Add m-esr52 at 52.6.0

1 files changed, 3990 insertions, 0 deletions

diff --git a/js/src/jsobj.cpp b/js/src/jsobj.cpp
new file mode 100644
index 000000000..a39a4b0a0
--- /dev/null
+++ b/js/src/jsobj.cpp
@@ -0,0 +1,3990 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * 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/. */
+
+/*
+ * JS object implementation.
+ */
+
+#include "jsobjinlines.h"
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/MemoryReporting.h"
+#include "mozilla/SizePrintfMacros.h"
+#include "mozilla/TemplateLib.h"
+
+#include <string.h>
+
+#include "jsapi.h"
+#include "jsarray.h"
+#include "jsatom.h"
+#include "jscntxt.h"
+#include "jsfriendapi.h"
+#include "jsfun.h"
+#include "jsgc.h"
+#include "jsiter.h"
+#include "jsnum.h"
+#include "jsopcode.h"
+#include "jsprf.h"
+#include "jsscript.h"
+#include "jsstr.h"
+#include "jstypes.h"
+#include "jsutil.h"
+#include "jswatchpoint.h"
+#include "jswin.h"
+#include "jswrapper.h"
+
+#include "builtin/Eval.h"
+#include "builtin/Object.h"
+#include "builtin/SymbolObject.h"
+#include "frontend/BytecodeCompiler.h"
+#include "gc/Marking.h"
+#include "gc/Policy.h"
+#include "jit/BaselineJIT.h"
+#include "js/MemoryMetrics.h"
+#include "js/Proxy.h"
+#include "js/UbiNode.h"
+#include "js/UniquePtr.h"
+#include "vm/ArgumentsObject.h"
+#include "vm/Interpreter.h"
+#include "vm/ProxyObject.h"
+#include "vm/RegExpStaticsObject.h"
+#include "vm/Shape.h"
+#include "vm/TypedArrayCommon.h"
+
+#include "jsatominlines.h"
+#include "jsboolinlines.h"
+#include "jscntxtinlines.h"
+#include "jscompartmentinlines.h"
+
+#include "vm/ArrayObject-inl.h"
+#include "vm/BooleanObject-inl.h"
+#include "vm/Caches-inl.h"
+#include "vm/Interpreter-inl.h"
+#include "vm/NativeObject-inl.h"
+#include "vm/NumberObject-inl.h"
+#include "vm/Shape-inl.h"
+#include "vm/StringObject-inl.h"
+
+using namespace js;
+using namespace js::gc;
+
+using mozilla::DebugOnly;
+using mozilla::Maybe;
+
+void
+js::ReportNotObject(JSContext* cx, const Value& v)
+{
+    MOZ_ASSERT(!v.isObject());
+
+    RootedValue value(cx, v);
+    UniqueChars bytes = DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, value, nullptr);
+    if (bytes)
+        JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_NOT_NONNULL_OBJECT,
+                                   bytes.get());
+}
+
+JS_PUBLIC_API(const char*)
+JS::InformalValueTypeName(const Value& v)
+{
+    if (v.isObject())
+        return v.toObject().getClass()->name;
+    if (v.isString())
+        return "string";
+    if (v.isSymbol())
+        return "symbol";
+    if (v.isNumber())
+        return "number";
+    if (v.isBoolean())
+        return "boolean";
+    if (v.isNull())
+        return "null";
+    if (v.isUndefined())
+        return "undefined";
+    return "value";
+}
+
+// ES6 draft rev37 6.2.4.4 FromPropertyDescriptor
+JS_PUBLIC_API(bool)
+JS::FromPropertyDescriptor(JSContext* cx, Handle<PropertyDescriptor> desc, MutableHandleValue vp)
+{
+    AssertHeapIsIdle(cx);
+    CHECK_REQUEST(cx);
+    assertSameCompartment(cx, desc);
+
+    // Step 1.
+    if (!desc.object()) {
+        vp.setUndefined();
+        return true;
+    }
+
+    return FromPropertyDescriptorToObject(cx, desc, vp);
+}
+
+bool
+js::FromPropertyDescriptorToObject(JSContext* cx, Handle<PropertyDescriptor> desc,
+                                   MutableHandleValue vp)
+{
+    // Step 2-3.
+    RootedObject obj(cx, NewBuiltinClassInstance<PlainObject>(cx));
+    if (!obj)
+        return false;
+
+    const JSAtomState& names = cx->names();
+
+    // Step 4.
+    if (desc.hasValue()) {
+        if (!DefineProperty(cx, obj, names.value, desc.value()))
+            return false;
+    }
+
+    // Step 5.
+    RootedValue v(cx);
+    if (desc.hasWritable()) {
+        v.setBoolean(desc.writable());
+        if (!DefineProperty(cx, obj, names.writable, v))
+            return false;
+    }
+
+    // Step 6.
+    if (desc.hasGetterObject()) {
+        if (JSObject* get = desc.getterObject())
+            v.setObject(*get);
+        else
+            v.setUndefined();
+        if (!DefineProperty(cx, obj, names.get, v))
+            return false;
+    }
+
+    // Step 7.
+    if (desc.hasSetterObject()) {
+        if (JSObject* set = desc.setterObject())
+            v.setObject(*set);
+        else
+            v.setUndefined();
+        if (!DefineProperty(cx, obj, names.set, v))
+            return false;
+    }
+
+    // Step 8.
+    if (desc.hasEnumerable()) {
+        v.setBoolean(desc.enumerable());
+        if (!DefineProperty(cx, obj, names.enumerable, v))
+            return false;
+    }
+
+    // Step 9.
+    if (desc.hasConfigurable()) {
+        v.setBoolean(desc.configurable());
+        if (!DefineProperty(cx, obj, names.configurable, v))
+            return false;
+    }
+
+    vp.setObject(*obj);
+    return true;
+}
+
+bool
+js::GetFirstArgumentAsObject(JSContext* cx, const CallArgs& args, const char* method,
+                             MutableHandleObject objp)
+{
+    if (args.length() == 0) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_MORE_ARGS_NEEDED,
+                                  method, "0", "s");
+        return false;
+    }
+
+    HandleValue v = args[0];
+    if (!v.isObject()) {
+        UniqueChars bytes = DecompileValueGenerator(cx, JSDVG_SEARCH_STACK, v, nullptr);
+        if (!bytes)
+            return false;
+        JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, JSMSG_UNEXPECTED_TYPE,
+                                   bytes.get(), "not an object");
+        return false;
+    }
+
+    objp.set(&v.toObject());
+    return true;
+}
+
+static bool
+GetPropertyIfPresent(JSContext* cx, HandleObject obj, HandleId id, MutableHandleValue vp,
+                     bool* foundp)
+{
+    if (!HasProperty(cx, obj, id, foundp))
+        return false;
+    if (!*foundp) {
+        vp.setUndefined();
+        return true;
+    }
+
+    return GetProperty(cx, obj, obj, id, vp);
+}
+
+bool
+js::Throw(JSContext* cx, jsid id, unsigned errorNumber)
+{
+    MOZ_ASSERT(js_ErrorFormatString[errorNumber].argCount == 1);
+
+    RootedValue idVal(cx, IdToValue(id));
+    JSString* idstr = ValueToSource(cx, idVal);
+    if (!idstr)
+       return false;
+    JSAutoByteString bytes(cx, idstr);
+    if (!bytes)
+        return false;
+    JS_ReportErrorNumberLatin1(cx, GetErrorMessage, nullptr, errorNumber, bytes.ptr());
+    return false;
+}
+
+bool
+js::Throw(JSContext* cx, JSObject* obj, unsigned errorNumber)
+{
+    if (js_ErrorFormatString[errorNumber].argCount == 1) {
+        RootedValue val(cx, ObjectValue(*obj));
+        ReportValueErrorFlags(cx, JSREPORT_ERROR, errorNumber,
+                              JSDVG_IGNORE_STACK, val, nullptr,
+                              nullptr, nullptr);
+    } else {
+        MOZ_ASSERT(js_ErrorFormatString[errorNumber].argCount == 0);
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, errorNumber);
+    }
+    return false;
+}
+
+
+/*** PropertyDescriptor operations and DefineProperties ******************************************/
+
+bool
+CheckCallable(JSContext* cx, JSObject* obj, const char* fieldName)
+{
+    if (obj && !obj->isCallable()) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_GET_SET_FIELD,
+                                  fieldName);
+        return false;
+    }
+    return true;
+}
+
+bool
+js::ToPropertyDescriptor(JSContext* cx, HandleValue descval, bool checkAccessors,
+                         MutableHandle<PropertyDescriptor> desc)
+{
+    // step 2
+    RootedObject obj(cx, NonNullObject(cx, descval));
+    if (!obj)
+        return false;
+
+    // step 3
+    desc.clear();
+
+    bool found = false;
+    RootedId id(cx);
+    RootedValue v(cx);
+    unsigned attrs = 0;
+
+    // step 4
+    id = NameToId(cx->names().enumerable);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    if (found) {
+        if (ToBoolean(v))
+            attrs |= JSPROP_ENUMERATE;
+    } else {
+        attrs |= JSPROP_IGNORE_ENUMERATE;
+    }
+
+    // step 5
+    id = NameToId(cx->names().configurable);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    if (found) {
+        if (!ToBoolean(v))
+            attrs |= JSPROP_PERMANENT;
+    } else {
+        attrs |= JSPROP_IGNORE_PERMANENT;
+    }
+
+    // step 6
+    id = NameToId(cx->names().value);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    if (found)
+        desc.value().set(v);
+    else
+        attrs |= JSPROP_IGNORE_VALUE;
+
+    // step 7
+    id = NameToId(cx->names().writable);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    if (found) {
+        if (!ToBoolean(v))
+            attrs |= JSPROP_READONLY;
+    } else {
+        attrs |= JSPROP_IGNORE_READONLY;
+    }
+
+    // step 8
+    bool hasGetOrSet;
+    id = NameToId(cx->names().get);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    hasGetOrSet = found;
+    if (found) {
+        if (v.isObject()) {
+            if (checkAccessors && !CheckCallable(cx, &v.toObject(), js_getter_str))
+                return false;
+            desc.setGetterObject(&v.toObject());
+        } else if (!v.isUndefined()) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_GET_SET_FIELD,
+                                      js_getter_str);
+            return false;
+        }
+        attrs |= JSPROP_GETTER | JSPROP_SHARED;
+    }
+
+    // step 9
+    id = NameToId(cx->names().set);
+    if (!GetPropertyIfPresent(cx, obj, id, &v, &found))
+        return false;
+    hasGetOrSet |= found;
+    if (found) {
+        if (v.isObject()) {
+            if (checkAccessors && !CheckCallable(cx, &v.toObject(), js_setter_str))
+                return false;
+            desc.setSetterObject(&v.toObject());
+        } else if (!v.isUndefined()) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_BAD_GET_SET_FIELD,
+                                      js_setter_str);
+            return false;
+        }
+        attrs |= JSPROP_SETTER | JSPROP_SHARED;
+    }
+
+    // step 10
+    if (hasGetOrSet) {
+        if (!(attrs & JSPROP_IGNORE_READONLY) || !(attrs & JSPROP_IGNORE_VALUE)) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_INVALID_DESCRIPTOR);
+            return false;
+        }
+
+        // By convention, these bits are not used on accessor descriptors.
+        attrs &= ~(JSPROP_IGNORE_READONLY | JSPROP_IGNORE_VALUE);
+    }
+
+    desc.setAttributes(attrs);
+    MOZ_ASSERT_IF(attrs & JSPROP_READONLY, !(attrs & (JSPROP_GETTER | JSPROP_SETTER)));
+    MOZ_ASSERT_IF(attrs & (JSPROP_GETTER | JSPROP_SETTER), attrs & JSPROP_SHARED);
+    return true;
+}
+
+bool
+js::CheckPropertyDescriptorAccessors(JSContext* cx, Handle<PropertyDescriptor> desc)
+{
+    if (desc.hasGetterObject()) {
+        if (!CheckCallable(cx, desc.getterObject(), js_getter_str))
+            return false;
+    }
+    if (desc.hasSetterObject()) {
+        if (!CheckCallable(cx, desc.setterObject(), js_setter_str))
+            return false;
+    }
+    return true;
+}
+
+void
+js::CompletePropertyDescriptor(MutableHandle<PropertyDescriptor> desc)
+{
+    desc.assertValid();
+
+    if (desc.isGenericDescriptor() || desc.isDataDescriptor()) {
+        if (!desc.hasWritable())
+            desc.attributesRef() |= JSPROP_READONLY;
+        desc.attributesRef() &= ~(JSPROP_IGNORE_READONLY | JSPROP_IGNORE_VALUE);
+    } else {
+        if (!desc.hasGetterObject())
+            desc.setGetterObject(nullptr);
+        if (!desc.hasSetterObject())
+            desc.setSetterObject(nullptr);
+        desc.attributesRef() |= JSPROP_GETTER | JSPROP_SETTER | JSPROP_SHARED;
+    }
+    if (!desc.hasConfigurable())
+        desc.attributesRef() |= JSPROP_PERMANENT;
+    desc.attributesRef() &= ~(JSPROP_IGNORE_PERMANENT | JSPROP_IGNORE_ENUMERATE);
+
+    desc.assertComplete();
+}
+
+bool
+js::ReadPropertyDescriptors(JSContext* cx, HandleObject props, bool checkAccessors,
+                            AutoIdVector* ids, MutableHandle<PropertyDescriptorVector> descs)
+{
+    if (!GetPropertyKeys(cx, props, JSITER_OWNONLY | JSITER_SYMBOLS, ids))
+        return false;
+
+    RootedId id(cx);
+    for (size_t i = 0, len = ids->length(); i < len; i++) {
+        id = (*ids)[i];
+        Rooted<PropertyDescriptor> desc(cx);
+        RootedValue v(cx);
+        if (!GetProperty(cx, props, props, id, &v) ||
+            !ToPropertyDescriptor(cx, v, checkAccessors, &desc) ||
+            !descs.append(desc))
+        {
+            return false;
+        }
+    }
+    return true;
+}
+
+/*** Seal and freeze *****************************************************************************/
+
+static unsigned
+GetSealedOrFrozenAttributes(unsigned attrs, IntegrityLevel level)
+{
+    /* Make all attributes permanent; if freezing, make data attributes read-only. */
+    if (level == IntegrityLevel::Frozen && !(attrs & (JSPROP_GETTER | JSPROP_SETTER)))
+        return JSPROP_PERMANENT | JSPROP_READONLY;
+    return JSPROP_PERMANENT;
+}
+
+/* ES6 draft rev 29 (6 Dec 2014) 7.3.13. */
+bool
+js::SetIntegrityLevel(JSContext* cx, HandleObject obj, IntegrityLevel level)
+{
+    assertSameCompartment(cx, obj);
+
+    // Steps 3-5. (Steps 1-2 are redundant assertions.)
+    if (!PreventExtensions(cx, obj, level))
+        return false;
+
+    // Steps 6-7.
+    AutoIdVector keys(cx);
+    if (!GetPropertyKeys(cx, obj, JSITER_HIDDEN | JSITER_OWNONLY | JSITER_SYMBOLS, &keys))
+        return false;
+
+    // Steps 8-9, loosely interpreted.
+    if (obj->isNative() && !obj->as<NativeObject>().inDictionaryMode() &&
+        !obj->is<TypedArrayObject>())
+    {
+        HandleNativeObject nobj = obj.as<NativeObject>();
+
+        // Seal/freeze non-dictionary objects by constructing a new shape
+        // hierarchy mirroring the original one, which can be shared if many
+        // objects with the same structure are sealed/frozen. If we use the
+        // generic path below then any non-empty object will be converted to
+        // dictionary mode.
+        RootedShape last(cx, EmptyShape::getInitialShape(cx, nobj->getClass(),
+                                                         nobj->taggedProto(),
+                                                         nobj->numFixedSlots(),
+                                                         nobj->lastProperty()->getObjectFlags()));
+        if (!last)
+            return false;
+
+        // Get an in-order list of the shapes in this object.
+        Rooted<ShapeVector> shapes(cx, ShapeVector(cx));
+        for (Shape::Range<NoGC> r(nobj->lastProperty()); !r.empty(); r.popFront()) {
+            if (!shapes.append(&r.front()))
+                return false;
+        }
+        Reverse(shapes.begin(), shapes.end());
+
+        for (Shape* shape : shapes) {
+            Rooted<StackShape> child(cx, StackShape(shape));
+            child.setAttrs(child.attrs() | GetSealedOrFrozenAttributes(child.attrs(), level));
+
+            if (!JSID_IS_EMPTY(child.get().propid) && level == IntegrityLevel::Frozen)
+                MarkTypePropertyNonWritable(cx, nobj, child.get().propid);
+
+            last = cx->zone()->propertyTree.getChild(cx, last, child);
+            if (!last)
+                return false;
+        }
+
+        MOZ_ASSERT(nobj->lastProperty()->slotSpan() == last->slotSpan());
+        JS_ALWAYS_TRUE(nobj->setLastProperty(cx, last));
+
+        // Ordinarily ArraySetLength handles this, but we're going behind its back
+        // right now, so we must do this manually.
+        //
+        // ArraySetLength also implements the capacity <= length invariant for
+        // arrays with non-writable length.  We don't need to do anything special
+        // for that, because capacity was zeroed out by preventExtensions.  (See
+        // the assertion about getDenseCapacity above.)
+        if (level == IntegrityLevel::Frozen && obj->is<ArrayObject>()) {
+            if (!obj->as<ArrayObject>().maybeCopyElementsForWrite(cx))
+                return false;
+            obj->as<ArrayObject>().getElementsHeader()->setNonwritableArrayLength();
+        }
+    } else {
+        RootedId id(cx);
+        Rooted<PropertyDescriptor> desc(cx);
+
+        const unsigned AllowConfigure = JSPROP_IGNORE_ENUMERATE | JSPROP_IGNORE_READONLY |
+                                        JSPROP_IGNORE_VALUE;
+        const unsigned AllowConfigureAndWritable = AllowConfigure & ~JSPROP_IGNORE_READONLY;
+
+        // 8.a/9.a. The two different loops are merged here.
+        for (size_t i = 0; i < keys.length(); i++) {
+            id = keys[i];
+
+            if (level == IntegrityLevel::Sealed) {
+                // 8.a.i.
+                desc.setAttributes(AllowConfigure | JSPROP_PERMANENT);
+            } else {
+                // 9.a.i-ii.
+                Rooted<PropertyDescriptor> currentDesc(cx);
+                if (!GetOwnPropertyDescriptor(cx, obj, id, &currentDesc))
+                    return false;
+
+                // 9.a.iii.
+                if (!currentDesc.object())
+                    continue;
+
+                // 9.a.iii.1-2
+                if (currentDesc.isAccessorDescriptor())
+                    desc.setAttributes(AllowConfigure | JSPROP_PERMANENT);
+                else
+                    desc.setAttributes(AllowConfigureAndWritable | JSPROP_PERMANENT | JSPROP_READONLY);
+            }
+
+            // 8.a.i-ii. / 9.a.iii.3-4
+            if (!DefineProperty(cx, obj, id, desc))
+                return false;
+        }
+    }
+
+    return true;
+}
+
+// ES6 draft rev33 (12 Feb 2015) 7.3.15
+bool
+js::TestIntegrityLevel(JSContext* cx, HandleObject obj, IntegrityLevel level, bool* result)
+{
+    // Steps 3-6. (Steps 1-2 are redundant assertions.)
+    bool status;
+    if (!IsExtensible(cx, obj, &status))
+        return false;
+    if (status) {
+        *result = false;
+        return true;
+    }
+
+    // Steps 7-8.
+    AutoIdVector props(cx);
+    if (!GetPropertyKeys(cx, obj, JSITER_HIDDEN | JSITER_OWNONLY | JSITER_SYMBOLS, &props))
+        return false;
+
+    // Step 9.
+    RootedId id(cx);
+    Rooted<PropertyDescriptor> desc(cx);
+    for (size_t i = 0, len = props.length(); i < len; i++) {
+        id = props[i];
+
+        // Steps 9.a-b.
+        if (!GetOwnPropertyDescriptor(cx, obj, id, &desc))
+            return false;
+
+        // Step 9.c.
+        if (!desc.object())
+            continue;
+
+        // Steps 9.c.i-ii.
+        if (desc.configurable() ||
+            (level == IntegrityLevel::Frozen && desc.isDataDescriptor() && desc.writable()))
+        {
+            *result = false;
+            return true;
+        }
+    }
+
+    // Step 10.
+    *result = true;
+    return true;
+}
+
+
+/* * */
+
+/*
+ * Get the GC kind to use for scripted 'new' on the given class.
+ * FIXME bug 547327: estimate the size from the allocation site.
+ */
+static inline gc::AllocKind
+NewObjectGCKind(const js::Class* clasp)
+{
+    if (clasp == &ArrayObject::class_)
+        return gc::AllocKind::OBJECT8;
+    if (clasp == &JSFunction::class_)
+        return gc::AllocKind::OBJECT2;
+    return gc::AllocKind::OBJECT4;
+}
+
+static inline JSObject*
+NewObject(ExclusiveContext* cx, HandleObjectGroup group, gc::AllocKind kind,
+          NewObjectKind newKind, uint32_t initialShapeFlags = 0)
+{
+    const Class* clasp = group->clasp();
+
+    MOZ_ASSERT(clasp != &ArrayObject::class_);
+    MOZ_ASSERT_IF(clasp == &JSFunction::class_,
+                  kind == AllocKind::FUNCTION || kind == AllocKind::FUNCTION_EXTENDED);
+
+    // For objects which can have fixed data following the object, only use
+    // enough fixed slots to cover the number of reserved slots in the object,
+    // regardless of the allocation kind specified.
+    size_t nfixed = ClassCanHaveFixedData(clasp)
+                    ? GetGCKindSlots(gc::GetGCObjectKind(clasp), clasp)
+                    : GetGCKindSlots(kind, clasp);
+
+    RootedShape shape(cx, EmptyShape::getInitialShape(cx, clasp, group->proto(), nfixed,
+                                                      initialShapeFlags));
+    if (!shape)
+        return nullptr;
+
+    gc::InitialHeap heap = GetInitialHeap(newKind, clasp);
+    JSObject* obj = JSObject::create(cx, kind, heap, shape, group);
+    if (!obj)
+        return nullptr;
+
+    if (newKind == SingletonObject) {
+        RootedObject nobj(cx, obj);
+        if (!JSObject::setSingleton(cx, nobj))
+            return nullptr;
+        obj = nobj;
+    }
+
+    probes::CreateObject(cx, obj);
+    return obj;
+}
+
+void
+NewObjectCache::fillProto(EntryIndex entry, const Class* clasp, js::TaggedProto proto,
+                          gc::AllocKind kind, NativeObject* obj)
+{
+    MOZ_ASSERT_IF(proto.isObject(), !proto.toObject()->is<GlobalObject>());
+    MOZ_ASSERT(obj->taggedProto() == proto);
+    return fill(entry, clasp, proto.raw(), kind, obj);
+}
+
+bool
+js::NewObjectWithTaggedProtoIsCachable(ExclusiveContext* cxArg, Handle<TaggedProto> proto,
+                                       NewObjectKind newKind, const Class* clasp)
+{
+    return cxArg->isJSContext() &&
+           proto.isObject() &&
+           newKind == GenericObject &&
+           clasp->isNative() &&
+           !proto.toObject()->is<GlobalObject>();
+}
+
+JSObject*
+js::NewObjectWithGivenTaggedProto(ExclusiveContext* cxArg, const Class* clasp,
+                                  Handle<TaggedProto> proto,
+                                  gc::AllocKind allocKind, NewObjectKind newKind,
+                                  uint32_t initialShapeFlags)
+{
+    if (CanBeFinalizedInBackground(allocKind, clasp))
+        allocKind = GetBackgroundAllocKind(allocKind);
+
+    bool isCachable = NewObjectWithTaggedProtoIsCachable(cxArg, proto, newKind, clasp);
+    if (isCachable) {
+        JSContext* cx = cxArg->asJSContext();
+        NewObjectCache& cache = cx->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        if (cache.lookupProto(clasp, proto.toObject(), allocKind, &entry)) {
+            JSObject* obj = cache.newObjectFromHit(cx, entry, GetInitialHeap(newKind, clasp));
+            if (obj)
+                return obj;
+        }
+    }
+
+    RootedObjectGroup group(cxArg, ObjectGroup::defaultNewGroup(cxArg, clasp, proto, nullptr));
+    if (!group)
+        return nullptr;
+
+    RootedObject obj(cxArg, NewObject(cxArg, group, allocKind, newKind, initialShapeFlags));
+    if (!obj)
+        return nullptr;
+
+    if (isCachable && !obj->as<NativeObject>().hasDynamicSlots()) {
+        NewObjectCache& cache = cxArg->asJSContext()->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        cache.lookupProto(clasp, proto.toObject(), allocKind, &entry);
+        cache.fillProto(entry, clasp, proto, allocKind, &obj->as<NativeObject>());
+    }
+
+    return obj;
+}
+
+static bool
+NewObjectIsCachable(ExclusiveContext* cxArg, NewObjectKind newKind, const Class* clasp)
+{
+    return cxArg->isJSContext() &&
+           newKind == GenericObject &&
+           clasp->isNative();
+}
+
+JSObject*
+js::NewObjectWithClassProtoCommon(ExclusiveContext* cx, const Class* clasp, HandleObject protoArg,
+                                  gc::AllocKind allocKind, NewObjectKind newKind)
+{
+    if (protoArg)
+        return NewObjectWithGivenTaggedProto(cx, clasp, AsTaggedProto(protoArg), allocKind, newKind);
+
+    if (CanBeFinalizedInBackground(allocKind, clasp))
+        allocKind = GetBackgroundAllocKind(allocKind);
+
+    Handle<GlobalObject*> global = cx->global();
+
+    bool isCachable = NewObjectIsCachable(cx, newKind, clasp);
+    if (isCachable) {
+        NewObjectCache& cache = cx->asJSContext()->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        if (cache.lookupGlobal(clasp, global, allocKind, &entry)) {
+            gc::InitialHeap heap = GetInitialHeap(newKind, clasp);
+            JSObject* obj = cache.newObjectFromHit(cx->asJSContext(), entry, heap);
+            if (obj)
+                return obj;
+        }
+    }
+
+    // Find the appropriate proto for clasp. Built-in classes have a cached
+    // proto on cx->global(); all others get %ObjectPrototype%.
+    JSProtoKey protoKey = JSCLASS_CACHED_PROTO_KEY(clasp);
+    if (protoKey == JSProto_Null)
+        protoKey = JSProto_Object;
+
+    RootedObject proto(cx);
+    if (!GetBuiltinPrototype(cx, protoKey, &proto))
+        return nullptr;
+
+    RootedObjectGroup group(cx, ObjectGroup::defaultNewGroup(cx, clasp, AsTaggedProto(proto)));
+    if (!group)
+        return nullptr;
+
+    JSObject* obj = NewObject(cx, group, allocKind, newKind);
+    if (!obj)
+        return nullptr;
+
+    if (isCachable && !obj->as<NativeObject>().hasDynamicSlots()) {
+        NewObjectCache& cache = cx->asJSContext()->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        cache.lookupGlobal(clasp, global, allocKind, &entry);
+        cache.fillGlobal(entry, clasp, global, allocKind,
+                         &obj->as<NativeObject>());
+    }
+
+    return obj;
+}
+
+static bool
+NewObjectWithGroupIsCachable(ExclusiveContext* cx, HandleObjectGroup group,
+                             NewObjectKind newKind)
+{
+    return group->proto().isObject() &&
+           newKind == GenericObject &&
+           group->clasp()->isNative() &&
+           (!group->newScript() || group->newScript()->analyzed()) &&
+           cx->isJSContext();
+}
+
+/*
+ * Create a plain object with the specified group. This bypasses getNewGroup to
+ * avoid losing creation site information for objects made by scripted 'new'.
+ */
+JSObject*
+js::NewObjectWithGroupCommon(ExclusiveContext* cx, HandleObjectGroup group,
+                             gc::AllocKind allocKind, NewObjectKind newKind)
+{
+    MOZ_ASSERT(gc::IsObjectAllocKind(allocKind));
+    if (CanBeFinalizedInBackground(allocKind, group->clasp()))
+        allocKind = GetBackgroundAllocKind(allocKind);
+
+    bool isCachable = NewObjectWithGroupIsCachable(cx, group, newKind);
+    if (isCachable) {
+        NewObjectCache& cache = cx->asJSContext()->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        if (cache.lookupGroup(group, allocKind, &entry)) {
+            JSObject* obj = cache.newObjectFromHit(cx->asJSContext(), entry,
+                                                   GetInitialHeap(newKind, group->clasp()));
+            if (obj)
+                return obj;
+        }
+    }
+
+    JSObject* obj = NewObject(cx, group, allocKind, newKind);
+    if (!obj)
+        return nullptr;
+
+    if (isCachable && !obj->as<NativeObject>().hasDynamicSlots()) {
+        NewObjectCache& cache = cx->asJSContext()->caches.newObjectCache;
+        NewObjectCache::EntryIndex entry = -1;
+        cache.lookupGroup(group, allocKind, &entry);
+        cache.fillGroup(entry, group, allocKind, &obj->as<NativeObject>());
+    }
+
+    return obj;
+}
+
+bool
+js::NewObjectScriptedCall(JSContext* cx, MutableHandleObject pobj)
+{
+    jsbytecode* pc;
+    RootedScript script(cx, cx->currentScript(&pc));
+    gc::AllocKind allocKind = NewObjectGCKind(&PlainObject::class_);
+    NewObjectKind newKind = GenericObject;
+    if (script && ObjectGroup::useSingletonForAllocationSite(script, pc, &PlainObject::class_))
+        newKind = SingletonObject;
+    RootedObject obj(cx, NewBuiltinClassInstance<PlainObject>(cx, allocKind, newKind));
+    if (!obj)
+        return false;
+
+    if (script) {
+        /* Try to specialize the group of the object to the scripted call site. */
+        if (!ObjectGroup::setAllocationSiteObjectGroup(cx, script, pc, obj, newKind == SingletonObject))
+            return false;
+    }
+
+    pobj.set(obj);
+    return true;
+}
+
+JSObject*
+js::CreateThis(JSContext* cx, const Class* newclasp, HandleObject callee)
+{
+    RootedObject proto(cx);
+    if (!GetPrototypeFromConstructor(cx, callee, &proto))
+        return nullptr;
+    gc::AllocKind kind = NewObjectGCKind(newclasp);
+    return NewObjectWithClassProto(cx, newclasp, proto, kind);
+}
+
+static inline JSObject*
+CreateThisForFunctionWithGroup(JSContext* cx, HandleObjectGroup group,
+                               NewObjectKind newKind)
+{
+    if (group->maybeUnboxedLayout() && newKind != SingletonObject)
+        return UnboxedPlainObject::create(cx, group, newKind);
+
+    if (TypeNewScript* newScript = group->newScript()) {
+        if (newScript->analyzed()) {
+            // The definite properties analysis has been performed for this
+            // group, so get the shape and alloc kind to use from the
+            // TypeNewScript's template.
+            RootedPlainObject templateObject(cx, newScript->templateObject());
+            MOZ_ASSERT(templateObject->group() == group);
+
+            RootedPlainObject res(cx, CopyInitializerObject(cx, templateObject, newKind));
+            if (!res)
+                return nullptr;
+
+            if (newKind == SingletonObject) {
+                Rooted<TaggedProto> proto(cx, TaggedProto(templateObject->staticPrototype()));
+                if (!res->splicePrototype(cx, &PlainObject::class_, proto))
+                    return nullptr;
+            } else {
+                res->setGroup(group);
+            }
+            return res;
+        }
+
+        // The initial objects registered with a TypeNewScript can't be in the
+        // nursery.
+        if (newKind == GenericObject)
+            newKind = TenuredObject;
+
+        // Not enough objects with this group have been created yet, so make a
+        // plain object and register it with the group. Use the maximum number
+        // of fixed slots, as is also required by the TypeNewScript.
+        gc::AllocKind allocKind = GuessObjectGCKind(NativeObject::MAX_FIXED_SLOTS);
+        PlainObject* res = NewObjectWithGroup<PlainObject>(cx, group, allocKind, newKind);
+        if (!res)
+            return nullptr;
+
+        // Make sure group->newScript is still there.
+        if (newKind != SingletonObject && group->newScript())
+            group->newScript()->registerNewObject(res);
+
+        return res;
+    }
+
+    gc::AllocKind allocKind = NewObjectGCKind(&PlainObject::class_);
+
+    if (newKind == SingletonObject) {
+        Rooted<TaggedProto> protoRoot(cx, group->proto());
+        return NewObjectWithGivenTaggedProto(cx, &PlainObject::class_, protoRoot, allocKind, newKind);
+    }
+    return NewObjectWithGroup<PlainObject>(cx, group, allocKind, newKind);
+}
+
+JSObject*
+js::CreateThisForFunctionWithProto(JSContext* cx, HandleObject callee, HandleObject newTarget,
+                                   HandleObject proto, NewObjectKind newKind /* = GenericObject */)
+{
+    RootedObject res(cx);
+
+    if (proto) {
+        RootedObjectGroup group(cx, ObjectGroup::defaultNewGroup(cx, nullptr, TaggedProto(proto),
+                                                                 newTarget));
+        if (!group)
+            return nullptr;
+
+        if (group->newScript() && !group->newScript()->analyzed()) {
+            bool regenerate;
+            if (!group->newScript()->maybeAnalyze(cx, group, &regenerate))
+                return nullptr;
+            if (regenerate) {
+                // The script was analyzed successfully and may have changed
+                // the new type table, so refetch the group.
+                group = ObjectGroup::defaultNewGroup(cx, nullptr, TaggedProto(proto),
+                                                     newTarget);
+                MOZ_ASSERT(group && group->newScript());
+            }
+        }
+
+        res = CreateThisForFunctionWithGroup(cx, group, newKind);
+    } else {
+        res = NewBuiltinClassInstance<PlainObject>(cx, newKind);
+    }
+
+    if (res) {
+        JSScript* script = callee->as<JSFunction>().getOrCreateScript(cx);
+        if (!script)
+            return nullptr;
+        TypeScript::SetThis(cx, script, TypeSet::ObjectType(res));
+    }
+
+    return res;
+}
+
+bool
+js::GetPrototypeFromConstructor(JSContext* cx, HandleObject newTarget, MutableHandleObject proto)
+{
+    RootedValue protov(cx);
+    if (!GetProperty(cx, newTarget, newTarget, cx->names().prototype, &protov))
+        return false;
+    proto.set(protov.isObject() ? &protov.toObject() : nullptr);
+    return true;
+}
+
+bool
+js::GetPrototypeFromCallableConstructor(JSContext* cx, const CallArgs& args, MutableHandleObject proto)
+{
+    RootedObject newTarget(cx);
+    if (args.isConstructing())
+        newTarget = &args.newTarget().toObject();
+    else
+        newTarget = &args.callee();
+    return GetPrototypeFromConstructor(cx, newTarget, proto);
+}
+
+JSObject*
+js::CreateThisForFunction(JSContext* cx, HandleObject callee, HandleObject newTarget,
+                          NewObjectKind newKind)
+{
+    RootedObject proto(cx);
+    if (!GetPrototypeFromConstructor(cx, newTarget, &proto))
+        return nullptr;
+
+    JSObject* obj = CreateThisForFunctionWithProto(cx, callee, newTarget, proto, newKind);
+
+    if (obj && newKind == SingletonObject) {
+        RootedPlainObject nobj(cx, &obj->as<PlainObject>());
+
+        /* Reshape the singleton before passing it as the 'this' value. */
+        NativeObject::clear(cx, nobj);
+
+        JSScript* calleeScript = callee->as<JSFunction>().nonLazyScript();
+        TypeScript::SetThis(cx, calleeScript, TypeSet::ObjectType(nobj));
+
+        return nobj;
+    }
+
+    return obj;
+}
+
+/* static */ bool
+JSObject::nonNativeSetProperty(JSContext* cx, HandleObject obj, HandleId id, HandleValue v,
+                               HandleValue receiver, ObjectOpResult& result)
+{
+    RootedValue value(cx, v);
+    if (MOZ_UNLIKELY(obj->watched())) {
+        WatchpointMap* wpmap = cx->compartment()->watchpointMap;
+        if (wpmap && !wpmap->triggerWatchpoint(cx, obj, id, &value))
+            return false;
+    }
+    return obj->getOpsSetProperty()(cx, obj, id, value, receiver, result);
+}
+
+/* static */ bool
+JSObject::nonNativeSetElement(JSContext* cx, HandleObject obj, uint32_t index, HandleValue v,
+                              HandleValue receiver, ObjectOpResult& result)
+{
+    RootedId id(cx);
+    if (!IndexToId(cx, index, &id))
+        return false;
+    return nonNativeSetProperty(cx, obj, id, v, receiver, result);
+}
+
+JS_FRIEND_API(bool)
+JS_CopyPropertyFrom(JSContext* cx, HandleId id, HandleObject target,
+                    HandleObject obj, PropertyCopyBehavior copyBehavior)
+{
+    // |obj| and |cx| are generally not same-compartment with |target| here.
+    assertSameCompartment(cx, obj, id);
+    Rooted<PropertyDescriptor> desc(cx);
+
+    if (!GetOwnPropertyDescriptor(cx, obj, id, &desc))
+        return false;
+    MOZ_ASSERT(desc.object());
+
+    // Silently skip JSGetterOp/JSSetterOp-implemented accessors.
+    if (desc.getter() && !desc.hasGetterObject())
+        return true;
+    if (desc.setter() && !desc.hasSetterObject())
+        return true;
+
+    if (copyBehavior == MakeNonConfigurableIntoConfigurable) {
+        // Mask off the JSPROP_PERMANENT bit.
+        desc.attributesRef() &= ~JSPROP_PERMANENT;
+    }
+
+    JSAutoCompartment ac(cx, target);
+    RootedId wrappedId(cx, id);
+    if (!cx->compartment()->wrap(cx, &desc))
+        return false;
+
+    return DefineProperty(cx, target, wrappedId, desc);
+}
+
+JS_FRIEND_API(bool)
+JS_CopyPropertiesFrom(JSContext* cx, HandleObject target, HandleObject obj)
+{
+    JSAutoCompartment ac(cx, obj);
+
+    AutoIdVector props(cx);
+    if (!GetPropertyKeys(cx, obj, JSITER_OWNONLY | JSITER_HIDDEN | JSITER_SYMBOLS, &props))
+        return false;
+
+    for (size_t i = 0; i < props.length(); ++i) {
+        if (!JS_CopyPropertyFrom(cx, props[i], target, obj))
+            return false;
+    }
+
+    return true;
+}
+
+static bool
+CopyProxyObject(JSContext* cx, Handle<ProxyObject*> from, Handle<ProxyObject*> to)
+{
+    MOZ_ASSERT(from->getClass() == to->getClass());
+
+    if (from->is<WrapperObject>() &&
+        (Wrapper::wrapperHandler(from)->flags() &
+         Wrapper::CROSS_COMPARTMENT))
+    {
+        to->setCrossCompartmentPrivate(GetProxyPrivate(from));
+    } else {
+        RootedValue v(cx, GetProxyPrivate(from));
+        if (!cx->compartment()->wrap(cx, &v))
+            return false;
+        to->setSameCompartmentPrivate(v);
+    }
+
+    RootedValue v(cx);
+    for (size_t n = 0; n < js::detail::PROXY_EXTRA_SLOTS; n++) {
+        v = GetProxyExtra(from, n);
+        if (!cx->compartment()->wrap(cx, &v))
+            return false;
+        SetProxyExtra(to, n, v);
+    }
+
+    return true;
+}
+
+JSObject*
+js::CloneObject(JSContext* cx, HandleObject obj, Handle<js::TaggedProto> proto)
+{
+    if (!obj->isNative() && !obj->is<ProxyObject>()) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_CLONE_OBJECT);
+        return nullptr;
+    }
+
+    RootedObject clone(cx);
+    if (obj->isNative()) {
+        clone = NewObjectWithGivenTaggedProto(cx, obj->getClass(), proto);
+        if (!clone)
+            return nullptr;
+
+        if (clone->is<JSFunction>() && (obj->compartment() != clone->compartment())) {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_CLONE_OBJECT);
+            return nullptr;
+        }
+
+        if (obj->as<NativeObject>().hasPrivate())
+            clone->as<NativeObject>().setPrivate(obj->as<NativeObject>().getPrivate());
+    } else {
+        ProxyOptions options;
+        options.setClass(obj->getClass());
+
+        clone = ProxyObject::New(cx, GetProxyHandler(obj), JS::NullHandleValue, proto, options);
+        if (!clone)
+            return nullptr;
+
+        if (!CopyProxyObject(cx, obj.as<ProxyObject>(), clone.as<ProxyObject>()))
+            return nullptr;
+    }
+
+    return clone;
+}
+
+static bool
+GetScriptArrayObjectElements(JSContext* cx, HandleObject obj, MutableHandle<GCVector<Value>> values)
+{
+    MOZ_ASSERT(!obj->isSingleton());
+    MOZ_ASSERT(obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>());
+    MOZ_ASSERT(!obj->isIndexed());
+
+    size_t length = GetAnyBoxedOrUnboxedArrayLength(obj);
+    if (!values.appendN(MagicValue(JS_ELEMENTS_HOLE), length))
+        return false;
+
+    size_t initlen = GetAnyBoxedOrUnboxedInitializedLength(obj);
+    for (size_t i = 0; i < initlen; i++)
+        values[i].set(GetAnyBoxedOrUnboxedDenseElement(obj, i));
+
+    return true;
+}
+
+static bool
+GetScriptPlainObjectProperties(JSContext* cx, HandleObject obj,
+                               MutableHandle<IdValueVector> properties)
+{
+    if (obj->is<PlainObject>()) {
+        PlainObject* nobj = &obj->as<PlainObject>();
+
+        if (!properties.appendN(IdValuePair(), nobj->slotSpan()))
+            return false;
+
+        for (Shape::Range<NoGC> r(nobj->lastProperty()); !r.empty(); r.popFront()) {
+            Shape& shape = r.front();
+            MOZ_ASSERT(shape.isDataDescriptor());
+            uint32_t slot = shape.slot();
+            properties[slot].get().id = shape.propid();
+            properties[slot].get().value = nobj->getSlot(slot);
+        }
+
+        for (size_t i = 0; i < nobj->getDenseInitializedLength(); i++) {
+            Value v = nobj->getDenseElement(i);
+            if (!v.isMagic(JS_ELEMENTS_HOLE) && !properties.append(IdValuePair(INT_TO_JSID(i), v)))
+                return false;
+        }
+
+        return true;
+    }
+
+    if (obj->is<UnboxedPlainObject>()) {
+        UnboxedPlainObject* nobj = &obj->as<UnboxedPlainObject>();
+
+        const UnboxedLayout& layout = nobj->layout();
+        if (!properties.appendN(IdValuePair(), layout.properties().length()))
+            return false;
+
+        for (size_t i = 0; i < layout.properties().length(); i++) {
+            const UnboxedLayout::Property& property = layout.properties()[i];
+            properties[i].get().id = NameToId(property.name);
+            properties[i].get().value = nobj->getValue(property);
+        }
+
+        return true;
+    }
+
+    MOZ_CRASH("Bad object kind");
+}
+
+static bool
+DeepCloneValue(JSContext* cx, Value* vp, NewObjectKind newKind)
+{
+    if (vp->isObject()) {
+        RootedObject obj(cx, &vp->toObject());
+        obj = DeepCloneObjectLiteral(cx, obj, newKind);
+        if (!obj)
+            return false;
+        vp->setObject(*obj);
+    }
+    return true;
+}
+
+JSObject*
+js::DeepCloneObjectLiteral(JSContext* cx, HandleObject obj, NewObjectKind newKind)
+{
+    /* NB: Keep this in sync with XDRObjectLiteral. */
+    MOZ_ASSERT_IF(obj->isSingleton(),
+                  cx->compartment()->behaviors().getSingletonsAsTemplates());
+    MOZ_ASSERT(obj->is<PlainObject>() || obj->is<UnboxedPlainObject>() ||
+               obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>());
+    MOZ_ASSERT(newKind != SingletonObject);
+
+    if (obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>()) {
+        Rooted<GCVector<Value>> values(cx, GCVector<Value>(cx));
+        if (!GetScriptArrayObjectElements(cx, obj, &values))
+            return nullptr;
+
+        // Deep clone any elements.
+        for (uint32_t i = 0; i < values.length(); ++i) {
+            if (!DeepCloneValue(cx, values[i].address(), newKind))
+                return nullptr;
+        }
+
+        ObjectGroup::NewArrayKind arrayKind = ObjectGroup::NewArrayKind::Normal;
+        if (obj->is<ArrayObject>() && obj->as<ArrayObject>().denseElementsAreCopyOnWrite())
+            arrayKind = ObjectGroup::NewArrayKind::CopyOnWrite;
+
+        return ObjectGroup::newArrayObject(cx, values.begin(), values.length(), newKind,
+                                           arrayKind);
+    }
+
+    Rooted<IdValueVector> properties(cx, IdValueVector(cx));
+    if (!GetScriptPlainObjectProperties(cx, obj, &properties))
+        return nullptr;
+
+    for (size_t i = 0; i < properties.length(); i++) {
+        if (!DeepCloneValue(cx, &properties[i].get().value, newKind))
+            return nullptr;
+    }
+
+    if (obj->isSingleton())
+        newKind = SingletonObject;
+
+    return ObjectGroup::newPlainObject(cx, properties.begin(), properties.length(), newKind);
+}
+
+static bool
+InitializePropertiesFromCompatibleNativeObject(JSContext* cx,
+                                               HandleNativeObject dst,
+                                               HandleNativeObject src)
+{
+    assertSameCompartment(cx, src, dst);
+    MOZ_ASSERT(src->getClass() == dst->getClass());
+    MOZ_ASSERT(dst->lastProperty()->getObjectFlags() == 0);
+    MOZ_ASSERT(!src->isSingleton());
+    MOZ_ASSERT(src->numFixedSlots() == dst->numFixedSlots());
+
+    if (!dst->ensureElements(cx, src->getDenseInitializedLength()))
+        return false;
+
+    uint32_t initialized = src->getDenseInitializedLength();
+    for (uint32_t i = 0; i < initialized; ++i) {
+        dst->setDenseInitializedLength(i + 1);
+        dst->initDenseElement(i, src->getDenseElement(i));
+    }
+
+    MOZ_ASSERT(!src->hasPrivate());
+    RootedShape shape(cx);
+    if (src->staticPrototype() == dst->staticPrototype()) {
+        shape = src->lastProperty();
+    } else {
+        // We need to generate a new shape for dst that has dst's proto but all
+        // the property information from src.  Note that we asserted above that
+        // dst's object flags are 0.
+        shape = EmptyShape::getInitialShape(cx, dst->getClass(), dst->taggedProto(),
+                                            dst->numFixedSlots(), 0);
+        if (!shape)
+            return false;
+
+        // Get an in-order list of the shapes in the src object.
+        Rooted<ShapeVector> shapes(cx, ShapeVector(cx));
+        for (Shape::Range<NoGC> r(src->lastProperty()); !r.empty(); r.popFront()) {
+            if (!shapes.append(&r.front()))
+                return false;
+        }
+        Reverse(shapes.begin(), shapes.end());
+
+        for (Shape* shape : shapes) {
+            Rooted<StackShape> child(cx, StackShape(shape));
+            shape = cx->zone()->propertyTree.getChild(cx, shape, child);
+            if (!shape)
+                return false;
+        }
+    }
+    size_t span = shape->slotSpan();
+    if (!dst->setLastProperty(cx, shape))
+        return false;
+    for (size_t i = JSCLASS_RESERVED_SLOTS(src->getClass()); i < span; i++)
+        dst->setSlot(i, src->getSlot(i));
+
+    return true;
+}
+
+JS_FRIEND_API(bool)
+JS_InitializePropertiesFromCompatibleNativeObject(JSContext* cx,
+                                                  HandleObject dst,
+                                                  HandleObject src)
+{
+    return InitializePropertiesFromCompatibleNativeObject(cx,
+                                                          dst.as<NativeObject>(),
+                                                          src.as<NativeObject>());
+}
+
+template<XDRMode mode>
+bool
+js::XDRObjectLiteral(XDRState<mode>* xdr, MutableHandleObject obj)
+{
+    /* NB: Keep this in sync with DeepCloneObjectLiteral. */
+
+    JSContext* cx = xdr->cx();
+    MOZ_ASSERT_IF(mode == XDR_ENCODE && obj->isSingleton(),
+                  cx->compartment()->behaviors().getSingletonsAsTemplates());
+
+    // Distinguish between objects and array classes.
+    uint32_t isArray = 0;
+    {
+        if (mode == XDR_ENCODE) {
+            MOZ_ASSERT(obj->is<PlainObject>() ||
+                       obj->is<UnboxedPlainObject>() ||
+                       obj->is<ArrayObject>() ||
+                       obj->is<UnboxedArrayObject>());
+            isArray = (obj->is<ArrayObject>() || obj->is<UnboxedArrayObject>()) ? 1 : 0;
+        }
+
+        if (!xdr->codeUint32(&isArray))
+            return false;
+    }
+
+    RootedValue tmpValue(cx), tmpIdValue(cx);
+    RootedId tmpId(cx);
+
+    if (isArray) {
+        Rooted<GCVector<Value>> values(cx, GCVector<Value>(cx));
+        if (mode == XDR_ENCODE && !GetScriptArrayObjectElements(cx, obj, &values))
+            return false;
+
+        uint32_t initialized;
+        if (mode == XDR_ENCODE)
+            initialized = values.length();
+        if (!xdr->codeUint32(&initialized))
+            return false;
+        if (mode == XDR_DECODE && !values.appendN(MagicValue(JS_ELEMENTS_HOLE), initialized))
+            return false;
+
+        // Recursively copy dense elements.
+        for (unsigned i = 0; i < initialized; i++) {
+            if (!xdr->codeConstValue(values[i]))
+                return false;
+        }
+
+        uint32_t copyOnWrite;
+        if (mode == XDR_ENCODE)
+            copyOnWrite = obj->is<ArrayObject>() &&
+                          obj->as<ArrayObject>().denseElementsAreCopyOnWrite();
+        if (!xdr->codeUint32(&copyOnWrite))
+            return false;
+
+        if (mode == XDR_DECODE) {
+            ObjectGroup::NewArrayKind arrayKind = copyOnWrite
+                                                  ? ObjectGroup::NewArrayKind::CopyOnWrite
+                                                  : ObjectGroup::NewArrayKind::Normal;
+            obj.set(ObjectGroup::newArrayObject(cx, values.begin(), values.length(),
+                                                TenuredObject, arrayKind));
+            if (!obj)
+                return false;
+        }
+
+        return true;
+    }
+
+    // Code the properties in the object.
+    Rooted<IdValueVector> properties(cx, IdValueVector(cx));
+    if (mode == XDR_ENCODE && !GetScriptPlainObjectProperties(cx, obj, &properties))
+        return false;
+
+    uint32_t nproperties = properties.length();
+    if (!xdr->codeUint32(&nproperties))
+        return false;
+
+    if (mode == XDR_DECODE && !properties.appendN(IdValuePair(), nproperties))
+        return false;
+
+    for (size_t i = 0; i < nproperties; i++) {
+        if (mode == XDR_ENCODE) {
+            tmpIdValue = IdToValue(properties[i].get().id);
+            tmpValue = properties[i].get().value;
+        }
+
+        if (!xdr->codeConstValue(&tmpIdValue) || !xdr->codeConstValue(&tmpValue))
+            return false;
+
+        if (mode == XDR_DECODE) {
+            if (!ValueToId<CanGC>(cx, tmpIdValue, &tmpId))
+                return false;
+            properties[i].get().id = tmpId;
+            properties[i].get().value = tmpValue;
+        }
+    }
+
+    // Code whether the object is a singleton.
+    uint32_t isSingleton;
+    if (mode == XDR_ENCODE)
+        isSingleton = obj->isSingleton() ? 1 : 0;
+    if (!xdr->codeUint32(&isSingleton))
+        return false;
+
+    if (mode == XDR_DECODE) {
+        NewObjectKind newKind = isSingleton ? SingletonObject : TenuredObject;
+        obj.set(ObjectGroup::newPlainObject(cx, properties.begin(), properties.length(), newKind));
+        if (!obj)
+            return false;
+    }
+
+    return true;
+}
+
+template bool
+js::XDRObjectLiteral(XDRState<XDR_ENCODE>* xdr, MutableHandleObject obj);
+
+template bool
+js::XDRObjectLiteral(XDRState<XDR_DECODE>* xdr, MutableHandleObject obj);
+
+bool
+NativeObject::fillInAfterSwap(JSContext* cx, const Vector<Value>& values, void* priv)
+{
+    // This object has just been swapped with some other object, and its shape
+    // no longer reflects its allocated size. Correct this information and
+    // fill the slots in with the specified values.
+    MOZ_ASSERT(slotSpan() == values.length());
+
+    // Make sure the shape's numFixedSlots() is correct.
+    size_t nfixed = gc::GetGCKindSlots(asTenured().getAllocKind(), getClass());
+    if (nfixed != shape_->numFixedSlots()) {
+        if (!generateOwnShape(cx))
+            return false;
+        shape_->setNumFixedSlots(nfixed);
+    }
+
+    if (hasPrivate())
+        setPrivate(priv);
+    else
+        MOZ_ASSERT(!priv);
+
+    if (slots_) {
+        js_free(slots_);
+        slots_ = nullptr;
+    }
+
+    if (size_t ndynamic = dynamicSlotsCount(nfixed, values.length(), getClass())) {
+        slots_ = cx->zone()->pod_malloc<HeapSlot>(ndynamic);
+        if (!slots_)
+            return false;
+        Debug_SetSlotRangeToCrashOnTouch(slots_, ndynamic);
+    }
+
+    initSlotRange(0, values.begin(), values.length());
+    return true;
+}
+
+void
+JSObject::fixDictionaryShapeAfterSwap()
+{
+    // Dictionary shapes can point back to their containing objects, so after
+    // swapping the guts of those objects fix the pointers up.
+    if (isNative() && as<NativeObject>().inDictionaryMode())
+        as<NativeObject>().shape_->listp = &as<NativeObject>().shape_;
+}
+
+/* Use this method with extreme caution. It trades the guts of two objects. */
+bool
+JSObject::swap(JSContext* cx, HandleObject a, HandleObject b)
+{
+    // Ensure swap doesn't cause a finalizer to not be run.
+    MOZ_ASSERT(IsBackgroundFinalized(a->asTenured().getAllocKind()) ==
+               IsBackgroundFinalized(b->asTenured().getAllocKind()));
+    MOZ_ASSERT(a->compartment() == b->compartment());
+
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+
+    AutoCompartment ac(cx, a);
+
+    if (!a->getGroup(cx))
+        oomUnsafe.crash("JSObject::swap");
+    if (!b->getGroup(cx))
+        oomUnsafe.crash("JSObject::swap");
+
+    /*
+     * Neither object may be in the nursery, but ensure we update any embedded
+     * nursery pointers in either object.
+     */
+    MOZ_ASSERT(!IsInsideNursery(a) && !IsInsideNursery(b));
+    cx->runtime()->gc.storeBuffer.putWholeCell(a);
+    cx->runtime()->gc.storeBuffer.putWholeCell(b);
+
+    unsigned r = NotifyGCPreSwap(a, b);
+
+    // Do the fundamental swapping of the contents of two objects.
+    MOZ_ASSERT(a->compartment() == b->compartment());
+    MOZ_ASSERT(a->is<JSFunction>() == b->is<JSFunction>());
+
+    // Don't try to swap functions with different sizes.
+    MOZ_ASSERT_IF(a->is<JSFunction>(), a->tenuredSizeOfThis() == b->tenuredSizeOfThis());
+
+    // Watch for oddball objects that have special organizational issues and
+    // can't be swapped.
+    MOZ_ASSERT(!a->is<RegExpObject>() && !b->is<RegExpObject>());
+    MOZ_ASSERT(!a->is<ArrayObject>() && !b->is<ArrayObject>());
+    MOZ_ASSERT(!a->is<ArrayBufferObject>() && !b->is<ArrayBufferObject>());
+    MOZ_ASSERT(!a->is<TypedArrayObject>() && !b->is<TypedArrayObject>());
+    MOZ_ASSERT(!a->is<TypedObject>() && !b->is<TypedObject>());
+
+    if (a->tenuredSizeOfThis() == b->tenuredSizeOfThis()) {
+        // When both objects are the same size, just do a plain swap of their
+        // contents.
+        size_t size = a->tenuredSizeOfThis();
+
+        char tmp[mozilla::tl::Max<sizeof(JSFunction), sizeof(JSObject_Slots16)>::value];
+        MOZ_ASSERT(size <= sizeof(tmp));
+
+        js_memcpy(tmp, a, size);
+        js_memcpy(a, b, size);
+        js_memcpy(b, tmp, size);
+
+        a->fixDictionaryShapeAfterSwap();
+        b->fixDictionaryShapeAfterSwap();
+    } else {
+        // Avoid GC in here to avoid confusing the tracing code with our
+        // intermediate state.
+        AutoSuppressGC suppress(cx);
+
+        // When the objects have different sizes, they will have different
+        // numbers of fixed slots before and after the swap, so the slots for
+        // native objects will need to be rearranged.
+        NativeObject* na = a->isNative() ? &a->as<NativeObject>() : nullptr;
+        NativeObject* nb = b->isNative() ? &b->as<NativeObject>() : nullptr;
+
+        // Remember the original values from the objects.
+        Vector<Value> avals(cx);
+        void* apriv = nullptr;
+        if (na) {
+            apriv = na->hasPrivate() ? na->getPrivate() : nullptr;
+            for (size_t i = 0; i < na->slotSpan(); i++) {
+                if (!avals.append(na->getSlot(i)))
+                    oomUnsafe.crash("JSObject::swap");
+            }
+        }
+        Vector<Value> bvals(cx);
+        void* bpriv = nullptr;
+        if (nb) {
+            bpriv = nb->hasPrivate() ? nb->getPrivate() : nullptr;
+            for (size_t i = 0; i < nb->slotSpan(); i++) {
+                if (!bvals.append(nb->getSlot(i)))
+                    oomUnsafe.crash("JSObject::swap");
+            }
+        }
+
+        // Swap the main fields of the objects, whether they are native objects or proxies.
+        char tmp[sizeof(JSObject_Slots0)];
+        js_memcpy(&tmp, a, sizeof tmp);
+        js_memcpy(a, b, sizeof tmp);
+        js_memcpy(b, &tmp, sizeof tmp);
+
+        a->fixDictionaryShapeAfterSwap();
+        b->fixDictionaryShapeAfterSwap();
+
+        if (na && !b->as<NativeObject>().fillInAfterSwap(cx, avals, apriv))
+            oomUnsafe.crash("fillInAfterSwap");
+        if (nb && !a->as<NativeObject>().fillInAfterSwap(cx, bvals, bpriv))
+            oomUnsafe.crash("fillInAfterSwap");
+    }
+
+    // Swapping the contents of two objects invalidates type sets which contain
+    // either of the objects, so mark all such sets as unknown.
+    MarkObjectGroupUnknownProperties(cx, a->group());
+    MarkObjectGroupUnknownProperties(cx, b->group());
+
+    /*
+     * We need a write barrier here. If |a| was marked and |b| was not, then
+     * after the swap, |b|'s guts would never be marked. The write barrier
+     * solves this.
+     *
+     * Normally write barriers happen before the write. However, that's not
+     * necessary here because nothing is being destroyed. We're just swapping.
+     */
+    JS::Zone* zone = a->zone();
+    if (zone->needsIncrementalBarrier()) {
+        a->traceChildren(zone->barrierTracer());
+        b->traceChildren(zone->barrierTracer());
+    }
+
+    NotifyGCPostSwap(a, b, r);
+    return true;
+}
+
+static bool
+DefineStandardSlot(JSContext* cx, HandleObject obj, JSProtoKey key, JSAtom* atom,
+                   HandleValue v, uint32_t attrs, bool& named)
+{
+    RootedId id(cx, AtomToId(atom));
+    named = DefineProperty(cx, obj, id, v, nullptr, nullptr, attrs);
+    return named;
+}
+
+static void
+SetClassObject(JSObject* obj, JSProtoKey key, JSObject* cobj, JSObject* proto)
+{
+    if (!obj->is<GlobalObject>())
+        return;
+
+    obj->as<GlobalObject>().setConstructor(key, ObjectOrNullValue(cobj));
+    obj->as<GlobalObject>().setPrototype(key, ObjectOrNullValue(proto));
+}
+
+static void
+ClearClassObject(JSObject* obj, JSProtoKey key)
+{
+    if (!obj->is<GlobalObject>())
+        return;
+
+    obj->as<GlobalObject>().setConstructor(key, UndefinedValue());
+    obj->as<GlobalObject>().setPrototype(key, UndefinedValue());
+}
+
+static NativeObject*
+DefineConstructorAndPrototype(JSContext* cx, HandleObject obj, JSProtoKey key, HandleAtom atom,
+                              HandleObject protoProto, const Class* clasp,
+                              Native constructor, unsigned nargs,
+                              const JSPropertySpec* ps, const JSFunctionSpec* fs,
+                              const JSPropertySpec* static_ps, const JSFunctionSpec* static_fs,
+                              NativeObject** ctorp, AllocKind ctorKind)
+{
+    /*
+     * Create a prototype object for this class.
+     *
+     * FIXME: lazy standard (built-in) class initialization and even older
+     * eager boostrapping code rely on all of these properties:
+     *
+     * 1. NewObject attempting to compute a default prototype object when
+     *    passed null for proto; and
+     *
+     * 2. NewObject tolerating no default prototype (null proto slot value)
+     *    due to this js::InitClass call coming from js::InitFunctionClass on an
+     *    otherwise-uninitialized global.
+     *
+     * 3. NewObject allocating a JSFunction-sized GC-thing when clasp is
+     *    &JSFunction::class_, not a JSObject-sized (smaller) GC-thing.
+     *
+     * The JS_NewObjectForGivenProto and JS_NewObject APIs also allow clasp to
+     * be &JSFunction::class_ (we could break compatibility easily). But
+     * fixing (3) is not enough without addressing the bootstrapping dependency
+     * on (1) and (2).
+     */
+
+    /*
+     * Create the prototype object.  (GlobalObject::createBlankPrototype isn't
+     * used because it won't let us use protoProto as the proto.
+     */
+    RootedNativeObject proto(cx, NewNativeObjectWithClassProto(cx, clasp, protoProto, SingletonObject));
+    if (!proto)
+        return nullptr;
+
+    /* After this point, control must exit via label bad or out. */
+    RootedNativeObject ctor(cx);
+    bool named = false;
+    bool cached = false;
+    if (!constructor) {
+        /*
+         * Lacking a constructor, name the prototype (e.g., Math) unless this
+         * class (a) is anonymous, i.e. for internal use only; (b) the class
+         * of obj (the global object) is has a reserved slot indexed by key;
+         * and (c) key is not the null key.
+         */
+        if (!(clasp->flags & JSCLASS_IS_ANONYMOUS) || !obj->is<GlobalObject>() ||
+            key == JSProto_Null)
+        {
+            uint32_t attrs = (clasp->flags & JSCLASS_IS_ANONYMOUS)
+                           ? JSPROP_READONLY | JSPROP_PERMANENT
+                           : 0;
+            RootedValue value(cx, ObjectValue(*proto));
+            if (!DefineStandardSlot(cx, obj, key, atom, value, attrs, named))
+                goto bad;
+        }
+
+        ctor = proto;
+    } else {
+        RootedFunction fun(cx, NewNativeConstructor(cx, constructor, nargs, atom, ctorKind));
+        if (!fun)
+            goto bad;
+
+        /*
+         * Set the class object early for standard class constructors. Type
+         * inference may need to access these, and js::GetBuiltinPrototype will
+         * fail if it tries to do a reentrant reconstruction of the class.
+         */
+        if (key != JSProto_Null) {
+            SetClassObject(obj, key, fun, proto);
+            cached = true;
+        }
+
+        RootedValue value(cx, ObjectValue(*fun));
+        if (!DefineStandardSlot(cx, obj, key, atom, value, 0, named))
+            goto bad;
+
+        /*
+         * Optionally construct the prototype object, before the class has
+         * been fully initialized.  Allow the ctor to replace proto with a
+         * different object, as is done for operator new.
+         */
+        ctor = fun;
+        if (!LinkConstructorAndPrototype(cx, ctor, proto))
+            goto bad;
+
+        /* Bootstrap Function.prototype (see also JS_InitStandardClasses). */
+        Rooted<TaggedProto> tagged(cx, TaggedProto(proto));
+        if (ctor->getClass() == clasp && !ctor->splicePrototype(cx, clasp, tagged))
+            goto bad;
+    }
+
+    if (!DefinePropertiesAndFunctions(cx, proto, ps, fs) ||
+        (ctor != proto && !DefinePropertiesAndFunctions(cx, ctor, static_ps, static_fs)))
+    {
+        goto bad;
+    }
+
+    /* If this is a standard class, cache its prototype. */
+    if (!cached && key != JSProto_Null)
+        SetClassObject(obj, key, ctor, proto);
+
+    if (ctorp)
+        *ctorp = ctor;
+    return proto;
+
+bad:
+    if (named) {
+        ObjectOpResult ignored;
+        RootedId id(cx, AtomToId(atom));
+
+        // XXX FIXME - absurd to call this here; instead define the property last.
+        DeleteProperty(cx, obj, id, ignored);
+    }
+    if (cached)
+        ClearClassObject(obj, key);
+    return nullptr;
+}
+
+NativeObject*
+js::InitClass(JSContext* cx, HandleObject obj, HandleObject protoProto_,
+              const Class* clasp, Native constructor, unsigned nargs,
+              const JSPropertySpec* ps, const JSFunctionSpec* fs,
+              const JSPropertySpec* static_ps, const JSFunctionSpec* static_fs,
+              NativeObject** ctorp, AllocKind ctorKind)
+{
+    RootedObject protoProto(cx, protoProto_);
+
+    /* Check function pointer members. */
+    MOZ_ASSERT(clasp->getGetProperty() != JS_PropertyStub);
+    MOZ_ASSERT(clasp->getSetProperty() != JS_StrictPropertyStub);
+
+    RootedAtom atom(cx, Atomize(cx, clasp->name, strlen(clasp->name)));
+    if (!atom)
+        return nullptr;
+
+    /*
+     * All instances of the class will inherit properties from the prototype
+     * object we are about to create (in DefineConstructorAndPrototype), which
+     * in turn will inherit from protoProto.
+     *
+     * When initializing a standard class (other than Object), if protoProto is
+     * null, default to Object.prototype. The engine's internal uses of
+     * js::InitClass depend on this nicety.
+     */
+    JSProtoKey key = JSCLASS_CACHED_PROTO_KEY(clasp);
+    if (key != JSProto_Null &&
+        !protoProto &&
+        !GetBuiltinPrototype(cx, JSProto_Object, &protoProto))
+    {
+        return nullptr;
+    }
+
+    return DefineConstructorAndPrototype(cx, obj, key, atom, protoProto, clasp, constructor, nargs,
+                                         ps, fs, static_ps, static_fs, ctorp, ctorKind);
+}
+
+void
+JSObject::fixupAfterMovingGC()
+{
+    // For copy-on-write objects that don't own their elements, fix up the
+    // elements pointer if it points to inline elements in the owning object.
+    if (is<NativeObject>()) {
+        NativeObject& obj = as<NativeObject>();
+        if (obj.denseElementsAreCopyOnWrite()) {
+            NativeObject* owner = obj.getElementsHeader()->ownerObject();
+            // Get the new owner pointer but don't call MaybeForwarded as we
+            // don't need to access the object's shape.
+            if (IsForwarded(owner))
+                owner = Forwarded(owner);
+            if (owner != &obj && owner->hasFixedElements())
+                obj.elements_ = owner->getElementsHeader()->elements();
+            MOZ_ASSERT(!IsForwarded(obj.getElementsHeader()->ownerObject().get()));
+        }
+    }
+}
+
+bool
+js::SetClassAndProto(JSContext* cx, HandleObject obj,
+                     const Class* clasp, Handle<js::TaggedProto> proto)
+{
+    // Regenerate the object's shape. If the object is a proto (isDelegate()),
+    // we also need to regenerate shapes for all of the objects along the old
+    // prototype chain, in case any entries were filled by looking up through
+    // obj. Stop when a non-native object is found, prototype lookups will not
+    // be cached across these.
+    //
+    // How this shape change is done is very delicate; the change can be made
+    // either by marking the object's prototype as uncacheable (such that the
+    // JIT'ed ICs cannot assume the shape determines the prototype) or by just
+    // generating a new shape for the object. Choosing the former is bad if the
+    // object is on the prototype chain of other objects, as the uncacheable
+    // prototype can inhibit iterator caches on those objects and slow down
+    // prototype accesses. Choosing the latter is bad if there are many similar
+    // objects to this one which will have their prototype mutated, as the
+    // generateOwnShape forces the object into dictionary mode and similar
+    // property lineages will be repeatedly cloned.
+    //
+    // :XXX: bug 707717 make this code less brittle.
+    RootedObject oldproto(cx, obj);
+    while (oldproto && oldproto->isNative()) {
+        if (oldproto->isSingleton()) {
+            // We always generate a new shape if the object is a singleton,
+            // regardless of the uncacheable-proto flag. ICs may rely on
+            // this.
+            if (!oldproto->as<NativeObject>().generateOwnShape(cx))
+                return false;
+        } else {
+            if (!oldproto->setUncacheableProto(cx))
+                return false;
+        }
+        if (!obj->isDelegate()) {
+            // If |obj| is not a proto of another object, we don't need to
+            // reshape the whole proto chain.
+            MOZ_ASSERT(obj == oldproto);
+            break;
+        }
+        oldproto = oldproto->staticPrototype();
+    }
+
+    if (proto.isObject() && !proto.toObject()->setDelegate(cx))
+        return false;
+
+    if (obj->isSingleton()) {
+        /*
+         * Just splice the prototype, but mark the properties as unknown for
+         * consistent behavior.
+         */
+        if (!obj->splicePrototype(cx, clasp, proto))
+            return false;
+        MarkObjectGroupUnknownProperties(cx, obj->group());
+        return true;
+    }
+
+    if (proto.isObject()) {
+        RootedObject protoObj(cx, proto.toObject());
+        if (!JSObject::setNewGroupUnknown(cx, clasp, protoObj))
+            return false;
+    }
+
+    ObjectGroup* group = ObjectGroup::defaultNewGroup(cx, clasp, proto);
+    if (!group)
+        return false;
+
+    /*
+     * Setting __proto__ on an object that has escaped and may be referenced by
+     * other heap objects can only be done if the properties of both objects
+     * are unknown. Type sets containing this object will contain the original
+     * type but not the new type of the object, so we need to treat all such
+     * type sets as unknown.
+     */
+    MarkObjectGroupUnknownProperties(cx, obj->group());
+    MarkObjectGroupUnknownProperties(cx, group);
+
+    obj->setGroup(group);
+
+    return true;
+}
+
+/* static */ bool
+JSObject::changeToSingleton(JSContext* cx, HandleObject obj)
+{
+    MOZ_ASSERT(!obj->isSingleton());
+
+    MarkObjectGroupUnknownProperties(cx, obj->group());
+
+    ObjectGroup* group = ObjectGroup::lazySingletonGroup(cx, obj->getClass(),
+                                                         obj->taggedProto());
+    if (!group)
+        return false;
+
+    obj->group_ = group;
+    return true;
+}
+
+static bool
+MaybeResolveConstructor(ExclusiveContext* cxArg, Handle<GlobalObject*> global, JSProtoKey key)
+{
+    if (global->isStandardClassResolved(key))
+        return true;
+    if (!cxArg->shouldBeJSContext())
+        return false;
+
+    JSContext* cx = cxArg->asJSContext();
+    return GlobalObject::resolveConstructor(cx, global, key);
+}
+
+bool
+js::GetBuiltinConstructor(ExclusiveContext* cx, JSProtoKey key, MutableHandleObject objp)
+{
+    MOZ_ASSERT(key != JSProto_Null);
+    Rooted<GlobalObject*> global(cx, cx->global());
+    if (!MaybeResolveConstructor(cx, global, key))
+        return false;
+
+    objp.set(&global->getConstructor(key).toObject());
+    return true;
+}
+
+bool
+js::GetBuiltinPrototype(ExclusiveContext* cx, JSProtoKey key, MutableHandleObject protop)
+{
+    MOZ_ASSERT(key != JSProto_Null);
+    Rooted<GlobalObject*> global(cx, cx->global());
+    if (!MaybeResolveConstructor(cx, global, key))
+        return false;
+
+    protop.set(&global->getPrototype(key).toObject());
+    return true;
+}
+
+bool
+js::IsStandardPrototype(JSObject* obj, JSProtoKey key)
+{
+    GlobalObject& global = obj->global();
+    Value v = global.getPrototype(key);
+    return v.isObject() && obj == &v.toObject();
+}
+
+
+/**
+ * Returns the original Object.prototype from the embedding-provided incumbent
+ * global.
+ *
+ * Really, we want the incumbent global itself so we can pass it to other
+ * embedding hooks which need it. Specifically, the enqueue promise hook
+ * takes an incumbent global so it can set that on the PromiseCallbackJob
+ * it creates.
+ *
+ * The reason for not just returning the global itself is that we'd need to
+ * wrap it into the current compartment, and later unwrap it. Unwrapping
+ * globals is tricky, though: we might accidentally unwrap through an inner
+ * to its outer window and end up with the wrong global. Plain objects don't
+ * have this problem, so we use the global's Object.prototype. The code using
+ * it - e.g. EnqueuePromiseReactionJob - can then unwrap the object and get
+ * its global without fear of unwrapping too far.
+ */
+bool
+js::GetObjectFromIncumbentGlobal(JSContext* cx, MutableHandleObject obj)
+{
+    RootedObject globalObj(cx, cx->runtime()->getIncumbentGlobal(cx));
+    if (!globalObj) {
+        obj.set(nullptr);
+        return true;
+    }
+
+    {
+        AutoCompartment ac(cx, globalObj);
+        obj.set(globalObj->as<GlobalObject>().getOrCreateObjectPrototype(cx));
+        if (!obj)
+            return false;
+    }
+
+    // The object might be from a different compartment, so wrap it.
+    if (obj && !cx->compartment()->wrap(cx, obj))
+        return false;
+
+    return true;
+}
+
+JSProtoKey
+JS::IdentifyStandardInstance(JSObject* obj)
+{
+    // Note: The prototype shares its JSClass with instances.
+    MOZ_ASSERT(!obj->is<CrossCompartmentWrapperObject>());
+    JSProtoKey key = StandardProtoKeyOrNull(obj);
+    if (key != JSProto_Null && !IsStandardPrototype(obj, key))
+        return key;
+    return JSProto_Null;
+}
+
+JSProtoKey
+JS::IdentifyStandardPrototype(JSObject* obj)
+{
+    // Note: The prototype shares its JSClass with instances.
+    MOZ_ASSERT(!obj->is<CrossCompartmentWrapperObject>());
+    JSProtoKey key = StandardProtoKeyOrNull(obj);
+    if (key != JSProto_Null && IsStandardPrototype(obj, key))
+        return key;
+    return JSProto_Null;
+}
+
+JSProtoKey
+JS::IdentifyStandardInstanceOrPrototype(JSObject* obj)
+{
+    return StandardProtoKeyOrNull(obj);
+}
+
+JSProtoKey
+JS::IdentifyStandardConstructor(JSObject* obj)
+{
+    // Note that NATIVE_CTOR does not imply that we are a standard constructor,
+    // but the converse is true (at least until we start having self-hosted
+    // constructors for standard classes). This lets us avoid a costly loop for
+    // many functions (which, depending on the call site, may be the common case).
+    if (!obj->is<JSFunction>() || !(obj->as<JSFunction>().flags() & JSFunction::NATIVE_CTOR))
+        return JSProto_Null;
+
+    GlobalObject& global = obj->global();
+    for (size_t k = 0; k < JSProto_LIMIT; ++k) {
+        JSProtoKey key = static_cast<JSProtoKey>(k);
+        if (global.getConstructor(key) == ObjectValue(*obj))
+            return key;
+    }
+
+    return JSProto_Null;
+}
+
+bool
+JSObject::isCallable() const
+{
+    if (is<JSFunction>())
+        return true;
+    return callHook() != nullptr;
+}
+
+bool
+JSObject::isConstructor() const
+{
+    if (is<JSFunction>()) {
+        const JSFunction& fun = as<JSFunction>();
+        return fun.isConstructor();
+    }
+    return constructHook() != nullptr;
+}
+
+JSNative
+JSObject::callHook() const
+{
+    const js::Class* clasp = getClass();
+
+    if (JSNative call = clasp->getCall())
+        return call;
+
+    if (is<js::ProxyObject>()) {
+        const js::ProxyObject& p = as<js::ProxyObject>();
+        if (p.handler()->isCallable(const_cast<JSObject*>(this)))
+            return js::proxy_Call;
+    }
+    return nullptr;
+}
+
+JSNative
+JSObject::constructHook() const
+{
+    const js::Class* clasp = getClass();
+
+    if (JSNative construct = clasp->getConstruct())
+        return construct;
+
+    if (is<js::ProxyObject>()) {
+        const js::ProxyObject& p = as<js::ProxyObject>();
+        if (p.handler()->isConstructor(const_cast<JSObject*>(this)))
+            return js::proxy_Construct;
+    }
+    return nullptr;
+}
+
+bool
+js::LookupProperty(JSContext* cx, HandleObject obj, js::HandleId id,
+                   MutableHandleObject objp, MutableHandleShape propp)
+{
+    /* NB: The logic of lookupProperty is implicitly reflected in
+     *     BaselineIC.cpp's |EffectlesslyLookupProperty| logic.
+     *     If this changes, please remember to update the logic there as well.
+     */
+    if (LookupPropertyOp op = obj->getOpsLookupProperty())
+        return op(cx, obj, id, objp, propp);
+    return LookupPropertyInline<CanGC>(cx, obj.as<NativeObject>(), id, objp, propp);
+}
+
+bool
+js::LookupName(JSContext* cx, HandlePropertyName name, HandleObject envChain,
+               MutableHandleObject objp, MutableHandleObject pobjp, MutableHandleShape propp)
+{
+    RootedId id(cx, NameToId(name));
+
+    for (RootedObject env(cx, envChain); env; env = env->enclosingEnvironment()) {
+        if (!LookupProperty(cx, env, id, pobjp, propp))
+            return false;
+        if (propp) {
+            objp.set(env);
+            return true;
+        }
+    }
+
+    objp.set(nullptr);
+    pobjp.set(nullptr);
+    propp.set(nullptr);
+    return true;
+}
+
+bool
+js::LookupNameNoGC(JSContext* cx, PropertyName* name, JSObject* envChain,
+                   JSObject** objp, JSObject** pobjp, Shape** propp)
+{
+    AutoAssertNoException nogc(cx);
+
+    MOZ_ASSERT(!*objp && !*pobjp && !*propp);
+
+    for (JSObject* env = envChain; env; env = env->enclosingEnvironment()) {
+        if (env->getOpsLookupProperty())
+            return false;
+        if (!LookupPropertyInline<NoGC>(cx, &env->as<NativeObject>(), NameToId(name), pobjp, propp))
+            return false;
+        if (*propp) {
+            *objp = env;
+            return true;
+        }
+    }
+
+    return true;
+}
+
+bool
+js::LookupNameWithGlobalDefault(JSContext* cx, HandlePropertyName name, HandleObject envChain,
+                                MutableHandleObject objp)
+{
+    RootedId id(cx, NameToId(name));
+
+    RootedObject pobj(cx);
+    RootedShape shape(cx);
+
+    RootedObject env(cx, envChain);
+    for (; !env->is<GlobalObject>(); env = env->enclosingEnvironment()) {
+        if (!LookupProperty(cx, env, id, &pobj, &shape))
+            return false;
+        if (shape)
+            break;
+    }
+
+    objp.set(env);
+    return true;
+}
+
+bool
+js::LookupNameUnqualified(JSContext* cx, HandlePropertyName name, HandleObject envChain,
+                          MutableHandleObject objp)
+{
+    RootedId id(cx, NameToId(name));
+
+    RootedObject pobj(cx);
+    RootedShape shape(cx);
+
+    RootedObject env(cx, envChain);
+    for (; !env->isUnqualifiedVarObj(); env = env->enclosingEnvironment()) {
+        if (!LookupProperty(cx, env, id, &pobj, &shape))
+            return false;
+        if (shape)
+            break;
+    }
+
+    // See note above RuntimeLexicalErrorObject.
+    if (pobj == env) {
+        bool isTDZ = false;
+        if (shape && name != cx->names().dotThis) {
+            // Treat Debugger environments specially for TDZ checks, as they
+            // look like non-native environments but in fact wrap native
+            // environments.
+            if (env->is<DebugEnvironmentProxy>()) {
+                RootedValue v(cx);
+                if (!env->as<DebugEnvironmentProxy>().getMaybeSentinelValue(cx, id, &v))
+                    return false;
+                isTDZ = IsUninitializedLexical(v);
+            } else {
+                isTDZ = IsUninitializedLexicalSlot(env, shape);
+            }
+        }
+
+        if (isTDZ) {
+            env = RuntimeLexicalErrorObject::create(cx, env, JSMSG_UNINITIALIZED_LEXICAL);
+            if (!env)
+                return false;
+        } else if (env->is<LexicalEnvironmentObject>() && !shape->writable()) {
+            // Assigning to a named lambda callee name is a no-op in sloppy mode.
+            Rooted<LexicalEnvironmentObject*> lexicalEnv(cx, &env->as<LexicalEnvironmentObject>());
+            if (lexicalEnv->isExtensible() ||
+                lexicalEnv->scope().kind() != ScopeKind::NamedLambda)
+            {
+                MOZ_ASSERT(name != cx->names().dotThis);
+                env = RuntimeLexicalErrorObject::create(cx, env, JSMSG_BAD_CONST_ASSIGN);
+                if (!env)
+                    return false;
+            }
+        }
+    }
+
+    objp.set(env);
+    return true;
+}
+
+bool
+js::HasOwnProperty(JSContext* cx, HandleObject obj, HandleId id, bool* result)
+{
+    if (obj->is<ProxyObject>())
+        return Proxy::hasOwn(cx, obj, id, result);
+
+    if (GetOwnPropertyOp op = obj->getOpsGetOwnPropertyDescriptor()) {
+        Rooted<PropertyDescriptor> desc(cx);
+        if (!op(cx, obj, id, &desc))
+            return false;
+        *result = !!desc.object();
+        return true;
+    }
+
+    RootedShape shape(cx);
+    if (!NativeLookupOwnProperty<CanGC>(cx, obj.as<NativeObject>(), id, &shape))
+        return false;
+    *result = (shape != nullptr);
+    return true;
+}
+
+bool
+js::LookupPropertyPure(ExclusiveContext* cx, JSObject* obj, jsid id, JSObject** objp,
+                       Shape** propp)
+{
+    bool isTypedArrayOutOfRange = false;
+    do {
+        if (!LookupOwnPropertyPure(cx, obj, id, propp, &isTypedArrayOutOfRange))
+            return false;
+
+        if (*propp) {
+            *objp = obj;
+            return true;
+        }
+
+        if (isTypedArrayOutOfRange) {
+            *objp = nullptr;
+            return true;
+        }
+
+        obj = obj->staticPrototype();
+    } while (obj);
+
+    *objp = nullptr;
+    *propp = nullptr;
+    return true;
+}
+
+bool
+js::LookupOwnPropertyPure(ExclusiveContext* cx, JSObject* obj, jsid id, Shape** propp,
+                          bool* isTypedArrayOutOfRange /* = nullptr */)
+{
+    JS::AutoCheckCannotGC nogc;
+    if (isTypedArrayOutOfRange)
+        *isTypedArrayOutOfRange = false;
+
+    if (obj->isNative()) {
+        // Search for a native dense element, typed array element, or property.
+
+        if (JSID_IS_INT(id) && obj->as<NativeObject>().containsDenseElement(JSID_TO_INT(id))) {
+            MarkDenseOrTypedArrayElementFound<NoGC>(propp);
+            return true;
+        }
+
+        if (obj->is<TypedArrayObject>()) {
+            uint64_t index;
+            if (IsTypedArrayIndex(id, &index)) {
+                if (index < obj->as<TypedArrayObject>().length()) {
+                    MarkDenseOrTypedArrayElementFound<NoGC>(propp);
+                } else {
+                    *propp = nullptr;
+                    if (isTypedArrayOutOfRange)
+                        *isTypedArrayOutOfRange = true;
+                }
+                return true;
+            }
+        }
+
+        if (Shape* shape = obj->as<NativeObject>().lookupPure(id)) {
+            *propp = shape;
+            return true;
+        }
+
+        // Fail if there's a resolve hook, unless the mayResolve hook tells
+        // us the resolve hook won't define a property with this id.
+        if (ClassMayResolveId(cx->names(), obj->getClass(), id, obj))
+            return false;
+    } else if (obj->is<UnboxedPlainObject>()) {
+        if (obj->as<UnboxedPlainObject>().containsUnboxedOrExpandoProperty(cx, id)) {
+            MarkNonNativePropertyFound<NoGC>(propp);
+            return true;
+        }
+    } else if (obj->is<UnboxedArrayObject>()) {
+        if (obj->as<UnboxedArrayObject>().containsProperty(cx, id)) {
+            MarkNonNativePropertyFound<NoGC>(propp);
+            return true;
+        }
+    } else if (obj->is<TypedObject>()) {
+        if (obj->as<TypedObject>().typeDescr().hasProperty(cx->names(), id)) {
+            MarkNonNativePropertyFound<NoGC>(propp);
+            return true;
+        }
+    } else {
+        return false;
+    }
+
+    *propp = nullptr;
+    return true;
+}
+
+static inline bool
+NativeGetPureInline(NativeObject* pobj, Shape* shape, Value* vp)
+{
+    /* Fail if we have a custom getter. */
+    if (!shape->hasDefaultGetter())
+        return false;
+
+    if (shape->hasSlot()) {
+        *vp = pobj->getSlot(shape->slot());
+        MOZ_ASSERT(!vp->isMagic());
+    } else {
+        vp->setUndefined();
+    }
+
+    return true;
+}
+
+bool
+js::GetPropertyPure(ExclusiveContext* cx, JSObject* obj, jsid id, Value* vp)
+{
+    JSObject* pobj;
+    Shape* shape;
+    if (!LookupPropertyPure(cx, obj, id, &pobj, &shape))
+        return false;
+
+    if (!shape) {
+        vp->setUndefined();
+        return true;
+    }
+
+    return pobj->isNative() && NativeGetPureInline(&pobj->as<NativeObject>(), shape, vp);
+}
+
+static inline bool
+NativeGetGetterPureInline(Shape* shape, JSFunction** fp)
+{
+    if (shape->hasGetterObject()) {
+        if (shape->getterObject()->is<JSFunction>()) {
+            *fp = &shape->getterObject()->as<JSFunction>();
+            return true;
+        }
+    }
+
+    *fp = nullptr;
+    return true;
+}
+
+bool
+js::GetGetterPure(ExclusiveContext* cx, JSObject* obj, jsid id, JSFunction** fp)
+{
+    /* Just like GetPropertyPure, but get getter function, without invoking
+     * it. */
+    JSObject* pobj;
+    Shape* shape;
+    if (!LookupPropertyPure(cx, obj, id, &pobj, &shape))
+        return false;
+
+    if (!shape) {
+        *fp = nullptr;
+        return true;
+    }
+
+    return pobj->isNative() && NativeGetGetterPureInline(shape, fp);
+}
+
+bool
+js::GetOwnGetterPure(ExclusiveContext* cx, JSObject* obj, jsid id, JSFunction** fp)
+{
+    JS::AutoCheckCannotGC nogc;
+    Shape* shape;
+    if (!LookupOwnPropertyPure(cx, obj, id, &shape))
+        return false;
+
+    if (!shape) {
+        *fp = nullptr;
+        return true;
+    }
+
+    return NativeGetGetterPureInline(shape, fp);
+}
+
+bool
+js::GetOwnNativeGetterPure(JSContext* cx, JSObject* obj, jsid id, JSNative* native)
+{
+    JS::AutoCheckCannotGC nogc;
+    *native = nullptr;
+    Shape* shape;
+    if (!LookupOwnPropertyPure(cx, obj, id, &shape))
+        return false;
+
+    if (!shape || IsImplicitDenseOrTypedArrayElement(shape) || !shape->hasGetterObject())
+        return true;
+
+    JSObject* getterObj = shape->getterObject();
+    if (!getterObj->is<JSFunction>())
+        return true;
+
+    JSFunction* getter = &getterObj->as<JSFunction>();
+    if (!getter->isNative())
+        return true;
+
+    *native = getter->native();
+    return true;
+}
+
+bool
+js::HasOwnDataPropertyPure(JSContext* cx, JSObject* obj, jsid id, bool* result)
+{
+    Shape* shape = nullptr;
+    if (!LookupOwnPropertyPure(cx, obj, id, &shape))
+        return false;
+
+    *result = shape && !IsImplicitDenseOrTypedArrayElement(shape) && shape->hasDefaultGetter() &&
+              shape->hasSlot();
+    return true;
+}
+
+bool
+JSObject::reportReadOnly(JSContext* cx, jsid id, unsigned report)
+{
+    RootedValue val(cx, IdToValue(id));
+    return ReportValueErrorFlags(cx, report, JSMSG_READ_ONLY,
+                                 JSDVG_IGNORE_STACK, val, nullptr,
+                                 nullptr, nullptr);
+}
+
+bool
+JSObject::reportNotConfigurable(JSContext* cx, jsid id, unsigned report)
+{
+    RootedValue val(cx, IdToValue(id));
+    return ReportValueErrorFlags(cx, report, JSMSG_CANT_DELETE,
+                                 JSDVG_IGNORE_STACK, val, nullptr,
+                                 nullptr, nullptr);
+}
+
+bool
+JSObject::reportNotExtensible(JSContext* cx, unsigned report)
+{
+    RootedValue val(cx, ObjectValue(*this));
+    return ReportValueErrorFlags(cx, report, JSMSG_OBJECT_NOT_EXTENSIBLE,
+                                 JSDVG_IGNORE_STACK, val, nullptr,
+                                 nullptr, nullptr);
+}
+
+bool
+js::GetPrototypeIfOrdinary(JSContext* cx, HandleObject obj, bool* isOrdinary,
+                           MutableHandleObject protop)
+{
+    if (obj->is<js::ProxyObject>())
+        return js::Proxy::getPrototypeIfOrdinary(cx, obj, isOrdinary, protop);
+
+    *isOrdinary = true;
+    protop.set(obj->staticPrototype());
+    return true;
+}
+
+/*** ES6 standard internal methods ***************************************************************/
+
+bool
+js::SetPrototype(JSContext* cx, HandleObject obj, HandleObject proto, JS::ObjectOpResult& result)
+{
+    // The proxy trap subsystem fully handles prototype-setting for proxies
+    // with dynamic [[Prototype]]s.
+    if (obj->hasDynamicPrototype()) {
+        MOZ_ASSERT(obj->is<ProxyObject>());
+        return Proxy::setPrototype(cx, obj, proto, result);
+    }
+
+    /*
+     * ES6 9.1.2 step 3-4 if |obj.[[Prototype]]| has SameValue as |proto| return true.
+     * Since the values in question are objects, we can just compare pointers.
+     */
+    if (proto == obj->staticPrototype())
+        return result.succeed();
+
+    /* Disallow mutation of immutable [[Prototype]]s. */
+    if (obj->staticPrototypeIsImmutable())
+        return result.fail(JSMSG_CANT_SET_PROTO);
+
+    /*
+     * Disallow mutating the [[Prototype]] on ArrayBuffer objects, which
+     * due to their complicated delegate-object shenanigans can't easily
+     * have a mutable [[Prototype]].
+     */
+    if (obj->is<ArrayBufferObject>()) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_SET_PROTO_OF,
+                                  "incompatible ArrayBuffer");
+        return false;
+    }
+
+    /*
+     * Disallow mutating the [[Prototype]] on Typed Objects, per the spec.
+     */
+    if (obj->is<TypedObject>()) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_SET_PROTO_OF,
+                                  "incompatible TypedObject");
+        return false;
+    }
+
+    /* ES6 9.1.2 step 5 forbids changing [[Prototype]] if not [[Extensible]]. */
+    bool extensible;
+    if (!IsExtensible(cx, obj, &extensible))
+        return false;
+    if (!extensible)
+        return result.fail(JSMSG_CANT_SET_PROTO);
+
+    // If this is a global object, resolve the Object class so that its
+    // [[Prototype]] chain is always properly immutable, even in the presence
+    // of lazy standard classes.
+    if (obj->is<GlobalObject>()) {
+        Rooted<GlobalObject*> global(cx, &obj->as<GlobalObject>());
+        if (!GlobalObject::ensureConstructor(cx, global, JSProto_Object))
+            return false;
+    }
+
+    /*
+     * ES6 9.1.2 step 6 forbids generating cyclical prototype chains. But we
+     * have to do this comparison on the observable WindowProxy, not on the
+     * possibly-Window object we're setting the proto on.
+     */
+    RootedObject objMaybeWindowProxy(cx, ToWindowProxyIfWindow(obj));
+    RootedObject obj2(cx, proto);
+    while (obj2) {
+        MOZ_ASSERT(!IsWindow(obj2));
+        if (obj2 == objMaybeWindowProxy)
+            return result.fail(JSMSG_CANT_SET_PROTO_CYCLE);
+
+        bool isOrdinary;
+        if (!GetPrototypeIfOrdinary(cx, obj2, &isOrdinary, &obj2))
+            return false;
+        if (!isOrdinary)
+            break;
+    }
+
+    // Convert unboxed objects to their native representations before changing
+    // their prototype/group, as they depend on the group for their layout.
+    if (!MaybeConvertUnboxedObjectToNative(cx, obj))
+        return false;
+
+    Rooted<TaggedProto> taggedProto(cx, TaggedProto(proto));
+    if (!SetClassAndProto(cx, obj, obj->getClass(), taggedProto))
+        return false;
+
+    return result.succeed();
+}
+
+bool
+js::SetPrototype(JSContext* cx, HandleObject obj, HandleObject proto)
+{
+    ObjectOpResult result;
+    return SetPrototype(cx, obj, proto, result) && result.checkStrict(cx, obj);
+}
+
+bool
+js::PreventExtensions(JSContext* cx, HandleObject obj, ObjectOpResult& result, IntegrityLevel level)
+{
+    if (obj->is<ProxyObject>())
+        return js::Proxy::preventExtensions(cx, obj, result);
+
+    if (!obj->nonProxyIsExtensible())
+        return result.succeed();
+
+    if (!MaybeConvertUnboxedObjectToNative(cx, obj))
+        return false;
+
+    // Force lazy properties to be resolved.
+    AutoIdVector props(cx);
+    if (!js::GetPropertyKeys(cx, obj, JSITER_HIDDEN | JSITER_OWNONLY, &props))
+        return false;
+
+    // Actually prevent extension. If the object is being frozen, do it by
+    // setting the frozen flag on both the object and the object group.
+    // Otherwise, fallback to sparsifying the object, which makes sure no
+    // element can be added without a call to isExtensible, at the cost of
+    // performance.
+    if (obj->isNative()) {
+        if (level == IntegrityLevel::Frozen) {
+            MarkObjectGroupFlags(cx, obj, OBJECT_FLAG_FROZEN);
+            if (!ObjectElements::FreezeElements(cx, obj.as<NativeObject>()))
+                return false;
+        } else if (!NativeObject::sparsifyDenseElements(cx, obj.as<NativeObject>())) {
+            return false;
+        }
+    }
+
+    if (!obj->setFlags(cx, BaseShape::NOT_EXTENSIBLE, JSObject::GENERATE_SHAPE)) {
+        // We failed to mark the object non-extensible, so reset the frozen
+        // flag on the elements.
+        MOZ_ASSERT(obj->nonProxyIsExtensible());
+        if (obj->isNative() && obj->as<NativeObject>().getElementsHeader()->isFrozen())
+            obj->as<NativeObject>().getElementsHeader()->markNotFrozen();
+        return false;
+    }
+
+    return result.succeed();
+}
+
+bool
+js::PreventExtensions(JSContext* cx, HandleObject obj, IntegrityLevel level)
+{
+    ObjectOpResult result;
+    return PreventExtensions(cx, obj, result, level) && result.checkStrict(cx, obj);
+}
+
+bool
+js::GetOwnPropertyDescriptor(JSContext* cx, HandleObject obj, HandleId id,
+                             MutableHandle<PropertyDescriptor> desc)
+{
+    if (GetOwnPropertyOp op = obj->getOpsGetOwnPropertyDescriptor()) {
+        bool ok = op(cx, obj, id, desc);
+        if (ok)
+            desc.assertCompleteIfFound();
+        return ok;
+    }
+
+    return NativeGetOwnPropertyDescriptor(cx, obj.as<NativeObject>(), id, desc);
+}
+
+bool
+js::DefineProperty(JSContext* cx, HandleObject obj, HandleId id, Handle<PropertyDescriptor> desc)
+{
+    ObjectOpResult result;
+    return DefineProperty(cx, obj, id, desc, result) &&
+           result.checkStrict(cx, obj, id);
+}
+
+bool
+js::DefineProperty(JSContext* cx, HandleObject obj, HandleId id, Handle<PropertyDescriptor> desc,
+                   ObjectOpResult& result)
+{
+    desc.assertValid();
+    if (DefinePropertyOp op = obj->getOpsDefineProperty())
+        return op(cx, obj, id, desc, result);
+    return NativeDefineProperty(cx, obj.as<NativeObject>(), id, desc, result);
+}
+
+bool
+js::DefineProperty(ExclusiveContext* cx, HandleObject obj, HandleId id, HandleValue value,
+                   JSGetterOp getter, JSSetterOp setter, unsigned attrs,
+                   ObjectOpResult& result)
+{
+    MOZ_ASSERT(!(attrs & JSPROP_PROPOP_ACCESSORS));
+
+    Rooted<PropertyDescriptor> desc(cx);
+    desc.initFields(nullptr, value, attrs, getter, setter);
+    if (DefinePropertyOp op = obj->getOpsDefineProperty()) {
+        if (!cx->shouldBeJSContext())
+            return false;
+        return op(cx->asJSContext(), obj, id, desc, result);
+    }
+    return NativeDefineProperty(cx, obj.as<NativeObject>(), id, desc, result);
+}
+
+bool
+js::DefineProperty(ExclusiveContext* cx, HandleObject obj, PropertyName* name, HandleValue value,
+                   JSGetterOp getter, JSSetterOp setter, unsigned attrs,
+                   ObjectOpResult& result)
+{
+    RootedId id(cx, NameToId(name));
+    return DefineProperty(cx, obj, id, value, getter, setter, attrs, result);
+}
+
+bool
+js::DefineElement(ExclusiveContext* cx, HandleObject obj, uint32_t index, HandleValue value,
+                  JSGetterOp getter, JSSetterOp setter, unsigned attrs,
+                  ObjectOpResult& result)
+{
+    MOZ_ASSERT(getter != JS_PropertyStub);
+    MOZ_ASSERT(setter != JS_StrictPropertyStub);
+
+    RootedId id(cx);
+    if (!IndexToId(cx, index, &id))
+        return false;
+    return DefineProperty(cx, obj, id, value, getter, setter, attrs, result);
+}
+
+bool
+js::DefineProperty(ExclusiveContext* cx, HandleObject obj, HandleId id, HandleValue value,
+                   JSGetterOp getter, JSSetterOp setter, unsigned attrs)
+{
+    ObjectOpResult result;
+    if (!DefineProperty(cx, obj, id, value, getter, setter, attrs, result))
+        return false;
+    if (!result) {
+        if (!cx->shouldBeJSContext())
+            return false;
+        result.reportError(cx->asJSContext(), obj, id);
+        return false;
+    }
+    return true;
+}
+
+bool
+js::DefineProperty(ExclusiveContext* cx, HandleObject obj, PropertyName* name, HandleValue value,
+                   JSGetterOp getter, JSSetterOp setter, unsigned attrs)
+{
+    RootedId id(cx, NameToId(name));
+    return DefineProperty(cx, obj, id, value, getter, setter, attrs);
+}
+
+bool
+js::DefineElement(ExclusiveContext* cx, HandleObject obj, uint32_t index, HandleValue value,
+                  JSGetterOp getter, JSSetterOp setter, unsigned attrs)
+{
+    MOZ_ASSERT(getter != JS_PropertyStub);
+    MOZ_ASSERT(setter != JS_StrictPropertyStub);
+
+    RootedId id(cx);
+    if (!IndexToId(cx, index, &id))
+        return false;
+    return DefineProperty(cx, obj, id, value, getter, setter, attrs);
+}
+
+
+/*** SpiderMonkey nonstandard internal methods ***************************************************/
+
+bool
+js::SetImmutablePrototype(ExclusiveContext* cx, HandleObject obj, bool* succeeded)
+{
+    if (obj->hasDynamicPrototype()) {
+        if (!cx->shouldBeJSContext())
+            return false;
+        return Proxy::setImmutablePrototype(cx->asJSContext(), obj, succeeded);
+    }
+
+    if (!obj->setFlags(cx, BaseShape::IMMUTABLE_PROTOTYPE))
+        return false;
+    *succeeded = true;
+    return true;
+}
+
+bool
+js::GetPropertyDescriptor(JSContext* cx, HandleObject obj, HandleId id,
+                          MutableHandle<PropertyDescriptor> desc)
+{
+    RootedObject pobj(cx);
+
+    for (pobj = obj; pobj;) {
+        if (pobj->is<ProxyObject>()) {
+            bool ok = Proxy::getPropertyDescriptor(cx, pobj, id, desc);
+            if (ok)
+                desc.assertCompleteIfFound();
+            return ok;
+        }
+
+        if (!GetOwnPropertyDescriptor(cx, pobj, id, desc))
+            return false;
+
+        if (desc.object())
+            return true;
+
+        if (!GetPrototype(cx, pobj, &pobj))
+            return false;
+    }
+
+    MOZ_ASSERT(!desc.object());
+    return true;
+}
+
+bool
+js::WatchGuts(JSContext* cx, JS::HandleObject origObj, JS::HandleId id, JS::HandleObject callable)
+{
+    RootedObject obj(cx, ToWindowIfWindowProxy(origObj));
+    if (obj->isNative()) {
+        // Use sparse indexes for watched objects, as dense elements can be
+        // written to without checking the watchpoint map.
+        if (!NativeObject::sparsifyDenseElements(cx, obj.as<NativeObject>()))
+            return false;
+
+        MarkTypePropertyNonData(cx, obj, id);
+    }
+
+    WatchpointMap* wpmap = cx->compartment()->watchpointMap;
+    if (!wpmap) {
+        wpmap = cx->runtime()->new_<WatchpointMap>();
+        if (!wpmap || !wpmap->init()) {
+            ReportOutOfMemory(cx);
+            js_delete(wpmap);
+            return false;
+        }
+        cx->compartment()->watchpointMap = wpmap;
+    }
+
+    return wpmap->watch(cx, obj, id, js::WatchHandler, callable);
+}
+
+bool
+js::UnwatchGuts(JSContext* cx, JS::HandleObject origObj, JS::HandleId id)
+{
+    // Looking in the map for an unsupported object will never hit, so we don't
+    // need to check for nativeness or watchable-ness here.
+    RootedObject obj(cx, ToWindowIfWindowProxy(origObj));
+    if (WatchpointMap* wpmap = cx->compartment()->watchpointMap)
+        wpmap->unwatch(obj, id, nullptr, nullptr);
+    return true;
+}
+
+bool
+js::WatchProperty(JSContext* cx, HandleObject obj, HandleId id, HandleObject callable)
+{
+    if (WatchOp op = obj->getOpsWatch())
+        return op(cx, obj, id, callable);
+
+    if (!obj->isNative() || obj->is<TypedArrayObject>()) {
+        JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_WATCH,
+                                  obj->getClass()->name);
+        return false;
+    }
+
+    return WatchGuts(cx, obj, id, callable);
+}
+
+bool
+js::UnwatchProperty(JSContext* cx, HandleObject obj, HandleId id)
+{
+    if (UnwatchOp op = obj->getOpsUnwatch())
+        return op(cx, obj, id);
+
+    return UnwatchGuts(cx, obj, id);
+}
+
+const char*
+js::GetObjectClassName(JSContext* cx, HandleObject obj)
+{
+    assertSameCompartment(cx, obj);
+
+    if (obj->is<ProxyObject>())
+        return Proxy::className(cx, obj);
+
+    return obj->getClass()->name;
+}
+
+
+/* * */
+
+bool
+js::HasDataProperty(JSContext* cx, NativeObject* obj, jsid id, Value* vp)
+{
+    if (JSID_IS_INT(id) && obj->containsDenseElement(JSID_TO_INT(id))) {
+        *vp = obj->getDenseElement(JSID_TO_INT(id));
+        return true;
+    }
+
+    if (Shape* shape = obj->lookup(cx, id)) {
+        if (shape->hasDefaultGetter() && shape->hasSlot()) {
+            *vp = obj->getSlot(shape->slot());
+            return true;
+        }
+    }
+
+    return false;
+}
+
+extern bool
+PropertySpecNameToId(JSContext* cx, const char* name, MutableHandleId id,
+                     js::PinningBehavior pin = js::DoNotPinAtom);
+
+static bool
+DefineFunctionFromSpec(JSContext* cx, HandleObject obj, const JSFunctionSpec* fs, unsigned flags,
+                       DefineAsIntrinsic intrinsic)
+{
+    GetterOp gop;
+    SetterOp sop;
+    if (flags & JSFUN_STUB_GSOPS) {
+        // JSFUN_STUB_GSOPS is a request flag only, not stored in fun->flags or
+        // the defined property's attributes.
+        flags &= ~JSFUN_STUB_GSOPS;
+        gop = nullptr;
+        sop = nullptr;
+    } else {
+        gop = obj->getClass()->getGetProperty();
+        sop = obj->getClass()->getSetProperty();
+        MOZ_ASSERT(gop != JS_PropertyStub);
+        MOZ_ASSERT(sop != JS_StrictPropertyStub);
+    }
+
+    RootedId id(cx);
+    if (!PropertySpecNameToId(cx, fs->name, &id))
+        return false;
+
+    JSFunction* fun = NewFunctionFromSpec(cx, fs, id);
+    if (!fun)
+        return false;
+
+    if (intrinsic == AsIntrinsic)
+        fun->setIsIntrinsic();
+
+    RootedValue funVal(cx, ObjectValue(*fun));
+    return DefineProperty(cx, obj, id, funVal, gop, sop, flags & ~JSFUN_FLAGS_MASK);
+}
+
+bool
+js::DefineFunctions(JSContext* cx, HandleObject obj, const JSFunctionSpec* fs,
+                    DefineAsIntrinsic intrinsic)
+{
+    for (; fs->name; fs++) {
+        if (!DefineFunctionFromSpec(cx, obj, fs, fs->flags, intrinsic))
+            return false;
+    }
+    return true;
+}
+
+
+/*** ToPrimitive *************************************************************/
+
+/*
+ * Gets |obj[id]|.  If that value's not callable, returns true and stores an
+ * object value in *vp.  If it's callable, calls it with no arguments and |obj|
+ * as |this|, returning the result in *vp.
+ *
+ * This is a mini-abstraction for ES6 draft rev 36 (2015 Mar 17),
+ * 7.1.1, second algorithm (OrdinaryToPrimitive), steps 5.a-c.
+ */
+static bool
+MaybeCallMethod(JSContext* cx, HandleObject obj, HandleId id, MutableHandleValue vp)
+{
+    if (!GetProperty(cx, obj, obj, id, vp))
+        return false;
+    if (!IsCallable(vp)) {
+        vp.setObject(*obj);
+        return true;
+    }
+
+    return js::Call(cx, vp, obj, vp);
+}
+
+static bool
+ReportCantConvert(JSContext* cx, unsigned errorNumber, HandleObject obj, JSType hint)
+{
+    const Class* clasp = obj->getClass();
+
+    // Avoid recursive death when decompiling in ReportValueError.
+    RootedString str(cx);
+    if (hint == JSTYPE_STRING) {
+        str = JS_AtomizeAndPinString(cx, clasp->name);
+        if (!str)
+            return false;
+    } else {
+        str = nullptr;
+    }
+
+    RootedValue val(cx, ObjectValue(*obj));
+    ReportValueError2(cx, errorNumber, JSDVG_SEARCH_STACK, val, str,
+                      hint == JSTYPE_VOID
+                      ? "primitive type"
+                      : hint == JSTYPE_STRING ? "string" : "number");
+    return false;
+}
+
+bool
+JS::OrdinaryToPrimitive(JSContext* cx, HandleObject obj, JSType hint, MutableHandleValue vp)
+{
+    MOZ_ASSERT(hint == JSTYPE_NUMBER || hint == JSTYPE_STRING || hint == JSTYPE_VOID);
+
+    Rooted<jsid> id(cx);
+
+    const Class* clasp = obj->getClass();
+    if (hint == JSTYPE_STRING) {
+        id = NameToId(cx->names().toString);
+
+        /* Optimize (new String(...)).toString(). */
+        if (clasp == &StringObject::class_) {
+            StringObject* nobj = &obj->as<StringObject>();
+            if (ClassMethodIsNative(cx, nobj, &StringObject::class_, id, str_toString)) {
+                vp.setString(nobj->unbox());
+                return true;
+            }
+        }
+
+        if (!MaybeCallMethod(cx, obj, id, vp))
+            return false;
+        if (vp.isPrimitive())
+            return true;
+
+        id = NameToId(cx->names().valueOf);
+        if (!MaybeCallMethod(cx, obj, id, vp))
+            return false;
+        if (vp.isPrimitive())
+            return true;
+    } else {
+        id = NameToId(cx->names().valueOf);
+
+        /* Optimize new String(...).valueOf(). */
+        if (clasp == &StringObject::class_) {
+            StringObject* nobj = &obj->as<StringObject>();
+            if (ClassMethodIsNative(cx, nobj, &StringObject::class_, id, str_toString)) {
+                vp.setString(nobj->unbox());
+                return true;
+            }
+        }
+
+        /* Optimize new Number(...).valueOf(). */
+        if (clasp == &NumberObject::class_) {
+            NumberObject* nobj = &obj->as<NumberObject>();
+            if (ClassMethodIsNative(cx, nobj, &NumberObject::class_, id, num_valueOf)) {
+                vp.setNumber(nobj->unbox());
+                return true;
+            }
+        }
+
+        if (!MaybeCallMethod(cx, obj, id, vp))
+            return false;
+        if (vp.isPrimitive())
+            return true;
+
+        id = NameToId(cx->names().toString);
+        if (!MaybeCallMethod(cx, obj, id, vp))
+            return false;
+        if (vp.isPrimitive())
+            return true;
+    }
+
+    return ReportCantConvert(cx, JSMSG_CANT_CONVERT_TO, obj, hint);
+}
+
+bool
+js::ToPrimitiveSlow(JSContext* cx, JSType preferredType, MutableHandleValue vp)
+{
+    // Step numbers refer to the first algorithm listed in ES6 draft rev 36
+    // (2015 Mar 17) 7.1.1 ToPrimitive.
+    MOZ_ASSERT(preferredType == JSTYPE_VOID ||
+               preferredType == JSTYPE_STRING ||
+               preferredType == JSTYPE_NUMBER);
+    RootedObject obj(cx, &vp.toObject());
+
+    // Steps 4-5.
+    RootedId id(cx, SYMBOL_TO_JSID(cx->wellKnownSymbols().toPrimitive));
+    RootedValue method(cx);
+    if (!GetProperty(cx, obj, obj, id, &method))
+        return false;
+
+    // Step 6.
+    if (!method.isUndefined()) {
+        // Step 6 of GetMethod. js::Call() below would do this check and throw a
+        // TypeError anyway, but this produces a better error message.
+        if (!IsCallable(method))
+            return ReportCantConvert(cx, JSMSG_TOPRIMITIVE_NOT_CALLABLE, obj, preferredType);
+
+        // Steps 1-3, 6.a-b.
+        RootedValue arg0(cx, StringValue(preferredType == JSTYPE_STRING
+                                         ? cx->names().string
+                                         : preferredType == JSTYPE_NUMBER
+                                         ? cx->names().number
+                                         : cx->names().default_));
+
+        if (!js::Call(cx, method, vp, arg0, vp))
+            return false;
+
+        // Steps 6.c-d.
+        if (vp.isObject())
+            return ReportCantConvert(cx, JSMSG_TOPRIMITIVE_RETURNED_OBJECT, obj, preferredType);
+        return true;
+    }
+
+    return OrdinaryToPrimitive(cx, obj, preferredType, vp);
+}
+
+
+/* * */
+
+bool
+js::IsDelegate(JSContext* cx, HandleObject obj, const js::Value& v, bool* result)
+{
+    if (v.isPrimitive()) {
+        *result = false;
+        return true;
+    }
+    return IsDelegateOfObject(cx, obj, &v.toObject(), result);
+}
+
+bool
+js::IsDelegateOfObject(JSContext* cx, HandleObject protoObj, JSObject* obj, bool* result)
+{
+    RootedObject obj2(cx, obj);
+    for (;;) {
+        if (!GetPrototype(cx, obj2, &obj2))
+            return false;
+        if (!obj2) {
+            *result = false;
+            return true;
+        }
+        if (obj2 == protoObj) {
+            *result = true;
+            return true;
+        }
+    }
+}
+
+JSObject*
+js::GetBuiltinPrototypePure(GlobalObject* global, JSProtoKey protoKey)
+{
+    MOZ_ASSERT(JSProto_Null <= protoKey);
+    MOZ_ASSERT(protoKey < JSProto_LIMIT);
+
+    if (protoKey != JSProto_Null) {
+        const Value& v = global->getPrototype(protoKey);
+        if (v.isObject())
+            return &v.toObject();
+    }
+
+    return nullptr;
+}
+
+JSObject*
+js::PrimitiveToObject(JSContext* cx, const Value& v)
+{
+    if (v.isString()) {
+        Rooted<JSString*> str(cx, v.toString());
+        return StringObject::create(cx, str);
+    }
+    if (v.isNumber())
+        return NumberObject::create(cx, v.toNumber());
+    if (v.isBoolean())
+        return BooleanObject::create(cx, v.toBoolean());
+    MOZ_ASSERT(v.isSymbol());
+    RootedSymbol symbol(cx, v.toSymbol());
+    return SymbolObject::create(cx, symbol);
+}
+
+/*
+ * Invokes the ES5 ToObject algorithm on vp, returning the result. If vp might
+ * already be an object, use ToObject. reportCantConvert controls how null and
+ * undefined errors are reported.
+ *
+ * Callers must handle the already-object case.
+ */
+JSObject*
+js::ToObjectSlow(JSContext* cx, JS::HandleValue val, bool reportScanStack)
+{
+    MOZ_ASSERT(!val.isMagic());
+    MOZ_ASSERT(!val.isObject());
+
+    if (val.isNullOrUndefined()) {
+        if (reportScanStack) {
+            ReportIsNullOrUndefined(cx, JSDVG_SEARCH_STACK, val, nullptr);
+        } else {
+            JS_ReportErrorNumberASCII(cx, GetErrorMessage, nullptr, JSMSG_CANT_CONVERT_TO,
+                                      val.isNull() ? "null" : "undefined", "object");
+        }
+        return nullptr;
+    }
+
+    return PrimitiveToObject(cx, val);
+}
+
+Value
+js::GetThisValue(JSObject* obj)
+{
+    if (obj->is<GlobalObject>())
+        return ObjectValue(*ToWindowProxyIfWindow(obj));
+
+    if (obj->is<LexicalEnvironmentObject>()) {
+        if (!obj->as<LexicalEnvironmentObject>().isExtensible())
+            return UndefinedValue();
+        return obj->as<LexicalEnvironmentObject>().thisValue();
+    }
+
+    if (obj->is<ModuleEnvironmentObject>())
+        return UndefinedValue();
+
+    if (obj->is<WithEnvironmentObject>())
+        return ObjectValue(*obj->as<WithEnvironmentObject>().withThis());
+
+    if (obj->is<NonSyntacticVariablesObject>())
+        return GetThisValue(obj->enclosingEnvironment());
+
+    return ObjectValue(*obj);
+}
+
+class GetObjectSlotNameFunctor : public JS::CallbackTracer::ContextFunctor
+{
+    JSObject* obj;
+
+  public:
+    explicit GetObjectSlotNameFunctor(JSObject* ctx) : obj(ctx) {}
+    virtual void operator()(JS::CallbackTracer* trc, char* buf, size_t bufsize) override;
+};
+
+void
+GetObjectSlotNameFunctor::operator()(JS::CallbackTracer* trc, char* buf, size_t bufsize)
+{
+    MOZ_ASSERT(trc->contextIndex() != JS::CallbackTracer::InvalidIndex);
+
+    uint32_t slot = uint32_t(trc->contextIndex());
+
+    Shape* shape;
+    if (obj->isNative()) {
+        shape = obj->as<NativeObject>().lastProperty();
+        while (shape && (!shape->hasSlot() || shape->slot() != slot))
+            shape = shape->previous();
+    } else {
+        shape = nullptr;
+    }
+
+    if (!shape) {
+        do {
+            const char* slotname = nullptr;
+            const char* pattern = nullptr;
+            if (obj->is<GlobalObject>()) {
+                pattern = "CLASS_OBJECT(%s)";
+                if (false)
+                    ;
+#define TEST_SLOT_MATCHES_PROTOTYPE(name,code,init,clasp) \
+                else if ((code) == slot) { slotname = js_##name##_str; }
+                JS_FOR_EACH_PROTOTYPE(TEST_SLOT_MATCHES_PROTOTYPE)
+#undef TEST_SLOT_MATCHES_PROTOTYPE
+            } else {
+                pattern = "%s";
+                if (obj->is<EnvironmentObject>()) {
+                    if (slot == EnvironmentObject::enclosingEnvironmentSlot()) {
+                        slotname = "enclosing_environment";
+                    } else if (obj->is<CallObject>()) {
+                        if (slot == CallObject::calleeSlot())
+                            slotname = "callee_slot";
+                    } else if (obj->is<WithEnvironmentObject>()) {
+                        if (slot == WithEnvironmentObject::objectSlot())
+                            slotname = "with_object";
+                        else if (slot == WithEnvironmentObject::thisSlot())
+                            slotname = "with_this";
+                    }
+                }
+            }
+
+            if (slotname)
+                snprintf(buf, bufsize, pattern, slotname);
+            else
+                snprintf(buf, bufsize, "**UNKNOWN SLOT %" PRIu32 "**", slot);
+        } while (false);
+    } else {
+        jsid propid = shape->propid();
+        if (JSID_IS_INT(propid)) {
+            snprintf(buf, bufsize, "%" PRId32, JSID_TO_INT(propid));
+        } else if (JSID_IS_ATOM(propid)) {
+            PutEscapedString(buf, bufsize, JSID_TO_ATOM(propid), 0);
+        } else if (JSID_IS_SYMBOL(propid)) {
+            snprintf(buf, bufsize, "**SYMBOL KEY**");
+        } else {
+            snprintf(buf, bufsize, "**FINALIZED ATOM KEY**");
+        }
+    }
+}
+
+bool
+js::ReportGetterOnlyAssignment(JSContext* cx, bool strict)
+{
+    return JS_ReportErrorFlagsAndNumberASCII(cx,
+                                             strict
+                                             ? JSREPORT_ERROR
+                                             : JSREPORT_WARNING | JSREPORT_STRICT,
+                                             GetErrorMessage, nullptr,
+                                             JSMSG_GETTER_ONLY);
+}
+
+
+/*** Debugging routines **************************************************************************/
+
+#ifdef DEBUG
+
+/*
+ * Routines to print out values during debugging.  These are FRIEND_API to help
+ * the debugger find them and to support temporarily hacking js::Dump* calls
+ * into other code.
+ */
+
+static void
+dumpValue(const Value& v, FILE* fp)
+{
+    if (v.isNull())
+        fprintf(fp, "null");
+    else if (v.isUndefined())
+        fprintf(fp, "undefined");
+    else if (v.isInt32())
+        fprintf(fp, "%d", v.toInt32());
+    else if (v.isDouble())
+        fprintf(fp, "%g", v.toDouble());
+    else if (v.isString())
+        v.toString()->dump(fp);
+    else if (v.isSymbol())
+        v.toSymbol()->dump(fp);
+    else if (v.isObject() && v.toObject().is<JSFunction>()) {
+        JSFunction* fun = &v.toObject().as<JSFunction>();
+        if (fun->displayAtom()) {
+            fputs("<function ", fp);
+            FileEscapedString(fp, fun->displayAtom(), 0);
+        } else {
+            fputs("<unnamed function", fp);
+        }
+        if (fun->hasScript()) {
+            JSScript* script = fun->nonLazyScript();
+            fprintf(fp, " (%s:%" PRIuSIZE ")",
+                    script->filename() ? script->filename() : "", script->lineno());
+        }
+        fprintf(fp, " at %p>", (void*) fun);
+    } else if (v.isObject()) {
+        JSObject* obj = &v.toObject();
+        const Class* clasp = obj->getClass();
+        fprintf(fp, "<%s%s at %p>",
+                clasp->name,
+                (clasp == &PlainObject::class_) ? "" : " object",
+                (void*) obj);
+    } else if (v.isBoolean()) {
+        if (v.toBoolean())
+            fprintf(fp, "true");
+        else
+            fprintf(fp, "false");
+    } else if (v.isMagic()) {
+        fprintf(fp, "<invalid");
+#ifdef DEBUG
+        switch (v.whyMagic()) {
+          case JS_ELEMENTS_HOLE:     fprintf(fp, " elements hole");      break;
+          case JS_NO_ITER_VALUE:     fprintf(fp, " no iter value");      break;
+          case JS_GENERATOR_CLOSING: fprintf(fp, " generator closing");  break;
+          case JS_OPTIMIZED_OUT:     fprintf(fp, " optimized out");      break;
+          default:                   fprintf(fp, " ?!");                 break;
+        }
+#endif
+        fprintf(fp, ">");
+    } else {
+        fprintf(fp, "unexpected value");
+    }
+}
+
+JS_FRIEND_API(void)
+js::DumpValue(const Value& val, FILE* fp)
+{
+    dumpValue(val, fp);
+    fputc('\n', fp);
+}
+
+JS_FRIEND_API(void)
+js::DumpId(jsid id, FILE* fp)
+{
+    fprintf(fp, "jsid %p = ", (void*) JSID_BITS(id));
+    dumpValue(IdToValue(id), fp);
+    fputc('\n', fp);
+}
+
+static void
+DumpProperty(const NativeObject* obj, Shape& shape, FILE* fp)
+{
+    jsid id = shape.propid();
+    uint8_t attrs = shape.attributes();
+
+    fprintf(fp, "    ((js::Shape*) %p) ", (void*) &shape);
+    if (attrs & JSPROP_ENUMERATE) fprintf(fp, "enumerate ");
+    if (attrs & JSPROP_READONLY) fprintf(fp, "readonly ");
+    if (attrs & JSPROP_PERMANENT) fprintf(fp, "permanent ");
+    if (attrs & JSPROP_SHARED) fprintf(fp, "shared ");
+
+    if (shape.hasGetterValue())
+        fprintf(fp, "getterValue=%p ", (void*) shape.getterObject());
+    else if (!shape.hasDefaultGetter())
+        fprintf(fp, "getterOp=%p ", JS_FUNC_TO_DATA_PTR(void*, shape.getterOp()));
+
+    if (shape.hasSetterValue())
+        fprintf(fp, "setterValue=%p ", (void*) shape.setterObject());
+    else if (!shape.hasDefaultSetter())
+        fprintf(fp, "setterOp=%p ", JS_FUNC_TO_DATA_PTR(void*, shape.setterOp()));
+
+    if (JSID_IS_ATOM(id) || JSID_IS_INT(id) || JSID_IS_SYMBOL(id))
+        dumpValue(js::IdToValue(id), fp);
+    else
+        fprintf(fp, "unknown jsid %p", (void*) JSID_BITS(id));
+
+    uint32_t slot = shape.hasSlot() ? shape.maybeSlot() : SHAPE_INVALID_SLOT;
+    fprintf(fp, ": slot %d", slot);
+    if (shape.hasSlot()) {
+        fprintf(fp, " = ");
+        dumpValue(obj->getSlot(slot), fp);
+    } else if (slot != SHAPE_INVALID_SLOT) {
+        fprintf(fp, " (INVALID!)");
+    }
+    fprintf(fp, "\n");
+}
+
+bool
+JSObject::uninlinedIsProxy() const
+{
+    return is<ProxyObject>();
+}
+
+void
+JSObject::dump(FILE* fp) const
+{
+    const JSObject* obj = this;
+    JSObject* globalObj = &global();
+    fprintf(fp, "object %p from global %p [%s]\n", (void*) obj,
+            (void*) globalObj, globalObj->getClass()->name);
+    const Class* clasp = obj->getClass();
+    fprintf(fp, "class %p %s\n", (const void*)clasp, clasp->name);
+
+    if (obj->hasLazyGroup()) {
+        fprintf(fp, "lazy group\n");
+    } else {
+        const ObjectGroup* group = obj->group();
+        fprintf(fp, "group %p\n", (const void*)group);
+    }
+
+    fprintf(fp, "flags:");
+    if (obj->isDelegate()) fprintf(fp, " delegate");
+    if (!obj->is<ProxyObject>() && !obj->nonProxyIsExtensible()) fprintf(fp, " not_extensible");
+    if (obj->isIndexed()) fprintf(fp, " indexed");
+    if (obj->isBoundFunction()) fprintf(fp, " bound_function");
+    if (obj->isQualifiedVarObj()) fprintf(fp, " varobj");
+    if (obj->isUnqualifiedVarObj()) fprintf(fp, " unqualified_varobj");
+    if (obj->watched()) fprintf(fp, " watched");
+    if (obj->isIteratedSingleton()) fprintf(fp, " iterated_singleton");
+    if (obj->isNewGroupUnknown()) fprintf(fp, " new_type_unknown");
+    if (obj->hasUncacheableProto()) fprintf(fp, " has_uncacheable_proto");
+    if (obj->hadElementsAccess()) fprintf(fp, " had_elements_access");
+    if (obj->wasNewScriptCleared()) fprintf(fp, " new_script_cleared");
+    if (obj->hasStaticPrototype() && obj->staticPrototypeIsImmutable())
+        fprintf(fp, " immutable_prototype");
+
+    if (obj->isNative()) {
+        const NativeObject* nobj = &obj->as<NativeObject>();
+        if (nobj->inDictionaryMode())
+            fprintf(fp, " inDictionaryMode");
+        if (nobj->hasShapeTable())
+            fprintf(fp, " hasShapeTable");
+    }
+    fprintf(fp, "\n");
+
+    if (obj->isNative()) {
+        const NativeObject* nobj = &obj->as<NativeObject>();
+        uint32_t slots = nobj->getDenseInitializedLength();
+        if (slots) {
+            fprintf(fp, "elements\n");
+            for (uint32_t i = 0; i < slots; i++) {
+                fprintf(fp, " %3d: ", i);
+                dumpValue(nobj->getDenseElement(i), fp);
+                fprintf(fp, "\n");
+                fflush(fp);
+            }
+        }
+    }
+
+    fprintf(fp, "proto ");
+    TaggedProto proto = obj->taggedProto();
+    if (proto.isDynamic())
+        fprintf(fp, "<dynamic>");
+    else
+        dumpValue(ObjectOrNullValue(proto.toObjectOrNull()), fp);
+    fputc('\n', fp);
+
+    if (clasp->flags & JSCLASS_HAS_PRIVATE)
+        fprintf(fp, "private %p\n", obj->as<NativeObject>().getPrivate());
+
+    if (!obj->isNative())
+        fprintf(fp, "not native\n");
+
+    uint32_t reservedEnd = JSCLASS_RESERVED_SLOTS(clasp);
+    uint32_t slots = obj->isNative() ? obj->as<NativeObject>().slotSpan() : 0;
+    uint32_t stop = obj->isNative() ? reservedEnd : slots;
+    if (stop > 0)
+        fprintf(fp, obj->isNative() ? "reserved slots:\n" : "slots:\n");
+    for (uint32_t i = 0; i < stop; i++) {
+        fprintf(fp, " %3d ", i);
+        if (i < reservedEnd)
+            fprintf(fp, "(reserved) ");
+        fprintf(fp, "= ");
+        dumpValue(obj->as<NativeObject>().getSlot(i), fp);
+        fputc('\n', fp);
+    }
+
+    if (obj->isNative()) {
+        fprintf(fp, "properties:\n");
+        Vector<Shape*, 8, SystemAllocPolicy> props;
+        for (Shape::Range<NoGC> r(obj->as<NativeObject>().lastProperty()); !r.empty(); r.popFront()) {
+            if (!props.append(&r.front())) {
+                fprintf(fp, "(OOM while appending properties)\n");
+                break;
+            }
+        }
+        for (size_t i = props.length(); i-- != 0;)
+            DumpProperty(&obj->as<NativeObject>(), *props[i], fp);
+    }
+    fputc('\n', fp);
+}
+
+// For debuggers.
+void
+JSObject::dump() const
+{
+    dump(stderr);
+}
+
+static void
+MaybeDumpScope(Scope* scope, FILE* fp)
+{
+    if (scope) {
+        fprintf(fp, "  scope: %s\n", ScopeKindString(scope->kind()));
+        for (BindingIter bi(scope); bi; bi++) {
+            fprintf(fp, "    ");
+            dumpValue(StringValue(bi.name()), fp);
+            fputc('\n', fp);
+        }
+    }
+}
+
+static void
+MaybeDumpValue(const char* name, const Value& v, FILE* fp)
+{
+    if (!v.isNull()) {
+        fprintf(fp, "  %s: ", name);
+        dumpValue(v, fp);
+        fputc('\n', fp);
+    }
+}
+
+JS_FRIEND_API(void)
+js::DumpInterpreterFrame(JSContext* cx, FILE* fp, InterpreterFrame* start)
+{
+    /* This should only called during live debugging. */
+    ScriptFrameIter i(cx);
+    if (!start) {
+        if (i.done()) {
+            fprintf(fp, "no stack for cx = %p\n", (void*) cx);
+            return;
+        }
+    } else {
+        while (!i.done() && !i.isJit() && i.interpFrame() != start)
+            ++i;
+
+        if (i.done()) {
+            fprintf(fp, "fp = %p not found in cx = %p\n",
+                    (void*)start, (void*)cx);
+            return;
+        }
+    }
+
+    for (; !i.done(); ++i) {
+        if (i.isJit())
+            fprintf(fp, "JIT frame\n");
+        else
+            fprintf(fp, "InterpreterFrame at %p\n", (void*) i.interpFrame());
+
+        if (i.isFunctionFrame()) {
+            fprintf(fp, "callee fun: ");
+            RootedValue v(cx);
+            JSObject* fun = i.callee(cx);
+            v.setObject(*fun);
+            dumpValue(v, fp);
+        } else {
+            fprintf(fp, "global or eval frame, no callee");
+        }
+        fputc('\n', fp);
+
+        fprintf(fp, "file %s line %" PRIuSIZE "\n",
+                i.script()->filename(), i.script()->lineno());
+
+        if (jsbytecode* pc = i.pc()) {
+            fprintf(fp, "  pc = %p\n", pc);
+            fprintf(fp, "  current op: %s\n", CodeName[*pc]);
+            MaybeDumpScope(i.script()->lookupScope(pc), fp);
+        }
+        if (i.isFunctionFrame())
+            MaybeDumpValue("this", i.thisArgument(cx), fp);
+        if (!i.isJit()) {
+            fprintf(fp, "  rval: ");
+            dumpValue(i.interpFrame()->returnValue(), fp);
+            fputc('\n', fp);
+        }
+
+        fprintf(fp, "  flags:");
+        if (i.isConstructing())
+            fprintf(fp, " constructing");
+        if (!i.isJit() && i.interpFrame()->isDebuggerEvalFrame())
+            fprintf(fp, " debugger eval");
+        if (i.isEvalFrame())
+            fprintf(fp, " eval");
+        fputc('\n', fp);
+
+        fprintf(fp, "  envChain: (JSObject*) %p\n", (void*) i.environmentChain(cx));
+
+        fputc('\n', fp);
+    }
+}
+
+#endif /* DEBUG */
+
+JS_FRIEND_API(void)
+js::DumpBacktrace(JSContext* cx, FILE* fp)
+{
+    Sprinter sprinter(cx, false);
+    if (!sprinter.init()) {
+        fprintf(fp, "js::DumpBacktrace: OOM\n");
+        return;
+    }
+    size_t depth = 0;
+    for (AllFramesIter i(cx); !i.done(); ++i, ++depth) {
+        const char* filename;
+        unsigned line;
+        if (i.hasScript()) {
+            filename = JS_GetScriptFilename(i.script());
+            line = PCToLineNumber(i.script(), i.pc());
+        } else {
+            filename = i.filename();
+            line = i.computeLine();
+        }
+        char frameType =
+            i.isInterp() ? 'i' :
+            i.isBaseline() ? 'b' :
+            i.isIon() ? 'I' :
+            i.isWasm() ? 'W' :
+            '?';
+
+        sprinter.printf("#%" PRIuSIZE " %14p %c   %s:%d",
+                        depth, i.rawFramePtr(), frameType, filename, line);
+
+        if (i.hasScript()) {
+            sprinter.printf(" (%p @ %" PRIuSIZE ")\n",
+                            i.script(), i.script()->pcToOffset(i.pc()));
+        } else {
+            sprinter.printf(" (%p)\n", i.pc());
+        }
+    }
+    fprintf(fp, "%s", sprinter.string());
+#ifdef XP_WIN32
+    if (IsDebuggerPresent())
+        OutputDebugStringA(sprinter.string());
+#endif
+}
+
+JS_FRIEND_API(void)
+js::DumpBacktrace(JSContext* cx)
+{
+    DumpBacktrace(cx, stdout);
+}
+
+/* * */
+
+js::gc::AllocKind
+JSObject::allocKindForTenure(const js::Nursery& nursery) const
+{
+    if (is<ArrayObject>()) {
+        const ArrayObject& aobj = as<ArrayObject>();
+        MOZ_ASSERT(aobj.numFixedSlots() == 0);
+
+        /* Use minimal size object if we are just going to copy the pointer. */
+        if (!nursery.isInside(aobj.getElementsHeader()))
+            return AllocKind::OBJECT0_BACKGROUND;
+
+        size_t nelements = aobj.getDenseCapacity();
+        return GetBackgroundAllocKind(GetGCArrayKind(nelements));
+    }
+
+    if (is<JSFunction>())
+        return as<JSFunction>().getAllocKind();
+
+    /*
+     * Typed arrays in the nursery may have a lazily allocated buffer, make
+     * sure there is room for the array's fixed data when moving the array.
+     */
+    if (is<TypedArrayObject>() && !as<TypedArrayObject>().hasBuffer()) {
+        size_t nbytes = as<TypedArrayObject>().byteLength();
+        if (as<TypedArrayObject>().hasInlineElements())
+            return GetBackgroundAllocKind(TypedArrayObject::AllocKindForLazyBuffer(nbytes));
+        return GetGCObjectKind(getClass());
+    }
+
+    // Proxies that are CrossCompartmentWrappers may be nursery allocated.
+    if (IsProxy(this))
+        return as<ProxyObject>().allocKindForTenure();
+
+    // Unboxed plain objects are sized according to the data they store.
+    if (is<UnboxedPlainObject>()) {
+        size_t nbytes = as<UnboxedPlainObject>().layoutDontCheckGeneration().size();
+        return GetGCObjectKindForBytes(UnboxedPlainObject::offsetOfData() + nbytes);
+    }
+
+    // Unboxed arrays use inline data if their size is small enough.
+    if (is<UnboxedArrayObject>()) {
+        const UnboxedArrayObject* nobj = &as<UnboxedArrayObject>();
+        size_t nbytes = UnboxedArrayObject::offsetOfInlineElements() +
+                        nobj->capacity() * nobj->elementSize();
+        if (nbytes <= JSObject::MAX_BYTE_SIZE)
+            return GetGCObjectKindForBytes(nbytes);
+        return AllocKind::OBJECT0;
+    }
+
+    // Inlined typed objects are followed by their data, so make sure we copy
+    // it all over to the new object.
+    if (is<InlineTypedObject>()) {
+        // Figure out the size of this object, from the prototype's TypeDescr.
+        // The objects we are traversing here are all tenured, so we don't need
+        // to check forwarding pointers.
+        TypeDescr& descr = as<InlineTypedObject>().typeDescr();
+        MOZ_ASSERT(!IsInsideNursery(&descr));
+        return InlineTypedObject::allocKindForTypeDescriptor(&descr);
+    }
+
+    // Outline typed objects use the minimum allocation kind.
+    if (is<OutlineTypedObject>())
+        return AllocKind::OBJECT0;
+
+    // All nursery allocatable non-native objects are handled above.
+    MOZ_ASSERT(isNative());
+
+    AllocKind kind = GetGCObjectFixedSlotsKind(as<NativeObject>().numFixedSlots());
+    MOZ_ASSERT(!IsBackgroundFinalized(kind));
+    if (!CanBeFinalizedInBackground(kind, getClass()))
+        return kind;
+    return GetBackgroundAllocKind(kind);
+}
+
+void
+JSObject::addSizeOfExcludingThis(mozilla::MallocSizeOf mallocSizeOf, JS::ClassInfo* info)
+{
+    if (is<NativeObject>() && as<NativeObject>().hasDynamicSlots())
+        info->objectsMallocHeapSlots += mallocSizeOf(as<NativeObject>().slots_);
+
+    if (is<NativeObject>() && as<NativeObject>().hasDynamicElements()) {
+        js::ObjectElements* elements = as<NativeObject>().getElementsHeader();
+        if (!elements->isCopyOnWrite() || elements->ownerObject() == this)
+            info->objectsMallocHeapElementsNormal += mallocSizeOf(elements);
+    }
+
+    // Other things may be measured in the future if DMD indicates it is worthwhile.
+    if (is<JSFunction>() ||
+        is<PlainObject>() ||
+        is<ArrayObject>() ||
+        is<CallObject>() ||
+        is<RegExpObject>() ||
+        is<ProxyObject>())
+    {
+        // Do nothing.  But this function is hot, and we win by getting the
+        // common cases out of the way early.  Some stats on the most common
+        // classes, as measured during a vanilla browser session:
+        // - (53.7%, 53.7%): Function
+        // - (18.0%, 71.7%): Object
+        // - (16.9%, 88.6%): Array
+        // - ( 3.9%, 92.5%): Call
+        // - ( 2.8%, 95.3%): RegExp
+        // - ( 1.0%, 96.4%): Proxy
+
+        // Note that any JSClass that is special cased below likely needs to
+        // specify the JSCLASS_DELAY_METADATA_CALLBACK flag, or else we will
+        // probably crash if the object metadata callback attempts to get the
+        // size of the new object (which Debugger code does) before private
+        // slots are initialized.
+    } else if (is<ArgumentsObject>()) {
+        info->objectsMallocHeapMisc += as<ArgumentsObject>().sizeOfMisc(mallocSizeOf);
+    } else if (is<RegExpStaticsObject>()) {
+        info->objectsMallocHeapMisc += as<RegExpStaticsObject>().sizeOfData(mallocSizeOf);
+    } else if (is<PropertyIteratorObject>()) {
+        info->objectsMallocHeapMisc += as<PropertyIteratorObject>().sizeOfMisc(mallocSizeOf);
+    } else if (is<ArrayBufferObject>()) {
+        ArrayBufferObject::addSizeOfExcludingThis(this, mallocSizeOf, info);
+    } else if (is<SharedArrayBufferObject>()) {
+        SharedArrayBufferObject::addSizeOfExcludingThis(this, mallocSizeOf, info);
+#ifdef JS_HAS_CTYPES
+    } else {
+        // This must be the last case.
+        info->objectsMallocHeapMisc +=
+            js::SizeOfDataIfCDataObject(mallocSizeOf, const_cast<JSObject*>(this));
+#endif
+    }
+}
+
+size_t
+JSObject::sizeOfIncludingThisInNursery() const
+{
+    // This function doesn't concern itself yet with typed objects (bug 1133593)
+    // nor unboxed objects (bug 1133592).
+
+    MOZ_ASSERT(!isTenured());
+
+    const Nursery& nursery = compartment()->runtimeFromAnyThread()->gc.nursery;
+    size_t size = Arena::thingSize(allocKindForTenure(nursery));
+
+    if (is<NativeObject>()) {
+        const NativeObject& native = as<NativeObject>();
+
+        size += native.numFixedSlots() * sizeof(Value);
+        size += native.numDynamicSlots() * sizeof(Value);
+
+        if (native.hasDynamicElements()) {
+            js::ObjectElements& elements = *native.getElementsHeader();
+            if (!elements.isCopyOnWrite() || elements.ownerObject() == this)
+                size += elements.capacity * sizeof(HeapSlot);
+        }
+
+        if (is<ArgumentsObject>())
+            size += as<ArgumentsObject>().sizeOfData();
+    }
+
+    return size;
+}
+
+JS::ubi::Node::Size
+JS::ubi::Concrete<JSObject>::size(mozilla::MallocSizeOf mallocSizeOf) const
+{
+    JSObject& obj = get();
+
+    if (!obj.isTenured())
+        return obj.sizeOfIncludingThisInNursery();
+
+    JS::ClassInfo info;
+    obj.addSizeOfExcludingThis(mallocSizeOf, &info);
+    return obj.tenuredSizeOfThis() + info.sizeOfAllThings();
+}
+
+const char16_t JS::ubi::Concrete<JSObject>::concreteTypeName[] = u"JSObject";
+
+void
+JSObject::traceChildren(JSTracer* trc)
+{
+    TraceEdge(trc, &group_, "group");
+
+    if (is<ShapedObject>())
+        as<ShapedObject>().traceShape(trc);
+
+    const Class* clasp = group_->clasp();
+    if (clasp->isNative()) {
+        NativeObject* nobj = &as<NativeObject>();
+
+        {
+            GetObjectSlotNameFunctor func(nobj);
+            JS::AutoTracingDetails ctx(trc, func);
+            JS::AutoTracingIndex index(trc);
+            // Tracing can mutate the target but cannot change the slot count,
+            // but the compiler has no way of knowing this.
+            const uint32_t nslots = nobj->slotSpan();
+            for (uint32_t i = 0; i < nslots; ++i) {
+                TraceManuallyBarrieredEdge(trc, nobj->getSlotRef(i).unsafeUnbarrieredForTracing(),
+                                           "object slot");
+                ++index;
+            }
+            MOZ_ASSERT(nslots == nobj->slotSpan());
+        }
+
+        do {
+            if (nobj->denseElementsAreCopyOnWrite()) {
+                GCPtrNativeObject& owner = nobj->getElementsHeader()->ownerObject();
+                if (owner != nobj) {
+                    TraceEdge(trc, &owner, "objectElementsOwner");
+                    break;
+                }
+            }
+
+            TraceRange(trc,
+                       nobj->getDenseInitializedLength(),
+                       static_cast<HeapSlot*>(nobj->getDenseElementsAllowCopyOnWrite()),
+                       "objectElements");
+        } while (false);
+    }
+
+    // Call the trace hook at the end so that during a moving GC the trace hook
+    // will see updated fields and slots.
+    if (clasp->hasTrace())
+        clasp->doTrace(trc, this);
+}
+
+static JSAtom*
+displayAtomFromObjectGroup(ObjectGroup& group)
+{
+    TypeNewScript* script = group.newScript();
+    if (!script)
+        return nullptr;
+
+    return script->function()->displayAtom();
+}
+
+bool
+JSObject::constructorDisplayAtom(JSContext* cx, js::MutableHandleAtom name)
+{
+    ObjectGroup *g = getGroup(cx);
+    if (!g)
+        return false;
+
+    name.set(displayAtomFromObjectGroup(*g));
+    return true;
+}
+
+JSAtom*
+JSObject::maybeConstructorDisplayAtom() const
+{
+    if (hasLazyGroup())
+        return nullptr;
+    return displayAtomFromObjectGroup(*group());
+}
+
+bool
+js::SpeciesConstructor(JSContext* cx, HandleObject obj, HandleValue defaultCtor, MutableHandleValue pctor)
+{
+    HandlePropertyName shName = cx->names().SpeciesConstructor;
+    RootedValue func(cx);
+    if (!GlobalObject::getSelfHostedFunction(cx, cx->global(), shName, shName, 2, &func))
+        return false;
+
+    FixedInvokeArgs<2> args(cx);
+
+    args[0].setObject(*obj);
+    args[1].set(defaultCtor);
+
+    if (!Call(cx, func, UndefinedHandleValue, args, pctor))
+        return false;
+
+    pctor.set(args.rval());
+    return true;
+}
+
+bool
+js::SpeciesConstructor(JSContext* cx, HandleObject obj, JSProtoKey ctorKey,
+                       MutableHandleValue pctor)
+{
+    if (!GlobalObject::ensureConstructor(cx, cx->global(), ctorKey))
+        return false;
+    RootedValue defaultCtor(cx, cx->global()->getConstructor(ctorKey));
+    return SpeciesConstructor(cx, obj, defaultCtor, pctor);
+}
+
+bool
+js::Unbox(JSContext* cx, HandleObject obj, MutableHandleValue vp)
+{
+    if (MOZ_UNLIKELY(obj->is<ProxyObject>()))
+        return Proxy::boxedValue_unbox(cx, obj, vp);
+
+    if (obj->is<BooleanObject>())
+        vp.setBoolean(obj->as<BooleanObject>().unbox());
+    else if (obj->is<NumberObject>())
+        vp.setNumber(obj->as<NumberObject>().unbox());
+    else if (obj->is<StringObject>())
+        vp.setString(obj->as<StringObject>().unbox());
+    else if (obj->is<DateObject>())
+        vp.set(obj->as<DateObject>().UTCTime());
+    else
+        vp.setUndefined();
+
+    return true;
+}