+    def checkMethod(method, QName, name,
+                    static=False, getter=False, setter=False, creator=False,
+                    deleter=False, legacycaller=False, stringifier=False):
+        harness.ok(isinstance(method, WebIDL.IDLMethod),
+                   "Should be an IDLMethod")
+        harness.check(method.identifier.QName(), QName, "Method has the right QName")
+        harness.check(method.identifier.name, name, "Method has the right name")
+        harness.check(method.isStatic(), static, "Method has the correct static value")
+        harness.check(method.isGetter(), getter, "Method has the correct getter value")
+        harness.check(method.isSetter(), setter, "Method has the correct setter value")
+        harness.check(method.isCreator(), creator, "Method has the correct creator value")
+        harness.check(method.isDeleter(), deleter, "Method has the correct deleter value")
+        harness.check(method.isLegacycaller(), legacycaller, "Method has the correct legacycaller value")
+        harness.check(method.isStringifier(), stringifier, "Method has the correct stringifier value")
+
+    harness.check(len(results), 2, "Expect 2 interfaces")
+
+    iface = results[0]
+    harness.check(len(iface.members), 7, "Expect 7 members")
+
+    checkMethod(iface.members[0], "::SpecialMethods::__indexedgetter", "__indexedgetter",
+                getter=True)
+    checkMethod(iface.members[1], "::SpecialMethods::__indexedsetter", "__indexedsetter",
+                setter=True)
+    checkMethod(iface.members[2], "::SpecialMethods::__indexedcreator", "__indexedcreator",
+                creator=True)
+    checkMethod(iface.members[3], "::SpecialMethods::__namedgetter", "__namedgetter",
+                getter=True)
+    checkMethod(iface.members[4], "::SpecialMethods::__namedsetter", "__namedsetter",
+                setter=True)
+    checkMethod(iface.members[5], "::SpecialMethods::__namedcreator", "__namedcreator",
+                creator=True)
+    checkMethod(iface.members[6], "::SpecialMethods::__nameddeleter", "__nameddeleter",
+                deleter=True)
+
+    iface = results[1]
+    harness.check(len(iface.members), 3, "Expect 3 members")
+
+    checkMethod(iface.members[0], "::SpecialMethodsCombination::__indexedsettercreator",
+                "__indexedsettercreator", setter=True, creator=True)
+    checkMethod(iface.members[1], "::SpecialMethodsCombination::__namedgetterdeleter",
+                "__namedgetterdeleter", getter=True, deleter=True)
+    checkMethod(iface.members[2], "::SpecialMethodsCombination::__namedsettercreator",
+                "__namedsettercreator", setter=True, creator=True)
+
+    parser = parser.reset();
+
+    threw = False
+    try:
+        parser.parse(
+            """
+            interface IndexedDeleter {
+              deleter void(unsigned long index);
+            };
+            """)
+        parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "There are no indexed deleters")
+        
+        
diff --git a/dom/bindings/parser/tests/test_special_methods_uniqueness.py b/dom/bindings/parser/tests/test_special_methods_uniqueness.py
new file mode 100644
index 000000000..42e2c5bb7
--- /dev/null
+++ b/dom/bindings/parser/tests/test_special_methods_uniqueness.py
@@ -0,0 +1,62 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodUniqueness1 {
+              getter deleter boolean (DOMString name);
+              getter boolean (DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodUniqueness1 {
+              deleter boolean (DOMString name);
+              getter deleter boolean (DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodUniqueness1 {
+              setter creator boolean (DOMString name);
+              creator boolean (DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    threw = False
+    try:
+        parser.parse("""
+            interface SpecialMethodUniqueness1 {
+              setter boolean (DOMString name);
+              creator setter boolean (DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_stringifier.py b/dom/bindings/parser/tests/test_stringifier.py
new file mode 100644
index 000000000..14c2c5226
--- /dev/null
+++ b/dom/bindings/parser/tests/test_stringifier.py
@@ -0,0 +1,46 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestStringifier {
+          stringifier;
+        };
+    """)
+
+    results = parser.finish()
+
+    harness.ok(isinstance(results[0].members[0], WebIDL.IDLMethod),
+               "Stringifer should be method")
+
+    parser = parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            interface TestStringifier {
+              stringifier;
+              stringifier;
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow two 'stringifier;'")
+
+    parser = parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            interface TestStringifier {
+              stringifier;
+              stringifier DOMString foo();
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should not allow a 'stringifier;' and a 'stringifier()'")
+
diff --git a/dom/bindings/parser/tests/test_treatNonCallableAsNull.py b/dom/bindings/parser/tests/test_treatNonCallableAsNull.py
new file mode 100644
index 000000000..7a0bde8a6
--- /dev/null
+++ b/dom/bindings/parser/tests/test_treatNonCallableAsNull.py
@@ -0,0 +1,71 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        [TreatNonCallableAsNull] callback Function = any(any... arguments);
+
+        interface TestTreatNonCallableAsNull1 {
+          attribute Function? onfoo;
+          attribute Function onbar;
+        };
+    """)
+
+    results = parser.finish()
+
+    iface = results[1]
+    attr = iface.members[0]
+    harness.check(attr.type.treatNonCallableAsNull(), True, "Got the expected value")
+    attr = iface.members[1]
+    harness.check(attr.type.treatNonCallableAsNull(), False, "Got the expected value")
+
+    parser = parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            callback Function = any(any... arguments);
+
+            interface TestTreatNonCallableAsNull2 {
+              [TreatNonCallableAsNull] attribute Function onfoo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            callback Function = any(any... arguments);
+
+            [TreatNonCallableAsNull]
+            interface TestTreatNonCallableAsNull3 {
+               attribute Function onfoo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+
+    threw = False
+    try:
+        parser.parse("""
+            [TreatNonCallableAsNull, TreatNonObjectAsNull]
+            callback Function = any(any... arguments);
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_typedef.py b/dom/bindings/parser/tests/test_typedef.py
new file mode 100644
index 000000000..8921985c5
--- /dev/null
+++ b/dom/bindings/parser/tests/test_typedef.py
@@ -0,0 +1,76 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+      typedef long mylong;
+      typedef long? mynullablelong;
+      interface Foo {
+        const mylong X = 5;
+        const mynullablelong Y = 7;
+        const mynullablelong Z = null;
+        void foo(mylong arg);
+      };
+    """)
+
+    results = parser.finish()
+
+    harness.check(results[2].members[1].type.name, "LongOrNull",
+                  "Should expand typedefs")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          typedef long? mynullablelong;
+          interface Foo {
+            void foo(mynullablelong? Y);
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on nullable inside nullable arg.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          typedef long? mynullablelong;
+          interface Foo {
+            const mynullablelong? X = 5;
+          };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on nullable inside nullable const.")
+    
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+          interface Foo {
+            const mynullablelong? X = 5;
+          };
+          typedef long? mynullablelong;
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown on nullable inside nullable const typedef "
+               "after interface.")
+
+    parser = parser.reset()
+    parser.parse("""
+      interface Foo {
+        const mylong X = 5;
+      };
+      typedef long mylong;
+    """)
+
+    results = parser.finish()
+
+    harness.check(results[0].members[0].type.name, "Long",
+                  "Should expand typedefs that come before interface")
diff --git a/dom/bindings/parser/tests/test_unenumerable_own_properties.py b/dom/bindings/parser/tests/test_unenumerable_own_properties.py
new file mode 100644
index 000000000..d017d5ce0
--- /dev/null
+++ b/dom/bindings/parser/tests/test_unenumerable_own_properties.py
@@ -0,0 +1,64 @@
+def WebIDLTest(parser, harness):
+
+    parser.parse(
+        """
+        interface Foo {};
+        [LegacyUnenumerableNamedProperties]
+        interface Bar : Foo {
+          getter long(DOMString name);
+        };
+        interface Baz : Bar {
+          getter long(DOMString name);
+        };
+        """);
+    results = parser.finish();
+    harness.check(len(results), 3, "Should have three interfaces")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [LegacyUnenumerableNamedProperties]
+            interface NoNamedGetter {
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [LegacyUnenumerableNamedProperties=Foo]
+            interface ShouldNotHaveArg {
+              getter long(DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            [LegacyUnenumerableNamedProperties]
+            interface Foo {
+              getter long(DOMString name);
+            };
+            interface Bar : Foo {};
+            [LegacyUnenumerableNamedProperties]
+            interface Baz : Bar {
+              getter long(DOMString name);
+            };
+        """)
+
+        results = parser.finish()
+    except Exception, x:
+        threw = True
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_unforgeable.py b/dom/bindings/parser/tests/test_unforgeable.py
new file mode 100644
index 000000000..3787e8c6a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_unforgeable.py
@@ -0,0 +1,253 @@
+def WebIDLTest(parser, harness):
+    parser.parse("""
+            interface Child : Parent {
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2,
+                  "Should be able to inherit from an interface with "
+                  "[Unforgeable] properties.")
+
+    parser = parser.reset();
+    parser.parse("""
+            interface Child : Parent {
+              const short foo = 10;
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2,
+                  "Should be able to inherit from an interface with "
+                  "[Unforgeable] properties even if we have a constant with "
+                  "the same name.")
+
+    parser = parser.reset();
+    parser.parse("""
+            interface Child : Parent {
+              static attribute short foo;
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2,
+                  "Should be able to inherit from an interface with "
+                  "[Unforgeable] properties even if we have a static attribute "
+                  "with the same name.")
+
+    parser = parser.reset();
+    parser.parse("""
+            interface Child : Parent {
+              static void foo();
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 2,
+                  "Should be able to inherit from an interface with "
+                  "[Unforgeable] properties even if we have a static operation "
+                  "with the same name.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+              void foo();
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should have thrown when shadowing unforgeable attribute on "
+               "parent with operation.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+              void foo();
+            };
+            interface Parent {
+              [Unforgeable] void foo();
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+    harness.ok(threw,
+               "Should have thrown when shadowing unforgeable operation on "
+               "parent with operation.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+              attribute short foo;
+            };
+            interface Parent {
+              [Unforgeable] readonly attribute long foo;
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+    harness.ok(threw,
+               "Should have thrown when shadowing unforgeable attribute on "
+               "parent with attribute.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+              attribute short foo;
+            };
+            interface Parent {
+              [Unforgeable] void foo();
+            };
+        """)
+
+        results = parser.finish()
+    except Exception,x:
+        threw = True
+    harness.ok(threw,
+               "Should have thrown when shadowing unforgeable operation on "
+               "parent with attribute.")
+
+    parser = parser.reset();
+    parser.parse("""
+            interface Child : Parent {
+            };
+            interface Parent {};
+            interface Consequential {
+              [Unforgeable] readonly attribute long foo;
+            };
+            Parent implements Consequential;
+        """)
+
+    results = parser.finish()
+    harness.check(len(results), 4,
+                  "Should be able to inherit from an interface with a "
+                  "consequential interface with [Unforgeable] properties.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+              void foo();
+            };
+            interface Parent {};
+            interface Consequential {
+              [Unforgeable] readonly attribute long foo;
+            };
+            Parent implements Consequential;
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown when shadowing unforgeable attribute "
+               "of parent's consequential interface.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+            };
+            interface Parent : GrandParent {};
+            interface GrandParent {};
+            interface Consequential {
+              [Unforgeable] readonly attribute long foo;
+            };
+            GrandParent implements Consequential;
+            interface ChildConsequential {
+              void foo();
+            };
+            Child implements ChildConsequential;
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown when our consequential interface shadows unforgeable attribute "
+               "of ancestor's consequential interface.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface Child : Parent {
+            };
+            interface Parent : GrandParent {};
+            interface GrandParent {};
+            interface Consequential {
+              [Unforgeable] void foo();
+            };
+            GrandParent implements Consequential;
+            interface ChildConsequential {
+              void foo();
+            };
+            Child implements ChildConsequential;
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown when our consequential interface shadows unforgeable operation "
+               "of ancestor's consequential interface.")
+
+    parser = parser.reset();
+    parser.parse("""
+        interface iface {
+          [Unforgeable] attribute long foo;
+        };
+    """)
+
+    results = parser.finish()
+    harness.check(len(results), 1,
+                  "Should allow writable [Unforgeable] attribute.")
+
+    parser = parser.reset();
+    threw = False
+    try:
+        parser.parse("""
+            interface iface {
+              [Unforgeable] static readonly attribute long foo;
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown for static [Unforgeable] attribute.")
diff --git a/dom/bindings/parser/tests/test_union.py b/dom/bindings/parser/tests/test_union.py
new file mode 100644
index 000000000..9c4f2a56a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_union.py
@@ -0,0 +1,168 @@
+import WebIDL
+import itertools
+import string
+
+# We'd like to use itertools.chain but it's 2.6 or higher.
+def chain(*iterables):
+    # chain('ABC', 'DEF') --> A B C D E F
+    for it in iterables:
+        for element in it:
+            yield element
+
+# We'd like to use itertools.combinations but it's 2.6 or higher.
+def combinations(iterable, r):
+    # combinations('ABCD', 2) --> AB AC AD BC BD CD
+    # combinations(range(4), 3) --> 012 013 023 123
+    pool = tuple(iterable)
+    n = len(pool)
+    if r > n:
+        return
+    indices = range(r)
+    yield tuple(pool[i] for i in indices)
+    while True:
+        for i in reversed(range(r)):
+            if indices[i] != i + n - r:
+                break
+        else:
+            return
+        indices[i] += 1
+        for j in range(i+1, r):
+            indices[j] = indices[j-1] + 1
+        yield tuple(pool[i] for i in indices)
+
+# We'd like to use itertools.combinations_with_replacement but it's 2.7 or
+# higher.
+def combinations_with_replacement(iterable, r):
+    # combinations_with_replacement('ABC', 2) --> AA AB AC BB BC CC
+    pool = tuple(iterable)
+    n = len(pool)
+    if not n and r:
+        return
+    indices = [0] * r
+    yield tuple(pool[i] for i in indices)
+    while True:
+        for i in reversed(range(r)):
+            if indices[i] != n - 1:
+                break
+        else:
+            return
+        indices[i:] = [indices[i] + 1] * (r - i)
+        yield tuple(pool[i] for i in indices)
+
+def WebIDLTest(parser, harness):
+    types = ["float",
+             "double",
+             "short",
+             "unsigned short",
+             "long",
+             "unsigned long",
+             "long long",
+             "unsigned long long",
+             "boolean",
+             "byte",
+             "octet",
+             "DOMString",
+             "ByteString",
+             "USVString",
+             #"sequence<float>",
+             "object",
+             "ArrayBuffer",
+             #"Date",
+             "TestInterface1",
+             "TestInterface2"]
+
+    testPre = """
+        interface TestInterface1 {
+        };
+        interface TestInterface2 {
+        };
+        """
+
+    interface = testPre + """
+        interface PrepareForTest {
+        """
+    for (i, type) in enumerate(types):
+        interface += string.Template("""
+          readonly attribute ${type} attr${i};
+        """).substitute(i=i, type=type)
+    interface += """
+        };
+        """
+
+    parser.parse(interface)
+    results = parser.finish()
+
+    iface = results[2]
+
+    parser = parser.reset()
+
+    def typesAreDistinguishable(t):
+        return all(u[0].isDistinguishableFrom(u[1]) for u in combinations(t, 2))
+    def typesAreNotDistinguishable(t):
+        return any(not u[0].isDistinguishableFrom(u[1]) for u in combinations(t, 2))
+    def unionTypeName(t):
+        if len(t) > 2:
+            t[0:2] = [unionTypeName(t[0:2])]
+        return "(" + " or ".join(t) + ")"
+
+    # typeCombinations is an iterable of tuples containing the name of the type
+    # as a string and the parsed IDL type.
+    def unionTypes(typeCombinations, predicate):
+        for c in typeCombinations:
+            if predicate(t[1] for t in c):
+                yield unionTypeName([t[0] for t in c])
+
+    # We limit invalid union types with a union member type to the subset of 3
+    # types with one invalid combination.
+    # typeCombinations is an iterable of tuples containing the name of the type
+    # as a string and the parsed IDL type.
+    def invalidUnionWithUnion(typeCombinations):
+        for c in typeCombinations:
+            if (typesAreNotDistinguishable((c[0][1], c[1][1])) and
+                typesAreDistinguishable((c[1][1], c[2][1])) and
+                typesAreDistinguishable((c[0][1], c[2][1]))):
+                yield unionTypeName([t[0] for t in c])
+
+    # Create a list of tuples containing the name of the type as a string and
+    # the parsed IDL type.
+    types = zip(types, (a.type for a in iface.members))
+
+    validUnionTypes = chain(unionTypes(combinations(types, 2), typesAreDistinguishable),
+                            unionTypes(combinations(types, 3), typesAreDistinguishable))
+    invalidUnionTypes = chain(unionTypes(combinations_with_replacement(types, 2), typesAreNotDistinguishable),
+                              invalidUnionWithUnion(combinations(types, 3)))
+    interface = testPre + """
+        interface TestUnion {
+        """
+    for (i, type) in enumerate(validUnionTypes):
+        interface += string.Template("""
+          void method${i}(${type} arg);
+          ${type} returnMethod${i}();
+          attribute ${type} attr${i};
+          void optionalMethod${i}(${type}? arg);
+        """).substitute(i=i, type=type)
+    interface += """
+        };
+        """
+    parser.parse(interface)
+    results = parser.finish()
+
+    parser = parser.reset()
+
+    for invalid in invalidUnionTypes:
+        interface = testPre + string.Template("""
+            interface TestUnion {
+              void method(${type} arg);
+            };
+        """).substitute(type=invalid)
+
+        threw = False
+        try:
+            parser.parse(interface)
+            results = parser.finish()
+        except:
+            threw = True
+
+        harness.ok(threw, "Should have thrown.")
+
+        parser = parser.reset()
diff --git a/dom/bindings/parser/tests/test_union_any.py b/dom/bindings/parser/tests/test_union_any.py
new file mode 100644
index 000000000..e34cadab4
--- /dev/null
+++ b/dom/bindings/parser/tests/test_union_any.py
@@ -0,0 +1,14 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface AnyNotInUnion {
+              void foo((any or DOMString) arg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown.")
diff --git a/dom/bindings/parser/tests/test_union_nullable.py b/dom/bindings/parser/tests/test_union_nullable.py
new file mode 100644
index 000000000..08430a94a
--- /dev/null
+++ b/dom/bindings/parser/tests/test_union_nullable.py
@@ -0,0 +1,53 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface OneNullableInUnion {
+              void foo((object? or DOMString?) arg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Two nullable member types of a union should have thrown.")
+
+    parser.reset()
+    threw = False
+
+    try:
+        parser.parse("""
+            interface NullableInNullableUnion {
+              void foo((object? or DOMString)? arg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "A nullable union type with a nullable member type should have "
+               "thrown.")
+
+    parser.reset()
+    threw = False
+
+    try:
+        parser.parse("""
+            interface NullableInUnionNullableUnionHelper {
+            };
+            interface NullableInUnionNullableUnion {
+              void foo(((object? or DOMString) or NullableInUnionNullableUnionHelper)? arg);
+            };
+        """)
+
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "A nullable union type with a nullable member type should have "
+               "thrown.")
diff --git a/dom/bindings/parser/tests/test_usvstring.py b/dom/bindings/parser/tests/test_usvstring.py
new file mode 100644
index 000000000..3a1369abd
--- /dev/null
+++ b/dom/bindings/parser/tests/test_usvstring.py
@@ -0,0 +1,36 @@
+# -*- coding: UTF-8 -*-
+
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        interface TestUSVString {
+          attribute USVString svs;
+        };
+    """)
+
+    results = parser.finish();
+
+    harness.check(len(results), 1, "Should be one production")
+    harness.ok(isinstance(results[0], WebIDL.IDLInterface),
+               "Should be an IDLInterface")
+    iface = results[0]
+    harness.check(iface.identifier.QName(), "::TestUSVString",
+                  "Interface has the right QName")
+    harness.check(iface.identifier.name, "TestUSVString",
+                  "Interface has the right name")
+    harness.check(iface.parent, None, "Interface has no parent")
+
+    members = iface.members
+    harness.check(len(members), 1, "Should be one member")
+
+    attr = members[0]
+    harness.ok(isinstance(attr, WebIDL.IDLAttribute), "Should be an IDLAttribute")
+    harness.check(attr.identifier.QName(), "::TestUSVString::svs",
+                  "Attr has correct QName")
+    harness.check(attr.identifier.name, "svs", "Attr has correct name")
+    harness.check(str(attr.type), "USVString",
+                  "Attr type is the correct name")
+    harness.ok(attr.type.isUSVString(), "Should be USVString type")
+    harness.ok(attr.type.isString(), "Should be String collective type")
+    harness.ok(not attr.type.isDOMString(), "Should be not be DOMString type")
diff --git a/dom/bindings/parser/tests/test_variadic_callback.py b/dom/bindings/parser/tests/test_variadic_callback.py
new file mode 100644
index 000000000..d9a78db20
--- /dev/null
+++ b/dom/bindings/parser/tests/test_variadic_callback.py
@@ -0,0 +1,10 @@
+import WebIDL
+
+def WebIDLTest(parser, harness):
+    parser.parse("""
+        callback TestVariadicCallback = any(any... arguments);
+    """)
+
+    results = parser.finish()
+
+    harness.ok(True, "TestVariadicCallback callback parsed without error.")
diff --git a/dom/bindings/parser/tests/test_variadic_constraints.py b/dom/bindings/parser/tests/test_variadic_constraints.py
new file mode 100644
index 000000000..7448e40d5
--- /dev/null
+++ b/dom/bindings/parser/tests/test_variadic_constraints.py
@@ -0,0 +1,63 @@
+def WebIDLTest(parser, harness):
+    threw = False
+    try:
+        parser.parse("""
+            interface VariadicConstraints1 {
+              void foo(byte... arg1, byte arg2);
+            };
+        """)
+        results = parser.finish()
+
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown on variadic argument followed by required "
+               "argument.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface VariadicConstraints2 {
+              void foo(byte... arg1, optional byte arg2);
+            };
+        """)
+        results = parser.finish();
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown on variadic argument followed by optional "
+               "argument.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface VariadicConstraints3 {
+              void foo(optional byte... arg1);
+            };
+        """)
+        results = parser.finish()
+
+    except:
+        threw = True
+
+    harness.ok(threw,
+               "Should have thrown on variadic argument explicitly flagged as "
+               "optional.")
+
+    parser = parser.reset()
+    threw = False
+    try:
+        parser.parse("""
+            interface VariadicConstraints4 {
+              void foo(byte... arg1 = 0);
+            };
+        """)
+        results = parser.finish()
+    except:
+        threw = True
+
+    harness.ok(threw, "Should have thrown on variadic argument with default value.")
diff --git a/dom/bindings/test/Makefile.in b/dom/bindings/test/Makefile.in
new file mode 100644
index 000000000..844a51c27
--- /dev/null
+++ b/dom/bindings/test/Makefile.in
@@ -0,0 +1,21 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+ifdef COMPILE_ENVIRONMENT
+
+include ../webidlsrcs.mk
+
+# $(test_sources) comes from webidlsrcs.mk.
+# TODO Update this variable in backend.mk.
+CPPSRCS += $(addprefix ../,$(test_sources))
+
+# Include rules.mk before any of our targets so our first target is coming from
+# rules.mk and running make with no target in this dir does the right thing.
+include $(topsrcdir)/config/rules.mk
+
+endif
+
+check::
+	PYTHONDONTWRITEBYTECODE=1 $(PYTHON) $(topsrcdir)/config/pythonpath.py \
+	  $(PLY_INCLUDE) $(srcdir)/../parser/runtests.py
diff --git a/dom/bindings/test/TestBindingHeader.h b/dom/bindings/test/TestBindingHeader.h
new file mode 100644
index 000000000..ca5aafdc5
--- /dev/null
+++ b/dom/bindings/test/TestBindingHeader.h
@@ -0,0 +1,1431 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef TestBindingHeader_h
+#define TestBindingHeader_h
+
+#include "mozilla/dom/BindingUtils.h"
+#include "mozilla/dom/Date.h"
+#include "mozilla/dom/MozMap.h"
+#include "mozilla/dom/TypedArray.h"
+#include "mozilla/ErrorResult.h"
+#include "nsCOMPtr.h"
+#include "nsGenericHTMLElement.h"
+#include "nsWrapperCache.h"
+
+// Forward declare this before we include TestCodeGenBinding.h, because that header relies on including
+// this one for it, for ParentDict. Hopefully it won't begin to rely on it in more fundamental ways.
+namespace mozilla {
+namespace dom {
+class TestExternalInterface;
+class Promise;
+} // namespace dom
+} // namespace mozilla
+
+// We don't export TestCodeGenBinding.h, but it's right in our parent dir.
+#include "../TestCodeGenBinding.h"
+
+extern bool TestFuncControlledMember(JSContext*, JSObject*);
+
+namespace mozilla {
+namespace dom {
+
+// IID for nsRenamedInterface
+#define NS_RENAMED_INTERFACE_IID \
+{ 0xd4b19ef3, 0xe68b, 0x4e3f, \
+ { 0x94, 0xbc, 0xc9, 0xde, 0x3a, 0x69, 0xb0, 0xe8 } }
+
+class nsRenamedInterface : public nsISupports,
+                           public nsWrapperCache
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_RENAMED_INTERFACE_IID)
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(nsRenamedInterface, NS_RENAMED_INTERFACE_IID)
+
+// IID for the IndirectlyImplementedInterface
+#define NS_INDIRECTLY_IMPLEMENTED_INTERFACE_IID \
+{ 0xfed55b69, 0x7012, 0x4849, \
+ { 0xaf, 0x56, 0x4b, 0xa9, 0xee, 0x41, 0x30, 0x89 } }
+
+class IndirectlyImplementedInterface : public nsISupports,
+                                       public nsWrapperCache
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_INDIRECTLY_IMPLEMENTED_INTERFACE_IID)
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  bool IndirectlyImplementedProperty();
+  void IndirectlyImplementedProperty(bool);
+  void IndirectlyImplementedMethod();
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(IndirectlyImplementedInterface, NS_INDIRECTLY_IMPLEMENTED_INTERFACE_IID)
+
+// IID for the TestExternalInterface
+#define NS_TEST_EXTERNAL_INTERFACE_IID \
+{ 0xd5ba0c99, 0x9b1d, 0x4e71, \
+ { 0x8a, 0x94, 0x56, 0x38, 0x6c, 0xa3, 0xda, 0x3d } }
+class TestExternalInterface : public nsISupports
+{
+public:
+  NS_DECLARE_STATIC_IID_ACCESSOR(NS_TEST_EXTERNAL_INTERFACE_IID)
+  NS_DECL_ISUPPORTS
+};
+
+NS_DEFINE_STATIC_IID_ACCESSOR(TestExternalInterface, NS_TEST_EXTERNAL_INTERFACE_IID)
+
+class TestNonWrapperCacheInterface : public nsISupports
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  bool WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto, JS::MutableHandle<JSObject*> aReflector);
+};
+
+class OnlyForUseInConstructor : public nsISupports,
+                                public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+};
+
+class TestInterface : public nsISupports,
+                      public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  // And now our actual WebIDL API
+  // Constructors
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, const nsAString&, ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, uint32_t, const Nullable<bool>&,
+                ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, TestInterface*, ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, uint32_t, IndirectlyImplementedInterface&, ErrorResult&);
+
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, Date&, ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, const ArrayBuffer&, ErrorResult&);
+  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, const Uint8Array&, ErrorResult&);
+  /*  static
+  already_AddRefed<TestInterface>
+    Constructor(const GlobalObject&, uint32_t, uint32_t,
+                const TestInterfaceOrOnlyForUseInConstructor&, ErrorResult&);
+  */
+
+  static
+  already_AddRefed<TestInterface> Test(const GlobalObject&, ErrorResult&);
+  static
+  already_AddRefed<TestInterface> Test(const GlobalObject&, const nsAString&,
+                                       ErrorResult&);
+  static
+  already_AddRefed<TestInterface> Test(const GlobalObject&, const nsACString&,
+                                       ErrorResult&);
+
+  static
+  already_AddRefed<TestInterface> Test2(const GlobalObject&,
+                                        const DictForConstructor&,
+                                        JS::Handle<JS::Value>,
+                                        JS::Handle<JSObject*>,
+                                        JS::Handle<JSObject*>,
+                                        const Sequence<Dict>&,
+                                        JS::Handle<JS::Value>,
+                                        const Optional<JS::Handle<JSObject*> >&,
+                                        const Optional<JS::Handle<JSObject*> >&,
+                                        ErrorResult&);
+
+  static
+  already_AddRefed<TestInterface> Test3(const GlobalObject&,
+                                        const LongOrAnyMozMap&,
+                                        ErrorResult&);
+
+  // Integer types
+  int8_t ReadonlyByte();
+  int8_t WritableByte();
+  void SetWritableByte(int8_t);
+  void PassByte(int8_t);
+  int8_t ReceiveByte();
+  void PassOptionalByte(const Optional<int8_t>&);
+  void PassOptionalByteBeforeRequired(const Optional<int8_t>&, int8_t);
+  void PassOptionalByteWithDefault(int8_t);
+  void PassOptionalByteWithDefaultBeforeRequired(int8_t, int8_t);
+  void PassNullableByte(const Nullable<int8_t>&);
+  void PassOptionalNullableByte(const Optional< Nullable<int8_t> >&);
+  void PassVariadicByte(const Sequence<int8_t>&);
+  int8_t CachedByte();
+  int8_t CachedConstantByte();
+  int8_t CachedWritableByte();
+  void SetCachedWritableByte(int8_t);
+  int8_t SideEffectFreeByte();
+  int8_t SetSideEffectFreeByte(int8_t);
+  int8_t DomDependentByte();
+  int8_t SetDomDependentByte(int8_t);
+  int8_t ConstantByte();
+  int8_t DeviceStateDependentByte();
+  int8_t ReturnByteSideEffectFree();
+  int8_t ReturnDOMDependentByte();
+  int8_t ReturnConstantByte();
+  int8_t ReturnDeviceStateDependentByte();
+
+  void UnsafePrerenderMethod();
+  int32_t UnsafePrerenderWritable();
+  void SetUnsafePrerenderWritable(int32_t);
+  int32_t UnsafePrerenderReadonly();
+  int16_t ReadonlyShort();
+  int16_t WritableShort();
+  void SetWritableShort(int16_t);
+  void PassShort(int16_t);
+  int16_t ReceiveShort();
+  void PassOptionalShort(const Optional<int16_t>&);
+  void PassOptionalShortWithDefault(int16_t);
+
+  int32_t ReadonlyLong();
+  int32_t WritableLong();
+  void SetWritableLong(int32_t);
+  void PassLong(int32_t);
+  int16_t ReceiveLong();
+  void PassOptionalLong(const Optional<int32_t>&);
+  void PassOptionalLongWithDefault(int32_t);
+
+  int64_t ReadonlyLongLong();
+  int64_t WritableLongLong();
+  void SetWritableLongLong(int64_t);
+  void PassLongLong(int64_t);
+  int64_t ReceiveLongLong();
+  void PassOptionalLongLong(const Optional<int64_t>&);
+  void PassOptionalLongLongWithDefault(int64_t);
+
+  uint8_t ReadonlyOctet();
+  uint8_t WritableOctet();
+  void SetWritableOctet(uint8_t);
+  void PassOctet(uint8_t);
+  uint8_t ReceiveOctet();
+  void PassOptionalOctet(const Optional<uint8_t>&);
+  void PassOptionalOctetWithDefault(uint8_t);
+
+  uint16_t ReadonlyUnsignedShort();
+  uint16_t WritableUnsignedShort();
+  void SetWritableUnsignedShort(uint16_t);
+  void PassUnsignedShort(uint16_t);
+  uint16_t ReceiveUnsignedShort();
+  void PassOptionalUnsignedShort(const Optional<uint16_t>&);
+  void PassOptionalUnsignedShortWithDefault(uint16_t);
+
+  uint32_t ReadonlyUnsignedLong();
+  uint32_t WritableUnsignedLong();
+  void SetWritableUnsignedLong(uint32_t);
+  void PassUnsignedLong(uint32_t);
+  uint32_t ReceiveUnsignedLong();
+  void PassOptionalUnsignedLong(const Optional<uint32_t>&);
+  void PassOptionalUnsignedLongWithDefault(uint32_t);
+
+  uint64_t ReadonlyUnsignedLongLong();
+  uint64_t WritableUnsignedLongLong();
+  void SetWritableUnsignedLongLong(uint64_t);
+  void PassUnsignedLongLong(uint64_t);
+  uint64_t ReceiveUnsignedLongLong();
+  void PassOptionalUnsignedLongLong(const Optional<uint64_t>&);
+  void PassOptionalUnsignedLongLongWithDefault(uint64_t);
+
+  float WritableFloat() const;
+  void SetWritableFloat(float);
+  float WritableUnrestrictedFloat() const;
+  void SetWritableUnrestrictedFloat(float);
+  Nullable<float> GetWritableNullableFloat() const;
+  void SetWritableNullableFloat(Nullable<float>);
+  Nullable<float> GetWritableNullableUnrestrictedFloat() const;
+  void SetWritableNullableUnrestrictedFloat(Nullable<float>);
+  double WritableDouble() const;
+  void SetWritableDouble(double);
+  double WritableUnrestrictedDouble() const;
+  void SetWritableUnrestrictedDouble(double);
+  Nullable<double> GetWritableNullableDouble() const;
+  void SetWritableNullableDouble(Nullable<double>);
+  Nullable<double> GetWritableNullableUnrestrictedDouble() const;
+  void SetWritableNullableUnrestrictedDouble(Nullable<double>);
+  void PassFloat(float, float, Nullable<float>, Nullable<float>,
+                 double, double, Nullable<double>, Nullable<double>,
+                 const Sequence<float>&, const Sequence<float>&,
+                 const Sequence<Nullable<float> >&,
+                 const Sequence<Nullable<float> >&,
+                 const Sequence<double>&, const Sequence<double>&,
+                 const Sequence<Nullable<double> >&,
+                 const Sequence<Nullable<double> >&);
+  void PassLenientFloat(float, float, Nullable<float>, Nullable<float>,
+                        double, double, Nullable<double>, Nullable<double>,
+                        const Sequence<float>&, const Sequence<float>&,
+                        const Sequence<Nullable<float> >&,
+                        const Sequence<Nullable<float> >&,
+                        const Sequence<double>&, const Sequence<double>&,
+                        const Sequence<Nullable<double> >&,
+                        const Sequence<Nullable<double> >&);
+  float LenientFloatAttr() const;
+  void SetLenientFloatAttr(float);
+  double LenientDoubleAttr() const;
+  void SetLenientDoubleAttr(double);
+
+  void PassUnrestricted(float arg1,
+                        float arg2,
+                        float arg3,
+                        float arg4,
+                        double arg5,
+                        double arg6,
+                        double arg7,
+                        double arg8);
+
+  // Interface types
+  already_AddRefed<TestInterface> ReceiveSelf();
+  already_AddRefed<TestInterface> ReceiveNullableSelf();
+  TestInterface* ReceiveWeakSelf();
+  TestInterface* ReceiveWeakNullableSelf();
+  void PassSelf(TestInterface&);
+  void PassNullableSelf(TestInterface*);
+  already_AddRefed<TestInterface> NonNullSelf();
+  void SetNonNullSelf(TestInterface&);
+  already_AddRefed<TestInterface> GetNullableSelf();
+  already_AddRefed<TestInterface> CachedSelf();
+  void SetNullableSelf(TestInterface*);
+  void PassOptionalSelf(const Optional<TestInterface*> &);
+  void PassOptionalNonNullSelf(const Optional<NonNull<TestInterface> >&);
+  void PassOptionalSelfWithDefault(TestInterface*);
+
+  already_AddRefed<TestNonWrapperCacheInterface> ReceiveNonWrapperCacheInterface();
+  already_AddRefed<TestNonWrapperCacheInterface> ReceiveNullableNonWrapperCacheInterface();
+  void ReceiveNonWrapperCacheInterfaceSequence(nsTArray<RefPtr<TestNonWrapperCacheInterface> >&);
+  void ReceiveNullableNonWrapperCacheInterfaceSequence(nsTArray<RefPtr<TestNonWrapperCacheInterface> >&);
+  void ReceiveNonWrapperCacheInterfaceNullableSequence(Nullable<nsTArray<RefPtr<TestNonWrapperCacheInterface> > >&);
+  void ReceiveNullableNonWrapperCacheInterfaceNullableSequence(Nullable<nsTArray<RefPtr<TestNonWrapperCacheInterface> > >&);
+
+  already_AddRefed<IndirectlyImplementedInterface> ReceiveOther();
+  already_AddRefed<IndirectlyImplementedInterface> ReceiveNullableOther();
+  IndirectlyImplementedInterface* ReceiveWeakOther();
+  IndirectlyImplementedInterface* ReceiveWeakNullableOther();
+  void PassOther(IndirectlyImplementedInterface&);
+  void PassNullableOther(IndirectlyImplementedInterface*);
+  already_AddRefed<IndirectlyImplementedInterface> NonNullOther();
+  void SetNonNullOther(IndirectlyImplementedInterface&);
+  already_AddRefed<IndirectlyImplementedInterface> GetNullableOther();
+  void SetNullableOther(IndirectlyImplementedInterface*);
+  void PassOptionalOther(const Optional<IndirectlyImplementedInterface*>&);
+  void PassOptionalNonNullOther(const Optional<NonNull<IndirectlyImplementedInterface> >&);
+  void PassOptionalOtherWithDefault(IndirectlyImplementedInterface*);
+
+  already_AddRefed<TestExternalInterface> ReceiveExternal();
+  already_AddRefed<TestExternalInterface> ReceiveNullableExternal();
+  TestExternalInterface* ReceiveWeakExternal();
+  TestExternalInterface* ReceiveWeakNullableExternal();
+  void PassExternal(TestExternalInterface*);
+  void PassNullableExternal(TestExternalInterface*);
+  already_AddRefed<TestExternalInterface> NonNullExternal();
+  void SetNonNullExternal(TestExternalInterface*);
+  already_AddRefed<TestExternalInterface> GetNullableExternal();
+  void SetNullableExternal(TestExternalInterface*);
+  void PassOptionalExternal(const Optional<TestExternalInterface*>&);
+  void PassOptionalNonNullExternal(const Optional<TestExternalInterface*>&);
+  void PassOptionalExternalWithDefault(TestExternalInterface*);
+
+  already_AddRefed<TestCallbackInterface> ReceiveCallbackInterface();
+  already_AddRefed<TestCallbackInterface> ReceiveNullableCallbackInterface();
+  TestCallbackInterface* ReceiveWeakCallbackInterface();
+  TestCallbackInterface* ReceiveWeakNullableCallbackInterface();
+  void PassCallbackInterface(TestCallbackInterface&);
+  void PassNullableCallbackInterface(TestCallbackInterface*);
+  already_AddRefed<TestCallbackInterface> NonNullCallbackInterface();
+  void SetNonNullCallbackInterface(TestCallbackInterface&);
+  already_AddRefed<TestCallbackInterface> GetNullableCallbackInterface();
+  void SetNullableCallbackInterface(TestCallbackInterface*);
+  void PassOptionalCallbackInterface(const Optional<RefPtr<TestCallbackInterface> >&);
+  void PassOptionalNonNullCallbackInterface(const Optional<OwningNonNull<TestCallbackInterface> >&);
+  void PassOptionalCallbackInterfaceWithDefault(TestCallbackInterface*);
+
+  already_AddRefed<IndirectlyImplementedInterface> ReceiveConsequentialInterface();
+  void PassConsequentialInterface(IndirectlyImplementedInterface&);
+
+  // Sequence types
+  void GetReadonlySequence(nsTArray<int32_t>&);
+  void GetReadonlySequenceOfDictionaries(JSContext*, nsTArray<Dict>&);
+  void GetReadonlyNullableSequenceOfDictionaries(JSContext*, Nullable<nsTArray<Dict> >&);
+  void GetReadonlyFrozenSequence(JSContext*, nsTArray<Dict>&);
+  void GetReadonlyFrozenNullableSequence(JSContext*, Nullable<nsTArray<Dict>>&);
+  void ReceiveSequence(nsTArray<int32_t>&);
+  void ReceiveNullableSequence(Nullable< nsTArray<int32_t> >&);
+  void ReceiveSequenceOfNullableInts(nsTArray< Nullable<int32_t> >&);
+  void ReceiveNullableSequenceOfNullableInts(Nullable< nsTArray< Nullable<int32_t> > >&);
+  void PassSequence(const Sequence<int32_t> &);
+  void PassNullableSequence(const Nullable< Sequence<int32_t> >&);
+  void PassSequenceOfNullableInts(const Sequence<Nullable<int32_t> >&);
+  void PassOptionalSequenceOfNullableInts(const Optional<Sequence<Nullable<int32_t> > > &);
+  void PassOptionalNullableSequenceOfNullableInts(const Optional<Nullable<Sequence<Nullable<int32_t> > > > &);
+  void ReceiveCastableObjectSequence(nsTArray< RefPtr<TestInterface> > &);
+  void ReceiveCallbackObjectSequence(nsTArray< RefPtr<TestCallbackInterface> > &);
+  void ReceiveNullableCastableObjectSequence(nsTArray< RefPtr<TestInterface> > &);
+  void ReceiveNullableCallbackObjectSequence(nsTArray< RefPtr<TestCallbackInterface> > &);
+  void ReceiveCastableObjectNullableSequence(Nullable< nsTArray< RefPtr<TestInterface> > >&);
+  void ReceiveNullableCastableObjectNullableSequence(Nullable< nsTArray< RefPtr<TestInterface> > >&);
+  void ReceiveWeakCastableObjectSequence(nsTArray<RefPtr<TestInterface>> &);
+  void ReceiveWeakNullableCastableObjectSequence(nsTArray<RefPtr<TestInterface>> &);
+  void ReceiveWeakCastableObjectNullableSequence(Nullable< nsTArray<RefPtr<TestInterface>> >&);
+  void ReceiveWeakNullableCastableObjectNullableSequence(Nullable< nsTArray<RefPtr<TestInterface>> >&);
+  void PassCastableObjectSequence(const Sequence< OwningNonNull<TestInterface> >&);
+  void PassNullableCastableObjectSequence(const Sequence< RefPtr<TestInterface> > &);
+  void PassCastableObjectNullableSequence(const Nullable< Sequence< OwningNonNull<TestInterface> > >&);
+  void PassNullableCastableObjectNullableSequence(const Nullable< Sequence< RefPtr<TestInterface> > >&);
+  void PassOptionalSequence(const Optional<Sequence<int32_t> >&);
+  void PassOptionalSequenceWithDefaultValue(const Sequence<int32_t> &);
+  void PassOptionalNullableSequence(const Optional<Nullable<Sequence<int32_t> > >&);
+  void PassOptionalNullableSequenceWithDefaultValue(const Nullable< Sequence<int32_t> >&);
+  void PassOptionalNullableSequenceWithDefaultValue2(const Nullable< Sequence<int32_t> >&);
+  void PassOptionalObjectSequence(const Optional<Sequence<OwningNonNull<TestInterface> > >&);
+  void PassExternalInterfaceSequence(const Sequence<RefPtr<TestExternalInterface> >&);
+  void PassNullableExternalInterfaceSequence(const Sequence<RefPtr<TestExternalInterface> >&);
+
+  void ReceiveStringSequence(nsTArray<nsString>&);
+  void PassStringSequence(const Sequence<nsString>&);
+
+  void ReceiveByteStringSequence(nsTArray<nsCString>&);
+  void PassByteStringSequence(const Sequence<nsCString>&);
+
+  void ReceiveAnySequence(JSContext*, nsTArray<JS::Value>&);
+  void ReceiveNullableAnySequence(JSContext*, Nullable<nsTArray<JS::Value> >&);
+  void ReceiveAnySequenceSequence(JSContext*, nsTArray<nsTArray<JS::Value> >&);
+
+  void ReceiveObjectSequence(JSContext*, nsTArray<JSObject*>&);
+  void ReceiveNullableObjectSequence(JSContext*, nsTArray<JSObject*>&);
+
+  void PassSequenceOfSequences(const Sequence< Sequence<int32_t> >&);
+  void PassSequenceOfSequencesOfSequences(const Sequence<Sequence<Sequence<int32_t>>>&);
+  void ReceiveSequenceOfSequences(nsTArray< nsTArray<int32_t> >&);
+  void ReceiveSequenceOfSequencesOfSequences(nsTArray<nsTArray<nsTArray<int32_t>>>&);
+
+  // MozMap types
+  void PassMozMap(const MozMap<int32_t> &);
+  void PassNullableMozMap(const Nullable< MozMap<int32_t> >&);
+  void PassMozMapOfNullableInts(const MozMap<Nullable<int32_t> >&);
+  void PassOptionalMozMapOfNullableInts(const Optional<MozMap<Nullable<int32_t> > > &);
+  void PassOptionalNullableMozMapOfNullableInts(const Optional<Nullable<MozMap<Nullable<int32_t> > > > &);
+  void PassCastableObjectMozMap(const MozMap< OwningNonNull<TestInterface> >&);
+  void PassNullableCastableObjectMozMap(const MozMap< RefPtr<TestInterface> > &);
+  void PassCastableObjectNullableMozMap(const Nullable< MozMap< OwningNonNull<TestInterface> > >&);
+  void PassNullableCastableObjectNullableMozMap(const Nullable< MozMap< RefPtr<TestInterface> > >&);
+  void PassOptionalMozMap(const Optional<MozMap<int32_t> >&);
+  void PassOptionalNullableMozMap(const Optional<Nullable<MozMap<int32_t> > >&);
+  void PassOptionalNullableMozMapWithDefaultValue(const Nullable< MozMap<int32_t> >&);
+  void PassOptionalObjectMozMap(const Optional<MozMap<OwningNonNull<TestInterface> > >&);
+  void PassExternalInterfaceMozMap(const MozMap<RefPtr<TestExternalInterface> >&);
+  void PassNullableExternalInterfaceMozMap(const MozMap<RefPtr<TestExternalInterface> >&);
+  void PassStringMozMap(const MozMap<nsString>&);
+  void PassByteStringMozMap(const MozMap<nsCString>&);
+  void PassMozMapOfMozMaps(const MozMap< MozMap<int32_t> >&);
+  void ReceiveMozMap(MozMap<int32_t>&);
+  void ReceiveNullableMozMap(Nullable<MozMap<int32_t>>&);
+  void ReceiveMozMapOfNullableInts(MozMap<Nullable<int32_t>>&);
+  void ReceiveNullableMozMapOfNullableInts(Nullable<MozMap<Nullable<int32_t>>>&);
+  void ReceiveMozMapOfMozMaps(MozMap<MozMap<int32_t>>&);
+  void ReceiveAnyMozMap(JSContext*, MozMap<JS::Value>&);
+
+  // Typed array types
+  void PassArrayBuffer(const ArrayBuffer&);
+  void PassNullableArrayBuffer(const Nullable<ArrayBuffer>&);
+  void PassOptionalArrayBuffer(const Optional<ArrayBuffer>&);
+  void PassOptionalNullableArrayBuffer(const Optional<Nullable<ArrayBuffer> >&);
+  void PassOptionalNullableArrayBufferWithDefaultValue(const Nullable<ArrayBuffer>&);
+  void PassArrayBufferView(const ArrayBufferView&);
+  void PassInt8Array(const Int8Array&);
+  void PassInt16Array(const Int16Array&);
+  void PassInt32Array(const Int32Array&);
+  void PassUint8Array(const Uint8Array&);
+  void PassUint16Array(const Uint16Array&);
+  void PassUint32Array(const Uint32Array&);
+  void PassUint8ClampedArray(const Uint8ClampedArray&);
+  void PassFloat32Array(const Float32Array&);
+  void PassFloat64Array(const Float64Array&);
+  void PassSequenceOfArrayBuffers(const Sequence<ArrayBuffer>&);
+  void PassSequenceOfNullableArrayBuffers(const Sequence<Nullable<ArrayBuffer> >&);
+  void PassMozMapOfArrayBuffers(const MozMap<ArrayBuffer>&);
+  void PassMozMapOfNullableArrayBuffers(const MozMap<Nullable<ArrayBuffer> >&);
+  void PassVariadicTypedArray(const Sequence<Float32Array>&);
+  void PassVariadicNullableTypedArray(const Sequence<Nullable<Float32Array> >&);
+  void ReceiveUint8Array(JSContext*, JS::MutableHandle<JSObject*>);
+  void SetUint8ArrayAttr(const Uint8Array&);
+  void GetUint8ArrayAttr(JSContext*, JS::MutableHandle<JSObject*>);
+
+  // DOMString types
+  void PassString(const nsAString&);
+  void PassNullableString(const nsAString&);
+  void PassOptionalString(const Optional<nsAString>&);
+  void PassOptionalStringWithDefaultValue(const nsAString&);
+  void PassOptionalNullableString(const Optional<nsAString>&);
+  void PassOptionalNullableStringWithDefaultValue(const nsAString&);
+  void PassVariadicString(const Sequence<nsString>&);
+  void ReceiveString(DOMString&);
+
+  // ByteString types
+  void PassByteString(const nsCString&);
+  void PassNullableByteString(const nsCString&);
+  void PassOptionalByteString(const Optional<nsCString>&);
+  void PassOptionalByteStringWithDefaultValue(const nsCString&);
+  void PassOptionalNullableByteString(const Optional<nsCString>&);
+  void PassOptionalNullableByteStringWithDefaultValue(const nsCString&);
+  void PassVariadicByteString(const Sequence<nsCString>&);
+  void PassOptionalUnionByteString(const Optional<ByteStringOrLong>&);
+  void PassOptionalUnionByteStringWithDefaultValue(const ByteStringOrLong&);
+
+  // USVString types
+  void PassUSVS(const nsAString&);
+  void PassNullableUSVS(const nsAString&);
+  void PassOptionalUSVS(const Optional<nsAString>&);
+  void PassOptionalUSVSWithDefaultValue(const nsAString&);
+  void PassOptionalNullableUSVS(const Optional<nsAString>&);
+  void PassOptionalNullableUSVSWithDefaultValue(const nsAString&);
+  void PassVariadicUSVS(const Sequence<nsString>&);
+  void ReceiveUSVS(DOMString&);
+
+  // Enumerated types
+  void PassEnum(TestEnum);
+  void PassNullableEnum(const Nullable<TestEnum>&);
+  void PassOptionalEnum(const Optional<TestEnum>&);
+  void PassEnumWithDefault(TestEnum);
+  void PassOptionalNullableEnum(const Optional<Nullable<TestEnum> >&);
+  void PassOptionalNullableEnumWithDefaultValue(const Nullable<TestEnum>&);
+  void PassOptionalNullableEnumWithDefaultValue2(const Nullable<TestEnum>&);
+  TestEnum ReceiveEnum();
+  Nullable<TestEnum> ReceiveNullableEnum();
+  TestEnum EnumAttribute();
+  TestEnum ReadonlyEnumAttribute();
+  void SetEnumAttribute(TestEnum);
+
+  // Callback types
+  void PassCallback(TestCallback&);
+  void PassNullableCallback(TestCallback*);
+  void PassOptionalCallback(const Optional<OwningNonNull<TestCallback> >&);
+  void PassOptionalNullableCallback(const Optional<RefPtr<TestCallback> >&);
+  void PassOptionalNullableCallbackWithDefaultValue(TestCallback*);
+  already_AddRefed<TestCallback> ReceiveCallback();
+  already_AddRefed<TestCallback> ReceiveNullableCallback();
+  void PassNullableTreatAsNullCallback(TestTreatAsNullCallback*);
+  void PassOptionalNullableTreatAsNullCallback(const Optional<RefPtr<TestTreatAsNullCallback> >&);
+  void PassOptionalNullableTreatAsNullCallbackWithDefaultValue(TestTreatAsNullCallback*);
+  void SetTreatAsNullCallback(TestTreatAsNullCallback&);
+  already_AddRefed<TestTreatAsNullCallback> TreatAsNullCallback();
+  void SetNullableTreatAsNullCallback(TestTreatAsNullCallback*);
+  already_AddRefed<TestTreatAsNullCallback> GetNullableTreatAsNullCallback();
+
+  void ForceCallbackGeneration(TestIntegerReturn&,
+                               TestNullableIntegerReturn&,
+                               TestBooleanReturn&,
+                               TestFloatReturn&,
+                               TestStringReturn&,
+                               TestEnumReturn&,
+                               TestInterfaceReturn&,
+                               TestNullableInterfaceReturn&,
+                               TestExternalInterfaceReturn&,
+                               TestNullableExternalInterfaceReturn&,
+                               TestCallbackInterfaceReturn&,
+                               TestNullableCallbackInterfaceReturn&,
+                               TestCallbackReturn&,
+                               TestNullableCallbackReturn&,
+                               TestObjectReturn&,
+                               TestNullableObjectReturn&,
+                               TestTypedArrayReturn&,
+                               TestNullableTypedArrayReturn&,
+                               TestSequenceReturn&,
+                               TestNullableSequenceReturn&,
+                               TestIntegerArguments&,
+                               TestInterfaceArguments&,
+                               TestStringEnumArguments&,
+                               TestObjectArguments&,
+                               TestOptionalArguments&);
+
+  // Any types
+  void PassAny(JSContext*, JS::Handle<JS::Value>);
+  void PassVariadicAny(JSContext*, const Sequence<JS::Value>&);
+  void PassOptionalAny(JSContext*, JS::Handle<JS::Value>);
+  void PassAnyDefaultNull(JSContext*, JS::Handle<JS::Value>);
+  void PassSequenceOfAny(JSContext*, const Sequence<JS::Value>&);
+  void PassNullableSequenceOfAny(JSContext*, const Nullable<Sequence<JS::Value> >&);
+  void PassOptionalSequenceOfAny(JSContext*, const Optional<Sequence<JS::Value> >&);
+  void PassOptionalNullableSequenceOfAny(JSContext*, const Optional<Nullable<Sequence<JS::Value> > >&);
+  void PassOptionalSequenceOfAnyWithDefaultValue(JSContext*, const Nullable<Sequence<JS::Value> >&);
+  void PassSequenceOfSequenceOfAny(JSContext*, const Sequence<Sequence<JS::Value> >&);
+  void PassSequenceOfNullableSequenceOfAny(JSContext*, const Sequence<Nullable<Sequence<JS::Value> > >&);
+  void PassNullableSequenceOfNullableSequenceOfAny(JSContext*, const Nullable<Sequence<Nullable<Sequence<JS::Value> > > >&);
+  void PassOptionalNullableSequenceOfNullableSequenceOfAny(JSContext*, const Optional<Nullable<Sequence<Nullable<Sequence<JS::Value> > > > >&);
+  void PassMozMapOfAny(JSContext*, const MozMap<JS::Value>&);
+  void PassNullableMozMapOfAny(JSContext*, const Nullable<MozMap<JS::Value> >&);
+  void PassOptionalMozMapOfAny(JSContext*, const Optional<MozMap<JS::Value> >&);
+  void PassOptionalNullableMozMapOfAny(JSContext*, const Optional<Nullable<MozMap<JS::Value> > >&);
+  void PassOptionalMozMapOfAnyWithDefaultValue(JSContext*, const Nullable<MozMap<JS::Value> >&);
+  void PassMozMapOfMozMapOfAny(JSContext*, const MozMap<MozMap<JS::Value> >&);
+  void PassMozMapOfNullableMozMapOfAny(JSContext*, const MozMap<Nullable<MozMap<JS::Value> > >&);
+  void PassNullableMozMapOfNullableMozMapOfAny(JSContext*, const Nullable<MozMap<Nullable<MozMap<JS::Value> > > >&);
+  void PassOptionalNullableMozMapOfNullableMozMapOfAny(JSContext*, const Optional<Nullable<MozMap<Nullable<MozMap<JS::Value>>>>>&);
+  void PassOptionalNullableMozMapOfNullableSequenceOfAny(JSContext*, const Optional<Nullable<MozMap<Nullable<Sequence<JS::Value>>>>>&);
+  void PassOptionalNullableSequenceOfNullableMozMapOfAny(JSContext*, const Optional<Nullable<Sequence<Nullable<MozMap<JS::Value>>>>>&);
+  void ReceiveAny(JSContext*, JS::MutableHandle<JS::Value>);
+
+  // object types
+  void PassObject(JSContext*, JS::Handle<JSObject*>);
+  void PassVariadicObject(JSContext*, const Sequence<JSObject*>&);
+  void PassNullableObject(JSContext*, JS::Handle<JSObject*>);
+  void PassVariadicNullableObject(JSContext*, const Sequence<JSObject*>&);
+  void PassOptionalObject(JSContext*, const Optional<JS::Handle<JSObject*> >&);
+  void PassOptionalNullableObject(JSContext*, const Optional<JS::Handle<JSObject*> >&);
+  void PassOptionalNullableObjectWithDefaultValue(JSContext*, JS::Handle<JSObject*>);
+  void PassSequenceOfObject(JSContext*, const Sequence<JSObject*>&);
+  void PassSequenceOfNullableObject(JSContext*, const Sequence<JSObject*>&);
+  void PassNullableSequenceOfObject(JSContext*, const Nullable<Sequence<JSObject*> >&);
+  void PassOptionalNullableSequenceOfNullableSequenceOfObject(JSContext*, const Optional<Nullable<Sequence<Nullable<Sequence<JSObject*> > > > >&);
+  void PassOptionalNullableSequenceOfNullableSequenceOfNullableObject(JSContext*, const Optional<Nullable<Sequence<Nullable<Sequence<JSObject*> > > > >&);
+  void PassMozMapOfObject(JSContext*, const MozMap<JSObject*>&);
+  void ReceiveObject(JSContext*, JS::MutableHandle<JSObject*>);
+  void ReceiveNullableObject(JSContext*, JS::MutableHandle<JSObject*>);
+
+  // Union types
+  void PassUnion(JSContext*, const ObjectOrLong& arg);
+  void PassUnionWithNullable(JSContext* cx, const ObjectOrNullOrLong& arg)
+  {
+    OwningObjectOrLong returnValue;
+    if (arg.IsNull()) {
+    } else if (arg.IsObject()) {
+      JS::Rooted<JSObject*> obj(cx, arg.GetAsObject());
+      JS_GetClass(obj);
+      returnValue.SetAsObject() = obj;
+    } else {
+      int32_t i = arg.GetAsLong();
+      i += 1;
+      returnValue.SetAsLong() = i;
+    }
+  }
+#ifdef DEBUG
+  void PassUnion2(const LongOrBoolean& arg);
+  void PassUnion3(JSContext*, const ObjectOrLongOrBoolean& arg);
+  void PassUnion4(const NodeOrLongOrBoolean& arg);
+  void PassUnion5(JSContext*, const ObjectOrBoolean& arg);
+  void PassUnion6(JSContext*, const ObjectOrString& arg);
+  void PassUnion7(JSContext*, const ObjectOrStringOrLong& arg);
+  void PassUnion8(JSContext*, const ObjectOrStringOrBoolean& arg);
+  void PassUnion9(JSContext*, const ObjectOrStringOrLongOrBoolean& arg);
+  void PassUnion10(const EventInitOrLong& arg);
+  void PassUnion11(JSContext*, const CustomEventInitOrLong& arg);
+  void PassUnion12(const EventInitOrLong& arg);
+  void PassUnion13(JSContext*, const ObjectOrLongOrNull& arg);
+  void PassUnion14(JSContext*, const ObjectOrLongOrNull& arg);
+  void PassUnion15(const LongSequenceOrLong&);
+  void PassUnion16(const Optional<LongSequenceOrLong>&);
+  void PassUnion17(const LongSequenceOrNullOrLong&);
+  void PassUnion18(JSContext*, const ObjectSequenceOrLong&);
+  void PassUnion19(JSContext*, const Optional<ObjectSequenceOrLong>&);
+  void PassUnion20(JSContext*, const ObjectSequenceOrLong&);
+  void PassUnion21(const LongMozMapOrLong&);
+  void PassUnion22(JSContext*, const ObjectMozMapOrLong&);
+  void PassUnion23(const ImageDataSequenceOrLong&);
+  void PassUnion24(const ImageDataOrNullSequenceOrLong&);
+  void PassUnion25(const ImageDataSequenceSequenceOrLong&);
+  void PassUnion26(const ImageDataOrNullSequenceSequenceOrLong&);
+  void PassUnion27(const StringSequenceOrEventInit&);
+  void PassUnion28(const EventInitOrStringSequence&);
+  void PassUnionWithCallback(const EventHandlerNonNullOrNullOrLong& arg);
+  void PassUnionWithByteString(const ByteStringOrLong&);
+  void PassUnionWithMozMap(const StringMozMapOrString&);
+  void PassUnionWithMozMapAndSequence(const StringMozMapOrStringSequence&);
+  void PassUnionWithSequenceAndMozMap(const StringSequenceOrStringMozMap&);
+  void PassUnionWithUSVS(const USVStringOrLong&);
+#endif
+  void PassNullableUnion(JSContext*, const Nullable<ObjectOrLong>&);
+  void PassOptionalUnion(JSContext*, const Optional<ObjectOrLong>&);
+  void PassOptionalNullableUnion(JSContext*, const Optional<Nullable<ObjectOrLong> >&);
+  void PassOptionalNullableUnionWithDefaultValue(JSContext*, const Nullable<ObjectOrLong>&);
+  //void PassUnionWithInterfaces(const TestInterfaceOrTestExternalInterface& arg);
+  //void PassUnionWithInterfacesAndNullable(const TestInterfaceOrNullOrTestExternalInterface& arg);
+  void PassUnionWithArrayBuffer(const ArrayBufferOrLong&);
+  void PassUnionWithString(JSContext*, const StringOrObject&);
+  void PassUnionWithEnum(JSContext*, const SupportedTypeOrObject&);
+  //void PassUnionWithCallback(JSContext*, const TestCallbackOrLong&);
+  void PassUnionWithObject(JSContext*, const ObjectOrLong&);
+
+  void PassUnionWithDefaultValue1(const DoubleOrString& arg);
+  void PassUnionWithDefaultValue2(const DoubleOrString& arg);
+  void PassUnionWithDefaultValue3(const DoubleOrString& arg);
+  void PassUnionWithDefaultValue4(const FloatOrString& arg);
+  void PassUnionWithDefaultValue5(const FloatOrString& arg);
+  void PassUnionWithDefaultValue6(const FloatOrString& arg);
+  void PassUnionWithDefaultValue7(const UnrestrictedDoubleOrString& arg);
+  void PassUnionWithDefaultValue8(const UnrestrictedDoubleOrString& arg);
+  void PassUnionWithDefaultValue9(const UnrestrictedDoubleOrString& arg);
+  void PassUnionWithDefaultValue10(const UnrestrictedDoubleOrString& arg);
+  void PassUnionWithDefaultValue11(const UnrestrictedFloatOrString& arg);
+  void PassUnionWithDefaultValue12(const UnrestrictedFloatOrString& arg);
+  void PassUnionWithDefaultValue13(const UnrestrictedFloatOrString& arg);
+  void PassUnionWithDefaultValue14(const DoubleOrByteString& arg);
+  void PassUnionWithDefaultValue15(const DoubleOrByteString& arg);
+  void PassUnionWithDefaultValue16(const DoubleOrByteString& arg);
+  void PassUnionWithDefaultValue17(const DoubleOrSupportedType& arg);
+  void PassUnionWithDefaultValue18(const DoubleOrSupportedType& arg);
+  void PassUnionWithDefaultValue19(const DoubleOrSupportedType& arg);
+
+  void PassNullableUnionWithDefaultValue1(const Nullable<DoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue2(const Nullable<DoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue3(const Nullable<DoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue4(const Nullable<FloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue5(const Nullable<FloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue6(const Nullable<FloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue7(const Nullable<UnrestrictedDoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue8(const Nullable<UnrestrictedDoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue9(const Nullable<UnrestrictedDoubleOrString>& arg);
+  void PassNullableUnionWithDefaultValue10(const Nullable<UnrestrictedFloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue11(const Nullable<UnrestrictedFloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue12(const Nullable<UnrestrictedFloatOrString>& arg);
+  void PassNullableUnionWithDefaultValue13(const Nullable<DoubleOrByteString>& arg);
+  void PassNullableUnionWithDefaultValue14(const Nullable<DoubleOrByteString>& arg);
+  void PassNullableUnionWithDefaultValue15(const Nullable<DoubleOrByteString>& arg);
+  void PassNullableUnionWithDefaultValue16(const Nullable<DoubleOrByteString>& arg);
+  void PassNullableUnionWithDefaultValue17(const Nullable<DoubleOrSupportedType>& arg);
+  void PassNullableUnionWithDefaultValue18(const Nullable<DoubleOrSupportedType>& arg);
+  void PassNullableUnionWithDefaultValue19(const Nullable<DoubleOrSupportedType>& arg);
+  void PassNullableUnionWithDefaultValue20(const Nullable<DoubleOrSupportedType>& arg);
+
+  void PassSequenceOfUnions(const Sequence<OwningCanvasPatternOrCanvasGradient>&);
+  void PassSequenceOfUnions2(JSContext*, const Sequence<OwningObjectOrLong>&);
+  void PassVariadicUnion(const Sequence<OwningCanvasPatternOrCanvasGradient>&);
+
+  void PassSequenceOfNullableUnions(const Sequence<Nullable<OwningCanvasPatternOrCanvasGradient>>&);
+  void PassVariadicNullableUnion(const Sequence<Nullable<OwningCanvasPatternOrCanvasGradient>>&);
+  void PassMozMapOfUnions(const MozMap<OwningCanvasPatternOrCanvasGradient>&);
+  void PassMozMapOfUnions2(JSContext*, const MozMap<OwningObjectOrLong>&);
+
+  void ReceiveUnion(OwningCanvasPatternOrCanvasGradient&);
+  void ReceiveUnion2(JSContext*, OwningObjectOrLong&);
+  void ReceiveUnionContainingNull(OwningCanvasPatternOrNullOrCanvasGradient&);
+  void ReceiveNullableUnion(Nullable<OwningCanvasPatternOrCanvasGradient>&);
+  void ReceiveNullableUnion2(JSContext*, Nullable<OwningObjectOrLong>&);
+  void GetWritableUnion(OwningCanvasPatternOrCanvasGradient&);
+  void SetWritableUnion(const CanvasPatternOrCanvasGradient&);
+  void GetWritableUnionContainingNull(OwningCanvasPatternOrNullOrCanvasGradient&);
+  void SetWritableUnionContainingNull(const CanvasPatternOrNullOrCanvasGradient&);
+  void GetWritableNullableUnion(Nullable<OwningCanvasPatternOrCanvasGradient>&);
+  void SetWritableNullableUnion(const Nullable<CanvasPatternOrCanvasGradient>&);
+
+  // Date types
+  void PassDate(Date);
+  void PassNullableDate(const Nullable<Date>&);
+  void PassOptionalDate(const Optional<Date>&);
+  void PassOptionalNullableDate(const Optional<Nullable<Date> >&);
+  void PassOptionalNullableDateWithDefaultValue(const Nullable<Date>&);
+  void PassDateSequence(const Sequence<Date>&);
+  void PassDateMozMap(const MozMap<Date>&);
+  void PassNullableDateSequence(const Sequence<Nullable<Date> >&);
+  Date ReceiveDate();
+  Nullable<Date> ReceiveNullableDate();
+
+  // Promise types
+  void PassPromise(Promise&);
+  void PassNullablePromise(Promise*);
+  void PassOptionalPromise(const Optional<OwningNonNull<Promise>>&);
+  void PassOptionalNullablePromise(const Optional<RefPtr<Promise>>&);
+  void PassOptionalNullablePromiseWithDefaultValue(Promise*);
+  void PassPromiseSequence(const Sequence<OwningNonNull<Promise>>&);
+  void PassPromiseMozMap(const MozMap<RefPtr<Promise>>&);
+  void PassNullablePromiseSequence(const Sequence<RefPtr<Promise>> &);
+  Promise* ReceivePromise();
+  already_AddRefed<Promise> ReceiveAddrefedPromise();
+
+  // binaryNames tests
+  void MethodRenamedTo();
+  void OtherMethodRenamedTo();
+  void MethodRenamedTo(int8_t);
+  int8_t AttributeGetterRenamedTo();
+  int8_t AttributeRenamedTo();
+  void SetAttributeRenamedTo(int8_t);
+  int8_t OtherAttributeRenamedTo();
+  void SetOtherAttributeRenamedTo(int8_t);
+
+  // Dictionary tests
+  void PassDictionary(JSContext*, const Dict&);
+  void PassDictionary2(JSContext*, const Dict&);
+  void GetReadonlyDictionary(JSContext*, Dict&);
+  void GetReadonlyNullableDictionary(JSContext*, Nullable<Dict>&);
+  void GetWritableDictionary(JSContext*, Dict&);
+  void SetWritableDictionary(JSContext*, const Dict&);
+  void GetReadonlyFrozenDictionary(JSContext*, Dict&);
+  void GetReadonlyFrozenNullableDictionary(JSContext*, Nullable<Dict>&);
+  void GetWritableFrozenDictionary(JSContext*, Dict&);
+  void SetWritableFrozenDictionary(JSContext*, const Dict&);
+  void ReceiveDictionary(JSContext*, Dict&);
+  void ReceiveNullableDictionary(JSContext*, Nullable<Dict>&);
+  void PassOtherDictionary(const GrandparentDict&);
+  void PassSequenceOfDictionaries(JSContext*, const Sequence<Dict>&);
+  void PassMozMapOfDictionaries(const MozMap<GrandparentDict>&);
+  void PassDictionaryOrLong(JSContext*, const Dict&);
+  void PassDictionaryOrLong(int32_t);
+  void PassDictContainingDict(JSContext*, const DictContainingDict&);
+  void PassDictContainingSequence(JSContext*, const DictContainingSequence&);
+  void ReceiveDictContainingSequence(JSContext*, DictContainingSequence&);
+  void PassVariadicDictionary(JSContext*, const Sequence<Dict>&);
+
+  // Typedefs
+  void ExerciseTypedefInterfaces1(TestInterface&);
+  already_AddRefed<TestInterface> ExerciseTypedefInterfaces2(TestInterface*);
+  void ExerciseTypedefInterfaces3(TestInterface&);
+
+  // Deprecated methods and attributes
+  int8_t DeprecatedAttribute();
+  int8_t SetDeprecatedAttribute(int8_t);
+  int8_t DeprecatedMethod();
+  int8_t DeprecatedMethodWithContext(JSContext*, const JS::Value&);
+
+  // Static methods and attributes
+  static void StaticMethod(const GlobalObject&, bool);
+  static void StaticMethodWithContext(const GlobalObject&, const JS::Value&);
+  static bool StaticAttribute(const GlobalObject&);
+  static void SetStaticAttribute(const GlobalObject&, bool);
+  static void Assert(const GlobalObject&, bool);
+
+  // Deprecated static methods and attributes
+  static int8_t StaticDeprecatedAttribute(const GlobalObject&);
+  static int8_t SetStaticDeprecatedAttribute(const GlobalObject&, int8_t);
+  static int8_t StaticDeprecatedMethod(const GlobalObject&);
+  static int8_t StaticDeprecatedMethodWithContext(const GlobalObject&, const JS::Value&);
+
+  // Overload resolution tests
+  bool Overload1(TestInterface&);
+  TestInterface* Overload1(const nsAString&, TestInterface&);
+  void Overload2(TestInterface&);
+  void Overload2(JSContext*, const Dict&);
+  void Overload2(bool);
+  void Overload2(const nsAString&);
+  void Overload2(Date);
+  void Overload3(TestInterface&);
+  void Overload3(const TestCallback&);
+  void Overload3(bool);
+  void Overload4(TestInterface&);
+  void Overload4(TestCallbackInterface&);
+  void Overload4(const nsAString&);
+  void Overload5(int32_t);
+  void Overload5(TestEnum);
+  void Overload6(int32_t);
+  void Overload6(bool);
+  void Overload7(int32_t);
+  void Overload7(bool);
+  void Overload7(const nsCString&);
+  void Overload8(int32_t);
+  void Overload8(TestInterface&);
+  void Overload9(const Nullable<int32_t>&);
+  void Overload9(const nsAString&);
+  void Overload10(const Nullable<int32_t>&);
+  void Overload10(JSContext*, JS::Handle<JSObject*>);
+  void Overload11(int32_t);
+  void Overload11(const nsAString&);
+  void Overload12(int32_t);
+  void Overload12(const Nullable<bool>&);
+  void Overload13(const Nullable<int32_t>&);
+  void Overload13(bool);
+  void Overload14(const Optional<int32_t>&);
+  void Overload14(TestInterface&);
+  void Overload15(int32_t);
+  void Overload15(const Optional<NonNull<TestInterface> >&);
+  void Overload16(int32_t);
+  void Overload16(const Optional<TestInterface*>&);
+  void Overload17(const Sequence<int32_t>&);
+  void Overload17(const MozMap<int32_t>&);
+  void Overload18(const MozMap<nsString>&);
+  void Overload18(const Sequence<nsString>&);
+  void Overload19(const Sequence<int32_t>&);
+  void Overload19(JSContext*, const Dict&);
+  void Overload20(JSContext*, const Dict&);
+  void Overload20(const Sequence<int32_t>&);
+  
+  // Variadic handling
+  void PassVariadicThirdArg(const nsAString&, int32_t,
+                            const Sequence<OwningNonNull<TestInterface> >&);
+
+  // Conditionally exposed methods/attributes
+  bool Prefable1();
+  bool Prefable2();
+  bool Prefable3();
+  bool Prefable4();
+  bool Prefable5();
+  bool Prefable6();
+  bool Prefable7();
+  bool Prefable8();
+  bool Prefable9();
+  void Prefable10();
+  void Prefable11();
+  bool Prefable12();
+  void Prefable13();
+  bool Prefable14();
+  bool Prefable15();
+  bool Prefable16();
+  void Prefable17();
+  void Prefable18();
+  void Prefable19();
+  void Prefable20();
+  void Prefable21();
+  void Prefable22();
+  void Prefable23();
+  void Prefable24();
+
+  // Conditionally exposed methods/attributes involving [SecureContext]
+  bool ConditionalOnSecureContext1();
+  bool ConditionalOnSecureContext2();
+  bool ConditionalOnSecureContext3();
+  bool ConditionalOnSecureContext4();
+  void ConditionalOnSecureContext5();
+  void ConditionalOnSecureContext6();
+  void ConditionalOnSecureContext7();
+  void ConditionalOnSecureContext8();
+
+  // Miscellania
+  int32_t AttrWithLenientThis();
+  void SetAttrWithLenientThis(int32_t);
+  uint32_t UnforgeableAttr();
+  uint32_t UnforgeableAttr2();
+  uint32_t UnforgeableMethod();
+  uint32_t UnforgeableMethod2();
+  void Stringify(nsString&);
+  void PassRenamedInterface(nsRenamedInterface&);
+  TestInterface* PutForwardsAttr();
+  TestInterface* PutForwardsAttr2();
+  TestInterface* PutForwardsAttr3();
+  void GetJsonifierShouldSkipThis(JSContext*, JS::MutableHandle<JS::Value>);
+  void SetJsonifierShouldSkipThis(JSContext*, JS::Rooted<JS::Value>&);
+  TestParentInterface* JsonifierShouldSkipThis2();
+  void SetJsonifierShouldSkipThis2(TestParentInterface&);
+  TestCallbackInterface* JsonifierShouldSkipThis3();
+  void SetJsonifierShouldSkipThis3(TestCallbackInterface&);
+  void ThrowingMethod(ErrorResult& aRv);
+  bool GetThrowingAttr(ErrorResult& aRv) const;
+  void SetThrowingAttr(bool arg, ErrorResult& aRv);
+  bool GetThrowingGetterAttr(ErrorResult& aRv) const;
+  void SetThrowingGetterAttr(bool arg);
+  bool ThrowingSetterAttr() const;
+  void SetThrowingSetterAttr(bool arg, ErrorResult& aRv);
+  void NeedsSubjectPrincipalMethod(nsIPrincipal&);
+  bool NeedsSubjectPrincipalAttr(nsIPrincipal&);
+  void SetNeedsSubjectPrincipalAttr(bool, nsIPrincipal&);
+  void NeedsCallerTypeMethod(CallerType);
+  bool NeedsCallerTypeAttr(CallerType);
+  void SetNeedsCallerTypeAttr(bool, CallerType);
+  int16_t LegacyCall(const JS::Value&, uint32_t, TestInterface&);
+  void PassArgsWithDefaults(JSContext*, const Optional<int32_t>&,
+                            TestInterface*, const Dict&, double,
+                            const Optional<float>&);
+
+  void SetDashed_attribute(int8_t);
+  int8_t Dashed_attribute();
+  void Dashed_method();
+
+  // Methods and properties imported via "implements"
+  bool ImplementedProperty();
+  void SetImplementedProperty(bool);
+  void ImplementedMethod();
+  bool ImplementedParentProperty();
+  void SetImplementedParentProperty(bool);
+  void ImplementedParentMethod();
+  bool IndirectlyImplementedProperty();
+  void SetIndirectlyImplementedProperty(bool);
+  void IndirectlyImplementedMethod();
+  uint32_t DiamondImplementedProperty();
+
+  // Test EnforceRange/Clamp
+  void DontEnforceRangeOrClamp(int8_t);
+  void DoEnforceRange(int8_t);
+  void DoClamp(int8_t);
+  void SetEnforcedByte(int8_t);
+  int8_t EnforcedByte();
+  void SetClampedByte(int8_t);
+  int8_t ClampedByte();
+
+private:
+  // We add signatures here that _could_ start matching if the codegen
+  // got data types wrong.  That way if it ever does we'll have a call
+  // to these private deleted methods and compilation will fail.
+  void SetReadonlyByte(int8_t) = delete;
+  template<typename T>
+  void SetWritableByte(T) = delete;
+  template<typename T>
+  void PassByte(T) = delete;
+  void PassNullableByte(Nullable<int8_t>&) = delete;
+  template<typename T>
+  void PassOptionalByte(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalByteWithDefault(T) = delete;
+  void PassVariadicByte(Sequence<int8_t>&) = delete;
+
+  void SetReadonlyShort(int16_t) = delete;
+  template<typename T>
+  void SetWritableShort(T) = delete;
+  template<typename T>
+  void PassShort(T) = delete;
+  template<typename T>
+  void PassOptionalShort(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalShortWithDefault(T) = delete;
+
+  void SetReadonlyLong(int32_t) = delete;
+  template<typename T>
+  void SetWritableLong(T) = delete;
+  template<typename T>
+  void PassLong(T) = delete;
+  template<typename T>
+  void PassOptionalLong(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalLongWithDefault(T) = delete;
+
+  void SetReadonlyLongLong(int64_t) = delete;
+  template<typename T>
+  void SetWritableLongLong(T) = delete;
+  template<typename T>
+  void PassLongLong(T) = delete;
+  template<typename T>
+  void PassOptionalLongLong(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalLongLongWithDefault(T) = delete;
+
+  void SetReadonlyOctet(uint8_t) = delete;
+  template<typename T>
+  void SetWritableOctet(T) = delete;
+  template<typename T>
+  void PassOctet(T) = delete;
+  template<typename T>
+  void PassOptionalOctet(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalOctetWithDefault(T) = delete;
+
+  void SetReadonlyUnsignedShort(uint16_t) = delete;
+  template<typename T>
+  void SetWritableUnsignedShort(T) = delete;
+  template<typename T>
+  void PassUnsignedShort(T) = delete;
+  template<typename T>
+  void PassOptionalUnsignedShort(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalUnsignedShortWithDefault(T) = delete;
+
+  void SetReadonlyUnsignedLong(uint32_t) = delete;
+  template<typename T>
+  void SetWritableUnsignedLong(T) = delete;
+  template<typename T>
+  void PassUnsignedLong(T) = delete;
+  template<typename T>
+  void PassOptionalUnsignedLong(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalUnsignedLongWithDefault(T) = delete;
+
+  void SetReadonlyUnsignedLongLong(uint64_t) = delete;
+  template<typename T>
+  void SetWritableUnsignedLongLong(T) = delete;
+  template<typename T>
+  void PassUnsignedLongLong(T) = delete;
+  template<typename T>
+  void PassOptionalUnsignedLongLong(const Optional<T>&) = delete;
+  template<typename T>
+  void PassOptionalUnsignedLongLongWithDefault(T) = delete;
+
+  // Enforce that only const things are passed for sequences
+  void PassSequence(Sequence<int32_t> &) = delete;
+  void PassNullableSequence(Nullable< Sequence<int32_t> >&) = delete;
+  void PassOptionalNullableSequenceWithDefaultValue(Nullable< Sequence<int32_t> >&) = delete;
+  void PassSequenceOfAny(JSContext*, Sequence<JS::Value>&) = delete;
+  void PassNullableSequenceOfAny(JSContext*, Nullable<Sequence<JS::Value> >&) = delete;
+  void PassOptionalSequenceOfAny(JSContext*, Optional<Sequence<JS::Value> >&) = delete;
+  void PassOptionalNullableSequenceOfAny(JSContext*, Optional<Nullable<Sequence<JS::Value> > >&) = delete;
+  void PassOptionalSequenceOfAnyWithDefaultValue(JSContext*, Nullable<Sequence<JS::Value> >&) = delete;
+  void PassSequenceOfSequenceOfAny(JSContext*, Sequence<Sequence<JS::Value> >&) = delete;
+  void PassSequenceOfNullableSequenceOfAny(JSContext*, Sequence<Nullable<Sequence<JS::Value> > >&) = delete;
+  void PassNullableSequenceOfNullableSequenceOfAny(JSContext*, Nullable<Sequence<Nullable<Sequence<JS::Value> > > >&) = delete;
+  void PassOptionalNullableSequenceOfNullableSequenceOfAny(JSContext*, Optional<Nullable<Sequence<Nullable<Sequence<JS::Value> > > > >&) = delete;
+  void PassSequenceOfObject(JSContext*, Sequence<JSObject*>&) = delete;
+  void PassSequenceOfNullableObject(JSContext*, Sequence<JSObject*>&) = delete;
+  void PassOptionalNullableSequenceOfNullableSequenceOfObject(JSContext*, Optional<Nullable<Sequence<Nullable<Sequence<JSObject*> > > > >&) = delete;
+  void PassOptionalNullableSequenceOfNullableSequenceOfNullableObject(JSContext*, Optional<Nullable<Sequence<Nullable<Sequence<JSObject*> > > > >&) = delete;
+
+  // Enforce that only const things are passed for optional
+  void PassOptionalByte(Optional<int8_t>&) = delete;
+  void PassOptionalNullableByte(Optional<Nullable<int8_t> >&) = delete;
+  void PassOptionalShort(Optional<int16_t>&) = delete;
+  void PassOptionalLong(Optional<int32_t>&) = delete;
+  void PassOptionalLongLong(Optional<int64_t>&) = delete;
+  void PassOptionalOctet(Optional<uint8_t>&) = delete;
+  void PassOptionalUnsignedShort(Optional<uint16_t>&) = delete;
+  void PassOptionalUnsignedLong(Optional<uint32_t>&) = delete;
+  void PassOptionalUnsignedLongLong(Optional<uint64_t>&) = delete;
+  void PassOptionalSelf(Optional<TestInterface*> &) = delete;
+  void PassOptionalNonNullSelf(Optional<NonNull<TestInterface> >&) = delete;
+  void PassOptionalOther(Optional<IndirectlyImplementedInterface*>&);
+  void PassOptionalNonNullOther(Optional<NonNull<IndirectlyImplementedInterface> >&);
+  void PassOptionalExternal(Optional<TestExternalInterface*>&) = delete;
+  void PassOptionalNonNullExternal(Optional<TestExternalInterface*>&) = delete;
+  void PassOptionalSequence(Optional<Sequence<int32_t> >&) = delete;
+  void PassOptionalNullableSequence(Optional<Nullable<Sequence<int32_t> > >&) = delete;
+  void PassOptionalObjectSequence(Optional<Sequence<OwningNonNull<TestInterface> > >&) = delete;
+  void PassOptionalArrayBuffer(Optional<ArrayBuffer>&) = delete;
+  void PassOptionalNullableArrayBuffer(Optional<ArrayBuffer*>&) = delete;
+  void PassOptionalEnum(Optional<TestEnum>&) = delete;
+  void PassOptionalCallback(JSContext*, Optional<OwningNonNull<TestCallback> >&) = delete;
+  void PassOptionalNullableCallback(JSContext*, Optional<RefPtr<TestCallback> >&) = delete;
+  void PassOptionalAny(Optional<JS::Handle<JS::Value> >&) = delete;
+
+  // And test that string stuff is always const
+  void PassString(nsAString&) = delete;
+  void PassNullableString(nsAString&) = delete;
+  void PassOptionalString(Optional<nsAString>&) = delete;
+  void PassOptionalStringWithDefaultValue(nsAString&) = delete;
+  void PassOptionalNullableString(Optional<nsAString>&) = delete;
+  void PassOptionalNullableStringWithDefaultValue(nsAString&) = delete;
+  void PassVariadicString(Sequence<nsString>&) = delete;
+
+  // cstrings should be const as well
+  void PassByteString(nsCString&) = delete;
+  void PassNullableByteString(nsCString&) = delete;
+  void PassOptionalByteString(Optional<nsCString>&) = delete;
+  void PassOptionalByteStringWithDefaultValue(nsCString&) = delete;
+  void PassOptionalNullableByteString(Optional<nsCString>&) = delete;
+  void PassOptionalNullableByteStringWithDefaultValue(nsCString&) = delete;
+  void PassVariadicByteString(Sequence<nsCString>&) = delete;
+
+  // Make sure dictionary arguments are always const
+  void PassDictionary(JSContext*, Dict&) = delete;
+  void PassOtherDictionary(GrandparentDict&) = delete;
+  void PassSequenceOfDictionaries(JSContext*, Sequence<Dict>&) = delete;
+  void PassDictionaryOrLong(JSContext*, Dict&) = delete;
+  void PassDictContainingDict(JSContext*, DictContainingDict&) = delete;
+  void PassDictContainingSequence(DictContainingSequence&) = delete;
+
+  // Make sure various nullable things are always const
+  void PassNullableEnum(Nullable<TestEnum>&) = delete;
+
+  // Make sure unions are always const
+  void PassUnion(JSContext*, ObjectOrLong& arg) = delete;
+  void PassUnionWithNullable(JSContext*, ObjectOrNullOrLong& arg) = delete;
+  void PassNullableUnion(JSContext*, Nullable<ObjectOrLong>&) = delete;
+  void PassOptionalUnion(JSContext*, Optional<ObjectOrLong>&) = delete;
+  void PassOptionalNullableUnion(JSContext*, Optional<Nullable<ObjectOrLong> >&) = delete;
+  void PassOptionalNullableUnionWithDefaultValue(JSContext*, Nullable<ObjectOrLong>&) = delete;
+
+  // Make sure various date stuff is const as needed
+  void PassNullableDate(Nullable<Date>&) = delete;
+  void PassOptionalDate(Optional<Date>&) = delete;
+  void PassOptionalNullableDate(Optional<Nullable<Date> >&) = delete;
+  void PassOptionalNullableDateWithDefaultValue(Nullable<Date>&) = delete;
+  void PassDateSequence(Sequence<Date>&) = delete;
+  void PassNullableDateSequence(Sequence<Nullable<Date> >&) = delete;
+
+  // Make sure variadics are const as needed
+  void PassVariadicAny(JSContext*, Sequence<JS::Value>&) = delete;
+  void PassVariadicObject(JSContext*, Sequence<JSObject*>&) = delete;
+  void PassVariadicNullableObject(JSContext*, Sequence<JSObject*>&) = delete;
+
+  // Ensure NonNull does not leak in
+  void PassSelf(NonNull<TestInterface>&) = delete;
+  void PassSelf(OwningNonNull<TestInterface>&) = delete;
+  void PassSelf(const NonNull<TestInterface>&) = delete;
+  void PassSelf(const OwningNonNull<TestInterface>&) = delete;
+  void PassOther(NonNull<IndirectlyImplementedInterface>&) = delete;
+  void PassOther(const NonNull<IndirectlyImplementedInterface>&) = delete;
+  void PassOther(OwningNonNull<IndirectlyImplementedInterface>&) = delete;
+  void PassOther(const OwningNonNull<IndirectlyImplementedInterface>&) = delete;
+  void PassCallbackInterface(OwningNonNull<TestCallbackInterface>&) = delete;
+  void PassCallbackInterface(const OwningNonNull<TestCallbackInterface>&) = delete;
+  void PassCallbackInterface(NonNull<TestCallbackInterface>&) = delete;
+  void PassCallbackInterface(const NonNull<TestCallbackInterface>&) = delete;
+  void PassCallback(OwningNonNull<TestCallback>&) = delete;
+  void PassCallback(const OwningNonNull<TestCallback>&) = delete;
+  void PassCallback(NonNull<TestCallback>&) = delete;
+  void PassCallback(const NonNull<TestCallback>&) = delete;
+  void PassString(const NonNull<nsAString>&) = delete;
+  void PassString(NonNull<nsAString>&) = delete;
+  void PassString(const OwningNonNull<nsAString>&) = delete;
+  void PassString(OwningNonNull<nsAString>&) = delete;
+};
+
+class TestIndexedGetterInterface : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  uint32_t IndexedGetter(uint32_t, bool&);
+  uint32_t IndexedGetter(uint32_t&) = delete;
+  uint32_t Item(uint32_t&);
+  uint32_t Item(uint32_t, bool&) = delete;
+  uint32_t Length();
+  void LegacyCall(JS::Handle<JS::Value>);
+};
+
+class TestNamedGetterInterface : public nsISupports,
+                                 public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void NamedGetter(const nsAString&, bool&, nsAString&);
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestIndexedGetterAndSetterAndNamedGetterInterface : public nsISupports,
+                                                          public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void NamedGetter(const nsAString&, bool&, nsAString&);
+  void GetSupportedNames(nsTArray<nsString>&);
+  int32_t IndexedGetter(uint32_t, bool&);
+  void IndexedSetter(uint32_t, int32_t);
+  uint32_t Length();
+};
+
+class TestIndexedAndNamedGetterInterface : public nsISupports,
+                                           public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  uint32_t IndexedGetter(uint32_t, bool&);
+  void NamedGetter(const nsAString&, bool&, nsAString&);
+  void NamedItem(const nsAString&, nsAString&);
+  uint32_t Length();
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestIndexedSetterInterface : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void IndexedSetter(uint32_t, const nsAString&);
+  void IndexedGetter(uint32_t, bool&, nsString&);
+  uint32_t Length();
+  void SetItem(uint32_t, const nsAString&);
+};
+
+class TestNamedSetterInterface : public nsISupports,
+                                 public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void NamedSetter(const nsAString&, TestIndexedSetterInterface&);
+  TestIndexedSetterInterface* NamedGetter(const nsAString&, bool&);
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestIndexedAndNamedSetterInterface : public nsISupports,
+                                           public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void IndexedSetter(uint32_t, TestIndexedSetterInterface&);
+  TestIndexedSetterInterface* IndexedGetter(uint32_t, bool&);
+  uint32_t Length();
+  void NamedSetter(const nsAString&, TestIndexedSetterInterface&);
+  TestIndexedSetterInterface* NamedGetter(const nsAString&, bool&);
+  void SetNamedItem(const nsAString&, TestIndexedSetterInterface&);
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestIndexedAndNamedGetterAndSetterInterface : public TestIndexedSetterInterface
+{
+public:
+  uint32_t IndexedGetter(uint32_t, bool&);
+  uint32_t Item(uint32_t);
+  void NamedGetter(const nsAString&, bool&, nsAString&);
+  void NamedItem(const nsAString&, nsAString&);
+  void IndexedSetter(uint32_t, int32_t&);
+  void IndexedSetter(uint32_t, const nsAString&) = delete;
+  void NamedSetter(const nsAString&, const nsAString&);
+  void Stringify(nsAString&);
+  uint32_t Length();
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestCppKeywordNamedMethodsInterface : public nsISupports,
+                                            public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  bool Continue();
+  bool Delete();
+  int32_t Volatile();
+};
+
+class TestNamedDeleterInterface : public nsISupports,
+                                  public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  void NamedDeleter(const nsAString&, bool&);
+  long NamedGetter(const nsAString&, bool&);
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestNamedDeleterWithRetvalInterface : public nsISupports,
+                                            public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+
+  bool NamedDeleter(const nsAString&, bool&);
+  bool NamedDeleter(const nsAString&) = delete;
+  long NamedGetter(const nsAString&, bool&);
+  bool DelNamedItem(const nsAString&);
+  bool DelNamedItem(const nsAString&, bool&) = delete;
+  void GetSupportedNames(nsTArray<nsString>&);
+};
+
+class TestParentInterface : public nsISupports,
+                            public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  virtual nsISupports* GetParentObject();
+};
+
+class TestChildInterface : public TestParentInterface
+{
+};
+
+class TestDeprecatedInterface : public nsISupports, public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  static
+  already_AddRefed<TestDeprecatedInterface>
+    Constructor(const GlobalObject&, ErrorResult&);
+
+  static void AlsoDeprecated(const GlobalObject&);
+
+  virtual nsISupports* GetParentObject();
+};
+
+class TestInterfaceWithPromiseConstructorArg : public nsISupports, public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  static
+  already_AddRefed<TestInterfaceWithPromiseConstructorArg>
+    Constructor(const GlobalObject&, Promise&, ErrorResult&);
+
+  virtual nsISupports* GetParentObject();
+};
+
+class TestSecureContextInterface : public nsISupports, public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  static
+  already_AddRefed<TestSecureContextInterface>
+    Constructor(const GlobalObject&, ErrorResult&);
+
+  static void AlsoSecureContext(const GlobalObject&);
+
+  virtual nsISupports* GetParentObject();
+};
+
+class TestNamespace {
+public:
+  static bool Foo(const GlobalObject&);
+  static int32_t Bar(const GlobalObject&);
+  static void Baz(const GlobalObject&);
+};
+
+class TestRenamedNamespace {
+};
+
+class TestProtoObjectHackedNamespace {
+};
+
+class TestWorkerExposedInterface : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  NS_DECL_ISUPPORTS
+
+  // We need a GetParentObject to make binding codegen happy
+  nsISupports* GetParentObject();
+
+  void NeedsSubjectPrincipalMethod(Maybe<nsIPrincipal*>);
+  bool NeedsSubjectPrincipalAttr(Maybe<nsIPrincipal*>);
+  void SetNeedsSubjectPrincipalAttr(bool, Maybe<nsIPrincipal*>);
+  void NeedsCallerTypeMethod(CallerType);
+  bool NeedsCallerTypeAttr(CallerType);
+  void SetNeedsCallerTypeAttr(bool, CallerType);
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif /* TestBindingHeader_h */
diff --git a/dom/bindings/test/TestCImplementedInterface.h b/dom/bindings/test/TestCImplementedInterface.h
new file mode 100644
index 000000000..64b5c9954
--- /dev/null
+++ b/dom/bindings/test/TestCImplementedInterface.h
@@ -0,0 +1,43 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#ifndef TestCImplementedInterface_h
+#define TestCImplementedInterface_h
+
+#include "../TestJSImplGenBinding.h"
+
+namespace mozilla {
+namespace dom {
+
+class TestCImplementedInterface : public TestJSImplInterface
+{
+public:
+  TestCImplementedInterface(JS::Handle<JSObject*> aJSImpl,
+                            nsIGlobalObject* aParent)
+    : TestJSImplInterface(aJSImpl, aParent)
+  {}
+};
+
+class TestCImplementedInterface2 : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  explicit TestCImplementedInterface2(nsIGlobalObject* aParent)
+  {}
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestCImplementedInterface2)
+
+  // We need a GetParentObject to make binding codegen happy
+  nsISupports* GetParentObject();
+};
+
+
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // TestCImplementedInterface_h
diff --git a/dom/bindings/test/TestCodeGen.webidl b/dom/bindings/test/TestCodeGen.webidl
new file mode 100644
index 000000000..4fb9be270
--- /dev/null
+++ b/dom/bindings/test/TestCodeGen.webidl
@@ -0,0 +1,1264 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+typedef long myLong;
+typedef TestInterface AnotherNameForTestInterface;
+typedef TestInterface? NullableTestInterface;
+typedef CustomEventInit TestDictionaryTypedef;
+
+interface TestExternalInterface;
+
+[Pref="xyz"]
+interface TestRenamedInterface {
+};
+
+callback interface TestCallbackInterface {
+  readonly attribute long foo;
+  attribute DOMString bar;
+  void doSomething();
+  long doSomethingElse(DOMString arg, TestInterface otherArg);
+  void doSequenceLongArg(sequence<long> arg);
+  void doSequenceStringArg(sequence<DOMString> arg);
+  void doMozMapLongArg(MozMap<long> arg);
+  sequence<long> getSequenceOfLong();
+  sequence<TestInterface> getSequenceOfInterfaces();
+  sequence<TestInterface>? getNullableSequenceOfInterfaces();
+  sequence<TestInterface?> getSequenceOfNullableInterfaces();
+  sequence<TestInterface?>? getNullableSequenceOfNullableInterfaces();
+  sequence<TestCallbackInterface> getSequenceOfCallbackInterfaces();
+  sequence<TestCallbackInterface>? getNullableSequenceOfCallbackInterfaces();
+  sequence<TestCallbackInterface?> getSequenceOfNullableCallbackInterfaces();
+  sequence<TestCallbackInterface?>? getNullableSequenceOfNullableCallbackInterfaces();
+  MozMap<long> getMozMapOfLong();
+  Dict? getDictionary();
+  void passArrayBuffer(ArrayBuffer arg);
+  void passNullableArrayBuffer(ArrayBuffer? arg);
+  void passOptionalArrayBuffer(optional ArrayBuffer arg);
+  void passOptionalNullableArrayBuffer(optional ArrayBuffer? arg);
+  void passOptionalNullableArrayBufferWithDefaultValue(optional ArrayBuffer? arg= null);
+  void passArrayBufferView(ArrayBufferView arg);
+  void passInt8Array(Int8Array arg);
+  void passInt16Array(Int16Array arg);
+  void passInt32Array(Int32Array arg);
+  void passUint8Array(Uint8Array arg);
+  void passUint16Array(Uint16Array arg);
+  void passUint32Array(Uint32Array arg);
+  void passUint8ClampedArray(Uint8ClampedArray arg);
+  void passFloat32Array(Float32Array arg);
+  void passFloat64Array(Float64Array arg);
+  void passSequenceOfArrayBuffers(sequence<ArrayBuffer> arg);
+  void passSequenceOfNullableArrayBuffers(sequence<ArrayBuffer?> arg);
+  void passVariadicTypedArray(Float32Array... arg);
+  void passVariadicNullableTypedArray(Float32Array?... arg);
+  Uint8Array receiveUint8Array();
+  attribute Uint8Array uint8ArrayAttr;
+  Promise<void> receivePromise();
+};
+
+callback interface TestSingleOperationCallbackInterface {
+  TestInterface doSomething(short arg, sequence<double> anotherArg);
+};
+
+enum TestEnum {
+  "1",
+  "a",
+  "b"
+};
+
+callback TestCallback = void();
+[TreatNonCallableAsNull] callback TestTreatAsNullCallback = void();
+
+// Callback return value tests
+callback TestIntegerReturn = long();
+callback TestNullableIntegerReturn = long?();
+callback TestBooleanReturn = boolean();
+callback TestFloatReturn = float();
+callback TestStringReturn = DOMString(long arg);
+callback TestEnumReturn = TestEnum();
+callback TestInterfaceReturn = TestInterface();
+callback TestNullableInterfaceReturn = TestInterface?();
+callback TestExternalInterfaceReturn = TestExternalInterface();
+callback TestNullableExternalInterfaceReturn = TestExternalInterface?();
+callback TestCallbackInterfaceReturn = TestCallbackInterface();
+callback TestNullableCallbackInterfaceReturn = TestCallbackInterface?();
+callback TestCallbackReturn = TestCallback();
+callback TestNullableCallbackReturn = TestCallback?();
+callback TestObjectReturn = object();
+callback TestNullableObjectReturn = object?();
+callback TestTypedArrayReturn = ArrayBuffer();
+callback TestNullableTypedArrayReturn = ArrayBuffer?();
+callback TestSequenceReturn = sequence<boolean>();
+callback TestNullableSequenceReturn = sequence<boolean>?();
+// Callback argument tests
+callback TestIntegerArguments = sequence<long>(long arg1, long? arg2,
+                                               sequence<long> arg3,
+                                               sequence<long?>? arg4);
+callback TestInterfaceArguments = void(TestInterface arg1, TestInterface? arg2,
+                                       TestExternalInterface arg3,
+                                       TestExternalInterface? arg4,
+                                       TestCallbackInterface arg5,
+                                       TestCallbackInterface? arg6,
+                                       sequence<TestInterface> arg7,
+                                       sequence<TestInterface?>? arg8,
+                                       sequence<TestExternalInterface> arg9,
+                                       sequence<TestExternalInterface?>? arg10,
+                                       sequence<TestCallbackInterface> arg11,
+                                       sequence<TestCallbackInterface?>? arg12);
+callback TestStringEnumArguments = void(DOMString myString, DOMString? nullString,
+                                        TestEnum myEnum);
+callback TestObjectArguments = void(object anObj, object? anotherObj,
+                                    ArrayBuffer buf, ArrayBuffer? buf2);
+callback TestOptionalArguments = void(optional DOMString aString,
+                                      optional object something,
+                                      optional sequence<TestInterface> aSeq,
+                                      optional TestInterface? anInterface,
+                                      optional TestInterface anotherInterface,
+                                      optional long aLong);
+// If you add a new test callback, add it to the forceCallbackGeneration
+// method on TestInterface so it actually gets tested.
+
+TestInterface implements ImplementedInterface;
+
+// This interface is only for use in the constructor below
+interface OnlyForUseInConstructor {
+};
+
+[Constructor,
+ Constructor(DOMString str),
+ Constructor(unsigned long num, boolean? boolArg),
+ Constructor(TestInterface? iface),
+ Constructor(long arg1, IndirectlyImplementedInterface iface),
+ Constructor(Date arg1),
+ Constructor(ArrayBuffer arrayBuf),
+ Constructor(Uint8Array typedArr),
+ // Constructor(long arg1, long arg2, (TestInterface or OnlyForUseInConstructor) arg3),
+ NamedConstructor=Test,
+ NamedConstructor=Test(DOMString str),
+ NamedConstructor=Test2(DictForConstructor dict, any any1, object obj1,
+                        object? obj2, sequence<Dict> seq, optional any any2,
+                        optional object obj3, optional object? obj4),
+ NamedConstructor=Test3((long or MozMap<any>) arg1)
+ ]
+interface TestInterface {
+  // Integer types
+  // XXXbz add tests for throwing versions of all the integer stuff
+  readonly attribute byte readonlyByte;
+  attribute byte writableByte;
+  void passByte(byte arg);
+  byte receiveByte();
+  void passOptionalByte(optional byte arg);
+  void passOptionalByteBeforeRequired(optional byte arg1, byte arg2);
+  void passOptionalByteWithDefault(optional byte arg = 0);
+  void passOptionalByteWithDefaultBeforeRequired(optional byte arg1 = 0, byte arg2);
+  void passNullableByte(byte? arg);
+  void passOptionalNullableByte(optional byte? arg);
+  void passVariadicByte(byte... arg);
+  [StoreInSlot, Pure]
+  readonly attribute byte cachedByte;
+  [StoreInSlot, Constant]
+  readonly attribute byte cachedConstantByte;
+  [StoreInSlot, Pure]
+  attribute byte cachedWritableByte;
+  [Affects=Nothing]
+  attribute byte sideEffectFreeByte;
+  [Affects=Nothing, DependsOn=DOMState]
+  attribute byte domDependentByte;
+  [Affects=Nothing, DependsOn=Nothing]
+  readonly attribute byte constantByte;
+  [DependsOn=DeviceState, Affects=Nothing]
+  readonly attribute byte deviceStateDependentByte;
+  [Affects=Nothing]
+  byte returnByteSideEffectFree();
+  [Affects=Nothing, DependsOn=DOMState]
+  byte returnDOMDependentByte();
+  [Affects=Nothing, DependsOn=Nothing]
+  byte returnConstantByte();
+  [DependsOn=DeviceState, Affects=Nothing]
+  byte returnDeviceStateDependentByte();
+
+  [UnsafeInPrerendering]
+  void unsafePrerenderMethod();
+  [UnsafeInPrerendering]
+  attribute long unsafePrerenderWritable;
+  [UnsafeInPrerendering]
+  readonly attribute long unsafePrerenderReadonly;
+  readonly attribute short readonlyShort;
+  attribute short writableShort;
+  void passShort(short arg);
+  short receiveShort();
+  void passOptionalShort(optional short arg);
+  void passOptionalShortWithDefault(optional short arg = 5);
+
+  readonly attribute long readonlyLong;
+  attribute long writableLong;
+  void passLong(long arg);
+  long receiveLong();
+  void passOptionalLong(optional long arg);
+  void passOptionalLongWithDefault(optional long arg = 7);
+
+  readonly attribute long long readonlyLongLong;
+  attribute long long writableLongLong;
+  void passLongLong(long long arg);
+  long long receiveLongLong();
+  void passOptionalLongLong(optional long long arg);
+  void passOptionalLongLongWithDefault(optional long long arg = -12);
+
+  readonly attribute octet readonlyOctet;
+  attribute octet writableOctet;
+  void passOctet(octet arg);
+  octet receiveOctet();
+  void passOptionalOctet(optional octet arg);
+  void passOptionalOctetWithDefault(optional octet arg = 19);
+
+  readonly attribute unsigned short readonlyUnsignedShort;
+  attribute unsigned short writableUnsignedShort;
+  void passUnsignedShort(unsigned short arg);
+  unsigned short receiveUnsignedShort();
+  void passOptionalUnsignedShort(optional unsigned short arg);
+  void passOptionalUnsignedShortWithDefault(optional unsigned short arg = 2);
+
+  readonly attribute unsigned long readonlyUnsignedLong;
+  attribute unsigned long writableUnsignedLong;
+  void passUnsignedLong(unsigned long arg);
+  unsigned long receiveUnsignedLong();
+  void passOptionalUnsignedLong(optional unsigned long arg);
+  void passOptionalUnsignedLongWithDefault(optional unsigned long arg = 6);
+
+  readonly attribute unsigned long long readonlyUnsignedLongLong;
+  attribute unsigned long long  writableUnsignedLongLong;
+  void passUnsignedLongLong(unsigned long long arg);
+  unsigned long long receiveUnsignedLongLong();
+  void passOptionalUnsignedLongLong(optional unsigned long long arg);
+  void passOptionalUnsignedLongLongWithDefault(optional unsigned long long arg = 17);
+
+  attribute float writableFloat;
+  attribute unrestricted float writableUnrestrictedFloat;
+  attribute float? writableNullableFloat;
+  attribute unrestricted float? writableNullableUnrestrictedFloat;
+  attribute double writableDouble;
+  attribute unrestricted double writableUnrestrictedDouble;
+  attribute double? writableNullableDouble;
+  attribute unrestricted double? writableNullableUnrestrictedDouble;
+  void passFloat(float arg1, unrestricted float arg2,
+                 float? arg3, unrestricted float? arg4,
+                 double arg5, unrestricted double arg6,
+                 double? arg7, unrestricted double? arg8,
+                 sequence<float> arg9, sequence<unrestricted float> arg10,
+                 sequence<float?> arg11, sequence<unrestricted float?> arg12,
+                 sequence<double> arg13, sequence<unrestricted double> arg14,
+                 sequence<double?> arg15, sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  void passLenientFloat(float arg1, unrestricted float arg2,
+                        float? arg3, unrestricted float? arg4,
+                        double arg5, unrestricted double arg6,
+                        double? arg7, unrestricted double? arg8,
+                        sequence<float> arg9,
+                        sequence<unrestricted float> arg10,
+                        sequence<float?> arg11,
+                        sequence<unrestricted float?> arg12,
+                        sequence<double> arg13,
+                        sequence<unrestricted double> arg14,
+                        sequence<double?> arg15,
+                        sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  attribute float lenientFloatAttr;
+  [LenientFloat]
+  attribute double lenientDoubleAttr;
+
+  void passUnrestricted(optional unrestricted float arg1 = 0,
+                        optional unrestricted float arg2 = Infinity,
+                        optional unrestricted float arg3 = -Infinity,
+                        optional unrestricted float arg4 = NaN,
+                        optional unrestricted double arg5 = 0,
+                        optional unrestricted double arg6 = Infinity,
+                        optional unrestricted double arg7 = -Infinity,
+                        optional unrestricted double arg8 = NaN);
+
+  // Castable interface types
+  // XXXbz add tests for throwing versions of all the castable interface stuff
+  TestInterface receiveSelf();
+  TestInterface? receiveNullableSelf();
+  TestInterface receiveWeakSelf();
+  TestInterface? receiveWeakNullableSelf();
+  void passSelf(TestInterface arg);
+  void passNullableSelf(TestInterface? arg);
+  attribute TestInterface nonNullSelf;
+  attribute TestInterface? nullableSelf;
+  [Cached, Pure]
+  readonly attribute TestInterface cachedSelf;
+  // Optional arguments
+  void passOptionalSelf(optional TestInterface? arg);
+  void passOptionalNonNullSelf(optional TestInterface arg);
+  void passOptionalSelfWithDefault(optional TestInterface? arg = null);
+
+  // Non-wrapper-cache interface types
+  [NewObject]
+  TestNonWrapperCacheInterface receiveNonWrapperCacheInterface();
+  [NewObject]
+  TestNonWrapperCacheInterface? receiveNullableNonWrapperCacheInterface();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface> receiveNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?> receiveNullableNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface>? receiveNonWrapperCacheInterfaceNullableSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?>? receiveNullableNonWrapperCacheInterfaceNullableSequence();
+
+  // Non-castable interface types
+  IndirectlyImplementedInterface receiveOther();
+  IndirectlyImplementedInterface? receiveNullableOther();
+  IndirectlyImplementedInterface receiveWeakOther();
+  IndirectlyImplementedInterface? receiveWeakNullableOther();
+  void passOther(IndirectlyImplementedInterface arg);
+  void passNullableOther(IndirectlyImplementedInterface? arg);
+  attribute IndirectlyImplementedInterface nonNullOther;
+  attribute IndirectlyImplementedInterface? nullableOther;
+  // Optional arguments
+  void passOptionalOther(optional IndirectlyImplementedInterface? arg);
+  void passOptionalNonNullOther(optional IndirectlyImplementedInterface arg);
+  void passOptionalOtherWithDefault(optional IndirectlyImplementedInterface? arg = null);
+
+  // External interface types
+  TestExternalInterface receiveExternal();
+  TestExternalInterface? receiveNullableExternal();
+  TestExternalInterface receiveWeakExternal();
+  TestExternalInterface? receiveWeakNullableExternal();
+  void passExternal(TestExternalInterface arg);
+  void passNullableExternal(TestExternalInterface? arg);
+  attribute TestExternalInterface nonNullExternal;
+  attribute TestExternalInterface? nullableExternal;
+  // Optional arguments
+  void passOptionalExternal(optional TestExternalInterface? arg);
+  void passOptionalNonNullExternal(optional TestExternalInterface arg);
+  void passOptionalExternalWithDefault(optional TestExternalInterface? arg = null);
+
+  // Callback interface types
+  TestCallbackInterface receiveCallbackInterface();
+  TestCallbackInterface? receiveNullableCallbackInterface();
+  TestCallbackInterface receiveWeakCallbackInterface();
+  TestCallbackInterface? receiveWeakNullableCallbackInterface();
+  void passCallbackInterface(TestCallbackInterface arg);
+  void passNullableCallbackInterface(TestCallbackInterface? arg);
+  attribute TestCallbackInterface nonNullCallbackInterface;
+  attribute TestCallbackInterface? nullableCallbackInterface;
+  // Optional arguments
+  void passOptionalCallbackInterface(optional TestCallbackInterface? arg);
+  void passOptionalNonNullCallbackInterface(optional TestCallbackInterface arg);
+  void passOptionalCallbackInterfaceWithDefault(optional TestCallbackInterface? arg = null);
+
+  // Miscellaneous interface tests
+  IndirectlyImplementedInterface receiveConsequentialInterface();
+  void passConsequentialInterface(IndirectlyImplementedInterface arg);
+
+  // Sequence types
+  [Cached, Pure]
+  readonly attribute sequence<long> readonlySequence;
+  [Cached, Pure]
+  readonly attribute sequence<Dict> readonlySequenceOfDictionaries;
+  [Cached, Pure]
+  readonly attribute sequence<Dict>? readonlyNullableSequenceOfDictionaries;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<Dict> readonlyFrozenSequence;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<Dict>? readonlyFrozenNullableSequence;
+  sequence<long> receiveSequence();
+  sequence<long>? receiveNullableSequence();
+  sequence<long?> receiveSequenceOfNullableInts();
+  sequence<long?>? receiveNullableSequenceOfNullableInts();
+  void passSequence(sequence<long> arg);
+  void passNullableSequence(sequence<long>? arg);
+  void passSequenceOfNullableInts(sequence<long?> arg);
+  void passOptionalSequenceOfNullableInts(optional sequence<long?> arg);
+  void passOptionalNullableSequenceOfNullableInts(optional sequence<long?>? arg);
+  sequence<TestInterface> receiveCastableObjectSequence();
+  sequence<TestCallbackInterface> receiveCallbackObjectSequence();
+  sequence<TestInterface?> receiveNullableCastableObjectSequence();
+  sequence<TestCallbackInterface?> receiveNullableCallbackObjectSequence();
+  sequence<TestInterface>? receiveCastableObjectNullableSequence();
+  sequence<TestInterface?>? receiveNullableCastableObjectNullableSequence();
+  sequence<TestInterface> receiveWeakCastableObjectSequence();
+  sequence<TestInterface?> receiveWeakNullableCastableObjectSequence();
+  sequence<TestInterface>? receiveWeakCastableObjectNullableSequence();
+  sequence<TestInterface?>? receiveWeakNullableCastableObjectNullableSequence();
+  void passCastableObjectSequence(sequence<TestInterface> arg);
+  void passNullableCastableObjectSequence(sequence<TestInterface?> arg);
+  void passCastableObjectNullableSequence(sequence<TestInterface>? arg);
+  void passNullableCastableObjectNullableSequence(sequence<TestInterface?>? arg);
+  void passOptionalSequence(optional sequence<long> arg);
+  void passOptionalSequenceWithDefaultValue(optional sequence<long> arg = []);
+  void passOptionalNullableSequence(optional sequence<long>? arg);
+  void passOptionalNullableSequenceWithDefaultValue(optional sequence<long>? arg = null);
+  void passOptionalNullableSequenceWithDefaultValue2(optional sequence<long>? arg = []);
+  void passOptionalObjectSequence(optional sequence<TestInterface> arg);
+  void passExternalInterfaceSequence(sequence<TestExternalInterface> arg);
+  void passNullableExternalInterfaceSequence(sequence<TestExternalInterface?> arg);
+
+  sequence<DOMString> receiveStringSequence();
+  void passStringSequence(sequence<DOMString> arg);
+
+  sequence<ByteString> receiveByteStringSequence();
+  void passByteStringSequence(sequence<ByteString> arg);
+
+  sequence<any> receiveAnySequence();
+  sequence<any>? receiveNullableAnySequence();
+  sequence<sequence<any>> receiveAnySequenceSequence();
+
+  sequence<object> receiveObjectSequence();
+  sequence<object?> receiveNullableObjectSequence();
+
+  void passSequenceOfSequences(sequence<sequence<long>> arg);
+  void passSequenceOfSequencesOfSequences(sequence<sequence<sequence<long>>> arg);
+  sequence<sequence<long>> receiveSequenceOfSequences();
+  sequence<sequence<sequence<long>>> receiveSequenceOfSequencesOfSequences();
+
+  // MozMap types
+  void passMozMap(MozMap<long> arg);
+  void passNullableMozMap(MozMap<long>? arg);
+  void passMozMapOfNullableInts(MozMap<long?> arg);
+  void passOptionalMozMapOfNullableInts(optional MozMap<long?> arg);
+  void passOptionalNullableMozMapOfNullableInts(optional MozMap<long?>? arg);
+  void passCastableObjectMozMap(MozMap<TestInterface> arg);
+  void passNullableCastableObjectMozMap(MozMap<TestInterface?> arg);
+  void passCastableObjectNullableMozMap(MozMap<TestInterface>? arg);
+  void passNullableCastableObjectNullableMozMap(MozMap<TestInterface?>? arg);
+  void passOptionalMozMap(optional MozMap<long> arg);
+  void passOptionalNullableMozMap(optional MozMap<long>? arg);
+  void passOptionalNullableMozMapWithDefaultValue(optional MozMap<long>? arg = null);
+  void passOptionalObjectMozMap(optional MozMap<TestInterface> arg);
+  void passExternalInterfaceMozMap(MozMap<TestExternalInterface> arg);
+  void passNullableExternalInterfaceMozMap(MozMap<TestExternalInterface?> arg);
+  void passStringMozMap(MozMap<DOMString> arg);
+  void passByteStringMozMap(MozMap<ByteString> arg);
+  void passMozMapOfMozMaps(MozMap<MozMap<long>> arg);
+  MozMap<long> receiveMozMap();
+  MozMap<long>? receiveNullableMozMap();
+  MozMap<long?> receiveMozMapOfNullableInts();
+  MozMap<long?>? receiveNullableMozMapOfNullableInts();
+  MozMap<MozMap<long>> receiveMozMapOfMozMaps();
+  MozMap<any> receiveAnyMozMap();
+
+  // Typed array types
+  void passArrayBuffer(ArrayBuffer arg);
+  void passNullableArrayBuffer(ArrayBuffer? arg);
+  void passOptionalArrayBuffer(optional ArrayBuffer arg);
+  void passOptionalNullableArrayBuffer(optional ArrayBuffer? arg);
+  void passOptionalNullableArrayBufferWithDefaultValue(optional ArrayBuffer? arg= null);
+  void passArrayBufferView(ArrayBufferView arg);
+  void passInt8Array(Int8Array arg);
+  void passInt16Array(Int16Array arg);
+  void passInt32Array(Int32Array arg);
+  void passUint8Array(Uint8Array arg);
+  void passUint16Array(Uint16Array arg);
+  void passUint32Array(Uint32Array arg);
+  void passUint8ClampedArray(Uint8ClampedArray arg);
+  void passFloat32Array(Float32Array arg);
+  void passFloat64Array(Float64Array arg);
+  void passSequenceOfArrayBuffers(sequence<ArrayBuffer> arg);
+  void passSequenceOfNullableArrayBuffers(sequence<ArrayBuffer?> arg);
+  void passMozMapOfArrayBuffers(MozMap<ArrayBuffer> arg);
+  void passMozMapOfNullableArrayBuffers(MozMap<ArrayBuffer?> arg);
+  void passVariadicTypedArray(Float32Array... arg);
+  void passVariadicNullableTypedArray(Float32Array?... arg);
+  Uint8Array receiveUint8Array();
+  attribute Uint8Array uint8ArrayAttr;
+
+  // DOMString types
+  void passString(DOMString arg);
+  void passNullableString(DOMString? arg);
+  void passOptionalString(optional DOMString arg);
+  void passOptionalStringWithDefaultValue(optional DOMString arg = "abc");
+  void passOptionalNullableString(optional DOMString? arg);
+  void passOptionalNullableStringWithDefaultValue(optional DOMString? arg = null);
+  void passVariadicString(DOMString... arg);
+  DOMString receiveString();
+
+  // ByteString types
+  void passByteString(ByteString arg);
+  void passNullableByteString(ByteString? arg);
+  void passOptionalByteString(optional ByteString arg);
+  void passOptionalByteStringWithDefaultValue(optional ByteString arg = "abc");
+  void passOptionalNullableByteString(optional ByteString? arg);
+  void passOptionalNullableByteStringWithDefaultValue(optional ByteString? arg = null);
+  void passVariadicByteString(ByteString... arg);
+  void passOptionalUnionByteString(optional (ByteString or long) arg);
+  void passOptionalUnionByteStringWithDefaultValue(optional (ByteString or long) arg = "abc");
+
+  // USVString types
+  void passUSVS(USVString arg);
+  void passNullableUSVS(USVString? arg);
+  void passOptionalUSVS(optional USVString arg);
+  void passOptionalUSVSWithDefaultValue(optional USVString arg = "abc");
+  void passOptionalNullableUSVS(optional USVString? arg);
+  void passOptionalNullableUSVSWithDefaultValue(optional USVString? arg = null);
+  void passVariadicUSVS(USVString... arg);
+  USVString receiveUSVS();
+
+  // Enumerated types
+  void passEnum(TestEnum arg);
+  void passNullableEnum(TestEnum? arg);
+  void passOptionalEnum(optional TestEnum arg);
+  void passEnumWithDefault(optional TestEnum arg = "a");
+  void passOptionalNullableEnum(optional TestEnum? arg);
+  void passOptionalNullableEnumWithDefaultValue(optional TestEnum? arg = null);
+  void passOptionalNullableEnumWithDefaultValue2(optional TestEnum? arg = "a");
+  TestEnum receiveEnum();
+  TestEnum? receiveNullableEnum();
+  attribute TestEnum enumAttribute;
+  readonly attribute TestEnum readonlyEnumAttribute;
+
+  // Callback types
+  void passCallback(TestCallback arg);
+  void passNullableCallback(TestCallback? arg);
+  void passOptionalCallback(optional TestCallback arg);
+  void passOptionalNullableCallback(optional TestCallback? arg);
+  void passOptionalNullableCallbackWithDefaultValue(optional TestCallback? arg = null);
+  TestCallback receiveCallback();
+  TestCallback? receiveNullableCallback();
+  void passNullableTreatAsNullCallback(TestTreatAsNullCallback? arg);
+  void passOptionalNullableTreatAsNullCallback(optional TestTreatAsNullCallback? arg);
+  void passOptionalNullableTreatAsNullCallbackWithDefaultValue(optional TestTreatAsNullCallback? arg = null);
+  attribute TestTreatAsNullCallback treatAsNullCallback;
+  attribute TestTreatAsNullCallback? nullableTreatAsNullCallback;
+
+  // Force code generation of the various test callbacks we have.
+  void forceCallbackGeneration(TestIntegerReturn arg1,
+                               TestNullableIntegerReturn arg2,
+                               TestBooleanReturn arg3,
+                               TestFloatReturn arg4,
+                               TestStringReturn arg5,
+                               TestEnumReturn arg6,
+                               TestInterfaceReturn arg7,
+                               TestNullableInterfaceReturn arg8,
+                               TestExternalInterfaceReturn arg9,
+                               TestNullableExternalInterfaceReturn arg10,
+                               TestCallbackInterfaceReturn arg11,
+                               TestNullableCallbackInterfaceReturn arg12,
+                               TestCallbackReturn arg13,
+                               TestNullableCallbackReturn arg14,
+                               TestObjectReturn arg15,
+                               TestNullableObjectReturn arg16,
+                               TestTypedArrayReturn arg17,
+                               TestNullableTypedArrayReturn arg18,
+                               TestSequenceReturn arg19,
+                               TestNullableSequenceReturn arg20,
+                               TestIntegerArguments arg21,
+                               TestInterfaceArguments arg22,
+                               TestStringEnumArguments arg23,
+                               TestObjectArguments arg24,
+                               TestOptionalArguments arg25);
+
+  // Any types
+  void passAny(any arg);
+  void passVariadicAny(any... arg);
+  void passOptionalAny(optional any arg);
+  void passAnyDefaultNull(optional any arg = null);
+  void passSequenceOfAny(sequence<any> arg);
+  void passNullableSequenceOfAny(sequence<any>? arg);
+  void passOptionalSequenceOfAny(optional sequence<any> arg);
+  void passOptionalNullableSequenceOfAny(optional sequence<any>? arg);
+  void passOptionalSequenceOfAnyWithDefaultValue(optional sequence<any>? arg = null);
+  void passSequenceOfSequenceOfAny(sequence<sequence<any>> arg);
+  void passSequenceOfNullableSequenceOfAny(sequence<sequence<any>?> arg);
+  void passNullableSequenceOfNullableSequenceOfAny(sequence<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfAny(optional sequence<sequence<any>?>? arg);
+  void passMozMapOfAny(MozMap<any> arg);
+  void passNullableMozMapOfAny(MozMap<any>? arg);
+  void passOptionalMozMapOfAny(optional MozMap<any> arg);
+  void passOptionalNullableMozMapOfAny(optional MozMap<any>? arg);
+  void passOptionalMozMapOfAnyWithDefaultValue(optional MozMap<any>? arg = null);
+  void passMozMapOfMozMapOfAny(MozMap<MozMap<any>> arg);
+  void passMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?> arg);
+  void passNullableMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableMozMapOfAny(optional MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableSequenceOfAny(optional MozMap<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableMozMapOfAny(optional sequence<MozMap<any>?>? arg);
+  any receiveAny();
+
+  // object types
+  void passObject(object arg);
+  void passVariadicObject(object... arg);
+  void passNullableObject(object? arg);
+  void passVariadicNullableObject(object... arg);
+  void passOptionalObject(optional object arg);
+  void passOptionalNullableObject(optional object? arg);
+  void passOptionalNullableObjectWithDefaultValue(optional object? arg = null);
+  void passSequenceOfObject(sequence<object> arg);
+  void passSequenceOfNullableObject(sequence<object?> arg);
+  void passNullableSequenceOfObject(sequence<object>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfObject(optional sequence<sequence<object>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfNullableObject(optional sequence<sequence<object?>?>? arg);
+  void passMozMapOfObject(MozMap<object> arg);
+  object receiveObject();
+  object? receiveNullableObject();
+
+  // Union types
+  void passUnion((object or long) arg);
+  // Some  union tests are debug-only to avoid creating all those
+  // unused union types in opt builds.
+#ifdef DEBUG
+  void passUnion2((long or boolean) arg);
+  void passUnion3((object or long or boolean) arg);
+  void passUnion4((Node or long or boolean) arg);
+  void passUnion5((object or boolean) arg);
+  void passUnion6((object or DOMString) arg);
+  void passUnion7((object or DOMString or long) arg);
+  void passUnion8((object or DOMString or boolean) arg);
+  void passUnion9((object or DOMString or long or boolean) arg);
+  void passUnion10(optional (EventInit or long) arg);
+  void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
+  void passUnion15((sequence<long> or long) arg);
+  void passUnion16(optional (sequence<long> or long) arg);
+  void passUnion17(optional (sequence<long>? or long) arg = 5);
+  void passUnion18((sequence<object> or long) arg);
+  void passUnion19(optional (sequence<object> or long) arg);
+  void passUnion20(optional (sequence<object> or long) arg = []);
+  void passUnion21((MozMap<long> or long) arg);
+  void passUnion22((MozMap<object> or long) arg);
+  void passUnion23((sequence<ImageData> or long) arg);
+  void passUnion24((sequence<ImageData?> or long) arg);
+  void passUnion25((sequence<sequence<ImageData>> or long) arg);
+  void passUnion26((sequence<sequence<ImageData?>> or long) arg);
+  void passUnion27(optional (sequence<DOMString> or EventInit) arg);
+  void passUnion28(optional (EventInit or sequence<DOMString>) arg);
+  void passUnionWithCallback((EventHandler or long) arg);
+  void passUnionWithByteString((ByteString or long) arg);
+  void passUnionWithMozMap((MozMap<DOMString> or DOMString) arg);
+  void passUnionWithMozMapAndSequence((MozMap<DOMString> or sequence<DOMString>) arg);
+  void passUnionWithSequenceAndMozMap((sequence<DOMString> or MozMap<DOMString>) arg);
+  void passUnionWithUSVS((USVString or long) arg);
+#endif
+  void passUnionWithNullable((object? or long) arg);
+  void passNullableUnion((object or long)? arg);
+  void passOptionalUnion(optional (object or long) arg);
+  void passOptionalNullableUnion(optional (object or long)? arg);
+  void passOptionalNullableUnionWithDefaultValue(optional (object or long)? arg = null);
+  //void passUnionWithInterfaces((TestInterface or TestExternalInterface) arg);
+  //void passUnionWithInterfacesAndNullable((TestInterface? or TestExternalInterface) arg);
+  //void passUnionWithSequence((sequence<object> or long) arg);
+  void passUnionWithArrayBuffer((ArrayBuffer or long) arg);
+  void passUnionWithString((DOMString or object) arg);
+  // Using an enum in a union.  Note that we use some enum not declared in our
+  // binding file, because UnionTypes.h will need to include the binding header
+  // for this enum.  Pick an enum from an interface that won't drag in too much
+  // stuff.
+  void passUnionWithEnum((SupportedType or object) arg);
+
+  // Trying to use a callback in a union won't include the test
+  // headers, unfortunately, so won't compile.
+  //void passUnionWithCallback((TestCallback or long) arg);
+  void passUnionWithObject((object or long) arg);
+  //void passUnionWithDict((Dict or long) arg);
+
+  void passUnionWithDefaultValue1(optional (double or DOMString) arg = "");
+  void passUnionWithDefaultValue2(optional (double or DOMString) arg = 1);
+  void passUnionWithDefaultValue3(optional (double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue4(optional (float or DOMString) arg = "");
+  void passUnionWithDefaultValue5(optional (float or DOMString) arg = 1);
+  void passUnionWithDefaultValue6(optional (float or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue7(optional (unrestricted double or DOMString) arg = "");
+  void passUnionWithDefaultValue8(optional (unrestricted double or DOMString) arg = 1);
+  void passUnionWithDefaultValue9(optional (unrestricted double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue10(optional (unrestricted double or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue11(optional (unrestricted float or DOMString) arg = "");
+  void passUnionWithDefaultValue12(optional (unrestricted float or DOMString) arg = 1);
+  void passUnionWithDefaultValue13(optional (unrestricted float or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue14(optional (double or ByteString) arg = "");
+  void passUnionWithDefaultValue15(optional (double or ByteString) arg = 1);
+  void passUnionWithDefaultValue16(optional (double or ByteString) arg = 1.5);
+  void passUnionWithDefaultValue17(optional (double or SupportedType) arg = "text/html");
+  void passUnionWithDefaultValue18(optional (double or SupportedType) arg = 1);
+  void passUnionWithDefaultValue19(optional (double or SupportedType) arg = 1.5);
+
+  void passNullableUnionWithDefaultValue1(optional (double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue2(optional (double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue3(optional (double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue4(optional (float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue5(optional (float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue6(optional (float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue7(optional (unrestricted double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue8(optional (unrestricted double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue9(optional (unrestricted double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue10(optional (unrestricted float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue11(optional (unrestricted float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue12(optional (unrestricted float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue13(optional (double or ByteString)? arg = "");
+  void passNullableUnionWithDefaultValue14(optional (double or ByteString)? arg = 1);
+  void passNullableUnionWithDefaultValue15(optional (double or ByteString)? arg = 1.5);
+  void passNullableUnionWithDefaultValue16(optional (double or ByteString)? arg = null);
+  void passNullableUnionWithDefaultValue17(optional (double or SupportedType)? arg = "text/html");
+  void passNullableUnionWithDefaultValue18(optional (double or SupportedType)? arg = 1);
+  void passNullableUnionWithDefaultValue19(optional (double or SupportedType)? arg = 1.5);
+  void passNullableUnionWithDefaultValue20(optional (double or SupportedType)? arg = null);
+
+  void passSequenceOfUnions(sequence<(CanvasPattern or CanvasGradient)> arg);
+  void passSequenceOfUnions2(sequence<(object or long)> arg);
+  void passVariadicUnion((CanvasPattern or CanvasGradient)... arg);
+
+  void passSequenceOfNullableUnions(sequence<(CanvasPattern or CanvasGradient)?> arg);
+  void passVariadicNullableUnion((CanvasPattern or CanvasGradient)?... arg);
+  void passMozMapOfUnions(MozMap<(CanvasPattern or CanvasGradient)> arg);
+  // XXXbz no move constructor on some unions
+  // void passMozMapOfUnions2(MozMap<(object or long)> arg);
+
+  (CanvasPattern or CanvasGradient) receiveUnion();
+  (object or long) receiveUnion2();
+  (CanvasPattern? or CanvasGradient) receiveUnionContainingNull();
+  (CanvasPattern or CanvasGradient)? receiveNullableUnion();
+  (object or long)? receiveNullableUnion2();
+
+  attribute (CanvasPattern or CanvasGradient) writableUnion;
+  attribute (CanvasPattern? or CanvasGradient) writableUnionContainingNull;
+  attribute (CanvasPattern or CanvasGradient)? writableNullableUnion;
+
+  // Date types
+  void passDate(Date arg);
+  void passNullableDate(Date? arg);
+  void passOptionalDate(optional Date arg);
+  void passOptionalNullableDate(optional Date? arg);
+  void passOptionalNullableDateWithDefaultValue(optional Date? arg = null);
+  void passDateSequence(sequence<Date> arg);
+  void passNullableDateSequence(sequence<Date?> arg);
+  void passDateMozMap(MozMap<Date> arg);
+  Date receiveDate();
+  Date? receiveNullableDate();
+
+  // Promise types
+  void passPromise(Promise<any> arg);
+  void passNullablePromise(Promise<any>? arg);
+  void passOptionalPromise(optional Promise<any> arg);
+  void passOptionalNullablePromise(optional Promise<any>? arg);
+  void passOptionalNullablePromiseWithDefaultValue(optional Promise<any>? arg = null);
+  void passPromiseSequence(sequence<Promise<any>> arg);
+  void passNullablePromiseSequence(sequence<Promise<any>?> arg);
+  Promise<any> receivePromise();
+  Promise<any> receiveAddrefedPromise();
+
+  // binaryNames tests
+  void methodRenamedFrom();
+  [BinaryName="otherMethodRenamedTo"]
+  void otherMethodRenamedFrom();
+  void methodRenamedFrom(byte argument);
+  readonly attribute byte attributeGetterRenamedFrom;
+  attribute byte attributeRenamedFrom;
+  [BinaryName="otherAttributeRenamedTo"]
+  attribute byte otherAttributeRenamedFrom;
+
+  void passDictionary(optional Dict x);
+  void passDictionary2(Dict x);
+  [Cached, Pure]
+  readonly attribute Dict readonlyDictionary;
+  [Cached, Pure]
+  readonly attribute Dict? readonlyNullableDictionary;
+  [Cached, Pure]
+  attribute Dict writableDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict readonlyFrozenDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict? readonlyFrozenNullableDictionary;
+  [Cached, Pure, Frozen]
+  attribute Dict writableFrozenDictionary;
+  Dict receiveDictionary();
+  Dict? receiveNullableDictionary();
+  void passOtherDictionary(optional GrandparentDict x);
+  void passSequenceOfDictionaries(sequence<Dict> x);
+  void passMozMapOfDictionaries(MozMap<GrandparentDict> x);
+  // No support for nullable dictionaries inside a sequence (nor should there be)
+  //  void passSequenceOfNullableDictionaries(sequence<Dict?> x);
+  void passDictionaryOrLong(optional Dict x);
+  void passDictionaryOrLong(long x);
+
+  void passDictContainingDict(optional DictContainingDict arg);
+  void passDictContainingSequence(optional DictContainingSequence arg);
+  DictContainingSequence receiveDictContainingSequence();
+  void passVariadicDictionary(Dict... arg);
+
+  // EnforceRange/Clamp tests
+  void dontEnforceRangeOrClamp(byte arg);
+  void doEnforceRange([EnforceRange] byte arg);
+  void doClamp([Clamp] byte arg);
+  [EnforceRange] attribute byte enforcedByte;
+  [Clamp] attribute byte clampedByte;
+
+  // Typedefs
+  const myLong myLongConstant = 5;
+  void exerciseTypedefInterfaces1(AnotherNameForTestInterface arg);
+  AnotherNameForTestInterface exerciseTypedefInterfaces2(NullableTestInterface arg);
+  void exerciseTypedefInterfaces3(YetAnotherNameForTestInterface arg);
+
+  // Deprecated methods and attributes
+  [Deprecated="GetAttributeNode"]
+  attribute byte deprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  byte deprecatedMethod();
+  [Deprecated="GetAttributeNode"]
+  byte deprecatedMethodWithContext(any arg);
+
+  // Static methods and attributes
+  static attribute boolean staticAttribute;
+  static void staticMethod(boolean arg);
+  static void staticMethodWithContext(any arg);
+
+  // Testing static method with a reserved C++ keyword as the name
+  static void assert(boolean arg);
+
+  // Deprecated static methods and attributes
+  [Deprecated="GetAttributeNode"]
+  static attribute byte staticDeprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  static void staticDeprecatedMethod();
+  [Deprecated="GetAttributeNode"]
+  static void staticDeprecatedMethodWithContext(any arg);
+
+  // Overload resolution tests
+  //void overload1(DOMString... strs);
+  boolean overload1(TestInterface arg);
+  TestInterface overload1(DOMString strs, TestInterface arg);
+  void overload2(TestInterface arg);
+  void overload2(optional Dict arg);
+  void overload2(boolean arg);
+  void overload2(DOMString arg);
+  void overload2(Date arg);
+  void overload3(TestInterface arg);
+  void overload3(TestCallback arg);
+  void overload3(boolean arg);
+  void overload4(TestInterface arg);
+  void overload4(TestCallbackInterface arg);
+  void overload4(DOMString arg);
+  void overload5(long arg);
+  void overload5(TestEnum arg);
+  void overload6(long arg);
+  void overload6(boolean arg);
+  void overload7(long arg);
+  void overload7(boolean arg);
+  void overload7(ByteString arg);
+  void overload8(long arg);
+  void overload8(TestInterface arg);
+  void overload9(long? arg);
+  void overload9(DOMString arg);
+  void overload10(long? arg);
+  void overload10(object arg);
+  void overload11(long arg);
+  void overload11(DOMString? arg);
+  void overload12(long arg);
+  void overload12(boolean? arg);
+  void overload13(long? arg);
+  void overload13(boolean arg);
+  void overload14(optional long arg);
+  void overload14(TestInterface arg);
+  void overload15(long arg);
+  void overload15(optional TestInterface arg);
+  void overload16(long arg);
+  void overload16(optional TestInterface? arg);
+  void overload17(sequence<long> arg);
+  void overload17(MozMap<long> arg);
+  void overload18(MozMap<DOMString> arg);
+  void overload18(sequence<DOMString> arg);
+  void overload19(sequence<long> arg);
+  void overload19(optional Dict arg);
+  void overload20(optional Dict arg);
+  void overload20(sequence<long> arg);
+
+  // Variadic handling
+  void passVariadicThirdArg(DOMString arg1, long arg2, TestInterface... arg3);
+
+  // Conditionally exposed methods/attributes
+  [Pref="abc.def"]
+  readonly attribute boolean prefable1;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable2;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable3;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable4;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable5;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable6;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable7;
+  [Pref="ghi.jkl", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable8;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable9;
+  [Pref="abc.def"]
+  void prefable10();
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable11();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable12;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable13();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable14;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable15;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable16;
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  void prefable17();
+  [Func="TestFuncControlledMember"]
+  void prefable18();
+  [Func="TestFuncControlledMember"]
+  void prefable19();
+  [Pref="abc.def", Func="TestFuncControlledMember", ChromeOnly]
+  void prefable20();
+
+  // Conditionally exposed methods/attributes involving [SecureContext]
+  [SecureContext]
+  readonly attribute boolean conditionalOnSecureContext1;
+  [SecureContext, Pref="abc.def"]
+  readonly attribute boolean conditionalOnSecureContext2;
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean conditionalOnSecureContext3;
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean conditionalOnSecureContext4;
+  [SecureContext]
+  void conditionalOnSecureContext5();
+  [SecureContext, Pref="abc.def"]
+  void conditionalOnSecureContext6();
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void conditionalOnSecureContext7();
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  void conditionalOnSecureContext8();
+
+  // Miscellania
+  [LenientThis] attribute long attrWithLenientThis;
+  [Unforgeable] readonly attribute long unforgeableAttr;
+  [Unforgeable, ChromeOnly] readonly attribute long unforgeableAttr2;
+  [Unforgeable] long unforgeableMethod();
+  [Unforgeable, ChromeOnly] long unforgeableMethod2();
+  stringifier;
+  void passRenamedInterface(TestRenamedInterface arg);
+  [PutForwards=writableByte] readonly attribute TestInterface putForwardsAttr;
+  [PutForwards=writableByte, LenientThis] readonly attribute TestInterface putForwardsAttr2;
+  [PutForwards=writableByte, ChromeOnly] readonly attribute TestInterface putForwardsAttr3;
+  [Throws] void throwingMethod();
+  [Throws] attribute boolean throwingAttr;
+  [GetterThrows] attribute boolean throwingGetterAttr;
+  [SetterThrows] attribute boolean throwingSetterAttr;
+  [NeedsSubjectPrincipal] void needsSubjectPrincipalMethod();
+  [NeedsSubjectPrincipal] attribute boolean needsSubjectPrincipalAttr;
+  [NeedsCallerType] void needsCallerTypeMethod();
+  [NeedsCallerType] attribute boolean needsCallerTypeAttr;
+  legacycaller short(unsigned long arg1, TestInterface arg2);
+  void passArgsWithDefaults(optional long arg1,
+                            optional TestInterface? arg2 = null,
+                            optional Dict arg3, optional double arg4 = 5.0,
+                            optional float arg5);
+
+  attribute any jsonifierShouldSkipThis;
+  attribute TestParentInterface jsonifierShouldSkipThis2;
+  attribute TestCallbackInterface jsonifierShouldSkipThis3;
+  jsonifier;
+
+  attribute byte dashed-attribute;
+  void dashed-method();
+
+  // If you add things here, add them to TestExampleGen and TestJSImplGen as well
+};
+
+interface TestParentInterface {
+};
+
+interface TestChildInterface : TestParentInterface {
+};
+
+interface TestNonWrapperCacheInterface {
+};
+
+[NoInterfaceObject]
+interface ImplementedInterfaceParent {
+  void implementedParentMethod();
+  attribute boolean implementedParentProperty;
+
+  const long implementedParentConstant = 8;
+};
+
+ImplementedInterfaceParent implements IndirectlyImplementedInterface;
+
+[NoInterfaceObject]
+interface IndirectlyImplementedInterface {
+  void indirectlyImplementedMethod();
+  attribute boolean indirectlyImplementedProperty;
+
+  const long indirectlyImplementedConstant = 9;
+};
+
+[NoInterfaceObject]
+interface ImplementedInterface : ImplementedInterfaceParent {
+  void implementedMethod();
+  attribute boolean implementedProperty;
+
+  const long implementedConstant = 5;
+};
+
+[NoInterfaceObject]
+interface DiamondImplements {
+  readonly attribute long diamondImplementedProperty;
+};
+[NoInterfaceObject]
+interface DiamondBranch1A {
+};
+[NoInterfaceObject]
+interface DiamondBranch1B {
+};
+[NoInterfaceObject]
+interface DiamondBranch2A : DiamondImplements {
+};
+[NoInterfaceObject]
+interface DiamondBranch2B : DiamondImplements {
+};
+TestInterface implements DiamondBranch1A;
+TestInterface implements DiamondBranch1B;
+TestInterface implements DiamondBranch2A;
+TestInterface implements DiamondBranch2B;
+DiamondBranch1A implements DiamondImplements;
+DiamondBranch1B implements DiamondImplements;
+
+dictionary Dict : ParentDict {
+  TestEnum someEnum;
+  long x;
+  long a;
+  long b = 8;
+  long z = 9;
+  [EnforceRange] unsigned long enforcedUnsignedLong;
+  [Clamp] unsigned long clampedUnsignedLong;
+  DOMString str;
+  DOMString empty = "";
+  TestEnum otherEnum = "b";
+  DOMString otherStr = "def";
+  DOMString? yetAnotherStr = null;
+  DOMString template;
+  ByteString byteStr;
+  ByteString emptyByteStr = "";
+  ByteString otherByteStr = "def";
+  object someObj;
+  boolean prototype;
+  object? anotherObj = null;
+  TestCallback? someCallback = null;
+  any someAny;
+  any anotherAny = null;
+
+  unrestricted float  urFloat = 0;
+  unrestricted float  urFloat2 = 1.1;
+  unrestricted float  urFloat3 = -1.1;
+  unrestricted float? urFloat4 = null;
+  unrestricted float  infUrFloat = Infinity;
+  unrestricted float  negativeInfUrFloat = -Infinity;
+  unrestricted float  nanUrFloat = NaN;
+
+  unrestricted double  urDouble = 0;
+  unrestricted double  urDouble2 = 1.1;
+  unrestricted double  urDouble3 = -1.1;
+  unrestricted double? urDouble4 = null;
+  unrestricted double  infUrDouble = Infinity;
+  unrestricted double  negativeInfUrDouble = -Infinity;
+  unrestricted double  nanUrDouble = NaN;
+
+  (float or DOMString) floatOrString = "str";
+  (float or DOMString)? nullableFloatOrString = "str";
+  (object or long) objectOrLong;
+#ifdef DEBUG
+  (EventInit or long) eventInitOrLong;
+  (EventInit or long)? nullableEventInitOrLong;
+  (HTMLElement or long)? nullableHTMLElementOrLong;
+  // CustomEventInit is useful to test because it needs rooting.
+  (CustomEventInit or long) eventInitOrLong2;
+  (CustomEventInit or long)? nullableEventInitOrLong2;
+  (EventInit or long) eventInitOrLongWithDefaultValue = null;
+  (CustomEventInit or long) eventInitOrLongWithDefaultValue2 = null;
+  (EventInit or long) eventInitOrLongWithDefaultValue3 = 5;
+  (CustomEventInit or long) eventInitOrLongWithDefaultValue4 = 5;
+  (EventInit or long)? nullableEventInitOrLongWithDefaultValue = null;
+  (CustomEventInit or long)? nullableEventInitOrLongWithDefaultValue2 = null;
+  (EventInit or long)? nullableEventInitOrLongWithDefaultValue3 = 5;
+  (CustomEventInit or long)? nullableEventInitOrLongWithDefaultValue4 = 5;
+  (sequence<object> or long) objectSequenceOrLong;
+  (sequence<object> or long) objectSequenceOrLongWithDefaultValue1 = 1;
+  (sequence<object> or long) objectSequenceOrLongWithDefaultValue2 = [];
+  (sequence<object> or long)? nullableObjectSequenceOrLong;
+  (sequence<object> or long)? nullableObjectSequenceOrLongWithDefaultValue1 = 1;
+  (sequence<object> or long)? nullableObjectSequenceOrLongWithDefaultValue2 = [];
+#endif
+
+  ArrayBuffer arrayBuffer;
+  ArrayBuffer? nullableArrayBuffer;
+  Uint8Array uint8Array;
+  Float64Array? float64Array = null;
+
+  sequence<long> seq1;
+  sequence<long> seq2 = [];
+  sequence<long>? seq3;
+  sequence<long>? seq4 = null;
+  sequence<long>? seq5 = [];
+
+  long dashed-name;
+
+  required long requiredLong;
+  required object requiredObject;
+
+  CustomEventInit customEventInit;
+  TestDictionaryTypedef dictionaryTypedef;
+
+  Promise<void> promise;
+  sequence<Promise<void>> promiseSequence;
+};
+
+dictionary ParentDict : GrandparentDict {
+  long c = 5;
+  TestInterface someInterface;
+  TestInterface? someNullableInterface = null;
+  TestExternalInterface someExternalInterface;
+  any parentAny;
+};
+
+dictionary DictContainingDict {
+  Dict memberDict;
+};
+
+dictionary DictContainingSequence {
+  sequence<long> ourSequence;
+  sequence<TestInterface> ourSequence2;
+  sequence<any> ourSequence3;
+  sequence<object> ourSequence4;
+  sequence<object?> ourSequence5;
+  sequence<object>? ourSequence6;
+  sequence<object?>? ourSequence7;
+  sequence<object>? ourSequence8 = null;
+  sequence<object?>? ourSequence9 = null;
+  sequence<(float or DOMString)> ourSequence10;
+};
+
+dictionary DictForConstructor {
+  Dict dict;
+  DictContainingDict dict2;
+  sequence<Dict> seq1;
+  sequence<sequence<Dict>>? seq2;
+  sequence<sequence<Dict>?> seq3;
+  sequence<any> seq4;
+  sequence<any> seq5;
+  sequence<DictContainingSequence> seq6;
+  object obj1;
+  object? obj2;
+  any any1 = null;
+};
+
+dictionary DictWithConditionalMembers {
+  [ChromeOnly]
+  long chromeOnlyMember;
+  [Func="TestFuncControlledMember"]
+  long funcControlledMember;
+  [ChromeOnly, Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  long chromeOnlyFuncControlledMember;
+};
+
+interface TestIndexedGetterInterface {
+  getter long item(unsigned long idx);
+  readonly attribute unsigned long length;
+  legacycaller void();
+};
+
+interface TestNamedGetterInterface {
+  getter DOMString (DOMString name);
+};
+
+interface TestIndexedGetterAndSetterAndNamedGetterInterface {
+  getter DOMString (DOMString myName);
+  getter long (unsigned long index);
+  setter creator void (unsigned long index, long arg);
+};
+
+interface TestIndexedAndNamedGetterInterface {
+  getter long (unsigned long index);
+  getter DOMString namedItem(DOMString name);
+  readonly attribute unsigned long length;
+};
+
+interface TestIndexedSetterInterface {
+  setter creator void setItem(unsigned long idx, DOMString item);
+  getter DOMString (unsigned long idx);
+};
+
+interface TestNamedSetterInterface {
+  setter creator void (DOMString myName, TestIndexedSetterInterface item);
+  getter TestIndexedSetterInterface (DOMString name);
+};
+
+interface TestIndexedAndNamedSetterInterface {
+  setter creator void (unsigned long index, TestIndexedSetterInterface item);
+  getter TestIndexedSetterInterface (unsigned long index);
+  setter creator void setNamedItem(DOMString name, TestIndexedSetterInterface item);
+  getter TestIndexedSetterInterface (DOMString name);
+};
+
+interface TestIndexedAndNamedGetterAndSetterInterface : TestIndexedSetterInterface {
+  getter long item(unsigned long index);
+  getter DOMString namedItem(DOMString name);
+  setter creator void (unsigned long index, long item);
+  setter creator void (DOMString name, DOMString item);
+  stringifier DOMString ();
+  readonly attribute unsigned long length;
+};
+
+interface TestNamedDeleterInterface {
+  deleter void (DOMString name);
+  getter long (DOMString name);
+};
+
+interface TestNamedDeleterWithRetvalInterface {
+  deleter boolean delNamedItem(DOMString name);
+  getter long (DOMString name);
+};
+
+interface TestCppKeywordNamedMethodsInterface {
+  boolean continue();
+  boolean delete();
+  long volatile();
+};
+
+[Deprecated="GetAttributeNode", Constructor()]
+interface TestDeprecatedInterface {
+  static void alsoDeprecated();
+};
+
+
+[Constructor(Promise<void> promise)]
+interface TestInterfaceWithPromiseConstructorArg {
+};
+
+namespace TestNamespace {
+  readonly attribute boolean foo;
+  long bar();
+};
+
+partial namespace TestNamespace {
+  void baz();
+};
+
+[ClassString="RenamedNamespaceClassName"]
+namespace TestRenamedNamespace {
+};
+
+[ProtoObjectHack]
+namespace TestProtoObjectHackedNamespace {
+};
+
+[SecureContext]
+interface TestSecureContextInterface {
+  static void alsoSecureContext();
+};
+
+[Exposed=(Window,Worker)]
+interface TestWorkerExposedInterface {
+  [NeedsSubjectPrincipal] void needsSubjectPrincipalMethod();
+  [NeedsSubjectPrincipal] attribute boolean needsSubjectPrincipalAttr;
+  [NeedsCallerType] void needsCallerTypeMethod();
+  [NeedsCallerType] attribute boolean needsCallerTypeAttr;
+};
diff --git a/dom/bindings/test/TestDictionary.webidl b/dom/bindings/test/TestDictionary.webidl
new file mode 100644
index 000000000..3dd91bd65
--- /dev/null
+++ b/dom/bindings/test/TestDictionary.webidl
@@ -0,0 +1,9 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+dictionary GrandparentDict {
+  double someNum;
+};
\ No newline at end of file
diff --git a/dom/bindings/test/TestExampleGen.webidl b/dom/bindings/test/TestExampleGen.webidl
new file mode 100644
index 000000000..ea6387a84
--- /dev/null
+++ b/dom/bindings/test/TestExampleGen.webidl
@@ -0,0 +1,811 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+[Constructor,
+ Constructor(DOMString str),
+ Constructor(unsigned long num, boolean? boolArg),
+ Constructor(TestInterface? iface),
+ Constructor(long arg1, IndirectlyImplementedInterface iface),
+ Constructor(Date arg1),
+ Constructor(ArrayBuffer arrayBuf),
+ Constructor(Uint8Array typedArr),
+ // Constructor(long arg1, long arg2, (TestInterface or OnlyForUseInConstructor) arg3),
+ NamedConstructor=Example,
+ NamedConstructor=Example(DOMString str),
+ NamedConstructor=Example2(DictForConstructor dict, any any1, object obj1,
+                           object? obj2, sequence<Dict> seq, optional any any2,
+                           optional object obj3, optional object? obj4),
+ NamedConstructor=Example2((long or MozMap<any>) arg1)
+ ]
+interface TestExampleInterface {
+  // Integer types
+  // XXXbz add tests for throwing versions of all the integer stuff
+  readonly attribute byte readonlyByte;
+  attribute byte writableByte;
+  void passByte(byte arg);
+  byte receiveByte();
+  void passOptionalByte(optional byte arg);
+  void passOptionalByteBeforeRequired(optional byte arg1, byte arg2);
+  void passOptionalByteWithDefault(optional byte arg = 0);
+  void passOptionalByteWithDefaultBeforeRequired(optional byte arg1 = 0, byte arg2);
+  void passNullableByte(byte? arg);
+  void passOptionalNullableByte(optional byte? arg);
+  void passVariadicByte(byte... arg);
+  [Cached, Pure]
+  readonly attribute byte cachedByte;
+  [StoreInSlot, Constant]
+  readonly attribute byte cachedConstantByte;
+  [Cached, Pure]
+  attribute byte cachedWritableByte;
+  [Affects=Nothing]
+  attribute byte sideEffectFreeByte;
+  [Affects=Nothing, DependsOn=DOMState]
+  attribute byte domDependentByte;
+  [Affects=Nothing, DependsOn=Nothing]
+  readonly attribute byte constantByte;
+  [DependsOn=DeviceState, Affects=Nothing]
+  readonly attribute byte deviceStateDependentByte;
+  [Affects=Nothing]
+  byte returnByteSideEffectFree();
+  [Affects=Nothing, DependsOn=DOMState]
+  byte returnDOMDependentByte();
+  [Affects=Nothing, DependsOn=Nothing]
+  byte returnConstantByte();
+  [DependsOn=DeviceState, Affects=Nothing]
+  byte returnDeviceStateDependentByte();
+
+  readonly attribute short readonlyShort;
+  attribute short writableShort;
+  void passShort(short arg);
+  short receiveShort();
+  void passOptionalShort(optional short arg);
+  void passOptionalShortWithDefault(optional short arg = 5);
+
+  readonly attribute long readonlyLong;
+  attribute long writableLong;
+  void passLong(long arg);
+  long receiveLong();
+  void passOptionalLong(optional long arg);
+  void passOptionalLongWithDefault(optional long arg = 7);
+
+  readonly attribute long long readonlyLongLong;
+  attribute long long writableLongLong;
+  void passLongLong(long long arg);
+  long long receiveLongLong();
+  void passOptionalLongLong(optional long long arg);
+  void passOptionalLongLongWithDefault(optional long long arg = -12);
+
+  readonly attribute octet readonlyOctet;
+  attribute octet writableOctet;
+  void passOctet(octet arg);
+  octet receiveOctet();
+  void passOptionalOctet(optional octet arg);
+  void passOptionalOctetWithDefault(optional octet arg = 19);
+
+  readonly attribute unsigned short readonlyUnsignedShort;
+  attribute unsigned short writableUnsignedShort;
+  void passUnsignedShort(unsigned short arg);
+  unsigned short receiveUnsignedShort();
+  void passOptionalUnsignedShort(optional unsigned short arg);
+  void passOptionalUnsignedShortWithDefault(optional unsigned short arg = 2);
+
+  readonly attribute unsigned long readonlyUnsignedLong;
+  attribute unsigned long writableUnsignedLong;
+  void passUnsignedLong(unsigned long arg);
+  unsigned long receiveUnsignedLong();
+  void passOptionalUnsignedLong(optional unsigned long arg);
+  void passOptionalUnsignedLongWithDefault(optional unsigned long arg = 6);
+
+  readonly attribute unsigned long long readonlyUnsignedLongLong;
+  attribute unsigned long long  writableUnsignedLongLong;
+  void passUnsignedLongLong(unsigned long long arg);
+  unsigned long long receiveUnsignedLongLong();
+  void passOptionalUnsignedLongLong(optional unsigned long long arg);
+  void passOptionalUnsignedLongLongWithDefault(optional unsigned long long arg = 17);
+
+  attribute float writableFloat;
+  attribute unrestricted float writableUnrestrictedFloat;
+  attribute float? writableNullableFloat;
+  attribute unrestricted float? writableNullableUnrestrictedFloat;
+  attribute double writableDouble;
+  attribute unrestricted double writableUnrestrictedDouble;
+  attribute double? writableNullableDouble;
+  attribute unrestricted double? writableNullableUnrestrictedDouble;
+  void passFloat(float arg1, unrestricted float arg2,
+                 float? arg3, unrestricted float? arg4,
+                 double arg5, unrestricted double arg6,
+                 double? arg7, unrestricted double? arg8,
+                 sequence<float> arg9, sequence<unrestricted float> arg10,
+                 sequence<float?> arg11, sequence<unrestricted float?> arg12,
+                 sequence<double> arg13, sequence<unrestricted double> arg14,
+                 sequence<double?> arg15, sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  void passLenientFloat(float arg1, unrestricted float arg2,
+                        float? arg3, unrestricted float? arg4,
+                        double arg5, unrestricted double arg6,
+                        double? arg7, unrestricted double? arg8,
+                        sequence<float> arg9,
+                        sequence<unrestricted float> arg10,
+                        sequence<float?> arg11,
+                        sequence<unrestricted float?> arg12,
+                        sequence<double> arg13,
+                        sequence<unrestricted double> arg14,
+                        sequence<double?> arg15,
+                        sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  attribute float lenientFloatAttr;
+  [LenientFloat]
+  attribute double lenientDoubleAttr;
+
+  // Castable interface types
+  // XXXbz add tests for throwing versions of all the castable interface stuff
+  TestInterface receiveSelf();
+  TestInterface? receiveNullableSelf();
+  TestInterface receiveWeakSelf();
+  TestInterface? receiveWeakNullableSelf();
+  void passSelf(TestInterface arg);
+  void passNullableSelf(TestInterface? arg);
+  attribute TestInterface nonNullSelf;
+  attribute TestInterface? nullableSelf;
+  [Cached, Pure]
+  readonly attribute TestInterface cachedSelf;
+  // Optional arguments
+  void passOptionalSelf(optional TestInterface? arg);
+  void passOptionalNonNullSelf(optional TestInterface arg);
+  void passOptionalSelfWithDefault(optional TestInterface? arg = null);
+
+  // Non-wrapper-cache interface types
+  [NewObject]
+  TestNonWrapperCacheInterface receiveNonWrapperCacheInterface();
+  [NewObject]
+  TestNonWrapperCacheInterface? receiveNullableNonWrapperCacheInterface();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface> receiveNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?> receiveNullableNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface>? receiveNonWrapperCacheInterfaceNullableSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?>? receiveNullableNonWrapperCacheInterfaceNullableSequence();
+
+  // Non-castable interface types
+  IndirectlyImplementedInterface receiveOther();
+  IndirectlyImplementedInterface? receiveNullableOther();
+  IndirectlyImplementedInterface receiveWeakOther();
+  IndirectlyImplementedInterface? receiveWeakNullableOther();
+  void passOther(IndirectlyImplementedInterface arg);
+  void passNullableOther(IndirectlyImplementedInterface? arg);
+  attribute IndirectlyImplementedInterface nonNullOther;
+  attribute IndirectlyImplementedInterface? nullableOther;
+  // Optional arguments
+  void passOptionalOther(optional IndirectlyImplementedInterface? arg);
+  void passOptionalNonNullOther(optional IndirectlyImplementedInterface arg);
+  void passOptionalOtherWithDefault(optional IndirectlyImplementedInterface? arg = null);
+
+  // External interface types
+  TestExternalInterface receiveExternal();
+  TestExternalInterface? receiveNullableExternal();
+  TestExternalInterface receiveWeakExternal();
+  TestExternalInterface? receiveWeakNullableExternal();
+  void passExternal(TestExternalInterface arg);
+  void passNullableExternal(TestExternalInterface? arg);
+  attribute TestExternalInterface nonNullExternal;
+  attribute TestExternalInterface? nullableExternal;
+  // Optional arguments
+  void passOptionalExternal(optional TestExternalInterface? arg);
+  void passOptionalNonNullExternal(optional TestExternalInterface arg);
+  void passOptionalExternalWithDefault(optional TestExternalInterface? arg = null);
+
+  // Callback interface types
+  TestCallbackInterface receiveCallbackInterface();
+  TestCallbackInterface? receiveNullableCallbackInterface();
+  TestCallbackInterface receiveWeakCallbackInterface();
+  TestCallbackInterface? receiveWeakNullableCallbackInterface();
+  void passCallbackInterface(TestCallbackInterface arg);
+  void passNullableCallbackInterface(TestCallbackInterface? arg);
+  attribute TestCallbackInterface nonNullCallbackInterface;
+  attribute TestCallbackInterface? nullableCallbackInterface;
+  // Optional arguments
+  void passOptionalCallbackInterface(optional TestCallbackInterface? arg);
+  void passOptionalNonNullCallbackInterface(optional TestCallbackInterface arg);
+  void passOptionalCallbackInterfaceWithDefault(optional TestCallbackInterface? arg = null);
+
+  // Miscellaneous interface tests
+  IndirectlyImplementedInterface receiveConsequentialInterface();
+  void passConsequentialInterface(IndirectlyImplementedInterface arg);
+
+  // Sequence types
+  [Cached, Pure]
+  readonly attribute sequence<long> readonlySequence;
+  [Cached, Pure]
+  readonly attribute sequence<Dict> readonlySequenceOfDictionaries;
+  [Cached, Pure]
+  readonly attribute sequence<Dict>? readonlyNullableSequenceOfDictionaries;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<long> readonlyFrozenSequence;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<long>? readonlyFrozenNullableSequence;
+  sequence<long> receiveSequence();
+  sequence<long>? receiveNullableSequence();
+  sequence<long?> receiveSequenceOfNullableInts();
+  sequence<long?>? receiveNullableSequenceOfNullableInts();
+  void passSequence(sequence<long> arg);
+  void passNullableSequence(sequence<long>? arg);
+  void passSequenceOfNullableInts(sequence<long?> arg);
+  void passOptionalSequenceOfNullableInts(optional sequence<long?> arg);
+  void passOptionalNullableSequenceOfNullableInts(optional sequence<long?>? arg);
+  sequence<TestInterface> receiveCastableObjectSequence();
+  sequence<TestCallbackInterface> receiveCallbackObjectSequence();
+  sequence<TestInterface?> receiveNullableCastableObjectSequence();
+  sequence<TestCallbackInterface?> receiveNullableCallbackObjectSequence();
+  sequence<TestInterface>? receiveCastableObjectNullableSequence();
+  sequence<TestInterface?>? receiveNullableCastableObjectNullableSequence();
+  sequence<TestInterface> receiveWeakCastableObjectSequence();
+  sequence<TestInterface?> receiveWeakNullableCastableObjectSequence();
+  sequence<TestInterface>? receiveWeakCastableObjectNullableSequence();
+  sequence<TestInterface?>? receiveWeakNullableCastableObjectNullableSequence();
+  void passCastableObjectSequence(sequence<TestInterface> arg);
+  void passNullableCastableObjectSequence(sequence<TestInterface?> arg);
+  void passCastableObjectNullableSequence(sequence<TestInterface>? arg);
+  void passNullableCastableObjectNullableSequence(sequence<TestInterface?>? arg);
+  void passOptionalSequence(optional sequence<long> arg);
+  void passOptionalSequenceWithDefaultValue(optional sequence<long> arg = []);
+  void passOptionalNullableSequence(optional sequence<long>? arg);
+  void passOptionalNullableSequenceWithDefaultValue(optional sequence<long>? arg = null);
+  void passOptionalNullableSequenceWithDefaultValue2(optional sequence<long>? arg = []);
+  void passOptionalObjectSequence(optional sequence<TestInterface> arg);
+  void passExternalInterfaceSequence(sequence<TestExternalInterface> arg);
+  void passNullableExternalInterfaceSequence(sequence<TestExternalInterface?> arg);
+
+  sequence<DOMString> receiveStringSequence();
+  void passStringSequence(sequence<DOMString> arg);
+
+  sequence<ByteString> receiveByteStringSequence();
+  void passByteStringSequence(sequence<ByteString> arg);
+
+  sequence<any> receiveAnySequence();
+  sequence<any>? receiveNullableAnySequence();
+  //XXXbz No support for sequence of sequence return values yet.
+  //sequence<sequence<any>> receiveAnySequenceSequence();
+
+  sequence<object> receiveObjectSequence();
+  sequence<object?> receiveNullableObjectSequence();
+
+  void passSequenceOfSequences(sequence<sequence<long>> arg);
+  void passSequenceOfSequencesOfSequences(sequence<sequence<sequence<long>>> arg);
+  //XXXbz No support for sequence of sequence return values yet.
+  //sequence<sequence<long>> receiveSequenceOfSequences();
+
+  // MozMap types
+  void passMozMap(MozMap<long> arg);
+  void passNullableMozMap(MozMap<long>? arg);
+  void passMozMapOfNullableInts(MozMap<long?> arg);
+  void passOptionalMozMapOfNullableInts(optional MozMap<long?> arg);
+  void passOptionalNullableMozMapOfNullableInts(optional MozMap<long?>? arg);
+  void passCastableObjectMozMap(MozMap<TestInterface> arg);
+  void passNullableCastableObjectMozMap(MozMap<TestInterface?> arg);
+  void passCastableObjectNullableMozMap(MozMap<TestInterface>? arg);
+  void passNullableCastableObjectNullableMozMap(MozMap<TestInterface?>? arg);
+  void passOptionalMozMap(optional MozMap<long> arg);
+  void passOptionalNullableMozMap(optional MozMap<long>? arg);
+  void passOptionalNullableMozMapWithDefaultValue(optional MozMap<long>? arg = null);
+  void passOptionalObjectMozMap(optional MozMap<TestInterface> arg);
+  void passExternalInterfaceMozMap(MozMap<TestExternalInterface> arg);
+  void passNullableExternalInterfaceMozMap(MozMap<TestExternalInterface?> arg);
+  void passStringMozMap(MozMap<DOMString> arg);
+  void passByteStringMozMap(MozMap<ByteString> arg);
+  void passMozMapOfMozMaps(MozMap<MozMap<long>> arg);
+  MozMap<long> receiveMozMap();
+  MozMap<long>? receiveNullableMozMap();
+  MozMap<long?> receiveMozMapOfNullableInts();
+  MozMap<long?>? receiveNullableMozMapOfNullableInts();
+  //XXXbz No support for MozMap of MozMaps return values yet.
+  //MozMap<MozMap<long>> receiveMozMapOfMozMaps();
+  MozMap<any> receiveAnyMozMap();
+
+  // Typed array types
+  void passArrayBuffer(ArrayBuffer arg);
+  void passNullableArrayBuffer(ArrayBuffer? arg);
+  void passOptionalArrayBuffer(optional ArrayBuffer arg);
+  void passOptionalNullableArrayBuffer(optional ArrayBuffer? arg);
+  void passOptionalNullableArrayBufferWithDefaultValue(optional ArrayBuffer? arg= null);
+  void passArrayBufferView(ArrayBufferView arg);
+  void passInt8Array(Int8Array arg);
+  void passInt16Array(Int16Array arg);
+  void passInt32Array(Int32Array arg);
+  void passUint8Array(Uint8Array arg);
+  void passUint16Array(Uint16Array arg);
+  void passUint32Array(Uint32Array arg);
+  void passUint8ClampedArray(Uint8ClampedArray arg);
+  void passFloat32Array(Float32Array arg);
+  void passFloat64Array(Float64Array arg);
+  void passSequenceOfArrayBuffers(sequence<ArrayBuffer> arg);
+  void passSequenceOfNullableArrayBuffers(sequence<ArrayBuffer?> arg);
+  void passMozMapOfArrayBuffers(MozMap<ArrayBuffer> arg);
+  void passMozMapOfNullableArrayBuffers(MozMap<ArrayBuffer?> arg);
+  void passVariadicTypedArray(Float32Array... arg);
+  void passVariadicNullableTypedArray(Float32Array?... arg);
+  Uint8Array receiveUint8Array();
+  attribute Uint8Array uint8ArrayAttr;
+
+  // DOMString types
+  void passString(DOMString arg);
+  void passNullableString(DOMString? arg);
+  void passOptionalString(optional DOMString arg);
+  void passOptionalStringWithDefaultValue(optional DOMString arg = "abc");
+  void passOptionalNullableString(optional DOMString? arg);
+  void passOptionalNullableStringWithDefaultValue(optional DOMString? arg = null);
+  void passVariadicString(DOMString... arg);
+
+  // ByteString types
+  void passByteString(ByteString arg);
+  void passNullableByteString(ByteString? arg);
+  void passOptionalByteString(optional ByteString arg);
+  void passOptionalByteStringWithDefaultValue(optional ByteString arg = "abc");
+  void passOptionalNullableByteString(optional ByteString? arg);
+  void passOptionalNullableByteStringWithDefaultValue(optional ByteString? arg = null);
+  void passVariadicByteString(ByteString... arg);
+  void passUnionByteString((ByteString or long) arg);
+  void passOptionalUnionByteString(optional (ByteString or long) arg);
+  void passOptionalUnionByteStringWithDefaultValue(optional (ByteString or long) arg = "abc");
+
+  // USVString types
+  void passSVS(USVString arg);
+  void passNullableSVS(USVString? arg);
+  void passOptionalSVS(optional USVString arg);
+  void passOptionalSVSWithDefaultValue(optional USVString arg = "abc");
+  void passOptionalNullableSVS(optional USVString? arg);
+  void passOptionalNullableSVSWithDefaultValue(optional USVString? arg = null);
+  void passVariadicSVS(USVString... arg);
+  USVString receiveSVS();
+
+  // Enumerated types
+  void passEnum(TestEnum arg);
+  void passNullableEnum(TestEnum? arg);
+  void passOptionalEnum(optional TestEnum arg);
+  void passEnumWithDefault(optional TestEnum arg = "a");
+  void passOptionalNullableEnum(optional TestEnum? arg);
+  void passOptionalNullableEnumWithDefaultValue(optional TestEnum? arg = null);
+  void passOptionalNullableEnumWithDefaultValue2(optional TestEnum? arg = "a");
+  TestEnum receiveEnum();
+  TestEnum? receiveNullableEnum();
+  attribute TestEnum enumAttribute;
+  readonly attribute TestEnum readonlyEnumAttribute;
+
+  // Callback types
+  void passCallback(TestCallback arg);
+  void passNullableCallback(TestCallback? arg);
+  void passOptionalCallback(optional TestCallback arg);
+  void passOptionalNullableCallback(optional TestCallback? arg);
+  void passOptionalNullableCallbackWithDefaultValue(optional TestCallback? arg = null);
+  TestCallback receiveCallback();
+  TestCallback? receiveNullableCallback();
+  void passNullableTreatAsNullCallback(TestTreatAsNullCallback? arg);
+  void passOptionalNullableTreatAsNullCallback(optional TestTreatAsNullCallback? arg);
+  void passOptionalNullableTreatAsNullCallbackWithDefaultValue(optional TestTreatAsNullCallback? arg = null);
+
+  // Any types
+  void passAny(any arg);
+  void passVariadicAny(any... arg);
+  void passOptionalAny(optional any arg);
+  void passAnyDefaultNull(optional any arg = null);
+  void passSequenceOfAny(sequence<any> arg);
+  void passNullableSequenceOfAny(sequence<any>? arg);
+  void passOptionalSequenceOfAny(optional sequence<any> arg);
+  void passOptionalNullableSequenceOfAny(optional sequence<any>? arg);
+  void passOptionalSequenceOfAnyWithDefaultValue(optional sequence<any>? arg = null);
+  void passSequenceOfSequenceOfAny(sequence<sequence<any>> arg);
+  void passSequenceOfNullableSequenceOfAny(sequence<sequence<any>?> arg);
+  void passNullableSequenceOfNullableSequenceOfAny(sequence<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfAny(optional sequence<sequence<any>?>? arg);
+  void passMozMapOfAny(MozMap<any> arg);
+  void passNullableMozMapOfAny(MozMap<any>? arg);
+  void passOptionalMozMapOfAny(optional MozMap<any> arg);
+  void passOptionalNullableMozMapOfAny(optional MozMap<any>? arg);
+  void passOptionalMozMapOfAnyWithDefaultValue(optional MozMap<any>? arg = null);
+  void passMozMapOfMozMapOfAny(MozMap<MozMap<any>> arg);
+  void passMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?> arg);
+  void passNullableMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableMozMapOfAny(optional MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableSequenceOfAny(optional MozMap<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableMozMapOfAny(optional sequence<MozMap<any>?>? arg);
+  any receiveAny();
+
+  // object types
+  void passObject(object arg);
+  void passVariadicObject(object... arg);
+  void passNullableObject(object? arg);
+  void passVariadicNullableObject(object... arg);
+  void passOptionalObject(optional object arg);
+  void passOptionalNullableObject(optional object? arg);
+  void passOptionalNullableObjectWithDefaultValue(optional object? arg = null);
+  void passSequenceOfObject(sequence<object> arg);
+  void passSequenceOfNullableObject(sequence<object?> arg);
+  void passNullableSequenceOfObject(sequence<object>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfObject(optional sequence<sequence<object>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfNullableObject(optional sequence<sequence<object?>?>? arg);
+  void passMozMapOfObject(MozMap<object> arg);
+  object receiveObject();
+  object? receiveNullableObject();
+
+  // Union types
+  void passUnion((object or long) arg);
+  // Some union tests are debug-only to avoid creating all those
+  // unused union types in opt builds.
+#ifdef DEBUG
+  void passUnion2((long or boolean) arg);
+  void passUnion3((object or long or boolean) arg);
+  void passUnion4((Node or long or boolean) arg);
+  void passUnion5((object or boolean) arg);
+  void passUnion6((object or DOMString) arg);
+  void passUnion7((object or DOMString or long) arg);
+  void passUnion8((object or DOMString or boolean) arg);
+  void passUnion9((object or DOMString or long or boolean) arg);
+  void passUnion10(optional (EventInit or long) arg);
+  void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
+  void passUnion15((sequence<long> or long) arg);
+  void passUnion16(optional (sequence<long> or long) arg);
+  void passUnion17(optional (sequence<long>? or long) arg = 5);
+  void passUnion18((sequence<object> or long) arg);
+  void passUnion19(optional (sequence<object> or long) arg);
+  void passUnion20(optional (sequence<object> or long) arg = []);
+  void passUnion21((MozMap<long> or long) arg);
+  void passUnion22((MozMap<object> or long) arg);
+  void passUnion23((sequence<ImageData> or long) arg);
+  void passUnion24((sequence<ImageData?> or long) arg);
+  void passUnion25((sequence<sequence<ImageData>> or long) arg);
+  void passUnion26((sequence<sequence<ImageData?>> or long) arg);
+  void passUnion27(optional (sequence<DOMString> or EventInit) arg);
+  void passUnion28(optional (EventInit or sequence<DOMString>) arg);
+  void passUnionWithCallback((EventHandler or long) arg);
+  void passUnionWithByteString((ByteString or long) arg);
+  void passUnionWithMozMap((MozMap<DOMString> or DOMString) arg);
+  void passUnionWithMozMapAndSequence((MozMap<DOMString> or sequence<DOMString>) arg);
+  void passUnionWithSequenceAndMozMap((sequence<DOMString> or MozMap<DOMString>) arg);
+  void passUnionWithSVS((USVString or long) arg);
+#endif
+  void passUnionWithNullable((object? or long) arg);
+  void passNullableUnion((object or long)? arg);
+  void passOptionalUnion(optional (object or long) arg);
+  void passOptionalNullableUnion(optional (object or long)? arg);
+  void passOptionalNullableUnionWithDefaultValue(optional (object or long)? arg = null);
+  //void passUnionWithInterfaces((TestInterface or TestExternalInterface) arg);
+  //void passUnionWithInterfacesAndNullable((TestInterface? or TestExternalInterface) arg);
+  //void passUnionWithSequence((sequence<object> or long) arg);
+  void passUnionWithArrayBuffer((ArrayBuffer or long) arg);
+  void passUnionWithString((DOMString or object) arg);
+  // Using an enum in a union.  Note that we use some enum not declared in our
+  // binding file, because UnionTypes.h will need to include the binding header
+  // for this enum.  Pick an enum from an interface that won't drag in too much
+  // stuff.
+  void passUnionWithEnum((SupportedType or object) arg);
+
+  // Trying to use a callback in a union won't include the test
+  // headers, unfortunately, so won't compile.
+  //  void passUnionWithCallback((TestCallback or long) arg);
+  void passUnionWithObject((object or long) arg);
+  //void passUnionWithDict((Dict or long) arg);
+
+  void passUnionWithDefaultValue1(optional (double or DOMString) arg = "");
+  void passUnionWithDefaultValue2(optional (double or DOMString) arg = 1);
+  void passUnionWithDefaultValue3(optional (double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue4(optional (float or DOMString) arg = "");
+  void passUnionWithDefaultValue5(optional (float or DOMString) arg = 1);
+  void passUnionWithDefaultValue6(optional (float or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue7(optional (unrestricted double or DOMString) arg = "");
+  void passUnionWithDefaultValue8(optional (unrestricted double or DOMString) arg = 1);
+  void passUnionWithDefaultValue9(optional (unrestricted double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue10(optional (unrestricted double or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue11(optional (unrestricted float or DOMString) arg = "");
+  void passUnionWithDefaultValue12(optional (unrestricted float or DOMString) arg = 1);
+  void passUnionWithDefaultValue13(optional (unrestricted float or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue14(optional (double or ByteString) arg = "");
+  void passUnionWithDefaultValue15(optional (double or ByteString) arg = 1);
+  void passUnionWithDefaultValue16(optional (double or ByteString) arg = 1.5);
+  void passUnionWithDefaultValue17(optional (double or SupportedType) arg = "text/html");
+  void passUnionWithDefaultValue18(optional (double or SupportedType) arg = 1);
+  void passUnionWithDefaultValue19(optional (double or SupportedType) arg = 1.5);
+
+  void passNullableUnionWithDefaultValue1(optional (double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue2(optional (double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue3(optional (double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue4(optional (float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue5(optional (float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue6(optional (float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue7(optional (unrestricted double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue8(optional (unrestricted double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue9(optional (unrestricted double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue10(optional (unrestricted float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue11(optional (unrestricted float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue12(optional (unrestricted float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue13(optional (double or ByteString)? arg = "");
+  void passNullableUnionWithDefaultValue14(optional (double or ByteString)? arg = 1);
+  void passNullableUnionWithDefaultValue15(optional (double or ByteString)? arg = 1.5);
+  void passNullableUnionWithDefaultValue16(optional (double or ByteString)? arg = null);
+  void passNullableUnionWithDefaultValue17(optional (double or SupportedType)? arg = "text/html");
+  void passNullableUnionWithDefaultValue18(optional (double or SupportedType)? arg = 1);
+  void passNullableUnionWithDefaultValue19(optional (double or SupportedType)? arg = 1.5);
+  void passNullableUnionWithDefaultValue20(optional (double or SupportedType)? arg = null);
+
+  void passSequenceOfUnions(sequence<(CanvasPattern or CanvasGradient)> arg);
+  void passSequenceOfUnions2(sequence<(object or long)> arg);
+  void passVariadicUnion((CanvasPattern or CanvasGradient)... arg);
+
+  void passSequenceOfNullableUnions(sequence<(CanvasPattern or CanvasGradient)?> arg);
+  void passVariadicNullableUnion((CanvasPattern or CanvasGradient)?... arg);
+  void passMozMapOfUnions(MozMap<(CanvasPattern or CanvasGradient)> arg);
+  // XXXbz no move constructor on some unions
+  // void passMozMapOfUnions2(MozMap<(object or long)> arg);
+
+  (CanvasPattern or CanvasGradient) receiveUnion();
+  (object or long) receiveUnion2();
+  (CanvasPattern? or CanvasGradient) receiveUnionContainingNull();
+  (CanvasPattern or CanvasGradient)? receiveNullableUnion();
+  (object or long)? receiveNullableUnion2();
+
+  attribute (CanvasPattern or CanvasGradient) writableUnion;
+  attribute (CanvasPattern? or CanvasGradient) writableUnionContainingNull;
+  attribute (CanvasPattern or CanvasGradient)? writableNullableUnion;
+
+  // Date types
+  void passDate(Date arg);
+  void passNullableDate(Date? arg);
+  void passOptionalDate(optional Date arg);
+  void passOptionalNullableDate(optional Date? arg);
+  void passOptionalNullableDateWithDefaultValue(optional Date? arg = null);
+  void passDateSequence(sequence<Date> arg);
+  void passNullableDateSequence(sequence<Date?> arg);
+  void passDateMozMap(MozMap<Date> arg);
+  Date receiveDate();
+  Date? receiveNullableDate();
+
+  // Promise types
+  void passPromise(Promise<any> arg);
+  void passNullablePromise(Promise<any>? arg);
+  void passOptionalPromise(optional Promise<any> arg);
+  void passOptionalNullablePromise(optional Promise<any>? arg);
+  void passOptionalNullablePromiseWithDefaultValue(optional Promise<any>? arg = null);
+  void passPromiseSequence(sequence<Promise<any>> arg);
+  void passNullablePromiseSequence(sequence<Promise<any>?> arg);
+  Promise<any> receivePromise();
+  Promise<any> receiveAddrefedPromise();
+
+  // binaryNames tests
+  void methodRenamedFrom();
+  [BinaryName="otherMethodRenamedTo"]
+  void otherMethodRenamedFrom();
+  void methodRenamedFrom(byte argument);
+  readonly attribute byte attributeGetterRenamedFrom;
+  attribute byte attributeRenamedFrom;
+  [BinaryName="otherAttributeRenamedTo"]
+  attribute byte otherAttributeRenamedFrom;
+
+  void passDictionary(optional Dict x);
+  void passDictionary2(Dict x);
+  [Cached, Pure]
+  readonly attribute Dict readonlyDictionary;
+  [Cached, Pure]
+  readonly attribute Dict? readonlyNullableDictionary;
+  [Cached, Pure]
+  attribute Dict writableDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict readonlyFrozenDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict? readonlyFrozenNullableDictionary;
+  [Cached, Pure, Frozen]
+  attribute Dict writableFrozenDictionary;
+  Dict receiveDictionary();
+  Dict? receiveNullableDictionary();
+  void passOtherDictionary(optional GrandparentDict x);
+  void passSequenceOfDictionaries(sequence<Dict> x);
+  void passMozMapOfDictionaries(MozMap<GrandparentDict> x);
+  // No support for nullable dictionaries inside a sequence (nor should there be)
+  //  void passSequenceOfNullableDictionaries(sequence<Dict?> x);
+  void passDictionaryOrLong(optional Dict x);
+  void passDictionaryOrLong(long x);
+
+  void passDictContainingDict(optional DictContainingDict arg);
+  void passDictContainingSequence(optional DictContainingSequence arg);
+  DictContainingSequence receiveDictContainingSequence();
+  void passVariadicDictionary(Dict... arg);
+
+  // EnforceRange/Clamp tests
+  void dontEnforceRangeOrClamp(byte arg);
+  void doEnforceRange([EnforceRange] byte arg);
+  void doClamp([Clamp] byte arg);
+  [EnforceRange] attribute byte enforcedByte;
+  [Clamp] attribute byte clampedByte;
+
+  // Typedefs
+  const myLong myLongConstant = 5;
+  void exerciseTypedefInterfaces1(AnotherNameForTestInterface arg);
+  AnotherNameForTestInterface exerciseTypedefInterfaces2(NullableTestInterface arg);
+  void exerciseTypedefInterfaces3(YetAnotherNameForTestInterface arg);
+
+  // Deprecated methods and attributes
+  [Deprecated="GetAttributeNode"]
+  attribute boolean deprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  void deprecatedMethod(boolean arg);
+  [Deprecated="GetAttributeNode"]
+  void deprecatedMethodWithContext(any arg);
+
+  // Static methods and attributes
+  static attribute boolean staticAttribute;
+  static void staticMethod(boolean arg);
+  static void staticMethodWithContext(any arg);
+
+  // Deprecated methods and attributes;
+  [Deprecated="GetAttributeNode"]
+  static attribute boolean staticDeprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  static void staticDeprecatedMethod(boolean arg);
+  [Deprecated="GetAttributeNode"]
+  static void staticDeprecatedMethodWithContext(any arg);
+
+  // Overload resolution tests
+  //void overload1(DOMString... strs);
+  boolean overload1(TestInterface arg);
+  TestInterface overload1(DOMString strs, TestInterface arg);
+  void overload2(TestInterface arg);
+  void overload2(optional Dict arg);
+  void overload2(boolean arg);
+  void overload2(DOMString arg);
+  void overload2(Date arg);
+  void overload3(TestInterface arg);
+  void overload3(TestCallback arg);
+  void overload3(boolean arg);
+  void overload4(TestInterface arg);
+  void overload4(TestCallbackInterface arg);
+  void overload4(DOMString arg);
+  void overload5(long arg);
+  void overload5(TestEnum arg);
+  void overload6(long arg);
+  void overload6(boolean arg);
+  void overload7(long arg);
+  void overload7(boolean arg);
+  void overload7(ByteString arg);
+  void overload8(long arg);
+  void overload8(TestInterface arg);
+  void overload9(long? arg);
+  void overload9(DOMString arg);
+  void overload10(long? arg);
+  void overload10(object arg);
+  void overload11(long arg);
+  void overload11(DOMString? arg);
+  void overload12(long arg);
+  void overload12(boolean? arg);
+  void overload13(long? arg);
+  void overload13(boolean arg);
+  void overload14(optional long arg);
+  void overload14(TestInterface arg);
+  void overload15(long arg);
+  void overload15(optional TestInterface arg);
+  void overload16(long arg);
+  void overload16(optional TestInterface? arg);
+  void overload17(sequence<long> arg);
+  void overload17(MozMap<long> arg);
+  void overload18(MozMap<DOMString> arg);
+  void overload18(sequence<DOMString> arg);
+  void overload19(sequence<long> arg);
+  void overload19(optional Dict arg);
+  void overload20(optional Dict arg);
+  void overload20(sequence<long> arg);
+
+  // Variadic handling
+  void passVariadicThirdArg(DOMString arg1, long arg2, TestInterface... arg3);
+
+  // Conditionally exposed methods/attributes
+  [Pref="abc.def"]
+  readonly attribute boolean prefable1;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable2;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable3;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable4;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable5;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable6;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable7;
+  [Pref="ghi.jkl", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable8;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable9;
+  [Pref="abc.def"]
+  void prefable10();
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable11();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable12;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable13();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable14;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable15;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable16;
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  void prefable17();
+  [Func="TestFuncControlledMember"]
+  void prefable18();
+  [Func="TestFuncControlledMember"]
+  void prefable19();
+
+  // Conditionally exposed methods/attributes involving [SecureContext]
+  [SecureContext]
+  readonly attribute boolean conditionalOnSecureContext1;
+  [SecureContext, Pref="abc.def"]
+  readonly attribute boolean conditionalOnSecureContext2;
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean conditionalOnSecureContext3;
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean conditionalOnSecureContext4;
+  [SecureContext]
+  void conditionalOnSecureContext5();
+  [SecureContext, Pref="abc.def"]
+  void conditionalOnSecureContext6();
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void conditionalOnSecureContext7();
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  void conditionalOnSecureContext8();
+
+  // Miscellania
+  [LenientThis] attribute long attrWithLenientThis;
+  [Unforgeable] readonly attribute long unforgeableAttr;
+  [Unforgeable, ChromeOnly] readonly attribute long unforgeableAttr2;
+  [Unforgeable] long unforgeableMethod();
+  [Unforgeable, ChromeOnly] long unforgeableMethod2();
+  stringifier;
+  void passRenamedInterface(TestRenamedInterface arg);
+  [PutForwards=writableByte] readonly attribute TestExampleInterface putForwardsAttr;
+  [PutForwards=writableByte, LenientThis] readonly attribute TestExampleInterface putForwardsAttr2;
+  [PutForwards=writableByte, ChromeOnly] readonly attribute TestExampleInterface putForwardsAttr3;
+  [Throws] void throwingMethod();
+  [Throws] attribute boolean throwingAttr;
+  [GetterThrows] attribute boolean throwingGetterAttr;
+  [SetterThrows] attribute boolean throwingSetterAttr;
+  [NeedsSubjectPrincipal] void needsSubjectPrincipalMethod();
+  [NeedsSubjectPrincipal] attribute boolean needsSubjectPrincipalAttr;
+  [NeedsCallerType] void needsCallerTypeMethod();
+  [NeedsCallerType] attribute boolean needsCallerTypeAttr;
+  legacycaller short(unsigned long arg1, TestInterface arg2);
+  void passArgsWithDefaults(optional long arg1,
+                            optional TestInterface? arg2 = null,
+                            optional Dict arg3, optional double arg4 = 5.0,
+                            optional float arg5);
+  attribute any jsonifierShouldSkipThis;
+  attribute TestParentInterface jsonifierShouldSkipThis2;
+  attribute TestCallbackInterface jsonifierShouldSkipThis3;
+  jsonifier;
+
+  attribute byte dashed-attribute;
+  void dashed-method();
+
+  // If you add things here, add them to TestCodeGen and TestJSImplGen as well
+};
+
+interface TestExampleProxyInterface {
+  getter long longIndexedGetter(unsigned long ix);
+  setter creator void longIndexedSetter(unsigned long y, long z);
+  stringifier DOMString myStringifier();
+  getter short shortNameGetter(DOMString nom);
+  deleter void (DOMString nomnom);
+  setter creator void shortNamedSetter(DOMString me, short value);
+};
+
+[Exposed=(Window,Worker)]
+interface TestExampleWorkerInterface {
+  [NeedsSubjectPrincipal] void needsSubjectPrincipalMethod();
+  [NeedsSubjectPrincipal] attribute boolean needsSubjectPrincipalAttr;
+  [NeedsCallerType] void needsCallerTypeMethod();
+  [NeedsCallerType] attribute boolean needsCallerTypeAttr;
+};
diff --git a/dom/bindings/test/TestFunctions.cpp b/dom/bindings/test/TestFunctions.cpp
new file mode 100644
index 000000000..f05c92b48
--- /dev/null
+++ b/dom/bindings/test/TestFunctions.cpp
@@ -0,0 +1,94 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestFunctions.h"
+#include "mozilla/dom/TestFunctionsBinding.h"
+#include "nsStringBuffer.h"
+
+namespace mozilla {
+namespace dom {
+
+/* static */ TestFunctions*
+TestFunctions::Constructor(GlobalObject& aGlobal, ErrorResult& aRv)
+{
+  return new TestFunctions;
+}
+
+/* static */ void
+TestFunctions::ThrowUncatchableException(GlobalObject& aGlobal,
+                                         ErrorResult& aRv)
+{
+  aRv.ThrowUncatchableException();
+}
+
+/* static */ Promise*
+TestFunctions::PassThroughPromise(GlobalObject& aGlobal, Promise& aPromise)
+{
+  return &aPromise;
+}
+
+/* static */ already_AddRefed<Promise>
+TestFunctions::PassThroughCallbackPromise(GlobalObject& aGlobal,
+                                          PromiseReturner& aCallback,
+                                          ErrorResult& aRv)
+{
+  return aCallback.Call(aRv);
+}
+
+void
+TestFunctions::SetStringData(const nsAString& aString)
+{
+  mStringData = aString;
+}
+
+void
+TestFunctions::GetStringDataAsAString(nsAString& aString)
+{
+  aString = mStringData;
+}
+
+void
+TestFunctions::GetStringDataAsAString(uint32_t aLength, nsAString& aString)
+{
+  MOZ_RELEASE_ASSERT(aLength <= mStringData.Length(),
+                     "Bogus test passing in a too-big length");
+  aString.Assign(mStringData.BeginReading(), aLength);
+}
+
+void
+TestFunctions::GetStringDataAsDOMString(const Optional<uint32_t>& aLength,
+                                        DOMString& aString)
+{
+  uint32_t length;
+  if (aLength.WasPassed()) {
+    length = aLength.Value();
+    MOZ_RELEASE_ASSERT(length <= mStringData.Length(),
+                       "Bogus test passing in a too-big length");
+  } else {
+    length = mStringData.Length();
+  }
+
+  nsStringBuffer* buf = nsStringBuffer::FromString(mStringData);
+  if (buf) {
+    aString.SetStringBuffer(buf, length);
+    return;
+  }
+
+  // We better have an empty mStringData; otherwise why did we not have a string
+  // buffer?
+  MOZ_RELEASE_ASSERT(length == 0, "Why no stringbuffer?");
+  // No need to do anything here; aString is already empty.
+}
+
+bool
+TestFunctions::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
+                          JS::MutableHandle<JSObject*> aWrapper)
+{
+  return TestFunctionsBinding::Wrap(aCx, this, aGivenProto, aWrapper);
+}
+
+}
+}
diff --git a/dom/bindings/test/TestFunctions.h b/dom/bindings/test/TestFunctions.h
new file mode 100644
index 000000000..b35464824
--- /dev/null
+++ b/dom/bindings/test/TestFunctions.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestFunctions_h
+#define mozilla_dom_TestFunctions_h
+
+#include "mozilla/ErrorResult.h"
+#include "mozilla/dom/BindingDeclarations.h"
+#include "mozilla/dom/NonRefcountedDOMObject.h"
+#include "nsString.h"
+
+namespace mozilla {
+namespace dom {
+
+class Promise;
+class PromiseReturner;
+
+class TestFunctions : public NonRefcountedDOMObject {
+public:
+  static TestFunctions* Constructor(GlobalObject& aGlobal, ErrorResult& aRv);
+
+  static void
+  ThrowUncatchableException(GlobalObject& aGlobal, ErrorResult& aRv);
+
+  static Promise*
+  PassThroughPromise(GlobalObject& aGlobal, Promise& aPromise);
+
+  static already_AddRefed<Promise>
+  PassThroughCallbackPromise(GlobalObject& aGlobal,
+                             PromiseReturner& aCallback,
+                             ErrorResult& aRv);
+
+  void SetStringData(const nsAString& aString);
+
+  void GetStringDataAsAString(nsAString& aString);
+  void GetStringDataAsAString(uint32_t aLength, nsAString& aString);
+  void GetStringDataAsDOMString(const Optional<uint32_t>& aLength,
+                                DOMString& aString);
+
+  bool WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto,
+                  JS::MutableHandle<JSObject*> aWrapper);
+private:
+  nsString mStringData;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestFunctions_h
diff --git a/dom/bindings/test/TestInterfaceIterableDouble.cpp b/dom/bindings/test/TestInterfaceIterableDouble.cpp
new file mode 100644
index 000000000..33a4c97d1
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableDouble.cpp
@@ -0,0 +1,82 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceIterableDouble.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceIterableDouble, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceIterableDouble)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceIterableDouble)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceIterableDouble)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceIterableDouble::TestInterfaceIterableDouble(nsPIDOMWindowInner* aParent)
+  : mParent(aParent)
+{
+  mValues.AppendElement(std::pair<nsString, nsString>(NS_LITERAL_STRING("a"),
+                                                      NS_LITERAL_STRING("b")));
+  mValues.AppendElement(std::pair<nsString, nsString>(NS_LITERAL_STRING("c"),
+                                                      NS_LITERAL_STRING("d")));
+  mValues.AppendElement(std::pair<nsString, nsString>(NS_LITERAL_STRING("e"),
+                                                      NS_LITERAL_STRING("f")));
+}
+
+//static
+already_AddRefed<TestInterfaceIterableDouble>
+TestInterfaceIterableDouble::Constructor(const GlobalObject& aGlobal,
+                                         ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceIterableDouble> r = new TestInterfaceIterableDouble(window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceIterableDouble::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceIterableDoubleBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceIterableDouble::GetParentObject() const
+{
+  return mParent;
+}
+
+size_t
+TestInterfaceIterableDouble::GetIterableLength()
+{
+  return mValues.Length();
+}
+
+nsAString&
+TestInterfaceIterableDouble::GetKeyAtIndex(uint32_t aIndex)
+{
+  MOZ_ASSERT(aIndex < mValues.Length());
+  return mValues.ElementAt(aIndex).first;
+}
+
+nsAString&
+TestInterfaceIterableDouble::GetValueAtIndex(uint32_t aIndex)
+{
+  MOZ_ASSERT(aIndex < mValues.Length());
+  return mValues.ElementAt(aIndex).second;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceIterableDouble.h b/dom/bindings/test/TestInterfaceIterableDouble.h
new file mode 100644
index 000000000..1e9ff7acd
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableDouble.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceIterableDouble_h
+#define mozilla_dom_TestInterfaceIterableDouble_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl iterable interfaces, using
+// primitives for value type
+class TestInterfaceIterableDouble final : public nsISupports,
+                                          public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceIterableDouble)
+
+  explicit TestInterfaceIterableDouble(nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceIterableDouble>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+
+  size_t GetIterableLength();
+  nsAString& GetKeyAtIndex(uint32_t aIndex);
+  nsAString& GetValueAtIndex(uint32_t aIndex);
+private:
+  virtual ~TestInterfaceIterableDouble() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+  nsTArray<std::pair<nsString, nsString>> mValues;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceIterableDouble_h
diff --git a/dom/bindings/test/TestInterfaceIterableDoubleUnion.cpp b/dom/bindings/test/TestInterfaceIterableDoubleUnion.cpp
new file mode 100644
index 000000000..29151a4c5
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableDoubleUnion.cpp
@@ -0,0 +1,83 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceIterableDoubleUnion.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceIterableDoubleUnion, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceIterableDoubleUnion)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceIterableDoubleUnion)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceIterableDoubleUnion)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceIterableDoubleUnion::TestInterfaceIterableDoubleUnion(nsPIDOMWindowInner* aParent)
+  : mParent(aParent)
+{
+  OwningStringOrLong a;
+  a.SetAsLong() = 1;
+  mValues.AppendElement(std::pair<nsString, OwningStringOrLong>(NS_LITERAL_STRING("long"),
+                                                                a));
+  a.SetAsString() = NS_LITERAL_STRING("a");
+  mValues.AppendElement(std::pair<nsString, OwningStringOrLong>(NS_LITERAL_STRING("string"),
+                                                                a));
+}
+
+//static
+already_AddRefed<TestInterfaceIterableDoubleUnion>
+TestInterfaceIterableDoubleUnion::Constructor(const GlobalObject& aGlobal,
+                                              ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceIterableDoubleUnion> r = new TestInterfaceIterableDoubleUnion(window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceIterableDoubleUnion::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceIterableDoubleUnionBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceIterableDoubleUnion::GetParentObject() const
+{
+  return mParent;
+}
+
+size_t
+TestInterfaceIterableDoubleUnion::GetIterableLength()
+{
+  return mValues.Length();
+}
+
+nsAString&
+TestInterfaceIterableDoubleUnion::GetKeyAtIndex(uint32_t aIndex)
+{
+  MOZ_ASSERT(aIndex < mValues.Length());
+  return mValues.ElementAt(aIndex).first;
+}
+
+OwningStringOrLong&
+TestInterfaceIterableDoubleUnion::GetValueAtIndex(uint32_t aIndex)
+{
+  MOZ_ASSERT(aIndex < mValues.Length());
+  return mValues.ElementAt(aIndex).second;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceIterableDoubleUnion.h b/dom/bindings/test/TestInterfaceIterableDoubleUnion.h
new file mode 100644
index 000000000..ff6ea2175
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableDoubleUnion.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceIterableDoubleUnion_h
+#define mozilla_dom_TestInterfaceIterableDoubleUnion_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl iterable interfaces, using
+// primitives for value type
+class TestInterfaceIterableDoubleUnion final : public nsISupports,
+                                               public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceIterableDoubleUnion)
+
+  explicit TestInterfaceIterableDoubleUnion(nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceIterableDoubleUnion>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+
+  size_t GetIterableLength();
+  nsAString& GetKeyAtIndex(uint32_t aIndex);
+  OwningStringOrLong& GetValueAtIndex(uint32_t aIndex);
+private:
+  virtual ~TestInterfaceIterableDoubleUnion() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+  nsTArray<std::pair<nsString, OwningStringOrLong>> mValues;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceIterableDoubleUnion_h
diff --git a/dom/bindings/test/TestInterfaceIterableSingle.cpp b/dom/bindings/test/TestInterfaceIterableSingle.cpp
new file mode 100644
index 000000000..5f8d6c640
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableSingle.cpp
@@ -0,0 +1,77 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceIterableSingle.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceIterableSingle, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceIterableSingle)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceIterableSingle)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceIterableSingle)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceIterableSingle::TestInterfaceIterableSingle(nsPIDOMWindowInner* aParent)
+  : mParent(aParent)
+{
+  for (int i = 0; i < 3; ++i) {
+    mValues.AppendElement(i);
+  }
+}
+
+//static
+already_AddRefed<TestInterfaceIterableSingle>
+TestInterfaceIterableSingle::Constructor(const GlobalObject& aGlobal,
+                                         ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceIterableSingle> r = new TestInterfaceIterableSingle(window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceIterableSingle::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceIterableSingleBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceIterableSingle::GetParentObject() const
+{
+  return mParent;
+}
+
+uint32_t
+TestInterfaceIterableSingle::Length() const
+{
+  return mValues.Length();
+}
+
+int32_t
+TestInterfaceIterableSingle::IndexedGetter(uint32_t aIndex, bool& aFound) const
+{
+  if (aIndex >= mValues.Length()) {
+    aFound = false;
+    return 0;
+  }
+
+  aFound = true;
+  return mValues[aIndex];
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceIterableSingle.h b/dom/bindings/test/TestInterfaceIterableSingle.h
new file mode 100644
index 000000000..a071ada8b
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceIterableSingle.h
@@ -0,0 +1,51 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceIterableSingle_h
+#define mozilla_dom_TestInterfaceIterableSingle_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl iterable interfaces, using
+// primitives for value type
+class TestInterfaceIterableSingle final : public nsISupports,
+                                          public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceIterableSingle)
+
+  explicit TestInterfaceIterableSingle(nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceIterableSingle>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+
+  uint32_t Length() const;
+  int32_t IndexedGetter(uint32_t aIndex, bool& aFound) const;
+
+private:
+  virtual ~TestInterfaceIterableSingle() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+  nsTArray<int32_t> mValues;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceIterableSingle_h
diff --git a/dom/bindings/test/TestInterfaceJS.js b/dom/bindings/test/TestInterfaceJS.js
new file mode 100644
index 000000000..1a5bf8e61
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceJS.js
@@ -0,0 +1,166 @@
+/* -*- Mode: JavaScript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+function TestInterfaceJS(anyArg, objectArg) {}
+
+TestInterfaceJS.prototype = {
+  classID: Components.ID("{2ac4e026-cf25-47d5-b067-78d553c3cad8}"),
+  contractID: "@mozilla.org/dom/test-interface-js;1",
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsISupports,
+                                         Ci.nsIDOMGlobalPropertyInitializer]),
+
+  init: function(win) { this._win = win; },
+
+  __init: function (anyArg, objectArg, dictionaryArg) {
+    this._anyAttr = undefined;
+    this._objectAttr = null;
+    this._anyArg = anyArg;
+    this._objectArg = objectArg;
+    this._dictionaryArg = dictionaryArg;
+    this._cachedAttr = 15;
+  },
+
+  get anyArg() { return this._anyArg; },
+  get objectArg() { return this._objectArg; },
+  get dictionaryArg() { return this._dictionaryArg; },
+  get anyAttr() { return this._anyAttr; },
+  set anyAttr(val) { this._anyAttr = val; },
+  get objectAttr() { return this._objectAttr; },
+  set objectAttr(val) { this._objectAttr = val; },
+  get dictionaryAttr() { return this._dictionaryAttr; },
+  set dictionaryAttr(val) { this._dictionaryAttr = val; },
+  pingPongAny: function(any) { return any; },
+  pingPongObject: function(obj) { return obj; },
+  pingPongObjectOrString: function(objectOrString) { return objectOrString; },
+  pingPongDictionary: function(dict) { return dict; },
+  pingPongDictionaryOrLong: function(dictOrLong) { return dictOrLong.anyMember || dictOrLong; },
+  pingPongMap: function(map) { return JSON.stringify(map); },
+  objectSequenceLength: function(seq) { return seq.length; },
+  anySequenceLength: function(seq) { return seq.length; },
+
+
+  getCallerPrincipal: function() { return Cu.getWebIDLCallerPrincipal().origin; },
+
+  convertSVS: function(svs) { return svs; },
+
+  pingPongUnion: function(x) { return x; },
+  pingPongUnionContainingNull: function(x) { return x; },
+  pingPongNullableUnion: function(x) { return x; },
+  returnBadUnion: function(x) { return 3; },
+
+  get cachedAttr() { return this._cachedAttr; },
+  setCachedAttr: function(n) { this._cachedAttr = n; },
+  clearCachedAttrCache: function () { this.__DOM_IMPL__._clearCachedCachedAttrValue(); },
+
+  testSequenceOverload: function(arg) {},
+  testSequenceUnion: function(arg) {},
+
+  testThrowError: function() {
+    throw new this._win.Error("We are an Error");
+  },
+
+  testThrowDOMException: function() {
+    throw new this._win.DOMException("We are a DOMException",
+                                     "NotSupportedError");
+  },
+
+  testThrowTypeError: function() {
+    throw new this._win.TypeError("We are a TypeError");
+  },
+
+  testThrowCallbackError: function(callback) {
+    callback();
+  },
+
+  testThrowXraySelfHosted: function() {
+    this._win.Array.indexOf();
+  },
+
+  testThrowSelfHosted: function() {
+    Array.indexOf();
+  },
+
+  testPromiseWithThrowingChromePromiseInit: function() {
+    return new this._win.Promise(function() {
+      noSuchMethodExistsYo1();
+    })
+  },
+
+  testPromiseWithThrowingContentPromiseInit: function(func) {
+      return new this._win.Promise(func);
+  },
+
+  testPromiseWithDOMExceptionThrowingPromiseInit: function() {
+    return new this._win.Promise(() => {
+      throw new this._win.DOMException("We are a second DOMException",
+                                       "NotFoundError");
+    })
+  },
+
+  testPromiseWithThrowingChromeThenFunction: function() {
+    return this._win.Promise.resolve(5).then(function() {
+      noSuchMethodExistsYo2();
+    });
+  },
+
+  testPromiseWithThrowingContentThenFunction: function(func) {
+    return this._win.Promise.resolve(10).then(func);
+  },
+
+  testPromiseWithDOMExceptionThrowingThenFunction: function() {
+    return this._win.Promise.resolve(5).then(() => {
+      throw new this._win.DOMException("We are a third DOMException",
+                                       "NetworkError");
+    });
+  },
+
+  testPromiseWithThrowingChromeThenable: function() {
+    var thenable =  {
+      then: function() {
+        noSuchMethodExistsYo3()
+      }
+    };
+    return new this._win.Promise(function(resolve) {
+      resolve(thenable)
+    });
+  },
+
+  testPromiseWithThrowingContentThenable: function(thenable) {
+    // Waive Xrays on the thenable, because we're calling resolve() in the
+    // chrome compartment, so that's the compartment the "then" property get
+    // will happen in, and if we leave the Xray in place the function-valued
+    // property won't return the function.
+    return this._win.Promise.resolve(Cu.waiveXrays(thenable));
+  },
+
+  testPromiseWithDOMExceptionThrowingThenable: function() {
+    var thenable =  {
+      then: () => {
+        throw new this._win.DOMException("We are a fourth DOMException",
+                                         "TypeMismatchError");
+      }
+    };
+    return new this._win.Promise(function(resolve) {
+      resolve(thenable)
+    });
+  },
+
+  get onsomething() {
+    return this.__DOM_IMPL__.getEventHandler("onsomething");
+  },
+
+  set onsomething(val) {
+    this.__DOM_IMPL__.setEventHandler("onsomething", val);
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([TestInterfaceJS])
diff --git a/dom/bindings/test/TestInterfaceJS.manifest b/dom/bindings/test/TestInterfaceJS.manifest
new file mode 100644
index 000000000..161a42156
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceJS.manifest
@@ -0,0 +1,4 @@
+component {2ac4e026-cf25-47d5-b067-78d553c3cad8} TestInterfaceJS.js
+contract @mozilla.org/dom/test-interface-js;1 {2ac4e026-cf25-47d5-b067-78d553c3cad8}
+component {4bc6f6f3-e005-4f0a-b42d-4d1663a9013a} TestInterfaceJSMaplike.js
+contract @mozilla.org/dom/test-interface-js-maplike;1 {4bc6f6f3-e005-4f0a-b42d-4d1663a9013a}
diff --git a/dom/bindings/test/TestInterfaceJSMaplike.js b/dom/bindings/test/TestInterfaceJSMaplike.js
new file mode 100644
index 000000000..b108ef5b6
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceJSMaplike.js
@@ -0,0 +1,38 @@
+/* -*- Mode: JavaScript; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+const Cu = Components.utils;
+const Ci = Components.interfaces;
+
+Cu.import("resource://gre/modules/XPCOMUtils.jsm");
+Cu.import("resource://gre/modules/Services.jsm");
+
+function TestInterfaceJSMaplike() {}
+
+TestInterfaceJSMaplike.prototype = {
+  classID: Components.ID("{4bc6f6f3-e005-4f0a-b42d-4d1663a9013a}"),
+  contractID: "@mozilla.org/dom/test-interface-js-maplike;1",
+  QueryInterface: XPCOMUtils.generateQI([Ci.nsISupports,
+                                         Ci.nsIDOMGlobalPropertyInitializer]),
+
+  init: function(win) { this._win = win; },
+
+  __init: function () {},
+
+  setInternal: function(aKey, aValue) {
+    return this.__DOM_IMPL__.__set(aKey, aValue);
+  },
+
+  deleteInternal: function(aKey) {
+    return this.__DOM_IMPL__.__delete(aKey);
+  },
+
+  clearInternal: function() {
+    return this.__DOM_IMPL__.__clear();
+  }
+};
+
+this.NSGetFactory = XPCOMUtils.generateNSGetFactory([TestInterfaceJSMaplike])
diff --git a/dom/bindings/test/TestInterfaceMaplike.cpp b/dom/bindings/test/TestInterfaceMaplike.cpp
new file mode 100644
index 000000000..4abace83c
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceMaplike.cpp
@@ -0,0 +1,84 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceMaplike.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceMaplike, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceMaplike)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceMaplike)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceMaplike)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceMaplike::TestInterfaceMaplike(nsPIDOMWindowInner* aParent)
+: mParent(aParent)
+{
+}
+
+//static
+already_AddRefed<TestInterfaceMaplike>
+TestInterfaceMaplike::Constructor(const GlobalObject& aGlobal,
+                                  ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceMaplike> r = new TestInterfaceMaplike(window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceMaplike::WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceMaplikeBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceMaplike::GetParentObject() const
+{
+  return mParent;
+}
+
+void
+TestInterfaceMaplike::SetInternal(const nsAString& aKey, int32_t aValue)
+{
+  ErrorResult rv;
+  TestInterfaceMaplikeBinding::MaplikeHelpers::Set(this, aKey, aValue, rv);
+}
+
+void
+TestInterfaceMaplike::ClearInternal()
+{
+  ErrorResult rv;
+  TestInterfaceMaplikeBinding::MaplikeHelpers::Clear(this, rv);
+}
+
+bool
+TestInterfaceMaplike::DeleteInternal(const nsAString& aKey)
+{
+  ErrorResult rv;
+  return TestInterfaceMaplikeBinding::MaplikeHelpers::Delete(this, aKey, rv);
+}
+
+bool
+TestInterfaceMaplike::HasInternal(const nsAString& aKey)
+{
+  ErrorResult rv;
+  return TestInterfaceMaplikeBinding::MaplikeHelpers::Has(this, aKey, rv);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceMaplike.h b/dom/bindings/test/TestInterfaceMaplike.h
new file mode 100644
index 000000000..c012a7a21
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceMaplike.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceMaplike_h
+#define mozilla_dom_TestInterfaceMaplike_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl maplike interfaces, using
+// primitives for key and value types.
+class TestInterfaceMaplike final : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceMaplike)
+
+  explicit TestInterfaceMaplike(nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceMaplike>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+
+  // External access for testing internal convenience functions.
+  void SetInternal(const nsAString& aKey, int32_t aValue);
+  void ClearInternal();
+  bool DeleteInternal(const nsAString& aKey);
+  bool HasInternal(const nsAString& aKey);
+private:
+  virtual ~TestInterfaceMaplike() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceMaplike_h
diff --git a/dom/bindings/test/TestInterfaceMaplikeObject.cpp b/dom/bindings/test/TestInterfaceMaplikeObject.cpp
new file mode 100644
index 000000000..3dc1ffdc4
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceMaplikeObject.cpp
@@ -0,0 +1,88 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceMaplikeObject.h"
+#include "mozilla/dom/TestInterfaceMaplike.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceMaplikeObject, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceMaplikeObject)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceMaplikeObject)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceMaplikeObject)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceMaplikeObject::TestInterfaceMaplikeObject(nsPIDOMWindowInner* aParent)
+: mParent(aParent)
+{
+}
+
+//static
+already_AddRefed<TestInterfaceMaplikeObject>
+TestInterfaceMaplikeObject::Constructor(const GlobalObject& aGlobal,
+                                        ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceMaplikeObject> r =
+    new TestInterfaceMaplikeObject(window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceMaplikeObject::WrapObject(JSContext* aCx,
+                                       JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceMaplikeObjectBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceMaplikeObject::GetParentObject() const
+{
+  return mParent;
+}
+
+void
+TestInterfaceMaplikeObject::SetInternal(const nsAString& aKey)
+{
+  RefPtr<TestInterfaceMaplike> p(new TestInterfaceMaplike(mParent));
+  ErrorResult rv;
+  TestInterfaceMaplikeObjectBinding::MaplikeHelpers::Set(this, aKey, *p, rv);
+}
+
+void
+TestInterfaceMaplikeObject::ClearInternal()
+{
+  ErrorResult rv;
+  TestInterfaceMaplikeObjectBinding::MaplikeHelpers::Clear(this, rv);
+}
+
+bool
+TestInterfaceMaplikeObject::DeleteInternal(const nsAString& aKey)
+{
+  ErrorResult rv;
+  return TestInterfaceMaplikeObjectBinding::MaplikeHelpers::Delete(this, aKey, rv);
+}
+
+bool
+TestInterfaceMaplikeObject::HasInternal(const nsAString& aKey)
+{
+  ErrorResult rv;
+  return TestInterfaceMaplikeObjectBinding::MaplikeHelpers::Has(this, aKey, rv);
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceMaplikeObject.h b/dom/bindings/test/TestInterfaceMaplikeObject.h
new file mode 100644
index 000000000..af4660c0d
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceMaplikeObject.h
@@ -0,0 +1,52 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceMaplikeObject_h
+#define mozilla_dom_TestInterfaceMaplikeObject_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl maplike interfaces, using
+// primitives for key types and objects for value types.
+class TestInterfaceMaplikeObject final : public nsISupports,
+                                         public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceMaplikeObject)
+
+  explicit TestInterfaceMaplikeObject(nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceMaplikeObject>
+    Constructor(const GlobalObject& aGlobal,ErrorResult& rv);
+
+  // External access for testing internal convenience functions.
+  void SetInternal(const nsAString& aKey);
+  void ClearInternal();
+  bool DeleteInternal(const nsAString& aKey);
+  bool HasInternal(const nsAString& aKey);
+private:
+  virtual ~TestInterfaceMaplikeObject() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceMaplikeObject_h
diff --git a/dom/bindings/test/TestInterfaceSetlike.cpp b/dom/bindings/test/TestInterfaceSetlike.cpp
new file mode 100644
index 000000000..c9f556076
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceSetlike.cpp
@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceSetlike.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceSetlike, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceSetlike)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceSetlike)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceSetlike)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceSetlike::TestInterfaceSetlike(JSContext* aCx,
+                                           nsPIDOMWindowInner* aParent)
+: mParent(aParent)
+{
+}
+
+//static
+already_AddRefed<TestInterfaceSetlike>
+TestInterfaceSetlike::Constructor(const GlobalObject& aGlobal,
+                                  ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceSetlike> r = new TestInterfaceSetlike(nullptr, window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceSetlike::WrapObject(JSContext* aCx,
+                                 JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceSetlikeBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceSetlike::GetParentObject() const
+{
+  return mParent;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceSetlike.h b/dom/bindings/test/TestInterfaceSetlike.h
new file mode 100644
index 000000000..c9f464960
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceSetlike.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceSetlike_h
+#define mozilla_dom_TestInterfaceSetlike_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl setlike interfaces, using
+// primitives for key type.
+class TestInterfaceSetlike final : public nsISupports,
+                                   public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceSetlike)
+  explicit TestInterfaceSetlike(JSContext* aCx,
+                                nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceSetlike>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+private:
+  virtual ~TestInterfaceSetlike() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceSetlike_h
diff --git a/dom/bindings/test/TestInterfaceSetlikeNode.cpp b/dom/bindings/test/TestInterfaceSetlikeNode.cpp
new file mode 100644
index 000000000..5499553fa
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceSetlikeNode.cpp
@@ -0,0 +1,58 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/dom/TestInterfaceSetlikeNode.h"
+#include "mozilla/dom/TestInterfaceJSMaplikeSetlikeIterableBinding.h"
+#include "nsPIDOMWindow.h"
+#include "mozilla/dom/BindingUtils.h"
+
+namespace mozilla {
+namespace dom {
+
+NS_IMPL_CYCLE_COLLECTION_WRAPPERCACHE(TestInterfaceSetlikeNode, mParent)
+
+NS_IMPL_CYCLE_COLLECTING_ADDREF(TestInterfaceSetlikeNode)
+NS_IMPL_CYCLE_COLLECTING_RELEASE(TestInterfaceSetlikeNode)
+
+NS_INTERFACE_MAP_BEGIN_CYCLE_COLLECTION(TestInterfaceSetlikeNode)
+NS_WRAPPERCACHE_INTERFACE_MAP_ENTRY
+NS_INTERFACE_MAP_ENTRY(nsISupports)
+NS_INTERFACE_MAP_END
+
+TestInterfaceSetlikeNode::TestInterfaceSetlikeNode(JSContext* aCx,
+                                                   nsPIDOMWindowInner* aParent)
+: mParent(aParent)
+{
+}
+
+//static
+already_AddRefed<TestInterfaceSetlikeNode>
+TestInterfaceSetlikeNode::Constructor(const GlobalObject& aGlobal,
+                                      ErrorResult& aRv)
+{
+  nsCOMPtr<nsPIDOMWindowInner> window = do_QueryInterface(aGlobal.GetAsSupports());
+  if (!window) {
+    aRv.Throw(NS_ERROR_FAILURE);
+    return nullptr;
+  }
+
+  RefPtr<TestInterfaceSetlikeNode> r = new TestInterfaceSetlikeNode(nullptr, window);
+  return r.forget();
+}
+
+JSObject*
+TestInterfaceSetlikeNode::WrapObject(JSContext* aCx,
+                                     JS::Handle<JSObject*> aGivenProto)
+{
+  return TestInterfaceSetlikeNodeBinding::Wrap(aCx, this, aGivenProto);
+}
+
+nsPIDOMWindowInner*
+TestInterfaceSetlikeNode::GetParentObject() const
+{
+  return mParent;
+}
+
+} // namespace dom
+} // namespace mozilla
diff --git a/dom/bindings/test/TestInterfaceSetlikeNode.h b/dom/bindings/test/TestInterfaceSetlikeNode.h
new file mode 100644
index 000000000..05b14190e
--- /dev/null
+++ b/dom/bindings/test/TestInterfaceSetlikeNode.h
@@ -0,0 +1,46 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim:set ts=2 sw=2 sts=2 et cindent: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_dom_TestInterfaceSetlikeNode_h
+#define mozilla_dom_TestInterfaceSetlikeNode_h
+
+#include "nsWrapperCache.h"
+#include "nsCOMPtr.h"
+
+class nsPIDOMWindowInner;
+
+namespace mozilla {
+
+class ErrorResult;
+
+namespace dom {
+
+class GlobalObject;
+
+// Implementation of test binding for webidl setlike interfaces, using
+// primitives for key type.
+class TestInterfaceSetlikeNode final : public nsISupports,
+                                       public nsWrapperCache
+{
+public:
+  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
+  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(TestInterfaceSetlikeNode)
+  explicit TestInterfaceSetlikeNode(JSContext* aCx,
+                                    nsPIDOMWindowInner* aParent);
+  nsPIDOMWindowInner* GetParentObject() const;
+  virtual JSObject* WrapObject(JSContext* aCx,
+                               JS::Handle<JSObject*> aGivenProto) override;
+  static already_AddRefed<TestInterfaceSetlikeNode>
+    Constructor(const GlobalObject& aGlobal, ErrorResult& rv);
+private:
+  virtual ~TestInterfaceSetlikeNode() {}
+  nsCOMPtr<nsPIDOMWindowInner> mParent;
+};
+
+} // namespace dom
+} // namespace mozilla
+
+#endif // mozilla_dom_TestInterfaceSetlikeNode_h
diff --git a/dom/bindings/test/TestJSImplGen.webidl b/dom/bindings/test/TestJSImplGen.webidl
new file mode 100644
index 000000000..a131dcdfe
--- /dev/null
+++ b/dom/bindings/test/TestJSImplGen.webidl
@@ -0,0 +1,836 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+typedef TestJSImplInterface AnotherNameForTestJSImplInterface;
+typedef TestJSImplInterface YetAnotherNameForTestJSImplInterface;
+typedef TestJSImplInterface? NullableTestJSImplInterface;
+
+callback MyTestCallback = void();
+
+enum MyTestEnum {
+  "a",
+  "b"
+};
+
+// We don't support multiple constructors (bug 869268) or named constructors
+// for JS-implemented WebIDL.
+[Constructor(DOMString str, unsigned long num, boolean? boolArg,
+             TestInterface? iface, long arg1,
+             DictForConstructor dict, any any1,
+             object obj1,
+             object? obj2, sequence<Dict> seq, optional any any2,
+             optional object obj3,
+             optional object? obj4,
+             Uint8Array typedArr,
+             ArrayBuffer arrayBuf),
+ JSImplementation="@mozilla.org/test-js-impl-interface;1"]
+interface TestJSImplInterface {
+  // Integer types
+  // XXXbz add tests for throwing versions of all the integer stuff
+  readonly attribute byte readonlyByte;
+  attribute byte writableByte;
+  void passByte(byte arg);
+  byte receiveByte();
+  void passOptionalByte(optional byte arg);
+  void passOptionalByteBeforeRequired(optional byte arg1, byte arg2);
+  void passOptionalByteWithDefault(optional byte arg = 0);
+  void passOptionalByteWithDefaultBeforeRequired(optional byte arg1 = 0, byte arg2);
+  void passNullableByte(byte? arg);
+  void passOptionalNullableByte(optional byte? arg);
+  void passVariadicByte(byte... arg);
+  [Cached, Pure]
+  readonly attribute byte cachedByte;
+  [Cached, Constant]
+  readonly attribute byte cachedConstantByte;
+  [Cached, Pure]
+  attribute byte cachedWritableByte;
+  [Affects=Nothing]
+  attribute byte sideEffectFreeByte;
+  [Affects=Nothing, DependsOn=DOMState]
+  attribute byte domDependentByte;
+  [Affects=Nothing, DependsOn=Nothing]
+  readonly attribute byte constantByte;
+  [DependsOn=DeviceState, Affects=Nothing]
+  readonly attribute byte deviceStateDependentByte;
+  [Affects=Nothing]
+  byte returnByteSideEffectFree();
+  [Affects=Nothing, DependsOn=DOMState]
+  byte returnDOMDependentByte();
+  [Affects=Nothing, DependsOn=Nothing]
+  byte returnConstantByte();
+  [DependsOn=DeviceState, Affects=Nothing]
+  byte returnDeviceStateDependentByte();
+
+  readonly attribute short readonlyShort;
+  attribute short writableShort;
+  void passShort(short arg);
+  short receiveShort();
+  void passOptionalShort(optional short arg);
+  void passOptionalShortWithDefault(optional short arg = 5);
+
+  readonly attribute long readonlyLong;
+  attribute long writableLong;
+  void passLong(long arg);
+  long receiveLong();
+  void passOptionalLong(optional long arg);
+  void passOptionalLongWithDefault(optional long arg = 7);
+
+  readonly attribute long long readonlyLongLong;
+  attribute long long writableLongLong;
+  void passLongLong(long long arg);
+  long long receiveLongLong();
+  void passOptionalLongLong(optional long long arg);
+  void passOptionalLongLongWithDefault(optional long long arg = -12);
+
+  readonly attribute octet readonlyOctet;
+  attribute octet writableOctet;
+  void passOctet(octet arg);
+  octet receiveOctet();
+  void passOptionalOctet(optional octet arg);
+  void passOptionalOctetWithDefault(optional octet arg = 19);
+
+  readonly attribute unsigned short readonlyUnsignedShort;
+  attribute unsigned short writableUnsignedShort;
+  void passUnsignedShort(unsigned short arg);
+  unsigned short receiveUnsignedShort();
+  void passOptionalUnsignedShort(optional unsigned short arg);
+  void passOptionalUnsignedShortWithDefault(optional unsigned short arg = 2);
+
+  readonly attribute unsigned long readonlyUnsignedLong;
+  attribute unsigned long writableUnsignedLong;
+  void passUnsignedLong(unsigned long arg);
+  unsigned long receiveUnsignedLong();
+  void passOptionalUnsignedLong(optional unsigned long arg);
+  void passOptionalUnsignedLongWithDefault(optional unsigned long arg = 6);
+
+  readonly attribute unsigned long long readonlyUnsignedLongLong;
+  attribute unsigned long long  writableUnsignedLongLong;
+  void passUnsignedLongLong(unsigned long long arg);
+  unsigned long long receiveUnsignedLongLong();
+  void passOptionalUnsignedLongLong(optional unsigned long long arg);
+  void passOptionalUnsignedLongLongWithDefault(optional unsigned long long arg = 17);
+
+  attribute float writableFloat;
+  attribute unrestricted float writableUnrestrictedFloat;
+  attribute float? writableNullableFloat;
+  attribute unrestricted float? writableNullableUnrestrictedFloat;
+  attribute double writableDouble;
+  attribute unrestricted double writableUnrestrictedDouble;
+  attribute double? writableNullableDouble;
+  attribute unrestricted double? writableNullableUnrestrictedDouble;
+  void passFloat(float arg1, unrestricted float arg2,
+                 float? arg3, unrestricted float? arg4,
+                 double arg5, unrestricted double arg6,
+                 double? arg7, unrestricted double? arg8,
+                 sequence<float> arg9, sequence<unrestricted float> arg10,
+                 sequence<float?> arg11, sequence<unrestricted float?> arg12,
+                 sequence<double> arg13, sequence<unrestricted double> arg14,
+                 sequence<double?> arg15, sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  void passLenientFloat(float arg1, unrestricted float arg2,
+                        float? arg3, unrestricted float? arg4,
+                        double arg5, unrestricted double arg6,
+                        double? arg7, unrestricted double? arg8,
+                        sequence<float> arg9,
+                        sequence<unrestricted float> arg10,
+                        sequence<float?> arg11,
+                        sequence<unrestricted float?> arg12,
+                        sequence<double> arg13,
+                        sequence<unrestricted double> arg14,
+                        sequence<double?> arg15,
+                        sequence<unrestricted double?> arg16);
+  [LenientFloat]
+  attribute float lenientFloatAttr;
+  [LenientFloat]
+  attribute double lenientDoubleAttr;
+
+  // Castable interface types
+  // XXXbz add tests for throwing versions of all the castable interface stuff
+  TestJSImplInterface receiveSelf();
+  TestJSImplInterface? receiveNullableSelf();
+
+  TestJSImplInterface receiveWeakSelf();
+  TestJSImplInterface? receiveWeakNullableSelf();
+
+  // A version to test for casting to TestJSImplInterface&
+  void passSelf(TestJSImplInterface arg);
+  void passNullableSelf(TestJSImplInterface? arg);
+  attribute TestJSImplInterface nonNullSelf;
+  attribute TestJSImplInterface? nullableSelf;
+  [Cached, Pure]
+  readonly attribute TestJSImplInterface cachedSelf;
+  // Optional arguments
+  void passOptionalSelf(optional TestJSImplInterface? arg);
+  void passOptionalNonNullSelf(optional TestJSImplInterface arg);
+  void passOptionalSelfWithDefault(optional TestJSImplInterface? arg = null);
+
+  // Non-wrapper-cache interface types
+  [NewObject]
+  TestNonWrapperCacheInterface receiveNonWrapperCacheInterface();
+  [NewObject]
+  TestNonWrapperCacheInterface? receiveNullableNonWrapperCacheInterface();
+
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface> receiveNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?> receiveNullableNonWrapperCacheInterfaceSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface>? receiveNonWrapperCacheInterfaceNullableSequence();
+  [NewObject]
+  sequence<TestNonWrapperCacheInterface?>? receiveNullableNonWrapperCacheInterfaceNullableSequence();
+
+  // Non-castable interface types
+  IndirectlyImplementedInterface receiveOther();
+  IndirectlyImplementedInterface? receiveNullableOther();
+  IndirectlyImplementedInterface receiveWeakOther();
+  IndirectlyImplementedInterface? receiveWeakNullableOther();
+
+  void passOther(IndirectlyImplementedInterface arg);
+  void passNullableOther(IndirectlyImplementedInterface? arg);
+  attribute IndirectlyImplementedInterface nonNullOther;
+  attribute IndirectlyImplementedInterface? nullableOther;
+  // Optional arguments
+  void passOptionalOther(optional IndirectlyImplementedInterface? arg);
+  void passOptionalNonNullOther(optional IndirectlyImplementedInterface arg);
+  void passOptionalOtherWithDefault(optional IndirectlyImplementedInterface? arg = null);
+
+  // External interface types
+  TestExternalInterface receiveExternal();
+  TestExternalInterface? receiveNullableExternal();
+  TestExternalInterface receiveWeakExternal();
+  TestExternalInterface? receiveWeakNullableExternal();
+  void passExternal(TestExternalInterface arg);
+  void passNullableExternal(TestExternalInterface? arg);
+  attribute TestExternalInterface nonNullExternal;
+  attribute TestExternalInterface? nullableExternal;
+  // Optional arguments
+  void passOptionalExternal(optional TestExternalInterface? arg);
+  void passOptionalNonNullExternal(optional TestExternalInterface arg);
+  void passOptionalExternalWithDefault(optional TestExternalInterface? arg = null);
+
+  // Callback interface types
+  TestCallbackInterface receiveCallbackInterface();
+  TestCallbackInterface? receiveNullableCallbackInterface();
+  TestCallbackInterface receiveWeakCallbackInterface();
+  TestCallbackInterface? receiveWeakNullableCallbackInterface();
+  void passCallbackInterface(TestCallbackInterface arg);
+  void passNullableCallbackInterface(TestCallbackInterface? arg);
+  attribute TestCallbackInterface nonNullCallbackInterface;
+  attribute TestCallbackInterface? nullableCallbackInterface;
+  // Optional arguments
+  void passOptionalCallbackInterface(optional TestCallbackInterface? arg);
+  void passOptionalNonNullCallbackInterface(optional TestCallbackInterface arg);
+  void passOptionalCallbackInterfaceWithDefault(optional TestCallbackInterface? arg = null);
+
+  // Miscellaneous interface tests
+  IndirectlyImplementedInterface receiveConsequentialInterface();
+  void passConsequentialInterface(IndirectlyImplementedInterface arg);
+
+  // Sequence types
+  [Cached, Pure]
+  readonly attribute sequence<long> readonlySequence;
+  [Cached, Pure]
+  readonly attribute sequence<Dict> readonlySequenceOfDictionaries;
+  [Cached, Pure]
+  readonly attribute sequence<Dict>? readonlyNullableSequenceOfDictionaries;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<long> readonlyFrozenSequence;
+  [Cached, Pure, Frozen]
+  readonly attribute sequence<long>? readonlyFrozenNullableSequence;
+  sequence<long> receiveSequence();
+  sequence<long>? receiveNullableSequence();
+  sequence<long?> receiveSequenceOfNullableInts();
+  sequence<long?>? receiveNullableSequenceOfNullableInts();
+  void passSequence(sequence<long> arg);
+  void passNullableSequence(sequence<long>? arg);
+  void passSequenceOfNullableInts(sequence<long?> arg);
+  void passOptionalSequenceOfNullableInts(optional sequence<long?> arg);
+  void passOptionalNullableSequenceOfNullableInts(optional sequence<long?>? arg);
+  sequence<TestJSImplInterface> receiveCastableObjectSequence();
+  sequence<TestCallbackInterface> receiveCallbackObjectSequence();
+  sequence<TestJSImplInterface?> receiveNullableCastableObjectSequence();
+  sequence<TestCallbackInterface?> receiveNullableCallbackObjectSequence();
+  sequence<TestJSImplInterface>? receiveCastableObjectNullableSequence();
+  sequence<TestJSImplInterface?>? receiveNullableCastableObjectNullableSequence();
+  sequence<TestJSImplInterface> receiveWeakCastableObjectSequence();
+  sequence<TestJSImplInterface?> receiveWeakNullableCastableObjectSequence();
+  sequence<TestJSImplInterface>? receiveWeakCastableObjectNullableSequence();
+  sequence<TestJSImplInterface?>? receiveWeakNullableCastableObjectNullableSequence();
+  void passCastableObjectSequence(sequence<TestJSImplInterface> arg);
+  void passNullableCastableObjectSequence(sequence<TestJSImplInterface?> arg);
+  void passCastableObjectNullableSequence(sequence<TestJSImplInterface>? arg);
+  void passNullableCastableObjectNullableSequence(sequence<TestJSImplInterface?>? arg);
+  void passOptionalSequence(optional sequence<long> arg);
+  void passOptionalSequenceWithDefaultValue(optional sequence<long> arg = []);
+  void passOptionalNullableSequence(optional sequence<long>? arg);
+  void passOptionalNullableSequenceWithDefaultValue(optional sequence<long>? arg = null);
+  void passOptionalNullableSequenceWithDefaultValue2(optional sequence<long>? arg = []);
+  void passOptionalObjectSequence(optional sequence<TestJSImplInterface> arg);
+  void passExternalInterfaceSequence(sequence<TestExternalInterface> arg);
+  void passNullableExternalInterfaceSequence(sequence<TestExternalInterface?> arg);
+
+  sequence<DOMString> receiveStringSequence();
+  sequence<ByteString> receiveByteStringSequence();
+  // Callback interface problem.  See bug 843261.
+  //void passStringSequence(sequence<DOMString> arg);
+  sequence<any> receiveAnySequence();
+  sequence<any>? receiveNullableAnySequence();
+  //XXXbz No support for sequence of sequence return values yet.
+  //sequence<sequence<any>> receiveAnySequenceSequence();
+
+  sequence<object> receiveObjectSequence();
+  sequence<object?> receiveNullableObjectSequence();
+
+  void passSequenceOfSequences(sequence<sequence<long>> arg);
+  void passSequenceOfSequencesOfSequences(sequence<sequence<sequence<long>>> arg);
+  //XXXbz No support for sequence of sequence return values yet.
+  //sequence<sequence<long>> receiveSequenceOfSequences();
+
+  // MozMap types
+  void passMozMap(MozMap<long> arg);
+  void passNullableMozMap(MozMap<long>? arg);
+  void passMozMapOfNullableInts(MozMap<long?> arg);
+  void passOptionalMozMapOfNullableInts(optional MozMap<long?> arg);
+  void passOptionalNullableMozMapOfNullableInts(optional MozMap<long?>? arg);
+  void passCastableObjectMozMap(MozMap<TestJSImplInterface> arg);
+  void passNullableCastableObjectMozMap(MozMap<TestJSImplInterface?> arg);
+  void passCastableObjectNullableMozMap(MozMap<TestJSImplInterface>? arg);
+  void passNullableCastableObjectNullableMozMap(MozMap<TestJSImplInterface?>? arg);
+  void passOptionalMozMap(optional MozMap<long> arg);
+  void passOptionalNullableMozMap(optional MozMap<long>? arg);
+  void passOptionalNullableMozMapWithDefaultValue(optional MozMap<long>? arg = null);
+  void passOptionalObjectMozMap(optional MozMap<TestJSImplInterface> arg);
+  void passExternalInterfaceMozMap(MozMap<TestExternalInterface> arg);
+  void passNullableExternalInterfaceMozMap(MozMap<TestExternalInterface?> arg);
+  void passStringMozMap(MozMap<DOMString> arg);
+  void passByteStringMozMap(MozMap<ByteString> arg);
+  void passMozMapOfMozMaps(MozMap<MozMap<long>> arg);
+  MozMap<long> receiveMozMap();
+  MozMap<long>? receiveNullableMozMap();
+  MozMap<long?> receiveMozMapOfNullableInts();
+  MozMap<long?>? receiveNullableMozMapOfNullableInts();
+  //XXXbz No support for MozMap of MozMaps return values yet.
+  //MozMap<MozMap<long>> receiveMozMapOfMozMaps();
+  MozMap<any> receiveAnyMozMap();
+
+  // Typed array types
+  void passArrayBuffer(ArrayBuffer arg);
+  void passNullableArrayBuffer(ArrayBuffer? arg);
+  void passOptionalArrayBuffer(optional ArrayBuffer arg);
+  void passOptionalNullableArrayBuffer(optional ArrayBuffer? arg);
+  void passOptionalNullableArrayBufferWithDefaultValue(optional ArrayBuffer? arg= null);
+  void passArrayBufferView(ArrayBufferView arg);
+  void passInt8Array(Int8Array arg);
+  void passInt16Array(Int16Array arg);
+  void passInt32Array(Int32Array arg);
+  void passUint8Array(Uint8Array arg);
+  void passUint16Array(Uint16Array arg);
+  void passUint32Array(Uint32Array arg);
+  void passUint8ClampedArray(Uint8ClampedArray arg);
+  void passFloat32Array(Float32Array arg);
+  void passFloat64Array(Float64Array arg);
+  void passSequenceOfArrayBuffers(sequence<ArrayBuffer> arg);
+  void passSequenceOfNullableArrayBuffers(sequence<ArrayBuffer?> arg);
+  void passMozMapOfArrayBuffers(MozMap<ArrayBuffer> arg);
+  void passMozMapOfNullableArrayBuffers(MozMap<ArrayBuffer?> arg);
+  void passVariadicTypedArray(Float32Array... arg);
+  void passVariadicNullableTypedArray(Float32Array?... arg);
+  Uint8Array receiveUint8Array();
+  attribute Uint8Array uint8ArrayAttr;
+
+  // DOMString types
+  void passString(DOMString arg);
+  void passNullableString(DOMString? arg);
+  void passOptionalString(optional DOMString arg);
+  void passOptionalStringWithDefaultValue(optional DOMString arg = "abc");
+  void passOptionalNullableString(optional DOMString? arg);
+  void passOptionalNullableStringWithDefaultValue(optional DOMString? arg = null);
+  void passVariadicString(DOMString... arg);
+
+  // ByteString types
+  void passByteString(ByteString arg);
+  void passNullableByteString(ByteString? arg);
+  void passOptionalByteString(optional ByteString arg);
+  void passOptionalByteStringWithDefaultValue(optional ByteString arg = "abc");
+  void passOptionalNullableByteString(optional ByteString? arg);
+  void passOptionalNullableByteStringWithDefaultValue(optional ByteString? arg = null);
+  void passVariadicByteString(ByteString... arg);
+  void passUnionByteString((ByteString or long) arg);
+  void passOptionalUnionByteString(optional (ByteString or long) arg);
+  void passOptionalUnionByteStringWithDefaultValue(optional (ByteString or long) arg = "abc");
+
+  // USVString types
+  void passSVS(USVString arg);
+  void passNullableSVS(USVString? arg);
+  void passOptionalSVS(optional USVString arg);
+  void passOptionalSVSWithDefaultValue(optional USVString arg = "abc");
+  void passOptionalNullableSVS(optional USVString? arg);
+  void passOptionalNullableSVSWithDefaultValue(optional USVString? arg = null);
+  void passVariadicSVS(USVString... arg);
+  USVString receiveSVS();
+
+  // Enumerated types
+  void passEnum(MyTestEnum arg);
+  void passNullableEnum(MyTestEnum? arg);
+  void passOptionalEnum(optional MyTestEnum arg);
+  void passEnumWithDefault(optional MyTestEnum arg = "a");
+  void passOptionalNullableEnum(optional MyTestEnum? arg);
+  void passOptionalNullableEnumWithDefaultValue(optional MyTestEnum? arg = null);
+  void passOptionalNullableEnumWithDefaultValue2(optional MyTestEnum? arg = "a");
+  MyTestEnum receiveEnum();
+  MyTestEnum? receiveNullableEnum();
+  attribute MyTestEnum enumAttribute;
+  readonly attribute MyTestEnum readonlyEnumAttribute;
+
+  // Callback types
+  void passCallback(MyTestCallback arg);
+  void passNullableCallback(MyTestCallback? arg);
+  void passOptionalCallback(optional MyTestCallback arg);
+  void passOptionalNullableCallback(optional MyTestCallback? arg);
+  void passOptionalNullableCallbackWithDefaultValue(optional MyTestCallback? arg = null);
+  MyTestCallback receiveCallback();
+  MyTestCallback? receiveNullableCallback();
+  // Hmm. These two don't work, I think because I need a locally modified version of TestTreatAsNullCallback.
+  //void passNullableTreatAsNullCallback(TestTreatAsNullCallback? arg);
+  //void passOptionalNullableTreatAsNullCallback(optional TestTreatAsNullCallback? arg);
+  void passOptionalNullableTreatAsNullCallbackWithDefaultValue(optional TestTreatAsNullCallback? arg = null);
+
+  // Any types
+  void passAny(any arg);
+  void passVariadicAny(any... arg);
+  void passOptionalAny(optional any arg);
+  void passAnyDefaultNull(optional any arg = null);
+  void passSequenceOfAny(sequence<any> arg);
+  void passNullableSequenceOfAny(sequence<any>? arg);
+  void passOptionalSequenceOfAny(optional sequence<any> arg);
+  void passOptionalNullableSequenceOfAny(optional sequence<any>? arg);
+  void passOptionalSequenceOfAnyWithDefaultValue(optional sequence<any>? arg = null);
+  void passSequenceOfSequenceOfAny(sequence<sequence<any>> arg);
+  void passSequenceOfNullableSequenceOfAny(sequence<sequence<any>?> arg);
+  void passNullableSequenceOfNullableSequenceOfAny(sequence<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfAny(optional sequence<sequence<any>?>? arg);
+  void passMozMapOfAny(MozMap<any> arg);
+  void passNullableMozMapOfAny(MozMap<any>? arg);
+  void passOptionalMozMapOfAny(optional MozMap<any> arg);
+  void passOptionalNullableMozMapOfAny(optional MozMap<any>? arg);
+  void passOptionalMozMapOfAnyWithDefaultValue(optional MozMap<any>? arg = null);
+  void passMozMapOfMozMapOfAny(MozMap<MozMap<any>> arg);
+  void passMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?> arg);
+  void passNullableMozMapOfNullableMozMapOfAny(MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableMozMapOfAny(optional MozMap<MozMap<any>?>? arg);
+  void passOptionalNullableMozMapOfNullableSequenceOfAny(optional MozMap<sequence<any>?>? arg);
+  void passOptionalNullableSequenceOfNullableMozMapOfAny(optional sequence<MozMap<any>?>? arg);
+  any receiveAny();
+
+  // object types
+  void passObject(object arg);
+  void passVariadicObject(object... arg);
+  void passNullableObject(object? arg);
+  void passVariadicNullableObject(object... arg);
+  void passOptionalObject(optional object arg);
+  void passOptionalNullableObject(optional object? arg);
+  void passOptionalNullableObjectWithDefaultValue(optional object? arg = null);
+  void passSequenceOfObject(sequence<object> arg);
+  void passSequenceOfNullableObject(sequence<object?> arg);
+  void passNullableSequenceOfObject(sequence<object>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfObject(optional sequence<sequence<object>?>? arg);
+  void passOptionalNullableSequenceOfNullableSequenceOfNullableObject(optional sequence<sequence<object?>?>? arg);
+  void passMozMapOfObject(MozMap<object> arg);
+  object receiveObject();
+  object? receiveNullableObject();
+
+  // Union types
+  void passUnion((object or long) arg);
+  // Some union tests are debug-only to avoid creating all those
+  // unused union types in opt builds.
+#ifdef DEBUG
+  void passUnion2((long or boolean) arg);
+  void passUnion3((object or long or boolean) arg);
+  void passUnion4((Node or long or boolean) arg);
+  void passUnion5((object or boolean) arg);
+  void passUnion6((object or DOMString) arg);
+  void passUnion7((object or DOMString or long) arg);
+  void passUnion8((object or DOMString or boolean) arg);
+  void passUnion9((object or DOMString or long or boolean) arg);
+  void passUnion10(optional (EventInit or long) arg);
+  void passUnion11(optional (CustomEventInit or long) arg);
+  void passUnion12(optional (EventInit or long) arg = 5);
+  void passUnion13(optional (object or long?) arg = null);
+  void passUnion14(optional (object or long?) arg = 5);
+  void passUnion15((sequence<long> or long) arg);
+  void passUnion16(optional (sequence<long> or long) arg);
+  void passUnion17(optional (sequence<long>? or long) arg = 5);
+  void passUnion18((sequence<object> or long) arg);
+  void passUnion19(optional (sequence<object> or long) arg);
+  void passUnion20(optional (sequence<object> or long) arg = []);
+  void passUnion21((MozMap<long> or long) arg);
+  void passUnion22((MozMap<object> or long) arg);
+  void passUnion23((sequence<ImageData> or long) arg);
+  void passUnion24((sequence<ImageData?> or long) arg);
+  void passUnion25((sequence<sequence<ImageData>> or long) arg);
+  void passUnion26((sequence<sequence<ImageData?>> or long) arg);
+  void passUnion27(optional (sequence<DOMString> or EventInit) arg);
+  void passUnion28(optional (EventInit or sequence<DOMString>) arg);
+  void passUnionWithCallback((EventHandler or long) arg);
+  void passUnionWithByteString((ByteString or long) arg);
+  void passUnionWithMozMap((MozMap<DOMString> or DOMString) arg);
+  void passUnionWithMozMapAndSequence((MozMap<DOMString> or sequence<DOMString>) arg);
+  void passUnionWithSequenceAndMozMap((sequence<DOMString> or MozMap<DOMString>) arg);
+  void passUnionWithSVS((USVString or long) arg);
+#endif
+  void passUnionWithNullable((object? or long) arg);
+  void passNullableUnion((object or long)? arg);
+  void passOptionalUnion(optional (object or long) arg);
+  void passOptionalNullableUnion(optional (object or long)? arg);
+  void passOptionalNullableUnionWithDefaultValue(optional (object or long)? arg = null);
+  //void passUnionWithInterfaces((TestJSImplInterface or TestExternalInterface) arg);
+  //void passUnionWithInterfacesAndNullable((TestJSImplInterface? or TestExternalInterface) arg);
+  //void passUnionWithSequence((sequence<object> or long) arg);
+  void passUnionWithArrayBuffer((ArrayBuffer or long) arg);
+  void passUnionWithString((DOMString or object) arg);
+  // Using an enum in a union.  Note that we use some enum not declared in our
+  // binding file, because UnionTypes.h will need to include the binding header
+  // for this enum.  Pick an enum from an interface that won't drag in too much
+  // stuff.
+  void passUnionWithEnum((SupportedType or object) arg);
+
+  // Trying to use a callback in a union won't include the test
+  // headers, unfortunately, so won't compile.
+  //  void passUnionWithCallback((MyTestCallback or long) arg);
+  void passUnionWithObject((object or long) arg);
+  //void passUnionWithDict((Dict or long) arg);
+
+  void passUnionWithDefaultValue1(optional (double or DOMString) arg = "");
+  void passUnionWithDefaultValue2(optional (double or DOMString) arg = 1);
+  void passUnionWithDefaultValue3(optional (double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue4(optional (float or DOMString) arg = "");
+  void passUnionWithDefaultValue5(optional (float or DOMString) arg = 1);
+  void passUnionWithDefaultValue6(optional (float or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue7(optional (unrestricted double or DOMString) arg = "");
+  void passUnionWithDefaultValue8(optional (unrestricted double or DOMString) arg = 1);
+  void passUnionWithDefaultValue9(optional (unrestricted double or DOMString) arg = 1.5);
+  void passUnionWithDefaultValue10(optional (unrestricted double or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue11(optional (unrestricted float or DOMString) arg = "");
+  void passUnionWithDefaultValue12(optional (unrestricted float or DOMString) arg = 1);
+  void passUnionWithDefaultValue13(optional (unrestricted float or DOMString) arg = Infinity);
+  void passUnionWithDefaultValue14(optional (double or ByteString) arg = "");
+  void passUnionWithDefaultValue15(optional (double or ByteString) arg = 1);
+  void passUnionWithDefaultValue16(optional (double or ByteString) arg = 1.5);
+  void passUnionWithDefaultValue17(optional (double or SupportedType) arg = "text/html");
+  void passUnionWithDefaultValue18(optional (double or SupportedType) arg = 1);
+  void passUnionWithDefaultValue19(optional (double or SupportedType) arg = 1.5);
+
+  void passNullableUnionWithDefaultValue1(optional (double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue2(optional (double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue3(optional (double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue4(optional (float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue5(optional (float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue6(optional (float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue7(optional (unrestricted double or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue8(optional (unrestricted double or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue9(optional (unrestricted double or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue10(optional (unrestricted float or DOMString)? arg = "");
+  void passNullableUnionWithDefaultValue11(optional (unrestricted float or DOMString)? arg = 1);
+  void passNullableUnionWithDefaultValue12(optional (unrestricted float or DOMString)? arg = null);
+  void passNullableUnionWithDefaultValue13(optional (double or ByteString)? arg = "");
+  void passNullableUnionWithDefaultValue14(optional (double or ByteString)? arg = 1);
+  void passNullableUnionWithDefaultValue15(optional (double or ByteString)? arg = 1.5);
+  void passNullableUnionWithDefaultValue16(optional (double or ByteString)? arg = null);
+  void passNullableUnionWithDefaultValue17(optional (double or SupportedType)? arg = "text/html");
+  void passNullableUnionWithDefaultValue18(optional (double or SupportedType)? arg = 1);
+  void passNullableUnionWithDefaultValue19(optional (double or SupportedType)? arg = 1.5);
+  void passNullableUnionWithDefaultValue20(optional (double or SupportedType)? arg = null);
+
+  void passSequenceOfUnions(sequence<(CanvasPattern or CanvasGradient)> arg);
+  void passSequenceOfUnions2(sequence<(object or long)> arg);
+  void passVariadicUnion((CanvasPattern or CanvasGradient)... arg);
+
+  void passSequenceOfNullableUnions(sequence<(CanvasPattern or CanvasGradient)?> arg);
+  void passVariadicNullableUnion((CanvasPattern or CanvasGradient)?... arg);
+  void passMozMapOfUnions(MozMap<(CanvasPattern or CanvasGradient)> arg);
+  // XXXbz no move constructor on some unions
+  // void passMozMapOfUnions2(MozMap<(object or long)> arg);
+
+  (CanvasPattern or CanvasGradient) receiveUnion();
+  (object or long) receiveUnion2();
+  (CanvasPattern? or CanvasGradient) receiveUnionContainingNull();
+  (CanvasPattern or CanvasGradient)? receiveNullableUnion();
+  (object or long)? receiveNullableUnion2();
+
+  attribute (CanvasPattern or CanvasGradient) writableUnion;
+  attribute (CanvasPattern? or CanvasGradient) writableUnionContainingNull;
+  attribute (CanvasPattern or CanvasGradient)? writableNullableUnion;
+
+  // Date types
+  void passDate(Date arg);
+  void passNullableDate(Date? arg);
+  void passOptionalDate(optional Date arg);
+  void passOptionalNullableDate(optional Date? arg);
+  void passOptionalNullableDateWithDefaultValue(optional Date? arg = null);
+  void passDateSequence(sequence<Date> arg);
+  void passNullableDateSequence(sequence<Date?> arg);
+  void passDateMozMap(MozMap<Date> arg);
+  Date receiveDate();
+  Date? receiveNullableDate();
+
+  // Promise types
+  void passPromise(Promise<any> arg);
+  void passNullablePromise(Promise<any>? arg);
+  void passOptionalPromise(optional Promise<any> arg);
+  void passOptionalNullablePromise(optional Promise<any>? arg);
+  void passOptionalNullablePromiseWithDefaultValue(optional Promise<any>? arg = null);
+  void passPromiseSequence(sequence<Promise<any>> arg);
+  void passNullablePromiseSequence(sequence<Promise<any>?> arg);
+  Promise<any> receivePromise();
+  Promise<any> receiveAddrefedPromise();
+
+  // binaryNames tests
+  void methodRenamedFrom();
+  [BinaryName="otherMethodRenamedTo"]
+  void otherMethodRenamedFrom();
+  void methodRenamedFrom(byte argument);
+  readonly attribute byte attributeGetterRenamedFrom;
+  attribute byte attributeRenamedFrom;
+  [BinaryName="otherAttributeRenamedTo"]
+  attribute byte otherAttributeRenamedFrom;
+
+  void passDictionary(optional Dict x);
+  void passDictionary2(Dict x);
+  [Cached, Pure]
+  readonly attribute Dict readonlyDictionary;
+  [Cached, Pure]
+  readonly attribute Dict? readonlyNullableDictionary;
+  [Cached, Pure]
+  attribute Dict writableDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict readonlyFrozenDictionary;
+  [Cached, Pure, Frozen]
+  readonly attribute Dict? readonlyFrozenNullableDictionary;
+  [Cached, Pure, Frozen]
+  attribute Dict writableFrozenDictionary;
+  Dict receiveDictionary();
+  Dict? receiveNullableDictionary();
+  void passOtherDictionary(optional GrandparentDict x);
+  void passSequenceOfDictionaries(sequence<Dict> x);
+  void passMozMapOfDictionaries(MozMap<GrandparentDict> x);
+  // No support for nullable dictionaries inside a sequence (nor should there be)
+  //  void passSequenceOfNullableDictionaries(sequence<Dict?> x);
+  void passDictionaryOrLong(optional Dict x);
+  void passDictionaryOrLong(long x);
+
+  void passDictContainingDict(optional DictContainingDict arg);
+  void passDictContainingSequence(optional DictContainingSequence arg);
+  DictContainingSequence receiveDictContainingSequence();
+  void passVariadicDictionary(Dict... arg);
+
+  // EnforceRange/Clamp tests
+  void dontEnforceRangeOrClamp(byte arg);
+  void doEnforceRange([EnforceRange] byte arg);
+  void doClamp([Clamp] byte arg);
+  [EnforceRange] attribute byte enforcedByte;
+  [Clamp] attribute byte clampedByte;
+
+  // Typedefs
+  const myLong myLongConstant = 5;
+  void exerciseTypedefInterfaces1(AnotherNameForTestJSImplInterface arg);
+  AnotherNameForTestJSImplInterface exerciseTypedefInterfaces2(NullableTestJSImplInterface arg);
+  void exerciseTypedefInterfaces3(YetAnotherNameForTestJSImplInterface arg);
+
+  // Deprecated methods and attributes
+  [Deprecated="GetAttributeNode"]
+  attribute byte deprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  byte deprecatedMethod();
+  [Deprecated="GetAttributeNode"]
+  void deprecatedMethodWithContext(any arg);
+
+  // Static methods and attributes
+  // FIXME: Bug 863952 Static things are not supported yet
+  /*
+  static attribute boolean staticAttribute;
+  static void staticMethod(boolean arg);
+  static void staticMethodWithContext(any arg);
+
+  // Deprecated static methods and attributes
+  [Deprecated="GetAttributeNode"]
+  static attribute byte staticDeprecatedAttribute;
+  [Deprecated="GetAttributeNode"]
+  static byte staticDeprecatedMethod();
+  [Deprecated="GetAttributeNode"]
+  static byte staticDeprecatedMethodWithContext();
+  */
+
+  // Overload resolution tests
+  //void overload1(DOMString... strs);
+  boolean overload1(TestJSImplInterface arg);
+  TestJSImplInterface overload1(DOMString strs, TestJSImplInterface arg);
+  void overload2(TestJSImplInterface arg);
+  void overload2(optional Dict arg);
+  void overload2(boolean arg);
+  void overload2(DOMString arg);
+  void overload2(Date arg);
+  void overload3(TestJSImplInterface arg);
+  void overload3(MyTestCallback arg);
+  void overload3(boolean arg);
+  void overload4(TestJSImplInterface arg);
+  void overload4(TestCallbackInterface arg);
+  void overload4(DOMString arg);
+  void overload5(long arg);
+  void overload5(MyTestEnum arg);
+  void overload6(long arg);
+  void overload6(boolean arg);
+  void overload7(long arg);
+  void overload7(boolean arg);
+  void overload7(ByteString arg);
+  void overload8(long arg);
+  void overload8(TestJSImplInterface arg);
+  void overload9(long? arg);
+  void overload9(DOMString arg);
+  void overload10(long? arg);
+  void overload10(object arg);
+  void overload11(long arg);
+  void overload11(DOMString? arg);
+  void overload12(long arg);
+  void overload12(boolean? arg);
+  void overload13(long? arg);
+  void overload13(boolean arg);
+  void overload14(optional long arg);
+  void overload14(TestInterface arg);
+  void overload15(long arg);
+  void overload15(optional TestInterface arg);
+  void overload16(long arg);
+  void overload16(optional TestInterface? arg);
+  void overload17(sequence<long> arg);
+  void overload17(MozMap<long> arg);
+  void overload18(MozMap<DOMString> arg);
+  void overload18(sequence<DOMString> arg);
+  void overload19(sequence<long> arg);
+  void overload19(optional Dict arg);
+  void overload20(optional Dict arg);
+  void overload20(sequence<long> arg);
+
+  // Variadic handling
+  void passVariadicThirdArg(DOMString arg1, long arg2, TestJSImplInterface... arg3);
+
+  // Conditionally exposed methods/attributes
+  [Pref="abc.def"]
+  readonly attribute boolean prefable1;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable2;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable3;
+  [Pref="ghi.jkl"]
+  readonly attribute boolean prefable4;
+  [Pref="abc.def"]
+  readonly attribute boolean prefable5;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable6;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable7;
+  [Pref="ghi.jkl", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable8;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean prefable9;
+  [Pref="abc.def"]
+  void prefable10();
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable11();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable12;
+  [Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void prefable13();
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable14;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable15;
+  [Func="TestFuncControlledMember"]
+  readonly attribute boolean prefable16;
+  [Pref="abc.def", Func="TestFuncControlledMember"]
+  void prefable17();
+  [Func="TestFuncControlledMember"]
+  void prefable18();
+  [Func="TestFuncControlledMember"]
+  void prefable19();
+  [Pref="abc.def", Func="TestFuncControlledMember", ChromeOnly]
+  void prefable20();
+
+  // Conditionally exposed methods/attributes involving [SecureContext]
+  [SecureContext]
+  readonly attribute boolean conditionalOnSecureContext1;
+  [SecureContext, Pref="abc.def"]
+  readonly attribute boolean conditionalOnSecureContext2;
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  readonly attribute boolean conditionalOnSecureContext3;
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  readonly attribute boolean conditionalOnSecureContext4;
+  [SecureContext]
+  void conditionalOnSecureContext5();
+  [SecureContext, Pref="abc.def"]
+  void conditionalOnSecureContext6();
+  [SecureContext, Pref="abc.def", Func="nsGenericHTMLElement::TouchEventsEnabled"]
+  void conditionalOnSecureContext7();
+  [SecureContext, Pref="abc.def", Func="TestFuncControlledMember"]
+  void conditionalOnSecureContext8();
+
+  // Miscellania
+  [LenientThis] attribute long attrWithLenientThis;
+  // FIXME: Bug 863954 Unforgeable things get all confused when
+  // non-JS-implemented interfaces inherit from JS-implemented ones or vice
+  // versa.
+  //   [Unforgeable] readonly attribute long unforgeableAttr;
+  //   [Unforgeable, ChromeOnly] readonly attribute long unforgeableAttr2;
+  //   [Unforgeable] long unforgeableMethod();
+  //   [Unforgeable, ChromeOnly] long unforgeableMethod2();
+  // FIXME: Bug 863955 No stringifiers yet
+  //   stringifier;
+  void passRenamedInterface(TestRenamedInterface arg);
+  [PutForwards=writableByte] readonly attribute TestJSImplInterface putForwardsAttr;
+  [PutForwards=writableByte, LenientThis] readonly attribute TestJSImplInterface putForwardsAttr2;
+  [PutForwards=writableByte, ChromeOnly] readonly attribute TestJSImplInterface putForwardsAttr3;
+  [Throws] void throwingMethod();
+  [Throws] attribute boolean throwingAttr;
+  [GetterThrows] attribute boolean throwingGetterAttr;
+  [SetterThrows] attribute boolean throwingSetterAttr;
+  // NeedsSubjectPrincipal not supported on JS-implemented things for
+  // now, because we always pass in the caller principal anyway.
+  //  [NeedsSubjectPrincipal] void needsSubjectPrincipalMethod();
+  //  [NeedsSubjectPrincipal] attribute boolean needsSubjectPrincipalAttr;
+  // legacycaller short(unsigned long arg1, TestInterface arg2);
+  void passArgsWithDefaults(optional long arg1,
+                            optional TestInterface? arg2 = null,
+                            optional Dict arg3, optional double arg4 = 5.0,
+                            optional float arg5);
+  attribute any jsonifierShouldSkipThis;
+  attribute TestParentInterface jsonifierShouldSkipThis2;
+  attribute TestCallbackInterface jsonifierShouldSkipThis3;
+  jsonifier;
+
+  attribute byte dashed-attribute;
+  void dashed-method();
+
+  // If you add things here, add them to TestCodeGen as well
+};
+
+[NavigatorProperty="TestNavigator", JSImplementation="@mozilla.org/test;1"]
+interface TestNavigator {
+};
+
+[Constructor, NavigatorProperty="TestNavigatorWithConstructor", JSImplementation="@mozilla.org/test;1"]
+interface TestNavigatorWithConstructor {
+};
+
+interface TestCImplementedInterface : TestJSImplInterface {
+};
+
+interface TestCImplementedInterface2 {
+};
+
+[NoInterfaceObject,
+ JSImplementation="@mozilla.org/test-js-impl-interface;2"]
+interface TestJSImplNoInterfaceObject {
+  [Cached, Pure]
+  readonly attribute byte cachedByte;
+};
diff --git a/dom/bindings/test/TestJSImplInheritanceGen.webidl b/dom/bindings/test/TestJSImplInheritanceGen.webidl
new file mode 100644
index 000000000..e62dbd10b
--- /dev/null
+++ b/dom/bindings/test/TestJSImplInheritanceGen.webidl
@@ -0,0 +1,29 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+[Constructor, JSImplementation="@mozilla.org/test-js-impl-interface2;1"]
+interface TestJSImplInterface2 :  TestCImplementedInterface {
+};
+
+[Constructor, JSImplementation="@mozilla.org/test-js-impl-interface3;1"]
+interface TestJSImplInterface3 : TestCImplementedInterface2 {
+};
+
+// Important: TestJSImplInterface5 needs to come before TestJSImplInterface6 in
+// this file to test what it's trying to test.
+[Constructor, JSImplementation="@mozilla.org/test-js-impl-interface5;1"]
+interface TestJSImplInterface5 : TestJSImplInterface6 {
+};
+
+// Important: TestJSImplInterface6 needs to come after TestJSImplInterface3 in
+// this file to test what it's trying to test.
+[Constructor, JSImplementation="@mozilla.org/test-js-impl-interface6;1"]
+interface TestJSImplInterface6 : TestJSImplInterface3 {
+};
+
+[Constructor, JSImplementation="@mozilla.org/test-js-impl-interface4;1"]
+interface TestJSImplInterface4 : EventTarget {
+};
diff --git a/dom/bindings/test/TestTypedef.webidl b/dom/bindings/test/TestTypedef.webidl
new file mode 100644
index 000000000..7f758c79e
--- /dev/null
+++ b/dom/bindings/test/TestTypedef.webidl
@@ -0,0 +1,7 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+typedef TestInterface YetAnotherNameForTestInterface;
diff --git a/dom/bindings/test/chrome.ini b/dom/bindings/test/chrome.ini
new file mode 100644
index 000000000..9fdbd7fd3
--- /dev/null
+++ b/dom/bindings/test/chrome.ini
@@ -0,0 +1,22 @@
+[DEFAULT]
+support-files =
+  !/dom/bindings/test/file_bug775543.html
+  !/dom/bindings/test/file_document_location_set_via_xray.html
+  !/dom/bindings/test/file_dom_xrays.html
+  !/dom/bindings/test/file_proxies_via_xray.html
+
+[test_bug775543.html]
+[test_document_location_set_via_xray.html]
+[test_dom_xrays.html]
+[test_proxies_via_xray.html]
+[test_document_location_via_xray_cached.html]
+[test_blacklisted_prerendering_function.xul]
+support-files =
+  file_focuser.html
+  file_fullScreenPropertyAccessor.html
+skip-if = e10s # prerendering doesn't work in e10s yet
+[test_kill_longrunning_prerendered_content.xul]
+skip-if = e10s # prerendering doesn't work in e10s yet
+[test_bug1123516_maplikesetlikechrome.xul]
+skip-if = debug == false
+[test_bug1287912.html]
diff --git a/dom/bindings/test/file_InstanceOf.html b/dom/bindings/test/file_InstanceOf.html
new file mode 100644
index 000000000..487010fa4
--- /dev/null
+++ b/dom/bindings/test/file_InstanceOf.html
@@ -0,0 +1,12 @@
+<!DOCTYPE HTML>
+<html>
+<body>
+<script type="application/javascript">
+function runTest()
+{
+  return [ parent.HTMLElement.prototype instanceof Element,
+           parent.HTMLElement.prototype instanceof parent.Element ];
+}
+</script>
+</body>
+</html>
diff --git a/dom/bindings/test/file_bug775543.html b/dom/bindings/test/file_bug775543.html
new file mode 100644
index 000000000..ee8c14c4d
--- /dev/null
+++ b/dom/bindings/test/file_bug775543.html
@@ -0,0 +1,5 @@
+<body>
+<script>
+worker = new Worker("a");
+</script>
+</body>
diff --git a/dom/bindings/test/file_document_location_set_via_xray.html b/dom/bindings/test/file_document_location_set_via_xray.html
new file mode 100644
index 000000000..323acba66
--- /dev/null
+++ b/dom/bindings/test/file_document_location_set_via_xray.html
@@ -0,0 +1,5 @@
+<body>
+<script>
+document.x = 5;
+</script>
+</body>
diff --git a/dom/bindings/test/file_dom_xrays.html b/dom/bindings/test/file_dom_xrays.html
new file mode 100644
index 000000000..36b3f8a30
--- /dev/null
+++ b/dom/bindings/test/file_dom_xrays.html
@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html>
+  <script>
+    window.expando = 42;
+    window.shadowedIframe = 42;
+    Object.setPrototypeOf(window, Object.create(Window.prototype,
+      {
+        shadowedIframe: { value: 42 },
+        iframe: { value: 42 },
+        document: { value: 42 },
+        addEventListener: { value: 42 },
+        toString: { value: 42 }
+      }));
+    window.documentElement.expando = 42;
+    Object.defineProperty(window.documentElement, "version", { value: 42 });
+  </script>
+  <iframe name="shadowedIframe" id="shadowedIframe"></iframe>
+  <iframe name="iframe" id="iframe"></iframe>
+  <iframe name="document" id="document"></iframe>
+  <iframe name="self" id="self"></iframe>
+  <iframe name="addEventListener" id="addEventListener"></iframe>
+  <iframe name="toString" id="toString"></iframe>
+  <iframe name="item" id="item"></iframe>
+</html>
diff --git a/dom/bindings/test/file_focuser.html b/dom/bindings/test/file_focuser.html
new file mode 100644
index 000000000..0d5240f95
--- /dev/null
+++ b/dom/bindings/test/file_focuser.html
@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+<div id="stage"></div>
+<script>
+  function stage(str) {
+    var s = document.getElementById("stage");
+    s.textContent = str;
+  }
+  stage("before");
+  setTimeout(function() {
+    stage("in timeout");
+  });
+  setInterval(function() {
+    stage("in interval");
+  });
+  addEventListener("keydown", function() {
+    stage("keydown");
+  }, false);
+  try {
+    focus();
+    stage("after");
+  } catch(e) {
+    stage("exception raised");
+  }
+</script>
diff --git a/dom/bindings/test/file_fullScreenPropertyAccessor.html b/dom/bindings/test/file_fullScreenPropertyAccessor.html
new file mode 100644
index 000000000..92a37e0ba
--- /dev/null
+++ b/dom/bindings/test/file_fullScreenPropertyAccessor.html
@@ -0,0 +1,24 @@
+<!DOCTYPE HTML>
+<div id="stage"></div>
+<script>
+  function stage(str) {
+    var s = document.getElementById("stage");
+    s.textContent = str;
+  }
+  stage("before");
+  setTimeout(function() {
+    stage("in timeout");
+  });
+  setInterval(function() {
+    stage("in interval");
+  });
+  addEventListener("keydown", function() {
+    stage("keydown");
+  }, false);
+  try {
+    window.fullScreen;
+    stage("after");
+  } catch(e) {
+    stage("exception raised");
+  }
+</script>
diff --git a/dom/bindings/test/file_proxies_via_xray.html b/dom/bindings/test/file_proxies_via_xray.html
new file mode 100644
index 000000000..2e9a31830
--- /dev/null
+++ b/dom/bindings/test/file_proxies_via_xray.html
@@ -0,0 +1,8 @@
+<!DOCTYPE html>
+<html>
+  <script>
+    document.x = 5
+  </script>
+  <img id="y" name="y"></div>
+  <img id="z" name="z"></div>
+</html>
diff --git a/dom/bindings/test/forOf_iframe.html b/dom/bindings/test/forOf_iframe.html
new file mode 100644
index 000000000..91417aba0
--- /dev/null
+++ b/dom/bindings/test/forOf_iframe.html
@@ -0,0 +1,13 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>iframe content for test_forOf_iframe.html</title>
+</head>
+<body>
+  <div id="basket">
+    <span id="egg0"></span>
+    <span id="egg1"><span id="duckling1"></span></span>
+    <span id="egg2"></span>
+  </div>
+</body>
+</html>
diff --git a/dom/bindings/test/mochitest.ini b/dom/bindings/test/mochitest.ini
new file mode 100644
index 000000000..2cd322e74
--- /dev/null
+++ b/dom/bindings/test/mochitest.ini
@@ -0,0 +1,79 @@
+[DEFAULT]
+support-files =
+  file_InstanceOf.html
+  file_bug775543.html
+  file_document_location_set_via_xray.html
+  file_dom_xrays.html
+  file_proxies_via_xray.html
+  forOf_iframe.html
+  !/js/xpconnect/tests/mochitest/file_empty.html
+
+[test_async_stacks.html]
+[test_ByteString.html]
+[test_InstanceOf.html]
+[test_bug560072.html]
+[test_bug742191.html]
+[test_bug759621.html]
+[test_bug773326.html]
+[test_bug788369.html]
+[test_bug852846.html]
+[test_bug862092.html]
+[test_bug1036214.html]
+skip-if = debug == false
+[test_bug963382.html]
+skip-if = debug == false
+[test_bug1041646.html]
+[test_bug1123875.html]
+[test_barewordGetsWindow.html]
+[test_callback_across_document_open.html]
+[test_callback_default_thisval.html]
+[test_cloneAndImportNode.html]
+[test_defineProperty.html]
+[test_enums.html]
+[test_exceptionThrowing.html]
+[test_exception_messages.html]
+[test_forOf.html]
+[test_integers.html]
+[test_interfaceName.html]
+[test_interfaceToString.html]
+[test_exceptions_from_jsimplemented.html]
+tags = webrtc
+[test_lenientThis.html]
+[test_lookupGetter.html]
+[test_namedNoIndexed.html]
+[test_named_getter_enumerability.html]
+[test_Object.prototype_props.html]
+[test_queryInterface.html]
+[test_returnUnion.html]
+skip-if = debug == false
+[test_usvstring.html]
+skip-if = debug == false
+[test_sequence_wrapping.html]
+subsuite = gpu
+[test_setWithNamedGetterNoNamedSetter.html]
+[test_throwing_method_noDCE.html]
+[test_treat_non_object_as_null.html]
+[test_traceProtos.html]
+[test_sequence_detection.html]
+skip-if = debug == false
+[test_exception_options_from_jsimplemented.html]
+skip-if = debug == false
+[test_promise_rejections_from_jsimplemented.html]
+skip-if = debug == false
+[test_worker_UnwrapArg.html]
+[test_unforgeablesonexpando.html]
+[test_crossOriginWindowSymbolAccess.html]
+[test_primitive_this.html]
+[test_callback_exceptions.html]
+[test_bug1123516_maplikesetlike.html]
+skip-if = debug == false
+[test_jsimplemented_eventhandler.html]
+skip-if = debug == false
+[test_iterable.html]
+skip-if = debug == false
+[test_oom_reporting.html]
+[test_domProxyArrayLengthGetter.html]
+[test_exceptionSanitization.html]
+skip-if = os == "android"
+[test_stringBindings.html]
+skip-if = debug == false
diff --git a/dom/bindings/test/moz.build b/dom/bindings/test/moz.build
new file mode 100644
index 000000000..7d0cb6c21
--- /dev/null
+++ b/dom/bindings/test/moz.build
@@ -0,0 +1,58 @@
+# -*- Mode: python; indent-tabs-mode: nil; tab-width: 40 -*-
+# vim: set filetype=python:
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+DEFINES.update({
+    'IMPL_LIBXUL': True,
+    'MOZILLA_INTERNAL_API': True,
+})
+
+# Do NOT export this library.  We don't actually want our test code
+# being added to libxul or anything.
+
+Library('dombindings_test_s')
+
+EXTRA_COMPONENTS += [
+    'TestInterfaceJS.js',
+    'TestInterfaceJS.manifest',
+    'TestInterfaceJSMaplike.js'
+]
+
+MOCHITEST_MANIFESTS += ['mochitest.ini']
+
+MOCHITEST_CHROME_MANIFESTS += ['chrome.ini']
+
+TEST_WEBIDL_FILES += [
+    'TestDictionary.webidl',
+    'TestJSImplInheritanceGen.webidl',
+    'TestTypedef.webidl',
+]
+
+PREPROCESSED_TEST_WEBIDL_FILES += [
+    'TestCodeGen.webidl',
+    'TestExampleGen.webidl',
+    'TestJSImplGen.webidl',
+]
+
+WEBIDL_EXAMPLE_INTERFACES += [
+    'TestExampleInterface',
+    'TestExampleProxyInterface',
+    'TestExampleWorkerInterface',
+]
+
+# Bug 932082 tracks having bindings use namespaced includes.
+LOCAL_INCLUDES += [
+    '!/dist/include/mozilla/dom',
+]
+
+LOCAL_INCLUDES += [
+    '!..',
+    '/dom/bindings',
+    '/js/xpconnect/src',
+    '/js/xpconnect/wrappers',
+]
+
+if CONFIG['GNU_CXX']:
+    CXXFLAGS += ['-Wno-error=shadow']
diff --git a/dom/bindings/test/test_ByteString.html b/dom/bindings/test/test_ByteString.html
new file mode 100644
index 000000000..c7e632117
--- /dev/null
+++ b/dom/bindings/test/test_ByteString.html
@@ -0,0 +1,32 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=796850
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for ByteString support</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=796850">Mozilla Bug 796850</a>
+<p id="display"></p>
+<pre id="test">
+<script type="application/javascript">
+
+  /** Test for Bug 796850 **/
+  var xhr = new XMLHttpRequest();
+  caught = false;
+  try {
+    xhr.open("\u5427", "about:mozilla", true);
+  }
+  catch (TypeError) {
+    caught = true;
+  }
+  ok(caught, "Character values > 255 not rejected for ByteString");
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_InstanceOf.html b/dom/bindings/test/test_InstanceOf.html
new file mode 100644
index 000000000..514ec1b2a
--- /dev/null
+++ b/dom/bindings/test/test_InstanceOf.html
@@ -0,0 +1,54 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=748983
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 748983</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=748983">Mozilla Bug 748983</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 748983 **/
+
+SimpleTest.waitForExplicitFinish();
+
+function runTest()
+{
+    ok(document instanceof EventTarget, "document is an event target")
+    ok(new XMLHttpRequest() instanceof XMLHttpRequest, "instanceof should work on XHR");
+    ok(HTMLElement.prototype instanceof Node, "instanceof needs to walk the prototype chain")
+
+    var otherWin = document.getElementById("testFrame").contentWindow;
+
+    ok(otherWin.HTMLElement.prototype instanceof otherWin.Node, "Same-origin instanceof of a interface prototype object should work, even if called cross-origin");
+    ok(!(otherWin.HTMLElement.prototype instanceof Node), "Cross-origin instanceof of a interface prototype object shouldn't work");
+
+    // We need to reset HTMLElement.prototype.__proto__ to the original value
+    // before using anything from the harness, otherwise the harness code breaks
+    // in weird ways.
+    HTMLElement.prototype.__proto__ = otherWin.Element.prototype;
+    var [ shouldSucceed, shouldFail ] = otherWin.runTest();
+    shouldSucceed = shouldSucceed && HTMLElement.prototype instanceof otherWin.Element;
+    shouldFail = shouldFail && HTMLElement.prototype instanceof Element;
+    HTMLElement.prototype.__proto__ = Element.prototype;
+
+    ok(shouldSucceed, "If an interface prototype object is on the protochain then instanceof with the interface object should succeed");
+    ok(!shouldFail, "If an interface prototype object is not on the protochain then instanceof with the interface object should succeed");
+
+    SimpleTest.finish();
+}
+
+</script>
+</pre>
+<iframe id="testFrame" src="file_InstanceOf.html" onload="runTest()"></iframe>
+</body>
+</html>
diff --git a/dom/bindings/test/test_Object.prototype_props.html b/dom/bindings/test/test_Object.prototype_props.html
new file mode 100644
index 000000000..03147eb03
--- /dev/null
+++ b/dom/bindings/test/test_Object.prototype_props.html
@@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for bug 987110</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  var props = Object.getOwnPropertyNames(Object.prototype);
+  // If you change this list, make sure it continues to match the list in
+  // Codegen.py's CGDictionary.getMemberDefinition method.
+  var expected = [
+      "constructor", "toSource", "toString", "toLocaleString", "valueOf",
+      "watch", "unwatch", "hasOwnProperty", "isPrototypeOf",
+      "propertyIsEnumerable", "__defineGetter__", "__defineSetter__",
+      "__lookupGetter__", "__lookupSetter__", "__proto__"
+    ];
+  assert_array_equals(props.sort(), expected.sort());
+}, "Own properties of Object.prototype");
+</script>
diff --git a/dom/bindings/test/test_async_stacks.html b/dom/bindings/test/test_async_stacks.html
new file mode 100644
index 000000000..8b655a14d
--- /dev/null
+++ b/dom/bindings/test/test_async_stacks.html
@@ -0,0 +1,108 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1148593
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1148593</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1148593 **/
+
+  SimpleTest.waitForExplicitFinish();
+
+  var TESTS;
+
+  function nextTest() {
+    var t = TESTS.pop();
+    if (t) {
+      t();
+    } else {
+      SimpleTest.finish();
+    }
+  }
+
+  function checkStack(functionName) {
+    try {
+      noSuchFunction();
+    } catch (e) {
+      ok(e.stack.indexOf(functionName) >= 0, "stack includes " + functionName);
+    }
+    nextTest();
+  }
+
+  function eventListener() {
+    checkStack("registerEventListener");
+  }
+  function registerEventListener(link) {
+    link.onload = eventListener;
+  }
+  function eventTest() {
+    var link = document.createElement("link");
+    link.rel = "stylesheet";
+    link.href = "data:text/css,";
+    registerEventListener(link);
+    document.body.appendChild(link);
+  }
+
+  function xhrListener() {
+    checkStack("xhrTest");
+  }
+  function xhrTest() {
+    var ourFile = location.href;
+    var x = new XMLHttpRequest();
+    x.onload = xhrListener;
+    x.open("get", ourFile, true);
+    x.send();
+  }
+
+  function rafListener() {
+    checkStack("rafTest");
+  }
+  function rafTest() {
+    requestAnimationFrame(rafListener);
+  }
+
+  var intervalId;
+  function intervalHandler() {
+    clearInterval(intervalId);
+    checkStack("intervalTest");
+  }
+  function intervalTest() {
+    intervalId = setInterval(intervalHandler, 5);
+  }
+
+  function postMessageHandler(ev) {
+    ev.stopPropagation();
+    checkStack("postMessageTest");
+  }
+  function postMessageTest() {
+    window.addEventListener("message", postMessageHandler, true);
+    window.postMessage("whatever", "*");
+  }
+
+  function runTests() {
+    TESTS = [postMessageTest, intervalTest, rafTest, xhrTest, eventTest];
+    nextTest();
+  }
+
+  addLoadEvent(function() {
+    SpecialPowers.pushPrefEnv(
+      {"set": [['javascript.options.asyncstack', true]]},
+      runTests);
+  });
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1148593">Mozilla Bug 1148593</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_barewordGetsWindow.html b/dom/bindings/test/test_barewordGetsWindow.html
new file mode 100644
index 000000000..e098eea53
--- /dev/null
+++ b/dom/bindings/test/test_barewordGetsWindow.html
@@ -0,0 +1,60 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=936056
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 936056</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 936056 **/
+  SimpleTest.waitForExplicitFinish();
+  window.onload = function() {
+    var desc = Object.getOwnPropertyDescriptor(frames[0], "document");
+    if (!desc || !desc.get) {
+      todo(false, "This test does nothing so far, but will once Window is on WebIDL bindings");
+      SimpleTest.finish();
+      return;
+    }
+    get = desc.get;
+    ok(get, "Couldn't find document getter");
+    Object.defineProperty(frames[0], "foo", { get: get, configurable: true });
+
+    var barewordFunc = frames[0].eval("(function (count) { var doc; for (var i = 0; i < count; ++i) doc = foo; return doc.documentElement; })");
+    var qualifiedFunc = frames[0].eval("(function (count) { var doc; for (var i = 0; i < count; ++i) doc = window.document; return doc.documentElement; })");
+    document.querySelector("iframe").onload = function () {
+      // interp
+      is(barewordFunc(1).textContent, "OLD", "Bareword should see own inner 1");
+      is(qualifiedFunc(1).textContent, "NEW",
+         "Qualified should see current inner 1");
+      // baseline
+      is(barewordFunc(100).textContent, "OLD", "Bareword should see own inner 2");
+      is(qualifiedFunc(100).textContent, "NEW",
+         "Qualified should see current inner 2");
+      // ion
+      is(barewordFunc(10000).textContent, "OLD", "Bareword should see own inner 3");
+      is(qualifiedFunc(10000).textContent, "NEW",
+         "Qualified should see current inner 2");
+      SimpleTest.finish();
+    }
+    frames[0].location = "data:text/plain,NEW";
+  }
+
+
+
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=936056">Mozilla Bug 936056</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe src="data:text/plain,OLD"></iframe>
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_blacklisted_prerendering_function.xul b/dom/bindings/test/test_blacklisted_prerendering_function.xul
new file mode 100644
index 000000000..02a76d88d
--- /dev/null
+++ b/dom/bindings/test/test_blacklisted_prerendering_function.xul
@@ -0,0 +1,124 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        onload="runTest();">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+
+<script class="testbody" type="application/javascript">
+<![CDATA[
+
+  SimpleTest.waitForExplicitFinish();
+
+  function Listener(aBrowser, aPrerendered, aCallback) {
+    this.init(aBrowser, aPrerendered, aCallback);
+  }
+
+  Listener.prototype = {
+    init: function(aBrowser, aPrerendered, aCallback) {
+      this.mBrowser = aBrowser;
+      this.mPrerendered = aPrerendered;
+      this.mCallback = aCallback;
+    },
+    QueryInterface: function(aIID) {
+      if (aIID.equals(Components.interfaces.nsIWebProgressListener) ||
+          aIID.equals(Components.interfaces.nsISupportsWeakReference) ||
+          aIID.equals(Components.interfaces.nsISupports))
+        return this;
+      throw Components.results.NS_NOINTERFACE;
+    },
+    onStateChange : function(aWebProgress, aRequest, aStateFlags, aStatus) {
+      if ((aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_STOP) &&
+          (aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_IS_DOCUMENT)) {
+        var doc = this.mBrowser.contentDocument;
+        var stage = doc.getElementById("stage");
+        if (this.mPrerendered) {
+          is(stage.textContent, "before", "The blacklisted call should properly be intercepted in prerendering mode");
+        } else {
+          // In normal mode, we may or may not have run the timeout and/or the interval.
+          switch (stage.textContent) {
+          case "after":
+          case "in timeout":
+          case "in interval":
+            ok(true, "The blacklisted call should work fine in normal mode");
+            break;
+          default:
+            ok(false, "The blacklisted call should work fine in normal mode");
+            break;
+          }
+        }
+        progress.removeProgressListener(progressListener);
+
+        // Set three timeouts to see if the interval triggered
+        var self = this;
+        function checkInterval() {
+          var expected = self.mPrerendered ? "before" : "in interval";
+          var desc = self.mPrerendered ? "No timer should be running" : "Timers should run as normal";
+          is(stage.textContent, expected, desc);
+          // Now, dispatch a key event to the window and see if the keydown handler runs
+          synthesizeKey("a", {}, self.mBrowser.contentWindow);
+          expected = self.mPrerendered ? "before" : "keydown";
+          desc = self.mPrerendered ? "No event handler should be running" : "Event handlers should run as normal";
+          is(stage.textContent, expected, desc);
+          self.mCallback();
+        }
+        setTimeout(function() {
+          setTimeout(function() {
+            setTimeout(function() {
+              checkInterval();
+            }, 0);
+          }, 0);
+        }, 0);
+      }
+    },
+    onProgressChange : function(aWebProgress, aRequest,
+                                aCurSelfProgress, aMaxSelfProgress,
+                                aCurTotalProgress, aMaxTotalProgress) {},
+    onLocationChange : function(aWebProgress, aRequest, aLocation, aFlags) {},
+    onStatusChange : function(aWebProgress, aRequest, aStatus, aMessage) {},
+    onSecurityChange : function(aWebProgress, aRequest, aState) {},
+    mBrowser: null,
+    mPrerendered: false,
+    mCallback: null
+  };
+
+  var progress, progressListener;
+
+  function runTest() {
+    testStep(false, "file_focuser.html", function() {
+      testStep(true, "file_focuser.html", function() {
+        testStep(false, "file_fullScreenPropertyAccessor.html", function() {
+          testStep(true, "file_fullScreenPropertyAccessor.html", function() {
+            SimpleTest.finish();
+          });
+        });
+      });
+    });
+  }
+
+  function testStep(aPrerendered, aFileName, aCallback) {
+    var browser = document.getElementById(aPrerendered ? "prerendered" : "normal");;
+    progressListener = new Listener(browser, aPrerendered, aCallback);
+    var docShell = browser.docShell;
+    progress = docShell.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
+                       .getInterface(Components.interfaces.nsIWebProgress);
+    progress.addProgressListener(progressListener,
+                                 Components.interfaces.nsIWebProgress.NOTIFY_ALL);
+    browser.loadURI("chrome://mochitests/content/chrome/dom/bindings/test/" + aFileName);
+  }
+
+]]>
+</script>
+
+<body  id="html_body" xmlns="http://www.w3.org/1999/xhtml">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1069719">Mozilla Bug 1069719</a>
+<p id="display"></p>
+
+<pre id="test">
+</pre>
+</body>
+<browser prerendered="true" id="prerendered"/>
+<browser id="normal"/>
+</window>
diff --git a/dom/bindings/test/test_bug1036214.html b/dom/bindings/test/test_bug1036214.html
new file mode 100644
index 000000000..dd98eb482
--- /dev/null
+++ b/dom/bindings/test/test_bug1036214.html
@@ -0,0 +1,123 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1036214
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1036214</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for subsumes-checking |any| and |object| for js-implemented WebIDL. **/
+  SimpleTest.waitForExplicitFinish();
+  var xoObjects = [];
+  function setup() {
+    xoObjects.push(window[0]);
+    xoObjects.push(window[0].location);
+    xoObjects.push(SpecialPowers.unwrap(SpecialPowers.wrap(window[0]).document));
+    xoObjects.push(SpecialPowers);
+    xoObjects.push(SpecialPowers.wrap);
+    SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, go);
+  }
+
+  function checkThrows(f, msg) {
+    try {
+      f();
+      ok(false, "Should have thrown: " + msg);
+    } catch (e) {
+      ok(true, "Threw correctly: " + msg);
+      ok(/denied|insecure/.test(e), "Threw security exception: " + e);
+    }
+  }
+
+  function go() {
+
+    //
+    // Test the basics of the test interface.
+    //
+
+    var any = { a: 11 };
+    var obj = { b: 22, c: "str" };
+    var obj2 = { foo: "baz" };
+    var myDict = { anyMember: 42, objectMember: { answer: 42 }, objectOrStringMember: { answer: "anobject" },
+                   anySequenceMember: [{}, 1, "thirdinsequence"],
+                   innerDictionary: { innerObject: { answer: "rabbithole" } } };
+    var t = new TestInterfaceJS(any, obj, myDict);
+    is(Object.getPrototypeOf(t), TestInterfaceJS.prototype, "Prototype setup works correctly");
+    is(t.anyArg, any, "anyArg is correct");
+    is(t.objectArg, obj, "objectArg is correct");
+    is(t.dictionaryArg.anyMember, 42, "dictionaryArg looks correct");
+    is(t.dictionaryArg.objectMember.answer, 42, "dictionaryArg looks correct");
+    t.anyAttr = 2;
+    is(t.anyAttr, 2, "ping-pong any attribute works");
+    t.objAttr = obj2;
+    is(t.objAttr, obj2, "ping-pong object attribute works");
+    t.dictionaryAttr = myDict;
+    is(t.dictionaryAttr.anyMember, 42, "ping-pong dictionary attribute works");
+    is(t.dictionaryAttr.objectMember.answer, 42, "ping-pong dictionary attribute works");
+
+    is(any, t.pingPongAny(any), "ping-pong works with any");
+    is(obj, t.pingPongObject(obj), "ping-pong works with obj");
+    is(obj, t.pingPongObjectOrString(obj), "ping-pong works with obj or string");
+    is("foo", t.pingPongObjectOrString("foo"), "ping-pong works with obj or string");
+    is(t.pingPongDictionary(myDict).anyMember, 42, "ping pong works with dict");
+    is(t.pingPongDictionary(myDict).objectMember.answer, 42, "ping pong works with dict");
+    is(t.pingPongDictionary(myDict).objectOrStringMember.answer, "anobject", "ping pong works with dict");
+    is(t.pingPongDictionary(myDict).anySequenceMember[2], "thirdinsequence", "ping pong works with dict");
+    is(t.pingPongDictionary(myDict).innerDictionary.innerObject.answer, "rabbithole", "ping pong works with layered dicts");
+    is(t.pingPongDictionaryOrLong({anyMember: 42}), 42, "ping pong (dict or long) works with dict");
+    is(t.pingPongDictionaryOrLong(42), 42, "ping pong (dict or long) works with long");
+    ok(/canary/.test(t.pingPongMap({ someVal: 42, someOtherVal: "canary" })), "ping pong works with mozmap");
+    is(t.objectSequenceLength([{}, {}, {}]), 3, "ping pong works with object sequence");
+    is(t.anySequenceLength([42, 'string', {}, undefined]), 4, "ping pong works with any sequence");
+
+    //
+    // Test that we throw in the cross-origin cases.
+    //
+
+    xoObjects.forEach(function(xoObj) {
+      var blank = new TestInterfaceJS();
+      checkThrows(() => new TestInterfaceJS(xoObj, undefined), "any param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, xoObj), "obj param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, undefined, { anyMember: xoObj }), "any dict param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, undefined, { objectMember: xoObj }), "object dict param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, undefined, { objectOrStringMember: xoObj }), "union dict param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, undefined, { anySequenceMember: [0, xoObj, 'hi' ] }), "sequence dict param for constructor");
+      checkThrows(() => new TestInterfaceJS(undefined, undefined, { innerDictionary: { innerObject: xoObj } }), "inner dict param for constructor");
+      checkThrows(() => t.anyAttr = xoObj, "anyAttr");
+      checkThrows(() => t.objectAttr = xoObj, "objAttr");
+      checkThrows(() => t.dictionaryAttr = { anyMember: xoObj }, "dictionaryAttr any");
+      checkThrows(() => t.dictionaryAttr = { objectMember: xoObj }, "dictionaryAttr object");
+      checkThrows(() => t.pingPongAny(xoObj), "pingpong any");
+      checkThrows(() => t.pingPongObject(xoObj), "pingpong obj");
+      checkThrows(() => t.pingPongObjectOrString(xoObj), "pingpong union");
+      checkThrows(() => t.pingPongDictionary({ anyMember: xoObj }), "dictionary pingpong any");
+      checkThrows(() => t.pingPongDictionary({ objectMember: xoObj }), "dictionary pingpong object");
+      checkThrows(() => t.pingPongDictionary({ anyMember: xoObj, objectMember: xoObj }), "dictionary pingpong both");
+      checkThrows(() => t.pingPongDictionary({ objectOrStringMember: xoObj }), "dictionary pingpong objectorstring");
+      checkThrows(() => t.pingPongDictionaryOrLong({ objectMember: xoObj }), "unionable dictionary");
+      checkThrows(() => t.pingPongDictionaryOrLong({ anyMember: xoObj }), "unionable dictionary");
+      checkThrows(() => t.pingPongMap({ someMember: 42, someOtherMember: {}, crossOriginMember: xoObj }), "mozmap");
+      checkThrows(() => t.objectSequenceLength([{}, {}, xoObj, {}]), "object sequence");
+      checkThrows(() => t.anySequenceLength([42, 'someString', xoObj, {}]), "any sequence");
+    });
+
+
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1036214">Mozilla Bug 1036214</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+<iframe id="ifr" onload="setup();" src="http://example.org/tests/js/xpconnect/tests/mochitest/file_empty.html"></iframe>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug1041646.html b/dom/bindings/test/test_bug1041646.html
new file mode 100644
index 000000000..22baed454
--- /dev/null
+++ b/dom/bindings/test/test_bug1041646.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1041646
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1041646</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1041646 **/
+  // We need to reject the promise with a DOMException, so make sure we have
+  // something that produces one.
+  function throwException() {
+    document.createTextNode("").appendChild(document);
+  }
+  try {
+    throwException();
+  } catch (e) {
+    ok(e instanceof DOMException, "This test won't test what it should be testing");
+  }
+
+  SimpleTest.waitForExplicitFinish();
+
+  // We want a new DOMException each time here.
+  for (var i = 0; i < 100; ++i) {
+    new Promise(throwException);
+  }
+
+  // Now make sure we wait for all those promises above to reject themselves
+  Promise.resolve(1).then(function() {
+    SpecialPowers.gc(); // This should not assert or crash
+    SimpleTest.finish();
+  });
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1041646">Mozilla Bug 1041646</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug1123516_maplikesetlike.html b/dom/bindings/test/test_bug1123516_maplikesetlike.html
new file mode 100644
index 000000000..18ede38ac
--- /dev/null
+++ b/dom/bindings/test/test_bug1123516_maplikesetlike.html
@@ -0,0 +1,271 @@
+<!-- Any copyright is dedicated to the Public Domain.
+- http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+    <head>
+        <title>Test Maplike Interface</title>
+        <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+        <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+    </head>
+    <body>
+        <script class="testbody" type="application/javascript">
+         SimpleTest.waitForExplicitFinish();
+         SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, function() {
+
+             base_properties = [["has", "function", 1],
+                                ["entries", "function", 0],
+                                ["keys", "function", 0],
+                                ["values", "function", 0],
+                                ["forEach", "function", 1],
+                                ["size", "number"]];
+             maplike_properties = base_properties.concat([["set", "function", 2]]);
+             setlike_properties = base_properties;
+             rw_properties = [["clear", "function", 0],
+                              ["delete", "function", 1]];
+             setlike_rw_properties = base_properties.concat(rw_properties).concat([["add", "function", 1]]);
+             maplike_rw_properties = maplike_properties.concat(rw_properties).concat([["get", "function",1]]);
+             var testExistence = function testExistence(prefix, obj, properties) {
+                 for (var [name, type, args] of properties) {
+                     // Properties are somewhere up the proto chain, hasOwnProperty won't work
+                     isnot(obj[name], undefined,
+                        `${prefix} object has property ${name}`);
+
+                     is(typeof obj[name], type,
+                        `${prefix} object property ${name} is a ${type}`);
+                     // Check function length
+                     if (type == "function") {
+                         is(obj[name].length, args,
+                            `${prefix} object property ${name} is length ${args}`);
+                         is(obj[name].name, name,
+                            `${prefix} object method name is ${name}`);
+                     }
+
+                     // Find where property is on proto chain, check for enumerablility there.
+                     var owner = obj;
+                     while (owner) {
+                         var propDesc = Object.getOwnPropertyDescriptor(owner, name);
+                         if (propDesc) {
+                             ok(!propDesc.enumerable,
+                                `${prefix} object property ${name} is not enumerable`);
+                             break;
+                         }
+                         owner = Object.getPrototypeOf(owner);
+                     }
+                 }
+             }
+
+             var m;
+             var testSet;
+             var testIndex;
+             // Simple map creation and functionality test
+             info("SimpleMap: Testing simple map creation and functionality");
+             m = new TestInterfaceMaplike();
+             ok(m, "SimpleMap: got a TestInterfaceMaplike object");
+             testExistence("SimpleMap: ", m, maplike_rw_properties);
+             is(m.size, 0, "SimpleMap: size should be zero");
+             ok(!m.has("test"), "SimpleMap: maplike has should return false");
+             is(m.get("test"), undefined, "SimpleMap: maplike get should return undefined on bogus lookup");
+             m1 = m.set("test", 1);
+             is(m, m1, "SimpleMap: return from set should be map object");
+             is(m.size, 1, "SimpleMap: size should be 1");
+             ok(m.has("test"), "SimpleMap: maplike has should return true");
+             is(m.get("test"), 1, "SimpleMap: maplike get should return value entered");
+             m2 = m.set("test2", 2);
+             is(m.size, 2, "SimpleMap: size should be 2");
+             testSet = [["test", 1], ["test2", 2]];
+             testIndex = 0;
+             m.forEach(function(v, k, o) {
+                 "use strict";
+                 is(o, m, "SimpleMap: foreach obj is correct");
+                 is(k, testSet[testIndex][0], "SimpleMap: foreach map key: " + k + " = " + testSet[testIndex][0]);
+                 is(v, testSet[testIndex][1], "SimpleMap: foreach map value: " + v + " = " + testSet[testIndex][1]);
+                 testIndex += 1;
+             });
+             is(testIndex, 2, "SimpleMap: foreach ran correct number of times");
+             ok(m.has("test2"), "SimpleMap: maplike has should return true");
+             is(m.get("test2"), 2, "SimpleMap: maplike get should return value entered");
+             is(m.delete("test2"), true, "SimpleMap: maplike deletion should return boolean");
+             is(m.size, 1, "SimpleMap: size should be 1");
+             iterable = false;
+             for (var e of m) {
+                 iterable = true;
+                 is(e[0], "test", "SimpleMap: iterable first array element should be key");
+                 is(e[1], 1, "SimpleMap: iterable second array element should be value");
+             }
+             is(m[Symbol.iterator].length, 0, "SimpleMap: @@iterator symbol is correct length");
+             is(m[Symbol.iterator].name, "entries", "SimpleMap: @@iterator symbol has correct name");
+             is(m[Symbol.iterator], m.entries, 'SimpleMap: @@iterator is an alias for "entries"');
+             ok(iterable, "SimpleMap: @@iterator symbol resolved correctly");
+             for (var k of m.keys()) {
+                 is(k, "test", "SimpleMap: first keys element should be 'test'");
+             }
+             for (var v of m.values()) {
+                 is(v, 1, "SimpleMap: first values elements should be 1");
+             }
+             for (var e of m.entries()) {
+                 is(e[0], "test", "SimpleMap: entries first array element should be 'test'");
+                 is(e[1], 1, "SimpleMap: entries second array element should be 1");
+             }
+             m.clear();
+             is(m.size, 0, "SimpleMap: size should be 0 after clear");
+
+             // Simple set creation and functionality test
+             info("SimpleSet: Testing simple set creation and functionality");
+             m = new TestInterfaceSetlike();
+             ok(m, "SimpleSet: got a TestInterfaceSetlike object");
+             testExistence("SimpleSet: ", m, setlike_rw_properties);
+             is(m.size, 0, "SimpleSet: size should be zero");
+             ok(!m.has("test"), "SimpleSet: maplike has should return false");
+             m1 = m.add("test");
+             is(m, m1, "SimpleSet: return from set should be map object");
+             is(m.size, 1, "SimpleSet: size should be 1");
+             ok(m.has("test"), "SimpleSet: maplike has should return true");
+             m2 = m.add("test2");
+             is(m.size, 2, "SimpleSet: size should be 2");
+             testSet = ["test", "test2"];
+             testIndex = 0;
+             m.forEach(function(v, k, o) {
+                 "use strict";
+                 is(o, m, "SimpleSet: foreach obj is correct");
+                 is(k, testSet[testIndex], "SimpleSet: foreach set key: " + k + " = " + testSet[testIndex]);
+                 testIndex += 1;
+             });
+             is(testIndex, 2, "SimpleSet: foreach ran correct number of times");
+             ok(m.has("test2"), "SimpleSet: maplike has should return true");
+             is(m.delete("test2"), true, "SimpleSet: maplike deletion should return true");
+             is(m.size, 1, "SimpleSet: size should be 1");
+             iterable = false;
+             for (var e of m) {
+                 iterable = true;
+                 is(e, "test", "SimpleSet: iterable first array element should be key");
+             }
+             is(m[Symbol.iterator].length, 0, "SimpleSet: @@iterator symbol is correct length");
+             is(m[Symbol.iterator].name, "values", "SimpleSet: @@iterator symbol has correct name");
+             is(m[Symbol.iterator], m.values, 'SimpleSet: @@iterator is an alias for "values"');
+             ok(iterable, "SimpleSet: @@iterator symbol resolved correctly");
+             for (var k of m.keys()) {
+                 is(k, "test", "SimpleSet: first keys element should be 'test'");
+             }
+             for (var v of m.values()) {
+                 is(v, "test", "SimpleSet: first values elements should be 'test'");
+             }
+             for (var e of m.entries()) {
+                 is(e[0], "test", "SimpleSet: Entries first array element should be 'test'");
+                 is(e[1], "test", "SimpleSet: Entries second array element should be 'test'");
+             }
+             m.clear();
+             is(m.size, 0, "SimpleSet: size should be 0 after clear");
+
+             // Map convenience function test
+             info("Testing map convenience functions");
+             m = new TestInterfaceMaplike();
+             ok(m, "MapConvenience: got a TestInterfaceMaplike object");
+             is(m.size, 0, "MapConvenience: size should be zero");
+             ok(!m.hasInternal("test"), "MapConvenience: maplike hasInternal should return false");
+             m.setInternal("test", 1);
+             is(m.size, 1, "MapConvenience: size should be 1");
+             ok(m.hasInternal("test"), "MapConvenience: maplike hasInternal should return true");
+             is(m.get("test"), 1, "MapConvenience: maplike get should return value entered");
+             m2 = m.setInternal("test2", 2);
+             is(m.size, 2, "size should be 2");
+             ok(m.hasInternal("test2"), "MapConvenience: maplike hasInternal should return true");
+             is(m.get("test2"), 2, "MapConvenience: maplike get should return value entered");
+             is(m.deleteInternal("test2"), true, "MapConvenience: maplike deleteInternal should return true");
+             is(m.size, 1, "MapConvenience: size should be 1");
+             m.clearInternal();
+             is(m.size, 0, "MapConvenience: size should be 0 after clearInternal");
+
+             // Map convenience function test using objects and readonly
+
+             info("Testing Map convenience function test using objects and readonly");
+             m = new TestInterfaceMaplikeObject();
+             ok(m, "ReadOnlyMapConvenience: got a TestInterfaceMaplikeObject object");
+             is(m.size, 0, "ReadOnlyMapConvenience: size should be zero");
+             is(m["set"], undefined, "ReadOnlyMapConvenience: readonly map, should be no set function");
+             is(m["clear"], undefined, "ReadOnlyMapConvenience: readonly map, should be no clear function");
+             is(m["delete"], undefined, "ReadOnlyMapConvenience: readonly map, should be no delete function");
+             ok(!m.hasInternal("test"), "ReadOnlyMapConvenience: maplike hasInternal should return false");
+             m.setInternal("test");
+             is(m.size, 1, "size should be 1");
+             ok(m.hasInternal("test"), "ReadOnlyMapConvenience: maplike hasInternal should return true");
+             m2 = m.setInternal("test2");
+             is(m.size, 2, "size should be 2");
+             ok(m.hasInternal("test2"), "ReadOnlyMapConvenience: maplike hasInternal should return true");
+             is(m.deleteInternal("test2"), true, "ReadOnlyMapConvenience: maplike deleteInternal should return true");
+             is(m.size, 1, "ReadOnlyMapConvenience: size should be 1");
+             m.clearInternal();
+             is(m.size, 0, "ReadOnlyMapConvenience: size should be 0 after clearInternal");
+
+             // JS implemented map creation convenience function test
+
+             info("JSMapConvenience: Testing JS implemented map creation convenience functions");
+             m = new TestInterfaceJSMaplike();
+             ok(m, "JSMapConvenience: got a TestInterfaceJSMaplike object");
+             is(m.size, 0, "JSMapConvenience: size should be zero");
+             ok(!m.has("test"), "JSMapConvenience: maplike has should return false");
+             m.setInternal("test", 1);
+             is(m.size, 1, "JSMapConvenience: size should be 1");
+             ok(m.has("test"), "JSMapConvenience: maplike has should return true");
+             is(m.get("test"), 1, "JSMapConvenience: maplike get should return value entered");
+             m2 = m.setInternal("test2", 2);
+             is(m.size, 2, "JSMapConvenience: size should be 2");
+             ok(m.has("test2"), "JSMapConvenience: maplike has should return true");
+             is(m.get("test2"), 2, "JSMapConvenience: maplike get should return value entered");
+             is(m.deleteInternal("test2"), true, "JSMapConvenience: maplike deleteInternal should return true");
+             is(m.size, 1, "JSMapConvenience: size should be 1");
+             for (var k of m.keys()) {
+                 is(k, "test", "JSMapConvenience: first keys element should be 'test'");
+             }
+             for (var v of m.values()) {
+                 is(v, 1, "JSMapConvenience: first values elements should be 1");
+             }
+             for (var e of m.entries()) {
+                 is(e[0], "test", "JSMapConvenience: entries first array element should be 'test'");
+                 is(e[1], 1, "JSMapConvenience: entries second array element should be 1");
+             }
+             m.clearInternal();
+             is(m.size, 0, "JSMapConvenience: size should be 0 after clearInternal");
+
+             // Test this override for forEach
+             info("ForEachThisOverride: Testing this override for forEach");
+             m = new TestInterfaceMaplike();
+             m.set("test", 1);
+             m.forEach(function(v, k, o) {
+                 "use strict";
+                 is(o, m, "ForEachThisOverride: foreach obj is correct");
+                 is(this, 5, "ForEachThisOverride: 'this' value should be correct");
+             }, 5);
+
+             // Test defaulting arguments on maplike to undefined
+             info("MapArgsDefault: Testing maplike defaulting arguments to undefined");
+             m = new TestInterfaceMaplike();
+             m.set();
+             is(m.size, 1, "MapArgsDefault: should have 1 entry");
+             m.forEach(function(v, k) {
+                 "use strict";
+                 is(typeof k, "string", "MapArgsDefault: key is a string");
+                 is(k, "undefined", "MapArgsDefault: key is the string undefined");
+                 is(v, 0, "MapArgsDefault: value is 0");
+             });
+             is(m.get(), 0, "MapArgsDefault: no argument to get() returns correct value");
+             m.delete();
+             is(m.size, 0, "MapArgsDefault: should have 0 entries");
+
+             // Test defaulting arguments on setlike to undefined
+             info("SetArgsDefault: Testing setlike defaulting arguments to undefined");
+             m = new TestInterfaceSetlike();
+             m.add();
+             is(m.size, 1, "SetArgsDefault: should have 1 entry");
+             m.forEach(function(v, k) {
+                 "use strict";
+                 is(typeof k, "string", "SetArgsDefault: key is a string");
+                 is(k, "undefined", "SetArgsDefault: key is the string undefined");
+             });
+             m.delete();
+             is(m.size, 0, "SetArgsDefault: should have 0 entries");
+
+             SimpleTest.finish();
+         });
+        </script>
+    </body>
+</html>
diff --git a/dom/bindings/test/test_bug1123516_maplikesetlikechrome.xul b/dom/bindings/test/test_bug1123516_maplikesetlikechrome.xul
new file mode 100644
index 000000000..4bc45cddd
--- /dev/null
+++ b/dom/bindings/test/test_bug1123516_maplikesetlikechrome.xul
@@ -0,0 +1,68 @@
+<?xml version="1.0"?>
+<?xml-stylesheet type="text/css" href="chrome://global/skin"?>
+<?xml-stylesheet type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"?>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1123516
+-->
+<window title="Mozilla Bug 1123516"
+        xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <iframe id="t"></iframe>
+
+  <!-- test results are displayed in the html:body -->
+  <body xmlns="http://www.w3.org/1999/xhtml">
+    <a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1123516"
+       target="_blank">Mozilla Bug 1123516</a>
+  </body>
+
+  <!-- test code goes here -->
+  <script type="application/javascript">
+   <![CDATA[
+
+     /** Test for Bug 1123516 **/
+     const Cu = Components.utils;
+     function doTest() {
+       var win = $("t").contentWindow;
+       var sandbox = Components.utils.Sandbox(win, { sandboxPrototype: win });
+       is(sandbox._content, undefined, "_content does nothing over Xray");
+       // Test cross-compartment usage of maplike/setlike WebIDL structures.
+       SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, function() {
+         try {
+           var maplike = Components.utils.evalInSandbox("var m = new TestInterfaceMaplike(); m;", sandbox);
+           maplike.set("test2", 2);
+           is(maplike.get("test2"), 2, "Should be able to create and use maplike/setlike across compartments");
+           var test = Components.utils.evalInSandbox("m.get('test2');", sandbox);
+           is(test, 2, "Maplike/setlike should still work in original compartment");
+           is(maplike.size, 1, "Testing size retrieval across compartments");
+         } catch(e) {
+           ok(false, "Shouldn't throw when working with cross-compartment maplike/setlike interfaces " + e)
+         };
+         try {
+           var setlike = Components.utils.evalInSandbox("var m = new TestInterfaceSetlikeNode(); m.add(document.documentElement); m;", sandbox);
+           is(TestInterfaceSetlikeNode.prototype.has.call(setlike, win.document.documentElement), true,
+              "Cross-compartment unwrapping/comparison has works");
+           // TODO: Should throw until iterators are handled by Xrays, Bug 1023984
+           try {
+             var e = TestInterfaceSetlikeNode.prototype.keys.call(setlike);
+             ok(false, "Calling iterators via xrays should fail");
+           } catch(e) {
+             ok(true, "Calling iterators via xrays should fail");
+           }
+
+           setlike.forEach((v,k,t) => { is(v, win.document.documentElement, "Cross-compartment forEach works"); });
+           TestInterfaceSetlikeNode.prototype.forEach.call(setlike,
+                                                           (v,k,t) => { is(v, win.document.documentElement, "Cross-compartment forEach works"); });
+           is(TestInterfaceSetlikeNode.prototype.delete.call(setlike, win.document.documentElement), true,
+              "Cross-compartment unwrapping/comparison delete works");
+         } catch(e) {
+           ok(false, "Shouldn't throw when working with cross-compartment maplike/setlike interfaces " + e)
+         };
+         SimpleTest.finish();
+       });
+     }
+
+     SimpleTest.waitForExplicitFinish();
+     addLoadEvent(doTest);
+   ]]>
+  </script>
+</window>
diff --git a/dom/bindings/test/test_bug1123875.html b/dom/bindings/test/test_bug1123875.html
new file mode 100644
index 000000000..5658091c4
--- /dev/null
+++ b/dom/bindings/test/test_bug1123875.html
@@ -0,0 +1,14 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Test for Bug 1123875</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+  test(() => {
+    assert_throws(new TypeError, () => {
+      "use strict";
+      document.childNodes.length = 0;
+    });
+  }, "setting a readonly attribute on a proxy in strict mode should throw a TypeError");
+</script>
diff --git a/dom/bindings/test/test_bug1287912.html b/dom/bindings/test/test_bug1287912.html
new file mode 100644
index 000000000..ae72b2316
--- /dev/null
+++ b/dom/bindings/test/test_bug1287912.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1287912
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1287912</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1287912">Mozilla Bug 1287912</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/"></iframe>
+</div>
+<pre id="test">
+<script type="application/javascript">
+function test()
+{
+  var win = document.getElementById("t").contentWindow;
+  is(Object.getPrototypeOf(win.Image), win.Function.prototype, "The __proto__ of a named constructor is Function.prototype");
+  is(win.Image.prototype, win.HTMLImageElement.prototype, "The prototype property of a named constructor is the interface prototype object");
+  is(win.HTMLImageElement['foo'], undefined, "Should not have a property named foo on the HTMLImageElement interface object");
+  is(win.Image['foo'], undefined, "Should not have a property named foo on the Image named constructor");
+
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug560072.html b/dom/bindings/test/test_bug560072.html
new file mode 100644
index 000000000..82bb1c2c6
--- /dev/null
+++ b/dom/bindings/test/test_bug560072.html
@@ -0,0 +1,33 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=560072
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 560072</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=560072">Mozilla Bug 560072</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 560072 **/
+is(document.body,
+   Object.getOwnPropertyDescriptor(HTMLDocument.prototype, "body").get.call(document),
+   "Should get body out of property descriptor");
+
+is(document.body,
+   Object.getOwnPropertyDescriptor(Object.getPrototypeOf(document), "body").get.call(document),
+   "Should get body out of property descriptor this way too");
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug742191.html b/dom/bindings/test/test_bug742191.html
new file mode 100644
index 000000000..b4b3151d7
--- /dev/null
+++ b/dom/bindings/test/test_bug742191.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=742191
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for invalid argument object</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=742191">Mozilla Bug 742191</a>
+<p id="display"></p>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 742191 **/
+function doTest() {
+  var gotTypeError = false;
+  var ctx = document.createElement("canvas").getContext("2d");
+  try {
+    ctx.drawImage({}, 0, 0);
+  } catch(e) {
+    if (e instanceof TypeError) {
+      gotTypeError = true;
+    }
+  }
+
+  ok(gotTypeError, "passing an invalid argument should cause a type error!");
+}
+doTest();
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug759621.html b/dom/bindings/test/test_bug759621.html
new file mode 100644
index 000000000..602a0cd7c
--- /dev/null
+++ b/dom/bindings/test/test_bug759621.html
@@ -0,0 +1,29 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=759621
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 759621</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=759621">Mozilla Bug 759621</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 759621 **/
+var l = document.getElementsByTagName("*");
+l.namedItem = "pass";
+is(l.namedItem, "pass", "Should be able to set expando shadowing a proto prop");
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug773326.html b/dom/bindings/test/test_bug773326.html
new file mode 100644
index 000000000..2e3b1ea30
--- /dev/null
+++ b/dom/bindings/test/test_bug773326.html
@@ -0,0 +1,11 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Test for Bug 773326</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+test(function() {
+  new Worker("data:text/javascript,new XMLHttpRequest(42)");
+}, "Should not crash")
+</script>
diff --git a/dom/bindings/test/test_bug775543.html b/dom/bindings/test/test_bug775543.html
new file mode 100644
index 000000000..d8df05f63
--- /dev/null
+++ b/dom/bindings/test/test_bug775543.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=775543
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 775543</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=775543">Mozilla Bug 775543</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/file_bug775543.html" onload="test();"></iframe>  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 775543 **/
+
+function test()
+{
+  var a = XPCNativeWrapper(document.getElementById("t").contentWindow.wrappedJSObject.worker);
+  isnot(XPCNativeWrapper.unwrap(a), a, "XPCNativeWrapper(Worker) should be an Xray wrapper");
+  a.toString();
+  ok(true, "Shouldn't crash when calling a method on an Xray wrapper around a worker");
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug788369.html b/dom/bindings/test/test_bug788369.html
new file mode 100644
index 000000000..787bd28fe
--- /dev/null
+++ b/dom/bindings/test/test_bug788369.html
@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=788369
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 788369</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=788369">Mozilla Bug 788369</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 788369 **/
+try {
+  var xhr = new(window.ActiveXObject || XMLHttpRequest)("Microsoft.XMLHTTP");
+  ok(xhr instanceof XMLHttpRequest, "Should have an XHR object");
+} catch (e) {
+  ok(false, "Should not throw exception when constructing: " + e);
+}
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug852846.html b/dom/bindings/test/test_bug852846.html
new file mode 100644
index 000000000..0ca2c7dad
--- /dev/null
+++ b/dom/bindings/test/test_bug852846.html
@@ -0,0 +1,34 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=852846
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 852846</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 852846 **/
+  var elem = document.createElement("div");
+  is(elem.style.color, "", "Shouldn't have color set on HTML element")
+  elem.style = "color: green";
+  is(elem.style.color, "green", "Should have color set on HTML element")
+
+  elem = document.createElementNS("http://www.w3.org/2000/svg", "svg");
+  is(elem.style.color, "", "Shouldn't have color set on SVG element")
+  elem.style = "color: green";
+  is(elem.style.color, "green", "Should have color set on SVG element")
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=852846">Mozilla Bug 852846</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug862092.html b/dom/bindings/test/test_bug862092.html
new file mode 100644
index 000000000..4b0633328
--- /dev/null
+++ b/dom/bindings/test/test_bug862092.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=862092
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 862092</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 862092 **/
+
+  SimpleTest.waitForExplicitFinish();
+  function runTest()
+  {
+    var frameDoc = document.getElementById("f").contentDocument;
+    var a = document.createElement("select");
+    a.expando = "test";
+    a = frameDoc.adoptNode(a)
+    is(a.expando, "test", "adoptNode needs to preserve expandos");
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body onload="runTest();">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=862092">Mozilla Bug 862092</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="f"></iframe>
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_bug963382.html b/dom/bindings/test/test_bug963382.html
new file mode 100644
index 000000000..f48d2e8b0
--- /dev/null
+++ b/dom/bindings/test/test_bug963382.html
@@ -0,0 +1,43 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=963382
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 963382</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for clearing cache attributes in JS-implemented WebIDL implementations. **/
+  SimpleTest.waitForExplicitFinish();
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, go);
+
+  function go() {
+    var t = new TestInterfaceJS();
+
+    // Test [Cached] attribute clearing.
+    is(t.cachedAttr, 15, "Initial value of number");
+
+    t.setCachedAttr(3);
+    is(t.cachedAttr, 15, "Setting the number on the inner JS object should not affect cached value");
+
+    t.clearCachedAttrCache();
+    is(t.cachedAttr, 3, "Setting the number on the inner JS object should affect cached value after clearing the cache.");
+
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=963382">Mozilla Bug 963382</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_callback_across_document_open.html b/dom/bindings/test/test_callback_across_document_open.html
new file mode 100644
index 000000000..2a505cefa
--- /dev/null
+++ b/dom/bindings/test/test_callback_across_document_open.html
@@ -0,0 +1,21 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for callback invocation for a callback that comes from a
+  no-longer-current window that still has an active document.</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<iframe srcdoc='<script>function f() { parent.callCount++; }</script>'></iframe>
+<script>
+  var callCount = 0;
+  var t = async_test("A test of callback invocation in a no-longer-current window with a still-active document");
+  window.addEventListener("load", t.step_func_done(function() {
+    var d = document.createElement("div");
+    d.addEventListener("xyz", frames[0].f);
+    frames[0].document.open();
+    frames[0].document.write("All gone");
+    frames[0].document.close();
+    d.dispatchEvent(new Event("xyz"));
+    assert_equals(callCount, 1, "Callback should have been called");
+  }));
+</script>
diff --git a/dom/bindings/test/test_callback_default_thisval.html b/dom/bindings/test/test_callback_default_thisval.html
new file mode 100644
index 000000000..d98ed87b2
--- /dev/null
+++ b/dom/bindings/test/test_callback_default_thisval.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=957929
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 957929</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 957929 **/
+  SimpleTest.waitForExplicitFinish();
+
+  function f() {
+    "use strict";
+    is(this, undefined, "Should have undefined this value");
+    SimpleTest.finish();
+  }
+
+  addLoadEvent(function() {
+    requestAnimationFrame(f);
+  });
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=957929">Mozilla Bug 957929</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_callback_exceptions.html b/dom/bindings/test/test_callback_exceptions.html
new file mode 100644
index 000000000..a40b0b94f
--- /dev/null
+++ b/dom/bindings/test/test_callback_exceptions.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for ...</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+promise_test(function(t) {
+  var iterator = document.createNodeIterator(document, NodeFilter.SHOW_ALL, JSON.parse);
+  return promise_rejects(t, new SyntaxError,
+                         Promise.resolve().then(iterator.nextNode.bind(iterator)));
+}, "Trying to use JSON.parse as filter should throw a catchable SyntaxError exception even when the filter is invoked async");
+
+promise_test(function(t) {
+  return promise_rejects(t, new SyntaxError, Promise.resolve('{').then(JSON.parse));
+}, "Trying to use JSON.parse as a promise callback should allow the next promise to handle the resulting exception.");
+</script>
diff --git a/dom/bindings/test/test_cloneAndImportNode.html b/dom/bindings/test/test_cloneAndImportNode.html
new file mode 100644
index 000000000..fc53c8747
--- /dev/null
+++ b/dom/bindings/test/test_cloneAndImportNode.html
@@ -0,0 +1,48 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=882541
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 882541</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 882541 **/
+  var div = document.createElement("div");
+  div.appendChild(document.createElement("span"));
+
+  var div2;
+
+  div2 = div.cloneNode();
+  is(div2.childNodes.length, 0, "cloneNode() should do a shallow clone");
+
+  div2 = div.cloneNode(undefined);
+  is(div2.childNodes.length, 0, "cloneNode(undefined) should do a shallow clone");
+
+  div2 = div.cloneNode(true);
+  is(div2.childNodes.length, 1, "cloneNode(true) should do a deep clone");
+
+  div2 = document.importNode(div);
+  is(div2.childNodes.length, 0, "importNode(node) should do a deep import");
+
+  div2 = document.importNode(div, undefined);
+  is(div2.childNodes.length, 0, "importNode(undefined) should do a shallow import");
+
+  div2 = document.importNode(div, true);
+  is(div2.childNodes.length, 1, "importNode(true) should do a deep import");
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=882541">Mozilla Bug 882541</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_crossOriginWindowSymbolAccess.html b/dom/bindings/test/test_crossOriginWindowSymbolAccess.html
new file mode 100644
index 000000000..7808631b6
--- /dev/null
+++ b/dom/bindings/test/test_crossOriginWindowSymbolAccess.html
@@ -0,0 +1,23 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for accessing symbols on a cross-origin window</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<iframe src="http://www1.w3c-test.org/common/blank.html"></iframe>
+<script>
+async_test(function (t) {
+  window.addEventListener("load", t.step_func(
+    function() {
+      assert_equals(document.querySelector("iframe").contentDocument, null, "Should have a crossorigin frame");
+      assert_throws(new Error(), function() {
+        frames[0][Symbol.iterator];
+      }, "Should throw exception on cross-origin Window symbol-named get");
+      assert_throws(new Error(), function() {
+        frames[0].location[Symbol.iterator];
+      }, "Should throw exception on cross-origin Location symbol-named get");
+      t.done();
+    }
+  ));
+}, "Check Symbol access on load");
+</script>
diff --git a/dom/bindings/test/test_defineProperty.html b/dom/bindings/test/test_defineProperty.html
new file mode 100644
index 000000000..f8f5f6283
--- /dev/null
+++ b/dom/bindings/test/test_defineProperty.html
@@ -0,0 +1,157 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=910220
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 910220</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=910220">Mozilla Bug 910220</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<form name="x"></form>
+</div>
+<pre id="test">
+</pre>
+<script type="application/javascript">
+
+/** Test for Bug 910220 **/
+
+function getX() {
+  return "x";
+}
+
+function namedSetStrict(obj) {
+  "use strict";
+  var threw;
+  try {
+    obj.x = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when setting named property on " + obj);
+
+  try {
+    obj[getX()] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when setting named property via SETELEM on " + obj);
+
+  try {
+    Object.defineProperty(obj, "x", { value: 17 });
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when defining named property on " + obj);
+}
+function namedSetNonStrict(obj) {
+  var threw;
+  try {
+    obj.x = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(!threw,
+     "Should not throw in non-strict mode when setting named property on " + obj);
+
+  try {
+    obj[getX()] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(!threw,
+     "Should not throw in non-strict mode when setting named property via SETELEM on" + obj);
+
+  try {
+    Object.defineProperty(obj, "x", { value: 17 });
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in non-strict mode when defining named property on " + obj);
+}
+for (var obj of [ document, document.forms ]) {
+  namedSetStrict(obj);
+  namedSetNonStrict(obj);
+}
+
+function indexedSetStrict(obj) {
+  "use strict";
+  var threw;
+  try {
+    obj[0] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when setting indexed property on " + obj);
+
+  try {
+    obj[1000] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when setting out of bounds indexed property on " + obj);
+
+  try {
+    Object.defineProperty(obj, "0", { value: 17 });
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in strict mode when defining indexed property on " + obj);
+}
+function indexedSetNonStrict(obj) {
+  var threw;
+  try {
+    obj[0] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(!threw,
+     "Should not throw in non-strict mode when setting indexed property on " + obj);
+
+  try {
+    obj[1000] = 5;
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(!threw,
+     "Should not throw in non-strict mode when setting out of bounds indexed property on " + obj);
+
+  try {
+    Object.defineProperty(obj, "0", { value: 17 });
+    threw = false;
+  } catch (e) {
+    threw = true;
+  }
+  ok(threw,
+     "Should throw in non-strict mode when defining indexed property on " + obj);
+}
+for (var obj of [ document.forms, document.childNodes ]) {
+  indexedSetStrict(obj);
+  indexedSetNonStrict(obj);
+}
+</script>
+</body>
+</html>
diff --git a/dom/bindings/test/test_document_location_set_via_xray.html b/dom/bindings/test/test_document_location_set_via_xray.html
new file mode 100644
index 000000000..cdadc5063
--- /dev/null
+++ b/dom/bindings/test/test_document_location_set_via_xray.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=905493
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 905493</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=905493">Mozilla Bug 905493</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/file_document_location_set_via_xray.html"></iframe>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 905493 **/
+
+function test()
+{
+  var doc = document.getElementById("t").contentWindow.document;
+  ok(!("x" in doc), "Should have an Xray here");
+  is(doc.x, undefined, "Really should have an Xray here");
+  is(doc.wrappedJSObject.x, 5, "And wrapping the right thing");
+  document.getElementById("t").onload = function() {
+    ok(true, "Load happened");
+    SimpleTest.finish();
+  };
+  try {
+    // Test the forwarding location setter
+    doc.location = "chrome://mochikit/content/tests/SimpleTest/test.css";
+  } catch (e) {
+    // Load failed
+    ok(false, "Load failed");
+    SimpleTest.finish();
+  }
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_document_location_via_xray_cached.html b/dom/bindings/test/test_document_location_via_xray_cached.html
new file mode 100644
index 000000000..20eef10fb
--- /dev/null
+++ b/dom/bindings/test/test_document_location_via_xray_cached.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1041731
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1041731</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1041731">Mozilla Bug 1041731</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/file_document_location_set_via_xray.html"></iframe>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 1041731 **/
+
+function test()
+{
+  var loc = document.getElementById("t").contentWindow.document.location;
+  is(loc.toString, loc.toString, "Unforgeable method on the Xray should be cached");
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_domProxyArrayLengthGetter.html b/dom/bindings/test/test_domProxyArrayLengthGetter.html
new file mode 100644
index 000000000..a62adff2e
--- /dev/null
+++ b/dom/bindings/test/test_domProxyArrayLengthGetter.html
@@ -0,0 +1,28 @@
+<!DOCTYPE html>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1221421
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1221421</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="text/javascript">
+
+  var x = document.documentElement.style;
+  x.__proto__ = [1, 2, 3];
+
+  var res = 0;
+  for (var h = 0; h < 5000; ++h) {
+    res += x.length;
+  }
+  is(res, 15000, "length getter should return array length");
+
+  </script>
+</head>
+
+<body>
+  <a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1221421">Mozilla Bug 1221421</a>
+</body>
+</html>
diff --git a/dom/bindings/test/test_dom_xrays.html b/dom/bindings/test/test_dom_xrays.html
new file mode 100644
index 000000000..0700db2f8
--- /dev/null
+++ b/dom/bindings/test/test_dom_xrays.html
@@ -0,0 +1,231 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=787070
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 787070</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=787070">Mozilla Bug 787070</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/file_dom_xrays.html"></iframe>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 1021066 **/
+
+var Cu = Components.utils;
+
+// values should contain the values that the property should have on each of
+// the objects on the prototype chain of obj. A value of undefined signals
+// that the value should not be present on that prototype.
+function checkXrayProperty(obj, name, values)
+{
+  var instance = obj;
+  do {
+    var value = values.shift();
+    if (typeof value == "undefined") {
+      ok(!obj.hasOwnProperty(name), "hasOwnProperty shouldn't see \"" + name + "\" through Xrays");
+      is(Object.getOwnPropertyDescriptor(obj, name), undefined, "getOwnPropertyDescriptor shouldn't see \"" + name + "\" through Xrays");
+      ok(Object.keys(obj).indexOf(name) == -1, "Enumerating the Xray should not return \"" + name + "\"");
+    } else {
+      ok(obj.hasOwnProperty(name), "hasOwnProperty should see \"" + name + "\" through Xrays");
+      var pd = Object.getOwnPropertyDescriptor(obj, name);
+      ok(pd, "getOwnPropertyDescriptor should see \"" + name + "\" through Xrays");
+      if (pd && pd.get) {
+        is(pd.get.call(instance), value, "Should get the right value for \"" + name + "\" through Xrays");
+      } else {
+        is(obj[name], value, "Should get the right value for \"" + name + "\" through Xrays");
+      }
+      if (pd && pd.enumerable) {
+        ok(Object.keys(obj).indexOf("" + name) > -1, "Enumerating the Xray should return \"" + name + "\"");
+      }
+    }
+  } while ((obj = Object.getPrototypeOf(obj)));
+}
+
+function checkWindowXrayProperty(obj, name, windowValue, windowPrototypeValue, namedPropertiesValue, eventTargetValue)
+{
+  checkXrayProperty(obj, name, [ windowValue, windowPrototypeValue, namedPropertiesValue, eventTargetValue ]);
+}
+
+function test()
+{
+  // Window
+  var win = document.getElementById("t").contentWindow;
+  var doc = document.getElementById("t").contentDocument;
+
+  var winProto = Object.getPrototypeOf(win);
+  is(winProto, win.Window.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  var namedPropertiesObject = Object.getPrototypeOf(winProto);
+  is(Cu.getClassName(namedPropertiesObject, /* unwrap = */ true), "WindowProperties", "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  var eventTargetProto = Object.getPrototypeOf(namedPropertiesObject);
+  is(eventTargetProto, win.EventTarget.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  // Xrays need to filter expandos.
+  checkWindowXrayProperty(win, "expando", undefined);
+  ok(!("expando" in win), "Xrays should filter expandos");
+
+  checkWindowXrayProperty(win, "shadowedIframe", undefined, undefined, doc.getElementById("shadowedIframe").contentWindow);
+  ok("shadowedIframe" in win, "Named properties should be exposed through Xrays");
+
+  // Named properties live on the named properties object for global objects.
+  checkWindowXrayProperty(win, "iframe", undefined, undefined, doc.getElementById("iframe").contentWindow);
+  ok("iframe" in win, "Named properties should be exposed through Xrays");
+
+  // Window properties live on the instance, shadowing the properties of the named property object.
+  checkWindowXrayProperty(win, "document", doc, undefined, doc.getElementById("document").contentWindow);
+  ok("document" in win, "WebIDL properties should be exposed through Xrays");
+
+  // Unforgeable properties live on the instance, shadowing the properties of the named property object.
+  checkWindowXrayProperty(win, "self", win, undefined, doc.getElementById("self").contentWindow);
+  ok("self" in win, "WebIDL properties should be exposed through Xrays");
+
+  // Object.prototype is at the end of the prototype chain.
+  var obj = win;
+  while ((proto = Object.getPrototypeOf(obj))) {
+    obj = proto;
+  }
+  is(obj, win.Object.prototype, "Object.prototype should be at the end of the prototype chain");
+
+  // Named properties shouldn't shadow WebIDL- or ECMAScript-defined properties.
+  checkWindowXrayProperty(win, "addEventListener", undefined, undefined, undefined, eventTargetProto.addEventListener);
+  is(win.addEventListener, eventTargetProto.addEventListener, "Named properties shouldn't shadow WebIDL-defined properties");
+
+  is(win.toString, win.Object.prototype.toString, "Named properties shouldn't shadow ECMAScript-defined properties");
+
+  // HTMLDocument
+  // Unforgeable properties live on the instance.
+  checkXrayProperty(doc, "location", [ win.location ]);
+  is(String(win.location), document.getElementById("t").src,
+     "Should have the right stringification");
+
+  // HTMLHtmlElement
+  var elem = doc.documentElement;
+
+  var elemProto = Object.getPrototypeOf(elem);
+  is(elemProto, win.HTMLHtmlElement.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  elemProto = Object.getPrototypeOf(elemProto);
+  is(elemProto, win.HTMLElement.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  elemProto = Object.getPrototypeOf(elemProto);
+  is(elemProto, win.Element.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  elemProto = Object.getPrototypeOf(elemProto);
+  is(elemProto, win.Node.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  elemProto = Object.getPrototypeOf(elemProto);
+  is(elemProto, win.EventTarget.prototype, "The proto chain of the Xray should mirror the prototype chain of the Xrayed object");
+
+  // Xrays need to filter expandos.
+  ok(!("expando" in elem), "Xrays should filter expandos");
+
+  // WebIDL-defined properties live on the prototype.
+  checkXrayProperty(elem, "version", [ undefined, "" ]);
+  is(elem.version, "", "WebIDL properties should be exposed through Xrays");
+
+  // HTMLCollection
+  var coll = doc.getElementsByTagName("iframe");
+
+  // Named properties live on the instance for non-global objects.
+  checkXrayProperty(coll, "iframe", [ doc.getElementById("iframe") ]);
+
+  // Indexed properties live on the instance.
+  checkXrayProperty(coll, 0, [ doc.getElementById("shadowedIframe") ]);
+
+  // WebIDL-defined properties live on the prototype, overriding any named properties.
+  checkXrayProperty(coll, "item", [ undefined, win.HTMLCollection.prototype.item ]);
+
+  // ECMAScript-defined properties live on the prototype, overriding any named properties.
+  checkXrayProperty(coll, "toString", [ undefined, undefined, win.Object.prototype.toString ]);
+
+  // Frozen arrays should come from our compartment, not the target one.
+  var languages1 = win.navigator.languages;
+  isnot(languages1, undefined, "Must have .languages");
+  ok(Array.isArray(languages1), ".languages should be an array");
+  ok(Object.isFrozen(languages1), ".languages should be a frozen array");
+  ok(!Cu.isXrayWrapper(languages1), "Should have our own version of array");
+  is(Cu.getGlobalForObject(languages1), window,
+     "languages1 should come from our window");
+  // We want to get .languages in the content compartment, but without waiving
+  // Xrays altogether.
+  var languages2 = win.eval("navigator.languages");
+  isnot(languages2, undefined, "Must still have .languages");
+  ok(Array.isArray(languages2), ".languages should still be an array");
+  ok(Cu.isXrayWrapper(languages2), "Should have xray for content version of array");
+  is(Cu.getGlobalForObject(languages2), win,
+     "languages2 come from the underlying window");
+  ok(Object.isFrozen(languages2.wrappedJSObject),
+     ".languages should still be a frozen array underneath");
+  isnot(languages1, languages2, "Must have distinct arrays");
+  isnot(languages1, languages2.wrappedJSObject,
+        "Must have distinct arrays no matter how we slice it");
+
+  // Check that DataTransfer's .types has the hack to alias contains()
+  // to includes().
+  var dataTransfer = new win.DataTransfer("foo", true);
+  is(dataTransfer.types.contains, dataTransfer.types.includes,
+     "Should have contains() set up as an alias to includes()");
+  // Waive Xrays on the dataTransfer itself, since the .types we get is
+  // different over Xrays vs not.
+  is(dataTransfer.wrappedJSObject.types.contains, undefined,
+     "Underlying object should not have contains() set up as an alias to " +
+     "includes()");
+
+  // Check that deleters work correctly in the [OverrideBuiltins] case.
+  var elem = win.document.documentElement;
+  var dataset = elem.dataset;
+  is(dataset.foo, undefined, "Should not have a 'foo' property");
+  ok(!('foo' in dataset), "Really should not have a 'foo' property");
+  is(elem.getAttribute("data-foo"), null,
+     "Should not have a 'data-foo' attribute");
+  ok(!elem.hasAttribute("data-foo"),
+     "Really should not have a 'data-foo' attribute");
+  dataset.foo = "bar";
+  is(dataset.foo, "bar", "Should now have a 'foo' property");
+  ok('foo' in dataset, "Really should have a 'foo' property");
+  is(elem.getAttribute("data-foo"), "bar",
+     "Should have a 'data-foo' attribute");
+  ok(elem.hasAttribute("data-foo"),
+     "Really should have a 'data-foo' attribute");
+  delete dataset.foo;
+  is(dataset.foo, undefined, "Should not have a 'foo' property again");
+  ok(!('foo' in dataset), "Really should not have a 'foo' property again");
+  is(elem.getAttribute("data-foo"), null,
+     "Should not have a 'data-foo' attribute again");
+  ok(!elem.hasAttribute("data-foo"),
+     "Really should not have a 'data-foo' attribute again");
+
+  // Check that deleters work correctly in the non-[OverrideBuiltins] case.
+  var storage = win.sessionStorage;
+  is(storage.foo, undefined, "Should not have a 'foo' property");
+  ok(!('foo' in storage), "Really should not have a 'foo' property");
+  is(storage.getItem("foo"), null, "Should not have an item named 'foo'");
+  storage.foo = "bar";
+  is(storage.foo, "bar", "Should have a 'foo' property");
+  ok('foo' in storage, "Really should have a 'foo' property");
+  is(storage.getItem("foo"), "bar", "Should have an item named 'foo'");
+  delete storage.foo
+  is(storage.foo, undefined, "Should not have a 'foo' property again");
+  ok(!('foo' in storage), "Really should not have a 'foo' property again");
+  is(storage.getItem("foo"), null, "Should not have an item named 'foo' again");
+
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_enums.html b/dom/bindings/test/test_enums.html
new file mode 100644
index 000000000..e5dc519a0
--- /dev/null
+++ b/dom/bindings/test/test_enums.html
@@ -0,0 +1,15 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>Enums</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+test(function() {
+  var xhr = new XMLHttpRequest();
+  xhr.open("get", "foo")
+  assert_equals(xhr.responseType, "");
+  xhr.responseType = "foo";
+  assert_equals(xhr.responseType, "");
+}, "Assigning an invalid value to an enum attribute should not throw.");
+</script>
diff --git a/dom/bindings/test/test_exceptionSanitization.html b/dom/bindings/test/test_exceptionSanitization.html
new file mode 100644
index 000000000..9a6ab6088
--- /dev/null
+++ b/dom/bindings/test/test_exceptionSanitization.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1295322
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1295322</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1295322">Mozilla Bug 1295322</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+  <script type="application/javascript">
+
+  /** Test for Bug 1295322 **/
+  iframe = document.createElement('iframe');
+  iframe.name = "eWin";
+  document.body.appendChild(iframe);
+
+  try{
+    // NOTE: The idea here is to call something that will end up throwing an
+    // exception in a JS component and then propagate back to C++ code before
+    // returning to us.  If opening a feed: URI stops doing that, we will need a
+    // new guinea pig here.
+    open('feed://java:script:codeshouldgohere','eWin');
+    ok(false, "Should have thrown!");
+  } catch(e){
+    try {
+      is(e.name, "NS_ERROR_UNEXPECTED", "Should have the right exception");
+      is(e.filename, location.href,
+         "Should not be seeing where the exception really came from");
+    } catch (e2) {
+      ok(false, "Should be able to work with the exception");
+    }
+  }
+  </script>
+</body>
+</html>
diff --git a/dom/bindings/test/test_exceptionThrowing.html b/dom/bindings/test/test_exceptionThrowing.html
new file mode 100644
index 000000000..376c2bc57
--- /dev/null
+++ b/dom/bindings/test/test_exceptionThrowing.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=847119
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 847119</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 847119 **/
+
+  var xhr = new XMLHttpRequest();
+  var domthrows = function() { xhr.open();  }
+
+  var count = 20000;
+  
+  function f() {
+    var k = 0;
+    for (var j = 0; j < count; ++j) {
+      try { domthrows(); } catch(e) { ++k; }
+    }
+    return k;
+  }
+  function g() { return count; }
+
+  is(f(), count, "Should get count exceptions");
+  for (var h of [f, g]) {
+    try { is(h(), count, "Should get count exceptions here too"); } catch (e) {}
+  }
+  ok(true, "We should get here");
+
+  var domthrows = function() { xhr.withCredentials = false; }
+  xhr.open("GET", "");
+  xhr.send();
+
+  is(f(), count, "Should get count exceptions from getter");
+  for (var h of [f, g]) {
+    try { is(h(), count, "Should get count exceptions from getter here too"); } catch (e) {}
+  }
+  ok(true, "We should get here too");
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=847119">Mozilla Bug 847119</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_exception_messages.html b/dom/bindings/test/test_exception_messages.html
new file mode 100644
index 000000000..a0f0cabe6
--- /dev/null
+++ b/dom/bindings/test/test_exception_messages.html
@@ -0,0 +1,82 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=882653
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 882653</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 882653 **/
+  // Each test is a string to eval, the expected exception message, and the
+  // test description.
+  var tests = [
+      [ 'document.documentElement.appendChild.call({}, new Image())',
+        "'appendChild' called on an object that does not implement interface Node.",
+        "bogus method this object" ],
+      [ 'Object.getOwnPropertyDescriptor(Document.prototype, "documentElement").get.call({})',
+        "'get documentElement' called on an object that does not implement interface Document.",
+        "bogus getter this object" ],
+      [ 'Object.getOwnPropertyDescriptor(Element.prototype, "innerHTML").set.call({})',
+        "'set innerHTML' called on an object that does not implement interface Element.",
+        "bogus setter this object" ],
+      [ 'document.documentElement.appendChild(5)',
+        "Argument 1 of Node.appendChild is not an object.",
+        "bogus interface argument" ],
+      [ 'document.documentElement.appendChild(null)',
+        "Argument 1 of Node.appendChild is not an object.",
+        "null interface argument" ],
+      [ 'document.createTreeWalker(document).currentNode = 5',
+        "Value being assigned to TreeWalker.currentNode is not an object.",
+        "interface setter call" ],
+      [ 'document.documentElement.appendChild({})',
+        "Argument 1 of Node.appendChild does not implement interface Node.",
+        "wrong interface argument" ],
+      [ 'document.createTreeWalker(document).currentNode = {}',
+        "Value being assigned to TreeWalker.currentNode does not implement interface Node.",
+        "wrong interface setter call" ],
+      [ 'document.createElement("canvas").getContext("2d").fill("bogus")',
+        "Argument 1 of CanvasRenderingContext2D.fill 'bogus' is not a valid value for enumeration CanvasWindingRule.",
+        "bogus enum value" ],
+      [ 'document.createTreeWalker(document, 0xFFFFFFFF, { acceptNode: 5 }).nextNode()',
+        "Property 'acceptNode' is not callable.",
+        "non-callable callback interface operation property" ],
+      [ '(new TextDecoder).decode(new Uint8Array(), new RegExp())',
+        "Argument 2 of TextDecoder.decode can't be converted to a dictionary.",
+        "regexp passed for a dictionary" ],
+      [ 'URL.createObjectURL(null, null)',
+        "Argument 1 is not valid for any of the 2-argument overloads of URL.createObjectURL.",
+        "overload resolution failure" ],
+      [ 'document.createElement("select").add({})',
+        "Argument 1 of HTMLSelectElement.add could not be converted to any of: HTMLOptionElement, HTMLOptGroupElement.",
+        "invalid value passed for union" ],
+      [ 'document.createElement("canvas").getContext("2d").createLinearGradient(0, 1, 0, 1).addColorStop(NaN, "")',
+        "Argument 1 of CanvasGradient.addColorStop is not a finite floating-point value.",
+        "invalid float" ]
+  ];
+
+  for (var i = 0; i < tests.length; ++i) {
+      msg = "Correct exception should be thrown for " + tests[i][2];
+      try {
+          eval(tests[i][0]);
+          ok(false, msg);
+      } catch (e) {
+          is(e.message, tests[i][1], msg);
+      }
+  }
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=882653">Mozilla Bug 882653</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_exception_options_from_jsimplemented.html b/dom/bindings/test/test_exception_options_from_jsimplemented.html
new file mode 100644
index 000000000..8a98a8fb6
--- /dev/null
+++ b/dom/bindings/test/test_exception_options_from_jsimplemented.html
@@ -0,0 +1,166 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1107592
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1107592</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1107592 **/
+
+  SimpleTest.waitForExplicitFinish();
+
+  function doTest() {
+    var file = location.href;
+    var asyncFrame;
+    /* Async parent frames from pushPrefEnv don't show up in e10s.  */
+    var isE10S = !SpecialPowers.isMainProcess();
+    if (!isE10S && SpecialPowers.getBoolPref("javascript.options.asyncstack")) {
+      asyncFrame = `Async*@${file}:153:3
+`;
+    } else {
+      asyncFrame = "";
+    }
+
+    var t = new TestInterfaceJS();
+    try {
+      t.testThrowError();
+    } catch (e) {
+      ok(e instanceof Error, "Should have an Error here");
+      ok(!(e instanceof DOMException), "Should not have DOMException here");
+      ok(!("code" in e), "Should not have a 'code' property");
+      is(e.name, "Error", "Should not have an interesting name here");
+      is(e.message, "We are an Error", "Should have the right message");
+      is(e.stack,
+         `doTest@${file}:31:7
+${asyncFrame}`,
+         "Exception stack should still only show our code");
+      is(e.fileName,
+         file,
+         "Should have the right file name");
+      is(e.lineNumber, 31, "Should have the right line number");
+      is(e.columnNumber, 7, "Should have the right column number");
+    }
+
+    try {
+      t.testThrowDOMException();
+    } catch (e) {
+      ok(e instanceof Error, "Should also have an Error here");
+      ok(e instanceof DOMException, "Should have DOMException here");
+      is(e.name, "NotSupportedError", "Should have the right name here");
+      is(e.message, "We are a DOMException",
+         "Should also have the right message");
+      is(e.code, DOMException.NOT_SUPPORTED_ERR,
+         "Should have the right 'code'");
+      is(e.stack,
+         `doTest@${file}:50:7
+${asyncFrame}`,
+         "Exception stack should still only show our code");
+      is(e.filename,
+         file,
+         "Should still have the right file name");
+      is(e.lineNumber, 50, "Should still have the right line number");
+      todo_isnot(e.columnNumber, 0,
+                 "No column number support for DOMException yet");
+    }
+
+    try {
+      t.testThrowTypeError();
+    } catch (e) {
+      ok(e instanceof TypeError, "Should have a TypeError here");
+      ok(!(e instanceof DOMException), "Should not have DOMException here (2)");
+      ok(!("code" in e), "Should not have a 'code' property (2)");
+      is(e.name, "TypeError", "Should be named TypeError");
+      is(e.message, "We are a TypeError",
+         "Should also have the right message (2)");
+      is(e.stack,
+         `doTest@${file}:72:7
+${asyncFrame}`,
+         "Exception stack for TypeError should only show our code");
+      is(e.fileName,
+         file,
+         "Should still have the right file name for TypeError");
+      is(e.lineNumber, 72, "Should still have the right line number for TypeError");
+      is(e.columnNumber, 7, "Should have the right column number for TypeError");
+    }
+
+    try {
+      t.testThrowCallbackError(function() { Array.indexOf() });
+    } catch (e) {
+      ok(e instanceof TypeError, "Should have a TypeError here (3)");
+      ok(!(e instanceof DOMException), "Should not have DOMException here (3)");
+      ok(!("code" in e), "Should not have a 'code' property (3)");
+      is(e.name, "TypeError", "Should be named TypeError (3)");
+      is(e.message, "missing argument 0 when calling function Array.indexOf",
+         "Should also have the right message (3)");
+      is(e.stack,
+         `doTest/<@${file}:92:45
+doTest@${file}:92:7
+${asyncFrame}`,
+         "Exception stack for TypeError should only show our code (3)");
+      is(e.fileName,
+         file,
+         "Should still have the right file name for TypeError (3)");
+      is(e.lineNumber, 92, "Should still have the right line number for TypeError (3)");
+      is(e.columnNumber, 45, "Should have the right column number for TypeError (3)");
+    }
+
+    try {
+      t.testThrowXraySelfHosted();
+    } catch (e) {
+      ok(!(e instanceof Error), "Should have an Exception here (4)");
+      ok(!(e instanceof DOMException), "Should not have DOMException here (4)");
+      ok(!("code" in e), "Should not have a 'code' property (4)");
+      is(e.name, "NS_ERROR_UNEXPECTED", "Name should be sanitized (4)");
+      is(e.message, "", "Message should be sanitized (5)");
+      is(e.stack,
+         `doTest@${file}:113:7
+${asyncFrame}`,
+         "Exception stack for sanitized exception should only show our code (4)");
+      is(e.filename,
+         file,
+         "Should still have the right file name for sanitized exception (4)");
+      is(e.lineNumber, 113, "Should still have the right line number for sanitized exception (4)");
+      todo_isnot(e.columnNumber, 0, "Should have the right column number for sanitized exception (4)");
+    }
+
+    try {
+      t.testThrowSelfHosted();
+    } catch (e) {
+      ok(!(e instanceof Error), "Should have an Exception here (5)");
+      ok(!(e instanceof DOMException), "Should not have DOMException here (5)");
+      ok(!("code" in e), "Should not have a 'code' property (5)");
+      is(e.name, "NS_ERROR_UNEXPECTED", "Name should be sanitized (5)");
+      is(e.message, "", "Message should be sanitized (5)");
+      is(e.stack,
+         `doTest@${file}:132:7
+${asyncFrame}`,
+         "Exception stack for sanitized exception should only show our code (5)");
+      is(e.filename,
+         file,
+         "Should still have the right file name for sanitized exception (5)");
+      is(e.lineNumber, 132, "Should still have the right line number for sanitized exception (5)");
+      todo_isnot(e.columnNumber, 0, "Should have the right column number for sanitized exception (5)");
+    }
+
+    SimpleTest.finish();
+  }
+
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]},
+                            doTest);
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1107592">Mozilla Bug 1107592</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_exceptions_from_jsimplemented.html b/dom/bindings/test/test_exceptions_from_jsimplemented.html
new file mode 100644
index 000000000..d0f599353
--- /dev/null
+++ b/dom/bindings/test/test_exceptions_from_jsimplemented.html
@@ -0,0 +1,56 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=923010
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 923010</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+  /** Test for Bug 923010 **/
+  try {
+    var conn = new RTCPeerConnection();
+
+    var candidate = new RTCIceCandidate({candidate: null });
+    conn.addIceCandidate(candidate)
+    .then(function() {
+      ok(false, "addIceCandidate succeeded when it should have failed");
+    }, function(reason) {
+      is(reason.lineNumber, 17, "Rejection should have been on line 17");
+      is(reason.message,
+         "Invalid candidate passed to addIceCandidate!",
+         "Should have the rejection we expect");
+    })
+    .catch(function(reason) {
+      ok(false, "unexpected error: " + reason);
+    });
+  } catch (e) {
+    // b2g has no WebRTC, apparently
+    todo(false, "No WebRTC on b2g yet");
+  }
+
+  conn.close();
+  try {
+      conn.setIdentityProvider("example.com", "foo");
+      ok(false, "That call to setIdentityProvider should have thrown");
+    } catch (e) {
+      is(e.lineNumber, 36, "Exception should have been on line 36");
+      is(e.message,
+         "Peer connection is closed",
+         "Should have the exception we expect");
+    }
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=923010">Mozilla Bug 923010</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_forOf.html b/dom/bindings/test/test_forOf.html
new file mode 100644
index 000000000..53969a23e
--- /dev/null
+++ b/dom/bindings/test/test_forOf.html
@@ -0,0 +1,86 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=725907
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 725907</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=725907">Mozilla Bug 725907</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<div id="basket">
+  <span id="egg0"></span>
+  <span id="egg1"><span id="duckling1"></span></span>
+  <span id="egg2"></span>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 725907 **/
+
+function runTestsForDocument(document, msgSuffix) {
+    function is(a, b, msg) { SimpleTest.is(a, b, msg + msgSuffix); }
+    function isnot(a, b, msg) { SimpleTest.isnot(a, b, msg + msgSuffix); }
+
+    var basket = document.getElementById("basket");
+    var egg3 = document.createElement("span");
+    egg3.id = "egg3";
+
+    var log = '';
+    for (var x of basket.childNodes) {
+        if (x.nodeType != x.TEXT_NODE)
+            log += x.id + ";";
+    }
+    is(log, "egg0;egg1;egg2;", "'for (x of div.childNodes)' should iterate over child nodes");
+
+    log = '';
+    for (var x of basket.childNodes) {
+        if (x.nodeType != x.TEXT_NODE) {
+            log += x.id + ";";
+            if (x.id == "egg1")
+                basket.appendChild(egg3);
+        }
+    }
+    is(log, "egg0;egg1;egg2;egg3;", "'for (x of div.childNodes)' should see elements added during iteration");
+
+    log = '';
+    basket.appendChild(document.createTextNode("some text"));
+    for (var x of basket.children)
+        log += x.id + ";";
+    is(log, "egg0;egg1;egg2;egg3;", "'for (x of div.children)' should iterate over child elements");
+
+    var count = 0;
+    for (var x of document.getElementsByClassName("hazardous-materials"))
+        count++;
+    is(count, 0, "'for (x of emptyNodeList)' loop should run zero times");
+
+    var log = '';
+    for (var x of document.querySelectorAll("span"))
+        log += x.id + ";";
+    is(log, "egg0;egg1;duckling1;egg2;egg3;", "for-of loop should work with a querySelectorAll() NodeList");
+}
+
+/* All the tests run twice. First, in this document, so without any wrappers. */
+runTestsForDocument(document, "");
+
+/* And once using the document of an iframe, so working with cross-compartment wrappers. */
+SimpleTest.waitForExplicitFinish();
+function iframeLoaded(iframe) {
+    runTestsForDocument(iframe.contentWindow.document, " (in iframe)");
+    SimpleTest.finish();
+}
+
+</script>
+
+<iframe src="forOf_iframe.html" onload="iframeLoaded(this)"></iframe>
+
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_integers.html b/dom/bindings/test/test_integers.html
new file mode 100644
index 000000000..c74b68216
--- /dev/null
+++ b/dom/bindings/test/test_integers.html
@@ -0,0 +1,50 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <meta charset="utf-8">
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+  <canvas id="c" width="1" height="1"></canvas>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+  function testInt64NonFinite(arg) {
+    // We can use a WebGLRenderingContext to test conversion to 64-bit signed
+    // ints edge cases.
+    var gl = $("c").getContext("experimental-webgl");
+    if (!gl) {
+      // No WebGL support on MacOS 10.5.  Just skip this test
+      todo(false, "WebGL not supported");
+      return;
+    }
+    var error = gl.getError()
+
+    // on the b2g emulator we get GL_INVALID_FRAMEBUFFER_OPERATION
+    if (error == 0x0506) // GL_INVALID_FRAMEBUFFER_OPERATION
+        return;
+
+    is(error, 0, "Should not start in an error state");
+
+    var b = gl.createBuffer();
+    gl.bindBuffer(gl.ARRAY_BUFFER, b);
+
+    var a = new Float32Array(1);
+    gl.bufferData(gl.ARRAY_BUFFER, a, gl.STATIC_DRAW);
+
+    gl.bufferSubData(gl.ARRAY_BUFFER, arg, a);
+
+    is(gl.getError(), 0, "Should have treated non-finite double as 0");
+  }
+
+  testInt64NonFinite(NaN);
+  testInt64NonFinite(Infinity);
+  testInt64NonFinite(-Infinity);
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_interfaceName.html b/dom/bindings/test/test_interfaceName.html
new file mode 100644
index 000000000..59828a2cf
--- /dev/null
+++ b/dom/bindings/test/test_interfaceName.html
@@ -0,0 +1,28 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1084001
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1084001</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1084001 **/
+  is(Image.name, "Image", "Image name");
+  is(Promise.name, "Promise", "Promise name");
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1084001">Mozilla Bug 1084001</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_interfaceToString.html b/dom/bindings/test/test_interfaceToString.html
new file mode 100644
index 000000000..c97b2f63b
--- /dev/null
+++ b/dom/bindings/test/test_interfaceToString.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=742156
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 742156</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=742156">Mozilla Bug 742156</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 742156 **/
+
+var nativeToString = ("" + String.replace).replace("replace", "EventTarget");
+try {
+    var eventTargetToString = "" + EventTarget;
+    is(eventTargetToString, nativeToString,
+       "Stringifying a DOM interface object should return the same string" +
+       "as stringifying a native function.");
+}
+catch (e) {
+    ok(false, "Stringifying a DOM interface object shouldn't throw.");
+}
+
+try {
+    eventTargetToString = Function.prototype.toString.call(EventTarget);
+    is(eventTargetToString, nativeToString,
+       "Stringifying a DOM interface object via Function.prototype.toString " +
+       "should return the same string as stringifying a native function.");
+}
+catch (e) {
+    ok(false, "Stringifying a DOM interface object shouldn't throw.");
+}
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_iterable.html b/dom/bindings/test/test_iterable.html
new file mode 100644
index 000000000..8ce818e76
--- /dev/null
+++ b/dom/bindings/test/test_iterable.html
@@ -0,0 +1,241 @@
+<!-- Any copyright is dedicated to the Public Domain.
+- http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+  <head>
+    <title>Test Iterable Interface</title>
+    <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+    <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+  </head>
+  <body>
+    <script class="testbody" type="application/javascript">
+     SimpleTest.waitForExplicitFinish();
+     SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, function() {
+
+       base_properties = [["entries", "function", 0],
+                          ["keys", "function", 0],
+                          ["values", "function", 0],
+                          ["forEach", "function", 1]]
+       var testExistence = function testExistence(prefix, obj, properties) {
+         for (var [name, type, args] of properties) {
+           // Properties are somewhere up the proto chain, hasOwnProperty won't work
+           isnot(obj[name], undefined,
+                 `${prefix} object has property ${name}`);
+
+           is(typeof obj[name], type,
+              `${prefix} object property ${name} is a ${type}`);
+           // Check function length
+           if (type == "function") {
+             is(obj[name].length, args,
+                `${prefix} object property ${name} is length ${args}`);
+             is(obj[name].name, name,
+                `${prefix} object method name is ${name}`);
+           }
+
+           // Find where property is on proto chain, check for enumerablility there.
+           var owner = obj;
+           while (owner) {
+             var propDesc = Object.getOwnPropertyDescriptor(owner, name);
+             if (propDesc) {
+               ok(propDesc.enumerable,
+                  `${prefix} object property ${name} is enumerable`);
+               break;
+             }
+             owner = Object.getPrototypeOf(owner);
+           }
+         }
+       }
+
+       var itr;
+       // Simple single type iterable creation and functionality test
+       info("IterableSingle: Testing simple iterable creation and functionality");
+       itr = new TestInterfaceIterableSingle();
+       testExistence("IterableSingle: ", itr, base_properties);
+       is(itr[Symbol.iterator], Array.prototype[Symbol.iterator],
+          "IterableSingle: Should be using %ArrayIterator% for @@iterator");
+       is(itr.keys, Array.prototype.keys,
+          "IterableSingle: Should be using %ArrayIterator% for 'keys'");
+       is(itr.entries, Array.prototype.entries,
+          "IterableSingle: Should be using %ArrayIterator% for 'entries'");
+       is(itr.values, itr[Symbol.iterator],
+          "IterableSingle: Should be using @@iterator for 'values'");
+       is(itr.forEach, Array.prototype.forEach,
+          "IterableSingle: Should be using %ArrayIterator% for 'forEach'");
+       var keys = [...itr.keys()];
+       var values = [...itr.values()];
+       var entries = [...itr.entries()];
+       var key_itr = itr.keys();
+       var value_itr = itr.values();
+       var entries_itr = itr.entries();
+       for (var i = 0; i < 3; ++i) {
+         var key = key_itr.next();
+         var value = value_itr.next();
+         var entry = entries_itr.next();
+         is(key.value, i, "IterableSingle: Key iterator value should be " + i);
+         is(key.value, keys[i],
+            "IterableSingle: Key iterator value should match destructuring " + i);
+         is(value.value, key.value, "IterableSingle: Value iterator value should be " + key.value);
+         is(value.value, values[i],
+            "IterableSingle: Value iterator value should match destructuring " + i);
+         is(entry.value[0], i, "IterableSingle: Entry iterator value 0 should be " + i);
+         is(entry.value[1], i, "IterableSingle: Entry iterator value 1 should be " + i);
+         is(entry.value[0], entries[i][0],
+            "IterableSingle: Entry iterator value 0 should match destructuring " + i);
+         is(entry.value[1], entries[i][1],
+            "IterableSingle: Entry iterator value 1 should match destructuring " + i);
+       }
+
+       var callsToForEachCallback = 0;
+       var thisArg = {};
+       itr.forEach(function(value, index, obj) {
+         is(index, callsToForEachCallback,
+            `IterableSingle: Should have the right index at ${callsToForEachCallback} calls to forEach callback`);
+         is(value, values[index],
+            `IterableSingle: Should have the right value at ${callsToForEachCallback} calls to forEach callback`);
+         is(this, thisArg,
+            "IterableSingle: Should have the right this value for forEach callback");
+         is(obj, itr,
+            "IterableSingle: Should have the right third arg for forEach callback");
+         ++callsToForEachCallback;
+       }, thisArg);
+       is(callsToForEachCallback, 3,
+          "IterableSingle: Should have right total number of calls to forEach callback");
+
+       var key = key_itr.next();
+       var value = value_itr.next();
+       var entry = entries_itr.next();
+       is(key.value, undefined, "IterableSingle: Key iterator value should be undefined");
+       is(key.done, true, "IterableSingle: Key iterator done should be true");
+       is(value.value, undefined, "IterableSingle: Value iterator value should be undefined");
+       is(value.done, true, "IterableSingle: Value iterator done should be true");
+       is(entry.value, undefined, "IterableDouble: Entry iterator value should be undefined");
+       is(entry.done, true, "IterableSingle: Entry iterator done should be true");
+       is(Object.prototype.toString.call(Object.getPrototypeOf(key_itr)),
+          "[object Array Iterator]",
+          "iterator prototype should have the right brand");
+
+       // Simple dual type iterable creation and functionality test
+       info("IterableDouble: Testing simple iterable creation and functionality");
+       itr = new TestInterfaceIterableDouble();
+       testExistence("IterableDouble: ", itr, base_properties);
+       is(itr.entries, itr[Symbol.iterator],
+          "IterableDouble: Should be using @@iterator for 'entries'");
+       var elements = [["a", "b"], ["c", "d"], ["e", "f"]]
+       var keys = [...itr.keys()];
+       var values = [...itr.values()];
+       var entries = [...itr.entries()];
+       var key_itr = itr.keys();
+       var value_itr = itr.values();
+       var entries_itr = itr.entries();
+       for (var i = 0; i < 3; ++i) {
+         var key = key_itr.next();
+         var value = value_itr.next();
+         var entry = entries_itr.next();
+         is(key.value, elements[i][0], "IterableDouble: Key iterator value should be " + elements[i][0]);
+         is(key.value, keys[i],
+            "IterableDouble: Key iterator value should match destructuring " + i);
+         is(value.value, elements[i][1], "IterableDouble: Value iterator value should be " + elements[i][1]);
+         is(value.value, values[i],
+            "IterableDouble: Value iterator value should match destructuring " + i);
+         is(entry.value[0], elements[i][0], "IterableDouble: Entry iterator value 0 should be " + elements[i][0]);
+         is(entry.value[1], elements[i][1], "IterableDouble: Entry iterator value 1 should be " + elements[i][1]);
+         is(entry.value[0], entries[i][0],
+            "IterableDouble: Entry iterator value 0 should match destructuring " + i);
+         is(entry.value[1], entries[i][1],
+            "IterableDouble: Entry iterator value 1 should match destructuring " + i);
+       }
+
+       callsToForEachCallback = 0;
+       thisArg = {};
+       itr.forEach(function(value, key, obj) {
+         is(key, keys[callsToForEachCallback],
+            `IterableDouble: Should have the right key at ${callsToForEachCallback} calls to forEach callback`);
+         is(value, values[callsToForEachCallback],
+            `IterableDouble: Should have the right value at ${callsToForEachCallback} calls to forEach callback`);
+         is(this, thisArg,
+            "IterableDouble: Should have the right this value for forEach callback");
+         is(obj, itr,
+            "IterableSingle: Should have the right third arg for forEach callback");
+         ++callsToForEachCallback;
+       }, thisArg);
+       is(callsToForEachCallback, 3,
+          "IterableDouble: Should have right total number of calls to forEach callback");
+
+       var key = key_itr.next();
+       var value = value_itr.next();
+       var entry = entries_itr.next()
+       is(key.value, undefined, "IterableDouble: Key iterator value should be undefined");
+       is(key.done, true, "IterableDouble: Key iterator done should be true");
+       is(value.value, undefined, "IterableDouble: Value iterator value should be undefined");
+       is(value.done, true, "IterableDouble: Value iterator done should be true");
+       is(entry.value, undefined, "IterableDouble: Entry iterator value should be undefined");
+       is(entry.done, true, "IterableDouble: Entry iterator done should be true");
+       is(Object.prototype.toString.call(Object.getPrototypeOf(key_itr)),
+          "[object TestInterfaceIterableDoubleIteratorPrototype]",
+          "iterator prototype should have the right brand");
+
+       // Simple dual type iterable creation and functionality test
+       info("IterableDoubleUnion: Testing simple iterable creation and functionality");
+       itr = new TestInterfaceIterableDoubleUnion();
+       testExistence("IterableDoubleUnion: ", itr, base_properties);
+       is(itr.entries, itr[Symbol.iterator],
+          "IterableDoubleUnion: Should be using @@iterator for 'entries'");
+       var elements = [["long", 1], ["string", "a"]]
+       var keys = [...itr.keys()];
+       var values = [...itr.values()];
+       var entries = [...itr.entries()];
+       var key_itr = itr.keys();
+       var value_itr = itr.values();
+       var entries_itr = itr.entries();
+       for (var i = 0; i < elements.length; ++i) {
+         var key = key_itr.next();
+         var value = value_itr.next();
+         var entry = entries_itr.next();
+         is(key.value, elements[i][0], "IterableDoubleUnion: Key iterator value should be " + elements[i][0]);
+         is(key.value, keys[i],
+            "IterableDoubleUnion: Key iterator value should match destructuring " + i);
+         is(value.value, elements[i][1], "IterableDoubleUnion: Value iterator value should be " + elements[i][1]);
+         is(value.value, values[i],
+            "IterableDoubleUnion: Value iterator value should match destructuring " + i);
+         is(entry.value[0], elements[i][0], "IterableDoubleUnion: Entry iterator value 0 should be " + elements[i][0]);
+         is(entry.value[1], elements[i][1], "IterableDoubleUnion: Entry iterator value 1 should be " + elements[i][1]);
+         is(entry.value[0], entries[i][0],
+            "IterableDoubleUnion: Entry iterator value 0 should match destructuring " + i);
+         is(entry.value[1], entries[i][1],
+            "IterableDoubleUnion: Entry iterator value 1 should match destructuring " + i);
+       }
+
+       callsToForEachCallback = 0;
+       thisArg = {};
+       itr.forEach(function(value, key, obj) {
+         is(key, keys[callsToForEachCallback],
+            `IterableDoubleUnion: Should have the right key at ${callsToForEachCallback} calls to forEach callback`);
+         is(value, values[callsToForEachCallback],
+            `IterableDoubleUnion: Should have the right value at ${callsToForEachCallback} calls to forEach callback`);
+         is(this, thisArg,
+            "IterableDoubleUnion: Should have the right this value for forEach callback");
+         is(obj, itr,
+            "IterableSingle: Should have the right third arg for forEach callback");
+         ++callsToForEachCallback;
+       }, thisArg);
+       is(callsToForEachCallback, 2,
+          "IterableDoubleUnion: Should have right total number of calls to forEach callback");
+
+       var key = key_itr.next();
+       var value = value_itr.next();
+       var entry = entries_itr.next()
+       is(key.value, undefined, "IterableDoubleUnion: Key iterator value should be undefined");
+       is(key.done, true, "IterableDoubleUnion: Key iterator done should be true");
+       is(value.value, undefined, "IterableDoubleUnion: Value iterator value should be undefined");
+       is(value.done, true, "IterableDoubleUnion: Value iterator done should be true");
+       is(entry.value, undefined, "IterableDoubleUnion: Entry iterator value should be undefined");
+       is(entry.done, true, "IterableDoubleUnion: Entry iterator done should be true");
+       is(Object.prototype.toString.call(Object.getPrototypeOf(key_itr)),
+          "[object TestInterfaceIterableDoubleUnionIteratorPrototype]",
+          "iterator prototype should have the right brand");
+
+       SimpleTest.finish();
+     });
+    </script>
+  </body>
+</html>
diff --git a/dom/bindings/test/test_jsimplemented_eventhandler.html b/dom/bindings/test/test_jsimplemented_eventhandler.html
new file mode 100644
index 000000000..2854a3112
--- /dev/null
+++ b/dom/bindings/test/test_jsimplemented_eventhandler.html
@@ -0,0 +1,47 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1186696
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1186696</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1186696 **/
+  SimpleTest.waitForExplicitFinish();
+
+  function doTest() {
+    var values = [ function() {}, 5, null, undefined, "some string", {} ];
+
+    while (values.length != 0) {
+      var value = values.pop();
+      var t = new TestInterfaceJS();
+      t.onsomething = value;
+      var gottenValue = t.onsomething;
+      if (typeof value == "object" || typeof value == "function") {
+        is(gottenValue, value, "Should get back the object-or-null we put in");
+      } else {
+        is(gottenValue, null, "Should get back null");
+      }
+    }
+
+    SimpleTest.finish();
+  }
+
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]},
+                            doTest);
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1186696">Mozilla Bug 1186696</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_kill_longrunning_prerendered_content.xul b/dom/bindings/test/test_kill_longrunning_prerendered_content.xul
new file mode 100644
index 000000000..d86b15ad9
--- /dev/null
+++ b/dom/bindings/test/test_kill_longrunning_prerendered_content.xul
@@ -0,0 +1,85 @@
+<?xml version="1.0"?>
+<?xml-stylesheet href="chrome://global/skin" type="text/css"?>
+<?xml-stylesheet href="chrome://mochikit/content/tests/SimpleTest/test.css" type="text/css"?>
+<window xmlns="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"
+        xmlns:html="http://www.w3.org/1999/xhtml"
+        onload="runTest();">
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/EventUtils.js"></script>
+
+<script class="testbody" type="application/javascript">
+<![CDATA[
+
+  SimpleTest.waitForExplicitFinish();
+
+  function Listener(aBrowser, aPrerendered, aCallback) {
+    this.init(aBrowser, aPrerendered, aCallback);
+  }
+
+  Listener.prototype = {
+    init: function(aBrowser, aCallback) {
+      this.mBrowser = aBrowser;
+      this.mCallback = aCallback;
+    },
+    QueryInterface: function(aIID) {
+      if (aIID.equals(Components.interfaces.nsIWebProgressListener) ||
+          aIID.equals(Components.interfaces.nsISupportsWeakReference) ||
+          aIID.equals(Components.interfaces.nsISupports))
+        return this;
+      throw Components.results.NS_NOINTERFACE;
+    },
+    onStateChange : function(aWebProgress, aRequest, aStateFlags, aStatus) {
+      if ((aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_STOP) &&
+          (aStateFlags & Components.interfaces.nsIWebProgressListener.STATE_IS_DOCUMENT)) {
+        setTimeout(this.mCallback, 0);
+      }
+    },
+    onProgressChange : function(aWebProgress, aRequest,
+                                aCurSelfProgress, aMaxSelfProgress,
+                                aCurTotalProgress, aMaxTotalProgress) {},
+    onLocationChange : function(aWebProgress, aRequest, aLocation, aFlags) {},
+    onStatusChange : function(aWebProgress, aRequest, aStatus, aMessage) {},
+    onSecurityChange : function(aWebProgress, aRequest, aState) {},
+    mBrowser: null,
+    mPrerendered: false,
+    mCallback: null
+  };
+
+  var progress, progressListener;
+
+  function runTest() {
+    SpecialPowers.pushPrefEnv({
+      "set": [
+        ["dom.max_script_run_time", 1]
+      ]
+    }, function() {
+      test(function() {
+        ok("The page is successfully interrupted.");
+        SimpleTest.finish();
+      });
+    });
+  }
+
+  function test(aCallback) {
+    var browser = document.getElementById("prerendered");;
+    progressListener = new Listener(browser, aCallback);
+    var docShell = browser.docShell;
+    progress = docShell.QueryInterface(Components.interfaces.nsIInterfaceRequestor)
+                       .getInterface(Components.interfaces.nsIWebProgress);
+    progress.addProgressListener(progressListener,
+                                 Components.interfaces.nsIWebProgress.NOTIFY_ALL);
+    browser.loadURI("data:text/html,<script>;for(;;);</script" + ">");
+  }
+
+]]>
+</script>
+
+<body  id="html_body" xmlns="http://www.w3.org/1999/xhtml">
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1050456">Mozilla Bug 1050456</a>
+<p id="display"></p>
+
+<pre id="test">
+</pre>
+</body>
+<browser prerendered="true" id="prerendered"/>
+</window>
diff --git a/dom/bindings/test/test_lenientThis.html b/dom/bindings/test/test_lenientThis.html
new file mode 100644
index 000000000..cfbdcebcd
--- /dev/null
+++ b/dom/bindings/test/test_lenientThis.html
@@ -0,0 +1,27 @@
+<!doctype html>
+<meta charset=utf-8>
+<title>[LenientThis]</title>
+<script src=/resources/testharness.js></script>
+<script src=/resources/testharnessreport.js></script>
+<div id=log></div>
+<script>
+function noop1() { }
+function noop2() { }
+
+test(function() {
+  var desc = Object.getOwnPropertyDescriptor(Document.prototype, "onreadystatechange");
+
+  document.onreadystatechange = noop1;
+  assert_equals(document.onreadystatechange, noop1, "document.onreadystatechange == noop1");
+  assert_equals(desc.get.call({ }), undefined, "document.onreadystatechange getter.call({}) == undefined");
+}, "invoking Document.onreadystatechange's getter with an invalid this object returns undefined");
+
+test(function() {
+  var desc = Object.getOwnPropertyDescriptor(Document.prototype, "onreadystatechange");
+
+  document.onreadystatechange = noop1;
+  assert_equals(document.onreadystatechange, noop1, "document.onreadystatechange == noop1");
+  assert_equals(desc.set.call({ }, noop2), undefined, "document.onreadystatechange setter.call({}) == undefined");
+  assert_equals(document.onreadystatechange, noop1, "document.onreadystatechange == noop1 (still)");
+}, "invoking Document.onreadystatechange's setter with an invalid this object does nothing and returns undefined");
+</script>
diff --git a/dom/bindings/test/test_lookupGetter.html b/dom/bindings/test/test_lookupGetter.html
new file mode 100644
index 000000000..306ee4f64
--- /dev/null
+++ b/dom/bindings/test/test_lookupGetter.html
@@ -0,0 +1,49 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=462428
+-->
+<head>
+  <title>Test for Bug 462428</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=462428">Mozilla Bug 462428</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 462428 **/
+var x = new XMLHttpRequest;
+x.open("GET", "");
+var getter = x.__lookupGetter__('readyState');
+ok(getter !== undefined, "But able to look it up the normal way");
+ok(!x.hasOwnProperty('readyState'), "property should still be on the prototype");
+
+var sawProp = false;
+for (var i in x) {
+    if (i === "readyState") {
+        sawProp = true;
+    }
+}
+
+ok(sawProp, "property should be enumerable");
+
+is(getter.call(x), 1, "the getter actually works");
+
+Object.getPrototypeOf(x).__defineSetter__('readyState', function() {});
+is(getter.call(x), 1, "the getter works after defineSetter");
+
+is(x.responseType, "", "Should have correct responseType up front");
+var setter = x.__lookupSetter__('responseType');
+setter.call(x, "document");
+is(x.responseType, "document", "the setter is bound correctly");
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_namedNoIndexed.html b/dom/bindings/test/test_namedNoIndexed.html
new file mode 100644
index 000000000..205ec89f9
--- /dev/null
+++ b/dom/bindings/test/test_namedNoIndexed.html
@@ -0,0 +1,36 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=808991
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 808991</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=808991">Mozilla Bug 808991</a>
+<p id="display"></p>
+<div id="content" style="display: none" data-1="foo" data-bar="baz">
+
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 808991 **/
+is($("content").dataset[1], "foo",
+   "Indexed props should work like named on dataset");
+is($("content").dataset["1"], "foo",
+   "Indexed props as strings should work like named on dataset");
+is($("content").dataset.bar, "baz",
+   "Named props should work on dataset");
+is($("content").dataset['bar'], "baz",
+   "Named props as strings should work on dataset");
+
+
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_named_getter_enumerability.html b/dom/bindings/test/test_named_getter_enumerability.html
new file mode 100644
index 000000000..641f78ab2
--- /dev/null
+++ b/dom/bindings/test/test_named_getter_enumerability.html
@@ -0,0 +1,40 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for named getter enumerability</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  var list = document.getElementsByTagName("div");
+  var desc = Object.getOwnPropertyDescriptor(list, "0");
+  assert_equals(typeof desc, "object", "Should have a '0' property");
+  assert_true(desc.enumerable, "'0' property should be enumerable");
+  desc = Object.getOwnPropertyDescriptor(list, "log");
+  assert_equals(typeof desc, "object", "Should have a 'log' property");
+  assert_false(desc.enumerable, "'log' property should not be enumerable");
+}, "Correct getOwnPropertyDescriptor behavior");
+test(function() {
+  var list = document.getElementsByTagName("div");
+  props = [];
+  for (var prop in list) {
+    props.push(prop);
+  }
+  assert_not_equals(props.indexOf("0"), -1, "Should enumerate '0'");
+  assert_equals(props.indexOf("log"), -1, "Should not enumerate 'log'");
+}, "Correct enumeration behavior");
+test(function() {
+  var list = document.getElementsByTagName("div");
+  props = Object.keys(list)
+  assert_not_equals(props.indexOf("0"), -1, "Keys should contain '0'");
+  assert_equals(props.indexOf("log"), -1, "Keys should not contain 'log'");
+}, "Correct keys() behavior");
+test(function() {
+  var list = document.getElementsByTagName("div");
+  props = Object.getOwnPropertyNames(list)
+  assert_not_equals(props.indexOf("0"), -1,
+                    "own prop names should contain '0'");
+  assert_not_equals(props.indexOf("log"), -1,
+                    "own prop names should contain 'log'");
+}, "Correct getOwnPropertyNames() behavior");
+</script>
diff --git a/dom/bindings/test/test_oom_reporting.html b/dom/bindings/test/test_oom_reporting.html
new file mode 100644
index 000000000..7323736e5
--- /dev/null
+++ b/dom/bindings/test/test_oom_reporting.html
@@ -0,0 +1,42 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug </title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug  **/
+  SimpleTest.waitForExplicitFinish();
+
+  SimpleTest.expectUncaughtException();
+  setTimeout(function() {
+    SpecialPowers.Cu.getJSTestingFunctions().throwOutOfMemory();
+  }, 0);
+
+  addEventListener("error", function(e) {
+    is(e.type, "error", "Should have an error event");
+    is(e.message, "uncaught exception: out of memory",
+       "Should have the right error message");
+    // Make sure we finish async, in case the expectUncaughtException assertion
+    // about having seen the exception runs after our listener
+    SimpleTest.executeSoon(SimpleTest.finish);
+  });
+
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=">Mozilla Bug </a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_primitive_this.html b/dom/bindings/test/test_primitive_this.html
new file mode 100644
index 000000000..d2b733dff
--- /dev/null
+++ b/dom/bindings/test/test_primitive_this.html
@@ -0,0 +1,45 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=603201
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 603201</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 603201 **/
+
+  SimpleTest.waitForExplicitFinish();
+  function runTest()
+  {
+    var nodes = document.body.childNodes;
+
+    Object.setPrototypeOf(Number.prototype, nodes);
+
+    Object.defineProperty(nodes, "getter", {get: function() {
+      "use strict";
+      is(this, 1);
+      return "getter";
+    }});
+    Object.defineProperty(Object.getPrototypeOf(nodes), "getter2", {get: function() {
+      "use strict";
+      is(this, 1);
+      return "getter2";
+    }});
+
+    var number = 1;
+    is(number.getter, "getter");
+    is(number.getter2, "getter2");
+
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body onload="runTest();">
+<pre>Test</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_promise_rejections_from_jsimplemented.html b/dom/bindings/test/test_promise_rejections_from_jsimplemented.html
new file mode 100644
index 000000000..5428030c5
--- /dev/null
+++ b/dom/bindings/test/test_promise_rejections_from_jsimplemented.html
@@ -0,0 +1,143 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1107592
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1107592</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1107592 **/
+
+  SimpleTest.waitForExplicitFinish();
+
+  function checkExn(lineNumber, name, message, code, filename, testNumber, stack, exn) {
+    is(exn.lineNumber, lineNumber,
+       "Should have the right line number in test " + testNumber);
+    is(exn.name, name,
+       "Should have the right exception name in test " + testNumber);
+    is("filename" in exn ? exn.filename : exn.fileName, filename,
+       "Should have the right file name in test " + testNumber);
+    is(exn.message, message,
+       "Should have the right message in test " + testNumber);
+    is(exn.code, code, "Should have the right .code in test " + testNumber);
+    if (message === "") {
+      is(exn.name, "InternalError",
+         "Should have one of our synthetic exceptions in test " + testNumber);
+    }
+    is(exn.stack, stack, "Should have the right stack in test " + testNumber);
+  }
+
+  function ensurePromiseFail(testNumber, value) {
+    ok(false, "Test " + testNumber + " should not have a fulfilled promise");
+  }
+
+  function doTest() {
+    var t = new TestInterfaceJS();
+    /* Async parent frames from pushPrefEnv don't show up in e10s.  */
+    var isE10S = !SpecialPowers.isMainProcess();
+    var asyncStack = SpecialPowers.getBoolPref("javascript.options.asyncstack");
+    var ourFile = location.href;
+    var unwrapError = "Promise rejection value is a non-unwrappable cross-compartment wrapper.";
+    var parentFrame = (asyncStack && !isE10S) ? `Async*@${ourFile}:130:3
+` : "";
+
+    Promise.all([
+      t.testPromiseWithThrowingChromePromiseInit().then(
+          ensurePromiseFail.bind(null, 1),
+          checkExn.bind(null, 49, "InternalError", unwrapError,
+                        undefined, ourFile, 1,
+                        `doTest@${ourFile}:49:7
+` +
+                        parentFrame)),
+      t.testPromiseWithThrowingContentPromiseInit(function() {
+          thereIsNoSuchContentFunction1();
+        }).then(
+          ensurePromiseFail.bind(null, 2),
+          checkExn.bind(null, 57, "ReferenceError",
+                        "thereIsNoSuchContentFunction1 is not defined",
+                        undefined, ourFile, 2,
+                        `doTest/<@${ourFile}:57:11
+doTest@${ourFile}:56:7
+` +
+                        parentFrame)),
+      t.testPromiseWithThrowingChromeThenFunction().then(
+          ensurePromiseFail.bind(null, 3),
+          checkExn.bind(null, 0, "InternalError", unwrapError, undefined, "", 3, asyncStack ? (`Async*doTest@${ourFile}:67:7
+` +
+                        parentFrame) : "")),
+      t.testPromiseWithThrowingContentThenFunction(function() {
+          thereIsNoSuchContentFunction2();
+        }).then(
+          ensurePromiseFail.bind(null, 4),
+          checkExn.bind(null, 73, "ReferenceError",
+                        "thereIsNoSuchContentFunction2 is not defined",
+                        undefined, ourFile, 4,
+                        `doTest/<@${ourFile}:73:11
+` +
+                        (asyncStack ? `Async*doTest@${ourFile}:72:7
+` : "") +
+                        parentFrame)),
+      t.testPromiseWithThrowingChromeThenable().then(
+          ensurePromiseFail.bind(null, 5),
+          checkExn.bind(null, 0, "InternalError", unwrapError, undefined, "", 5, asyncStack ? (`Async*doTest@${ourFile}:84:7
+` +
+                        parentFrame) : "")),
+      t.testPromiseWithThrowingContentThenable({
+            then: function() { thereIsNoSuchContentFunction3(); }
+        }).then(
+          ensurePromiseFail.bind(null, 6),
+          checkExn.bind(null, 90, "ReferenceError",
+                        "thereIsNoSuchContentFunction3 is not defined",
+                        undefined, ourFile, 6,
+                        `doTest/<.then@${ourFile}:90:32
+` + (asyncStack ? `Async*doTest@${ourFile}:89:7\n` + parentFrame : ""))),
+      t.testPromiseWithDOMExceptionThrowingPromiseInit().then(
+          ensurePromiseFail.bind(null, 7),
+          checkExn.bind(null, 98, "NotFoundError",
+                        "We are a second DOMException",
+                        DOMException.NOT_FOUND_ERR, ourFile, 7,
+                        `doTest@${ourFile}:98:7
+` +
+                        parentFrame)),
+      t.testPromiseWithDOMExceptionThrowingThenFunction().then(
+          ensurePromiseFail.bind(null, 8),
+          checkExn.bind(null, asyncStack ? 106 : 0, "NetworkError",
+                         "We are a third DOMException",
+                        DOMException.NETWORK_ERR, asyncStack ? ourFile : "", 8,
+                        (asyncStack ? `Async*doTest@${ourFile}:106:7
+` +
+                         parentFrame : ""))),
+      t.testPromiseWithDOMExceptionThrowingThenable().then(
+          ensurePromiseFail.bind(null, 9),
+          checkExn.bind(null, asyncStack ? 114 : 0, "TypeMismatchError",
+                        "We are a fourth DOMException",
+                        DOMException.TYPE_MISMATCH_ERR,
+                        asyncStack ? ourFile : "", 9,
+                        (asyncStack ? `Async*doTest@${ourFile}:114:7
+` +
+                         parentFrame : ""))),
+    ]).then(SimpleTest.finish,
+            function(err) {
+              ok(false, "One of our catch statements totally failed with err" + err + ', stack: ' + (err ? err.stack : ''));
+              SimpleTest.finish();
+            });
+  }
+
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]},
+                            doTest);
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1107592">Mozilla Bug 1107592</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_proxies_via_xray.html b/dom/bindings/test/test_proxies_via_xray.html
new file mode 100644
index 000000000..59affe6c0
--- /dev/null
+++ b/dom/bindings/test/test_proxies_via_xray.html
@@ -0,0 +1,99 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1021066
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1021066</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1021066">Mozilla Bug 1021066</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe id="t" src="http://example.org/tests/dom/bindings/test/file_proxies_via_xray.html"></iframe>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 1021066 **/
+
+function test()
+{
+  "use strict"; // So we'll get exceptions on sets
+  var doc = document.getElementById("t").contentWindow.document;
+  ok(!("x" in doc), "Should have an Xray here");
+  is(doc.x, undefined, "Really should have an Xray here");
+  is(doc.wrappedJSObject.x, 5, "And wrapping the right thing");
+
+  // Test overridebuiltins binding without named setter
+  is(doc.y, doc.getElementById("y"),
+     "Named getter should work on Document");
+  try {
+    doc.z = 5;
+    ok(false, "Should have thrown on set of readonly property on Document");
+  } catch (e) {
+    ok(/read-only/.test(e.message),
+       "Threw the right exception on set of readonly property on Document");
+  }
+
+  doc.w = 5;
+  is(doc.w, 5, "Should be able to set things that are not named props");
+
+  // Test non-overridebuiltins binding without named setter
+  var l = doc.getElementsByTagName("img");
+  is(l.y, doc.getElementById("y"),
+     "Named getter should work on HTMLCollection");
+  try {
+    l.z = 5;
+    ok(false, "Should have thrown on set of readonly property on HTMLCollection");
+  } catch (e) {
+    ok(/read-only/.test(e.message),
+       "Should throw the right exception on set of readonly property on HTMLCollection");
+  }
+  try {
+    l[10] = 5;
+    ok(false, "Should have thrown on set of indexed property on HTMLCollection");
+  } catch (e) {
+    ok(/doesn't have an indexed property setter/.test(e.message),
+       "Should throw the right exception on set of indexed property on HTMLCollection");
+  }
+
+  // Test overridebuiltins binding with named setter
+  var d = doc.documentElement.dataset;
+  d.foo = "bar";
+  // Check that this actually got passed on to the underlying object.
+  is(d.wrappedJSObject.foo, "bar",
+     "Set should get forwarded to the underlying object");
+  is(doc.documentElement.getAttribute("data-foo"), "bar",
+     "Attribute setter should have been called");
+  d.foo = "baz";
+  // Check that this actually got passed on to the underlying object.
+  is(d.wrappedJSObject.foo, "baz",
+     "Set should get forwarded to the underlying object again");
+  is(doc.documentElement.getAttribute("data-foo"), "baz",
+     "Attribute setter should have been called again");
+
+  // Test non-overridebuiltins binding with named setter
+  var s = doc.defaultView.localStorage;
+  s["test_proxies_via_xray"] = "bar";
+  // Check that this actually got passed on to the underlying object.
+  is(s.wrappedJSObject["test_proxies_via_xray"], "bar",
+     "Set should get forwarded to the underlying object without overridebuiltins");
+  s["test_proxies_via_xray"] = "baz";
+  // Check that this actually got passed on to the underlying object.
+  is(s.wrappedJSObject["test_proxies_via_xray"], "baz",
+     "Set should get forwarded to the underlying object again without overridebuiltins");
+
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+addLoadEvent(test);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_queryInterface.html b/dom/bindings/test/test_queryInterface.html
new file mode 100644
index 000000000..076bf9e7d
--- /dev/null
+++ b/dom/bindings/test/test_queryInterface.html
@@ -0,0 +1,41 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=827546
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 827546</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 827546 **/
+
+  var notEditable = document.createElement("div");
+  var thrown;
+  try {
+    thrown = false;
+    SpecialPowers.do_QueryInterface(notEditable, "nsIDOMNSEditableElement");
+  } catch (e) {
+    thrown = true;
+  }
+  ok(thrown,
+     "QI to nsIDOMNSEditableElement on a non-editable element should fail");
+
+  var editable = document.createElement("input");
+  ok(SpecialPowers.do_QueryInterface(editable, "nsIDOMNSEditableElement"),
+     "Editable element needs to support QI to nsIDOMNSEditableElement");
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=827546">Mozilla Bug 827546</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_returnUnion.html b/dom/bindings/test/test_returnUnion.html
new file mode 100644
index 000000000..5be10ba3c
--- /dev/null
+++ b/dom/bindings/test/test_returnUnion.html
@@ -0,0 +1,59 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1048659
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1048659</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for returning unions from JS-implemented WebIDL. **/
+  SimpleTest.waitForExplicitFinish();
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, go);
+
+  function go() {
+    var t = new TestInterfaceJS();
+    var t2 = new TestInterfaceJS();
+
+    is(t.pingPongUnion(t2), t2, "ping pong union for left case should be identity");
+    is(t.pingPongUnion(12), 12, "ping pong union for right case should be identity");
+
+    is(t.pingPongUnionContainingNull("this is not a string"), "this is not a string",
+      "ping pong union containing union for left case should be identity");
+    is(t.pingPongUnionContainingNull(null), null,
+      "ping pong union containing null for right case null should be identity");
+    is(t.pingPongUnionContainingNull(t2), t2,
+      "ping pong union containing null for right case should be identity");
+
+    is(t.pingPongNullableUnion(t2), t2, "ping pong nullable union for left case should be identity");
+    is(t.pingPongNullableUnion(12), 12, "ping pong nullable union for right case should be identity");
+    is(t.pingPongNullableUnion(null), null, "ping pong nullable union for null case should be identity");
+
+    var rejectedBadUnion = false;
+    var result = null;
+    try {
+      result = t.returnBadUnion();
+    } catch (e) {
+      rejectedBadUnion = true;
+    }
+    is(result, null, "bad union should not set a value for result");
+    ok(rejectedBadUnion, "bad union should throw an exception");
+
+    SimpleTest.finish();
+  }
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1048659">Mozilla Bug 1048659</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_sequence_detection.html b/dom/bindings/test/test_sequence_detection.html
new file mode 100644
index 000000000..80dfac4db
--- /dev/null
+++ b/dom/bindings/test/test_sequence_detection.html
@@ -0,0 +1,53 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1066432
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1066432</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1066432 **/
+  SimpleTest.waitForExplicitFinish();
+  SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, function() {
+    var testInterfaceJS = new TestInterfaceJS();
+    ok(testInterfaceJS, "got a TestInterfaceJS object");
+
+    var nonIterableObject = {[Symbol.iterator]: 5};
+
+    try {
+      testInterfaceJS.testSequenceOverload(nonIterableObject);
+      ok(false, "Should have thrown in the overload case");  // see long comment above!
+    } catch (e) {
+      is(e.name, "TypeError", "Should get a TypeError for the overload case");
+      ok(e.message.includes("not iterable"),
+         "Should have a message about being non-iterable in the overload case");
+    }
+
+    try {
+      testInterfaceJS.testSequenceUnion(nonIterableObject);
+      ok(false, "Should have thrown in the union case");
+    } catch (e) {
+      is(e.name, "TypeError", "Should get a TypeError for the union case");
+      ok(e.message.includes("not iterable"),
+         "Should have a message about being non-iterable in the union case");
+    }
+
+    SimpleTest.finish();
+  });
+
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1066432">Mozilla Bug 1066432</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_sequence_wrapping.html b/dom/bindings/test/test_sequence_wrapping.html
new file mode 100644
index 000000000..7132e5601
--- /dev/null
+++ b/dom/bindings/test/test_sequence_wrapping.html
@@ -0,0 +1,59 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=775852
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 775852</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=775852">Mozilla Bug 775852</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  <canvas width="1" height="1" id="c"></canvas>
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 775852 **/
+function doTest() {
+  var gl = $("c").getContext("experimental-webgl");
+  if (!gl) {
+    // No WebGL support on MacOS 10.5.  Just skip this test
+    todo(false, "WebGL not supported");
+    return;
+  }
+  var setterCalled = false;
+
+  extLength = gl.getSupportedExtensions().length;
+  ok(extLength > 0,
+     "This test won't work right if we have no supported extensions");
+
+  Object.defineProperty(Array.prototype, "0",
+    {
+      set: function(val) {
+             setterCalled = true;
+           }
+    });
+
+  // Test that our property got defined correctly
+  var arr = []
+  arr[0] = 5;
+  is(setterCalled, true, "Setter should be called when setting prop on array");
+
+  setterCalled = false;
+
+  is(gl.getSupportedExtensions().length, extLength,
+     "We should still have the same number of extensions");
+
+  is(setterCalled, false,
+     "Setter should not be called when getting supported extensions");
+}
+doTest();
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_setWithNamedGetterNoNamedSetter.html b/dom/bindings/test/test_setWithNamedGetterNoNamedSetter.html
new file mode 100644
index 000000000..52f56151d
--- /dev/null
+++ b/dom/bindings/test/test_setWithNamedGetterNoNamedSetter.html
@@ -0,0 +1,40 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1043690
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1043690</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1043690">Mozilla Bug 1043690</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+<form>
+  <input name="action">
+</form>
+</div>
+  <script type="application/javascript">
+
+  /** Test for Bug 1043690 **/
+  var f = document.querySelector("form");
+  var i = document.querySelector("input");
+  is(f.getAttribute("action"), null, "Should have no action attribute");
+  is(f.action, i, "form.action should be the input");
+  f.action = "http://example.org";
+  is(f.getAttribute("action"), "http://example.org",
+     "Should have an action attribute now");
+  is(f.action, i, "form.action should still be the input");
+  i.remove();
+  is(f.action, "http://example.org/",
+     "form.action should no longer be shadowed");
+
+
+  </script>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_stringBindings.html b/dom/bindings/test/test_stringBindings.html
new file mode 100644
index 000000000..1895b0342
--- /dev/null
+++ b/dom/bindings/test/test_stringBindings.html
@@ -0,0 +1,59 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1334537
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1334537</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1334537 **/
+  SimpleTest.waitForExplicitFinish();
+
+  function go() {
+    // Need a new global that will pick up our pref.
+    var ifr = document.createElement("iframe");
+    document.body.appendChild(ifr);
+
+    var t = new ifr.contentWindow.TestFunctions();
+    var testString = "abcdefghijklmnopqrstuvwxyz";
+    const substringLength = 10;
+    var shortTestString = testString.substring(0, substringLength);
+
+    t.setStringData(testString);
+    // Note: we want to do all our gets before we start running code we don't
+    // control inside the test harness, if we really want to exercise the string
+    // cache in controlled ways.
+
+    var asShortDOMString = t.getStringDataAsDOMString(substringLength);
+    var asFullDOMString = t.getStringDataAsDOMString();
+    var asShortAString = t.getStringDataAsAString(substringLength);
+    var asAString = t.getStringDataAsAString();
+
+    is(asShortAString, shortTestString, "Short DOMString should be short");
+    is(asFullDOMString, testString, "Full DOMString should be test string");
+    is(asShortAString, shortTestString, "Short AString should be short");
+    is(asAString, testString, "Full AString should be test string");
+
+    SimpleTest.finish();
+  }
+
+  addLoadEvent(function() {
+    SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]},
+                              go);
+  });
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1334537">Mozilla Bug 1334537</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_throwing_method_noDCE.html b/dom/bindings/test/test_throwing_method_noDCE.html
new file mode 100644
index 000000000..e952819a8
--- /dev/null
+++ b/dom/bindings/test/test_throwing_method_noDCE.html
@@ -0,0 +1,27 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test that we don't DCE functions that can throw</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<script>
+test(function() {
+  function test(root) {
+    var threw = false;
+    try {
+        root.querySelectorAll("");
+    } catch(e){ threw = true; };
+    // Hot loop to make sure the JIT heuristics ion-compile this function even
+    // though it's throwing exceptions (which would normally make us back off
+    // of ion compilation).
+    for (var i=0; i<1500; i++) {}
+    return threw;
+  }
+
+  var threw = false;
+  var el = document.createElement("div");
+  for (var i=0; i<200; i++)
+      threw = test(el);
+  assert_true(threw);
+}, "Shouldn't optimize away throwing functions");
+</script>
diff --git a/dom/bindings/test/test_traceProtos.html b/dom/bindings/test/test_traceProtos.html
new file mode 100644
index 000000000..17a5cb96d
--- /dev/null
+++ b/dom/bindings/test/test_traceProtos.html
@@ -0,0 +1,37 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=744772
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 744772</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=744772">Mozilla Bug 744772</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+  
+</div>
+<pre id="test">
+<script type="application/javascript">
+
+/** Test for Bug 744772 **/
+
+SimpleTest.waitForExplicitFinish();
+
+function callback() {
+  new XMLHttpRequest().upload;
+  ok(true, "Accessing unreferenced DOM interface objects shouldn't crash");
+  SimpleTest.finish();
+}
+
+delete window.XMLHttpRequestUpload;
+SpecialPowers.exactGC(callback);
+
+</script>
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_treat_non_object_as_null.html b/dom/bindings/test/test_treat_non_object_as_null.html
new file mode 100644
index 000000000..fbb6ceb66
--- /dev/null
+++ b/dom/bindings/test/test_treat_non_object_as_null.html
@@ -0,0 +1,39 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=952365
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 952365</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 952365 **/
+
+    var onvolumechange;
+    var x = {};
+    
+    (function() {
+       onvolumechange = x;
+       is(onvolumechange, x,
+          "Should preserve an object value when assigning to event handler");
+       // Test that we don't try to actually call the non-callable object
+       window.dispatchEvent(new Event("volumechange"));
+       onvolumechange = 5;
+       is(onvolumechange, null,
+          "Non-object values should become null when assigning to event handler");
+    })();
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=952365">Mozilla Bug 952365</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>
diff --git a/dom/bindings/test/test_unforgeablesonexpando.html b/dom/bindings/test/test_unforgeablesonexpando.html
new file mode 100644
index 000000000..419e6ac7d
--- /dev/null
+++ b/dom/bindings/test/test_unforgeablesonexpando.html
@@ -0,0 +1,18 @@
+<!DOCTYPE html>
+<meta charset=utf-8>
+<title>Test for making sure named getters don't override the unforgeable location on HTMLDocument</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<div id="log"></div>
+<img name="location">
+<script>
+test(function() {
+  assert_equals(document.location, window.location,
+                'The <img name="location"> should not override the location getter');
+}, "document.location is the right thing");
+test(function() {
+  var doc = new DOMParser().parseFromString("<img name='location'>", "text/html");
+  assert_equals(doc.location, null,
+                'The <img name="location"> should not override the location getter on a data document');
+}, "document.location is the right thing on non-rendered document");
+</script>
diff --git a/dom/bindings/test/test_usvstring.html b/dom/bindings/test/test_usvstring.html
new file mode 100644
index 000000000..cbb1e7971
--- /dev/null
+++ b/dom/bindings/test/test_usvstring.html
@@ -0,0 +1,41 @@
+<!-- Any copyright is dedicated to the Public Domain.
+   - http://creativecommons.org/publicdomain/zero/1.0/ -->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Test USVString</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<script class="testbody" type="application/javascript">
+SimpleTest.waitForExplicitFinish();
+SpecialPowers.pushPrefEnv({set: [['dom.expose_test_interfaces', true]]}, function() {
+  var testInterfaceJS = new TestInterfaceJS();
+  ok(testInterfaceJS, "got a TestInterfaceJS object");
+  // For expected values, see algorithm definition here:
+  //  http://heycam.github.io/webidl/#dfn-obtain-unicode
+  var testList = [
+    { string:   "foo",
+      expected: "foo" },
+    { string:   "This is U+2070E: \ud841\udf0e",
+      expected: "This is U+2070E: \ud841\udf0e" },
+    { string:   "Missing low surrogate: \ud841",
+      expected: "Missing low surrogate: \ufffd" },
+    { string:   "Missing low surrogate with trailer: \ud841!!",
+      expected: "Missing low surrogate with trailer: \ufffd!!" },
+    { string:   "Missing high surrogate: \udf0e",
+      expected: "Missing high surrogate: \ufffd" },
+    { string:   "Missing high surrogate with trailer: \udf0e!!",
+      expected: "Missing high surrogate with trailer: \ufffd!!" },
+    { string:   "U+2070E after malformed: \udf0e\ud841\udf0e",
+      expected: "U+2070E after malformed: \ufffd\ud841\udf0e" }
+  ];
+  testList.forEach(function(test) {
+    is(testInterfaceJS.convertSVS(test.string), test.expected, "Convert '" + test.string + "'");
+  });
+  SimpleTest.finish();
+});
+</script>
+</body>
+</html>
diff --git a/dom/bindings/test/test_worker_UnwrapArg.html b/dom/bindings/test/test_worker_UnwrapArg.html
new file mode 100644
index 000000000..1331a83f4
--- /dev/null
+++ b/dom/bindings/test/test_worker_UnwrapArg.html
@@ -0,0 +1,58 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1127206
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1127206</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+  <script type="application/javascript">
+
+  /** Test for Bug 1127206 **/
+  SimpleTest.waitForExplicitFinish();
+  var blob = new Blob([
+    `try { new File({}); }
+     catch (e) {
+       postMessage("throwing on random object");
+     }
+     try { new File(new Blob(["abc"])); }
+     catch (e)  {
+       postMessage("throwing on Blob");
+     }
+     try { new File("abc"); }
+     catch (e) {
+       postMessage("throwing on string");
+     }
+     postMessage('finishTest')`]);
+  var url = URL.createObjectURL(blob);
+  var w = new Worker(url);
+  var expectedResults = [
+    "throwing on random object",
+    "throwing on Blob",
+    "throwing on string",
+  ];
+  var curIndex = 0;
+  w.onmessage = function(e) {
+    if (curIndex == expectedResults.length) {
+      is(e.data, "finishTest", "What message is this?");
+      SimpleTest.finish();
+    } else {
+      is(e.data, expectedResults[curIndex],
+         "Message " + (curIndex+1) + " should be correct");
+      ++curIndex;
+    }
+  }
+  </script>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1127206">Mozilla Bug 1127206</a>
+<p id="display"></p>
+<div id="content" style="display: none">
+
+</div>
+<pre id="test">
+</pre>
+</body>
+</html>