Merge pull request #608 from janekptacijarabaci/_testBranch_js_modules_basic

Merge branch js modules basic

25 files changed, 158 insertions, 251 deletions

diff --git a/dom/base/nsScriptLoader.cpp b/dom/base/nsScriptLoader.cpp
index a6d20e363..433f6afa5 100644
--- a/dom/base/nsScriptLoader.cpp
+++ b/dom/base/nsScriptLoader.cpp
@@ -647,6 +647,19 @@ nsScriptLoader::CheckContentPolicy(nsIDocument* aDocument,
 }
 
 bool
+nsScriptLoader::ModuleScriptsEnabled()
+{
+  static bool sEnabledForContent = false;
+  static bool sCachedPref = false;
+  if (!sCachedPref) {
+    sCachedPref = true;
+    Preferences::AddBoolVarCache(&sEnabledForContent, "dom.moduleScripts.enabled", false);
+  }
+
+  return nsContentUtils::IsChromeDoc(mDocument) || sEnabledForContent;
+}
+
+bool
 nsScriptLoader::ModuleMapContainsModule(nsModuleLoadRequest *aRequest) const
 {
   // Returns whether we have fetched, or are currently fetching, a module script
@@ -1223,15 +1236,27 @@ nsScriptLoader::StartLoad(nsScriptLoadRequest *aRequest, const nsAString &aType,
   nsCOMPtr<nsIInterfaceRequestor> prompter(do_QueryInterface(docshell));
 
   nsSecurityFlags securityFlags;
-  // TODO: the spec currently gives module scripts different CORS behaviour to
-  // classic scripts.
-  securityFlags = aRequest->mCORSMode == CORS_NONE
-    ? nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL
-    : nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
-  if (aRequest->mCORSMode == CORS_ANONYMOUS) {
-    securityFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
-  } else if (aRequest->mCORSMode == CORS_USE_CREDENTIALS) {
-    securityFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
+  if (aRequest->IsModuleRequest()) {
+    // According to the spec, module scripts have different behaviour to classic
+    // scripts and always use CORS.
+    securityFlags = nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
+    if (aRequest->mCORSMode == CORS_NONE) {
+      securityFlags |= nsILoadInfo::SEC_COOKIES_OMIT;
+    } else if (aRequest->mCORSMode == CORS_ANONYMOUS) {
+      securityFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
+    } else {
+      MOZ_ASSERT(aRequest->mCORSMode == CORS_USE_CREDENTIALS);
+      securityFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
+    }
+  } else {
+    securityFlags = aRequest->mCORSMode == CORS_NONE
+      ? nsILoadInfo::SEC_ALLOW_CROSS_ORIGIN_DATA_IS_NULL
+      : nsILoadInfo::SEC_REQUIRE_CORS_DATA_INHERITS;
+    if (aRequest->mCORSMode == CORS_ANONYMOUS) {
+      securityFlags |= nsILoadInfo::SEC_COOKIES_SAME_ORIGIN;
+    } else if (aRequest->mCORSMode == CORS_USE_CREDENTIALS) {
+      securityFlags |= nsILoadInfo::SEC_COOKIES_INCLUDE;
+    }
   }
   securityFlags |= nsILoadInfo::SEC_ALLOW_CHROME;
 
@@ -1441,8 +1466,7 @@ nsScriptLoader::ProcessScriptElement(nsIScriptElement *aElement)
 
   nsScriptKind scriptKind = nsScriptKind::Classic;
   if (!type.IsEmpty()) {
-    // Support type="module" only for chrome documents.
-    if (nsContentUtils::IsChromeDoc(mDocument) && type.LowerCaseEqualsASCII("module")) {
+    if (ModuleScriptsEnabled() && type.LowerCaseEqualsASCII("module")) {
       scriptKind = nsScriptKind::Module;
     } else {
       NS_ENSURE_TRUE(ParseTypeAttribute(type, &version), false);
@@ -2761,7 +2785,7 @@ nsScriptLoader::PreloadURI(nsIURI *aURI, const nsAString &aCharset,
   }
 
   // TODO: Preload module scripts.
-  if (nsContentUtils::IsChromeDoc(mDocument) && aType.LowerCaseEqualsASCII("module")) {
+  if (ModuleScriptsEnabled() && aType.LowerCaseEqualsASCII("module")) {
     return;
   }
 
diff --git a/dom/base/nsScriptLoader.h b/dom/base/nsScriptLoader.h
index d30a58441..a00239be5 100644
--- a/dom/base/nsScriptLoader.h
+++ b/dom/base/nsScriptLoader.h
@@ -568,6 +568,8 @@ private:
   JS::SourceBufferHolder GetScriptSource(nsScriptLoadRequest* aRequest,
                                          nsAutoString& inlineData);
 
+  bool ModuleScriptsEnabled();
+
   void SetModuleFetchStarted(nsModuleLoadRequest *aRequest);
   void SetModuleFetchFinishedAndResumeWaitingRequests(nsModuleLoadRequest *aRequest,
                                                       nsresult aResult);
diff --git a/js/src/builtin/Iterator.js b/js/src/builtin/Iterator.js
index 735eec7a0..e25b76156 100644
--- a/js/src/builtin/Iterator.js
+++ b/js/src/builtin/Iterator.js
@@ -84,44 +84,3 @@ function LegacyIteratorShim() {
 function LegacyGeneratorIteratorShim() {
     return NewLegacyIterator(ToObject(this), LegacyGeneratorIterator);
 }
-
-// 7.4.8 CreateListIterator()
-function CreateListIterator(array) {
-    let iterator = NewListIterator();
-    UnsafeSetReservedSlot(iterator, ITERATOR_SLOT_TARGET, array);
-    UnsafeSetReservedSlot(iterator, ITERATOR_SLOT_NEXT_INDEX, 0);
-
-    // 7.4.8.1 ListIterator next()
-    // The spec requires that we use a new next function per iterator object.
-    let next = function() {
-        if (!IsObject(this) || !IsListIterator(this))
-            return callFunction(CallListIteratorMethodIfWrapped, this, "ListIteratorNext");
-
-        if (ActiveFunction() !== UnsafeGetReservedSlot(this, ITERATOR_SLOT_NEXT_METHOD))
-            ThrowTypeError(JSMSG_INCOMPATIBLE_METHOD, "next", "method", ToString(this));
-
-        let array = UnsafeGetObjectFromReservedSlot(this, ITERATOR_SLOT_TARGET);
-        let index = UnsafeGetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX);
-
-        if (index >= ToLength(array.length)) {
-            UnsafeSetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX, 1/0);
-            return { value: undefined, done: true };
-        }
-
-        UnsafeSetReservedSlot(this, ITERATOR_SLOT_NEXT_INDEX, index + 1);
-        return { value: array[index], done: false };
-    };
-
-    UnsafeSetReservedSlot(iterator, ITERATOR_SLOT_NEXT_METHOD, next);
-    iterator.next = next;
-
-    iterator[std_iterator] = ListIteratorIdentity;
-    return iterator;
-}
-
-function ListIteratorIdentity() {
-    if (!IsObject(this) || !IsListIterator(this))
-        return callFunction(CallListIteratorMethodIfWrapped, this, "ListIteratorIdentity");
-
-    return this;
-}
diff --git a/js/src/builtin/Module.js b/js/src/builtin/Module.js
index 7b70a7fe8..5c3d5e147 100644
--- a/js/src/builtin/Module.js
+++ b/js/src/builtin/Module.js
@@ -65,12 +65,12 @@ function ModuleGetExportedNames(exportStarSet = [])
     return exportedNames;
 }
 
-// 15.2.1.16.3 ResolveExport(exportName, resolveSet, exportStarSet)
-function ModuleResolveExport(exportName, resolveSet = [], exportStarSet = [])
+// 15.2.1.16.3 ResolveExport(exportName, resolveSet)
+function ModuleResolveExport(exportName, resolveSet = [])
 {
     if (!IsObject(this) || !IsModule(this)) {
         return callFunction(CallModuleMethodIfWrapped, this, exportName, resolveSet,
-                            exportStarSet, "ModuleResolveExport");
+                            "ModuleResolveExport");
     }
 
     // Step 1
@@ -100,38 +100,29 @@ function ModuleResolveExport(exportName, resolveSet = [], exportStarSet = [])
         let e = indirectExportEntries[i];
         if (exportName === e.exportName) {
             let importedModule = CallModuleResolveHook(module, e.moduleRequest,
-                                                       MODULE_STATE_INSTANTIATED);
-            let indirectResolution = callFunction(importedModule.resolveExport, importedModule,
-                                                  e.importName, resolveSet, exportStarSet);
-            if (indirectResolution !== null)
-                return indirectResolution;
+                                                       MODULE_STATE_PARSED);
+            return callFunction(importedModule.resolveExport, importedModule, e.importName,
+                                resolveSet);
         }
     }
 
     // Step 6
     if (exportName === "default") {
         // A default export cannot be provided by an export *.
-        ThrowSyntaxError(JSMSG_BAD_DEFAULT_EXPORT);
+        return null;
     }
 
     // Step 7
-    if (callFunction(ArrayIncludes, exportStarSet, module))
-        return null;
-
-    // Step 8
-    _DefineDataProperty(exportStarSet, exportStarSet.length, module);
-
-    // Step 9
     let starResolution = null;
 
-    // Step 10
+    // Step 8
     let starExportEntries = module.starExportEntries;
     for (let i = 0; i < starExportEntries.length; i++) {
         let e = starExportEntries[i];
         let importedModule = CallModuleResolveHook(module, e.moduleRequest,
-                                                   MODULE_STATE_INSTANTIATED);
+                                                   MODULE_STATE_PARSED);
         let resolution = callFunction(importedModule.resolveExport, importedModule,
-                                      exportName, resolveSet, exportStarSet);
+                                      exportName, resolveSet);
         if (resolution === "ambiguous")
             return resolution;
 
@@ -148,6 +139,7 @@ function ModuleResolveExport(exportName, resolveSet = [], exportStarSet = [])
         }
     }
 
+    // Step 9
     return starResolution;
 }
 
@@ -213,8 +205,8 @@ function GetModuleEnvironment(module)
 
 function RecordInstantationFailure(module)
 {
-    // Set the module's environment slot to 'null' to indicate a failed module
-    // instantiation.
+    // Set the module's state to 'failed' to indicate a failed module
+    // instantiation and reset the environment slot to 'undefined'.
     assert(IsModule(module), "Non-module passed to RecordInstantationFailure");
     SetModuleState(module, MODULE_STATE_FAILED);
     UnsafeSetReservedSlot(module, MODULE_OBJECT_ENVIRONMENT_SLOT, undefined);
@@ -275,11 +267,13 @@ function ModuleDeclarationInstantiation()
                     ThrowSyntaxError(JSMSG_MISSING_IMPORT, imp.importName);
                 if (resolution === "ambiguous")
                     ThrowSyntaxError(JSMSG_AMBIGUOUS_IMPORT, imp.importName);
+                if (resolution.module.state < MODULE_STATE_INSTANTIATED)
+                    ThrowInternalError(JSMSG_BAD_MODULE_STATE);
                 CreateImportBinding(env, imp.localName, resolution.module, resolution.bindingName);
             }
         }
 
-        // Step 16.iv
+        // Step 17.a.iii
         InstantiateModuleFunctionDeclarations(module);
     } catch (e) {
         RecordInstantationFailure(module);
@@ -318,11 +312,3 @@ function ModuleEvaluation()
     return EvaluateModule(module);
 }
 _SetCanonicalName(ModuleEvaluation, "ModuleEvaluation");
-
-function ModuleNamespaceEnumerate()
-{
-    if (!IsObject(this) || !IsModuleNamespace(this))
-        return callFunction(CallModuleMethodIfWrapped, this, "ModuleNamespaceEnumerate");
-
-    return CreateListIterator(ModuleNamespaceExports(this));
-}
diff --git a/js/src/builtin/ModuleObject.cpp b/js/src/builtin/ModuleObject.cpp
index 710c7a76c..333cb3e11 100644
--- a/js/src/builtin/ModuleObject.cpp
+++ b/js/src/builtin/ModuleObject.cpp
@@ -147,7 +147,7 @@ DEFINE_GETTER_FUNCTIONS(ExportEntryObject, moduleRequest, ModuleRequestSlot)
 DEFINE_GETTER_FUNCTIONS(ExportEntryObject, importName, ImportNameSlot)
 DEFINE_GETTER_FUNCTIONS(ExportEntryObject, localName, LocalNameSlot)
 
-DEFINE_ATOM_ACCESSOR_METHOD(ExportEntryObject, exportName)
+DEFINE_ATOM_OR_NULL_ACCESSOR_METHOD(ExportEntryObject, exportName)
 DEFINE_ATOM_OR_NULL_ACCESSOR_METHOD(ExportEntryObject, moduleRequest)
 DEFINE_ATOM_OR_NULL_ACCESSOR_METHOD(ExportEntryObject, importName)
 DEFINE_ATOM_OR_NULL_ACCESSOR_METHOD(ExportEntryObject, localName)
@@ -289,14 +289,6 @@ ModuleNamespaceObject::create(JSContext* cx, HandleModuleObject module)
     if (!object)
         return nullptr;
 
-    RootedId funName(cx, INTERNED_STRING_TO_JSID(cx, cx->names().Symbol_iterator_fun));
-    RootedFunction enumerateFun(cx);
-    enumerateFun = JS::GetSelfHostedFunction(cx, "ModuleNamespaceEnumerate", funName, 0);
-    if (!enumerateFun)
-        return nullptr;
-
-    SetProxyExtra(object, ProxyHandler::EnumerateFunctionSlot, ObjectValue(*enumerateFun));
-
     return &object->as<ModuleNamespaceObject>();
 }
 
@@ -338,14 +330,9 @@ ModuleNamespaceObject::addBinding(JSContext* cx, HandleAtom exportedName,
 const char ModuleNamespaceObject::ProxyHandler::family = 0;
 
 ModuleNamespaceObject::ProxyHandler::ProxyHandler()
-  : BaseProxyHandler(&family, true)
+  : BaseProxyHandler(&family, false)
 {}
 
-JS::Value ModuleNamespaceObject::ProxyHandler::getEnumerateFunction(HandleObject proxy) const
-{
-    return GetProxyExtra(proxy, EnumerateFunctionSlot);
-}
-
 bool
 ModuleNamespaceObject::ProxyHandler::getPrototype(JSContext* cx, HandleObject proxy,
                                                   MutableHandleObject protop) const
@@ -358,6 +345,8 @@ bool
 ModuleNamespaceObject::ProxyHandler::setPrototype(JSContext* cx, HandleObject proxy,
                                                   HandleObject proto, ObjectOpResult& result) const
 {
+    if (!proto)
+        return result.succeed();
     return result.failCantSetProto();
 }
 
@@ -402,21 +391,12 @@ ModuleNamespaceObject::ProxyHandler::getOwnPropertyDescriptor(JSContext* cx, Han
     Rooted<ModuleNamespaceObject*> ns(cx, &proxy->as<ModuleNamespaceObject>());
     if (JSID_IS_SYMBOL(id)) {
         Rooted<JS::Symbol*> symbol(cx, JSID_TO_SYMBOL(id));
-        if (symbol == cx->wellKnownSymbols().iterator) {
-            RootedValue enumerateFun(cx, getEnumerateFunction(proxy));
-            desc.object().set(proxy);
-            desc.setConfigurable(false);
-            desc.setEnumerable(false);
-            desc.setValue(enumerateFun);
-            return true;
-        }
-
         if (symbol == cx->wellKnownSymbols().toStringTag) {
             RootedValue value(cx, StringValue(cx->names().Module));
             desc.object().set(proxy);
             desc.setWritable(false);
             desc.setEnumerable(false);
-            desc.setConfigurable(true);
+            desc.setConfigurable(false);
             desc.setValue(value);
             return true;
         }
@@ -458,8 +438,8 @@ ModuleNamespaceObject::ProxyHandler::has(JSContext* cx, HandleObject proxy, Hand
     Rooted<ModuleNamespaceObject*> ns(cx, &proxy->as<ModuleNamespaceObject>());
     if (JSID_IS_SYMBOL(id)) {
         Rooted<JS::Symbol*> symbol(cx, JSID_TO_SYMBOL(id));
-        return symbol == cx->wellKnownSymbols().iterator ||
-               symbol == cx->wellKnownSymbols().toStringTag;
+        *bp = symbol == cx->wellKnownSymbols().toStringTag;
+        return true;
     }
 
     *bp = ns->bindings().has(id);
@@ -473,23 +453,21 @@ ModuleNamespaceObject::ProxyHandler::get(JSContext* cx, HandleObject proxy, Hand
     Rooted<ModuleNamespaceObject*> ns(cx, &proxy->as<ModuleNamespaceObject>());
     if (JSID_IS_SYMBOL(id)) {
         Rooted<JS::Symbol*> symbol(cx, JSID_TO_SYMBOL(id));
-        if (symbol == cx->wellKnownSymbols().iterator) {
-            vp.set(getEnumerateFunction(proxy));
-            return true;
-        }
-
         if (symbol == cx->wellKnownSymbols().toStringTag) {
             vp.setString(cx->names().Module);
             return true;
         }
 
-        return false;
+        vp.setUndefined();
+        return true;
     }
 
     ModuleEnvironmentObject* env;
     Shape* shape;
-    if (!ns->bindings().lookup(id, &env, &shape))
-        return false;
+    if (!ns->bindings().lookup(id, &env, &shape)) {
+        vp.setUndefined();
+        return true;
+    }
 
     RootedValue value(cx, env->getSlot(shape->slot()));
     if (value.isMagic(JS_UNINITIALIZED_LEXICAL)) {
@@ -526,7 +504,7 @@ ModuleNamespaceObject::ProxyHandler::ownPropertyKeys(JSContext* cx, HandleObject
     Rooted<ModuleNamespaceObject*> ns(cx, &proxy->as<ModuleNamespaceObject>());
     RootedObject exports(cx, &ns->exports());
     uint32_t count;
-    if (!GetLengthProperty(cx, exports, &count) || !props.reserve(props.length() + count))
+    if (!GetLengthProperty(cx, exports, &count) || !props.reserve(props.length() + count + 1))
         return false;
 
     Rooted<ValueVector> names(cx, ValueVector(cx));
@@ -536,6 +514,8 @@ ModuleNamespaceObject::ProxyHandler::ownPropertyKeys(JSContext* cx, HandleObject
     for (uint32_t i = 0; i < count; i++)
         props.infallibleAppend(AtomToId(&names[i].toString()->asAtom()));
 
+    props.infallibleAppend(SYMBOL_TO_JSID(cx->wellKnownSymbols().toStringTag));
+
     return true;
 }
 
@@ -1014,7 +994,7 @@ GlobalObject::initModuleProto(JSContext* cx, Handle<GlobalObject*> global)
 
     static const JSFunctionSpec protoFunctions[] = {
         JS_SELF_HOSTED_FN("getExportedNames", "ModuleGetExportedNames", 1, 0),
-        JS_SELF_HOSTED_FN("resolveExport", "ModuleResolveExport", 3, 0),
+        JS_SELF_HOSTED_FN("resolveExport", "ModuleResolveExport", 2, 0),
         JS_SELF_HOSTED_FN("declarationInstantiation", "ModuleDeclarationInstantiation", 0, 0),
         JS_SELF_HOSTED_FN("evaluation", "ModuleEvaluation", 0, 0),
         JS_FS_END
@@ -1164,6 +1144,13 @@ ModuleBuilder::processExport(frontend::ParseNode* pn)
     bool isDefault = pn->getKind() == PNK_EXPORT_DEFAULT;
     ParseNode* kid = isDefault ? pn->pn_left : pn->pn_kid;
 
+    if (isDefault && pn->pn_right) {
+        // This is an export default containing an expression.
+        RootedAtom localName(cx_, cx_->names().starDefaultStar);
+        RootedAtom exportName(cx_, cx_->names().default_);
+        return appendExportEntry(exportName, localName);
+    }
+
     switch (kid->getKind()) {
       case PNK_EXPORT_SPEC_LIST:
         MOZ_ASSERT(!isDefault);
@@ -1177,53 +1164,46 @@ ModuleBuilder::processExport(frontend::ParseNode* pn)
         break;
 
       case PNK_CLASS: {
-          const ClassNode& cls = kid->as<ClassNode>();
-          MOZ_ASSERT(cls.names());
-          RootedAtom localName(cx_, cls.names()->innerBinding()->pn_atom);
-          RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
-          if (!appendExportEntry(exportName, localName))
-              return false;
-          break;
+        const ClassNode& cls = kid->as<ClassNode>();
+        MOZ_ASSERT(cls.names());
+        RootedAtom localName(cx_, cls.names()->innerBinding()->pn_atom);
+        RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
+        if (!appendExportEntry(exportName, localName))
+            return false;
+        break;
       }
 
       case PNK_VAR:
       case PNK_CONST:
       case PNK_LET: {
-          MOZ_ASSERT(kid->isArity(PN_LIST));
-          for (ParseNode* var = kid->pn_head; var; var = var->pn_next) {
-              if (var->isKind(PNK_ASSIGN))
-                  var = var->pn_left;
-              MOZ_ASSERT(var->isKind(PNK_NAME));
-              RootedAtom localName(cx_, var->pn_atom);
-              RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
-              if (!appendExportEntry(exportName, localName))
-                  return false;
-          }
-          break;
+        MOZ_ASSERT(kid->isArity(PN_LIST));
+        for (ParseNode* var = kid->pn_head; var; var = var->pn_next) {
+            if (var->isKind(PNK_ASSIGN))
+                var = var->pn_left;
+            MOZ_ASSERT(var->isKind(PNK_NAME));
+            RootedAtom localName(cx_, var->pn_atom);
+            RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
+            if (!appendExportEntry(exportName, localName))
+                return false;
+        }
+        break;
       }
 
       case PNK_FUNCTION: {
-          RootedFunction func(cx_, kid->pn_funbox->function());
-          if (!func->isArrow()) {
-              RootedAtom localName(cx_, func->explicitName());
-              RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
-              MOZ_ASSERT_IF(isDefault, localName);
-              if (!appendExportEntry(exportName, localName))
-                  return false;
-              break;
-          }
-      }
-
-      MOZ_FALLTHROUGH; // Arrow functions are handled below.
-
-      default:
-        MOZ_ASSERT(isDefault);
-        RootedAtom localName(cx_, cx_->names().starDefaultStar);
-        RootedAtom exportName(cx_, cx_->names().default_);
+        RootedFunction func(cx_, kid->pn_funbox->function());
+        MOZ_ASSERT(!func->isArrow());
+        RootedAtom localName(cx_, func->explicitName());
+        RootedAtom exportName(cx_, isDefault ? cx_->names().default_ : localName.get());
+        MOZ_ASSERT_IF(isDefault, localName);
         if (!appendExportEntry(exportName, localName))
             return false;
         break;
+      }
+
+      default:
+        MOZ_CRASH("Unexpected parse node");
     }
+
     return true;
 }
 
diff --git a/js/src/builtin/ModuleObject.h b/js/src/builtin/ModuleObject.h
index d0ed8ed08..51a428271 100644
--- a/js/src/builtin/ModuleObject.h
+++ b/js/src/builtin/ModuleObject.h
@@ -142,15 +142,8 @@ class ModuleNamespaceObject : public ProxyObject
   private:
     struct ProxyHandler : public BaseProxyHandler
     {
-        enum
-        {
-            EnumerateFunctionSlot = 0
-        };
-
         ProxyHandler();
 
-        JS::Value getEnumerateFunction(HandleObject proxy) const;
-
         bool getOwnPropertyDescriptor(JSContext* cx, HandleObject proxy, HandleId id,
                                       MutableHandle<PropertyDescriptor> desc) const override;
         bool defineProperty(JSContext* cx, HandleObject proxy, HandleId id,
diff --git a/js/src/builtin/SelfHostingDefines.h b/js/src/builtin/SelfHostingDefines.h
index b57c17269..d676270a1 100644
--- a/js/src/builtin/SelfHostingDefines.h
+++ b/js/src/builtin/SelfHostingDefines.h
@@ -71,8 +71,6 @@
 // Used for list, i.e. Array and String, iterators.
 #define ITERATOR_SLOT_NEXT_INDEX 1
 #define ITERATOR_SLOT_ITEM_KIND 2
-// Used for ListIterator.
-#define ITERATOR_SLOT_NEXT_METHOD 2
 
 #define ITEM_KIND_KEY 0
 #define ITEM_KIND_VALUE 1
diff --git a/js/src/jit-test/modules/empty.js b/js/src/jit-test/modules/empty.js
new file mode 100644
index 000000000..bd9ec079d
--- /dev/null
+++ b/js/src/jit-test/modules/empty.js
@@ -0,0 +1 @@
+// Intentionally empty.
diff --git a/js/src/jit-test/modules/export-circular-nonexisting-binding-1.js b/js/src/jit-test/modules/export-circular-nonexisting-binding-1.js
new file mode 100644
index 000000000..2b91b6a28
--- /dev/null
+++ b/js/src/jit-test/modules/export-circular-nonexisting-binding-1.js
@@ -0,0 +1,4 @@
+import "export-circular-nonexisting-binding-2.js";
+
+export* from "empty.js";
+export {x} from "empty.js";
diff --git a/js/src/jit-test/modules/export-circular-nonexisting-binding-2.js b/js/src/jit-test/modules/export-circular-nonexisting-binding-2.js
new file mode 100644
index 000000000..ba7dcc1b4
--- /dev/null
+++ b/js/src/jit-test/modules/export-circular-nonexisting-binding-2.js
@@ -0,0 +1 @@
+export {x} from "export-circular-nonexisting-binding-1.js";
diff --git a/js/src/jit-test/modules/export-star-circular-1.js b/js/src/jit-test/modules/export-star-circular-1.js
new file mode 100644
index 000000000..9a0771b02
--- /dev/null
+++ b/js/src/jit-test/modules/export-star-circular-1.js
@@ -0,0 +1 @@
+export* from "export-star-circular-2.js";
diff --git a/js/src/jit-test/modules/export-star-circular-2.js b/js/src/jit-test/modules/export-star-circular-2.js
new file mode 100644
index 000000000..b273d9cef
--- /dev/null
+++ b/js/src/jit-test/modules/export-star-circular-2.js
@@ -0,0 +1,3 @@
+export {y as x} from "export-star-circular-1.js";
+
+export var y = "pass";
diff --git a/js/src/jit-test/tests/basic/bug1220766.js b/js/src/jit-test/tests/basic/bug1220766.js
deleted file mode 100644
index fca11eafe..000000000
--- a/js/src/jit-test/tests/basic/bug1220766.js
+++ /dev/null
@@ -1,3 +0,0 @@
-iter = getSelfHostedValue("CreateListIterator")([]);
-iter.next();
-iter.next();
diff --git a/js/src/jit-test/tests/modules/bug-1320993.js b/js/src/jit-test/tests/modules/bug-1320993.js
new file mode 100644
index 000000000..bece5731a
--- /dev/null
+++ b/js/src/jit-test/tests/modules/bug-1320993.js
@@ -0,0 +1,2 @@
+parseModule("export default (class {})");
+parseModule("export default (class A {})");
diff --git a/js/src/jit-test/tests/modules/export-circular-nonexisting-binding.js b/js/src/jit-test/tests/modules/export-circular-nonexisting-binding.js
new file mode 100644
index 000000000..387c7c369
--- /dev/null
+++ b/js/src/jit-test/tests/modules/export-circular-nonexisting-binding.js
@@ -0,0 +1,3 @@
+// |jit-test| module; error:SyntaxError
+
+import "export-circular-nonexisting-binding-1.js";
diff --git a/js/src/jit-test/tests/modules/export-star-cannot-rescue-missing-export.js b/js/src/jit-test/tests/modules/export-star-cannot-rescue-missing-export.js
new file mode 100644
index 000000000..f87829d89
--- /dev/null
+++ b/js/src/jit-test/tests/modules/export-star-cannot-rescue-missing-export.js
@@ -0,0 +1,4 @@
+// |jit-test| module; error:SyntaxError
+
+export { a } from "empty.js";
+export* from "module1.js";
diff --git a/js/src/jit-test/tests/modules/export-star-circular-dependencies.js b/js/src/jit-test/tests/modules/export-star-circular-dependencies.js
new file mode 100644
index 000000000..9aa612f08
--- /dev/null
+++ b/js/src/jit-test/tests/modules/export-star-circular-dependencies.js
@@ -0,0 +1,6 @@
+// |jit-test| module
+
+import { x, y } from "export-star-circular-1.js";
+
+assertEq(x, "pass");
+assertEq(y, "pass");
diff --git a/js/src/jit-test/tests/modules/import-namespace.js b/js/src/jit-test/tests/modules/import-namespace.js
index f44d4568a..0287f7a60 100644
--- a/js/src/jit-test/tests/modules/import-namespace.js
+++ b/js/src/jit-test/tests/modules/import-namespace.js
@@ -19,9 +19,19 @@ function testHasNames(names, expected) {
     });
 }
 
+function testEqualArrays(actual, expected) {
+	assertEq(Array.isArray(actual), true);
+	assertEq(Array.isArray(expected), true);
+    assertEq(actual.length, expected.length);
+    for (let i = 0; i < expected.length; i++) {
+    	assertEq(actual[i], expected[i]);
+    }
+}
+
 let a = moduleRepo['a'] = parseModule(
-    `export var a = 1;
-     export var b = 2;`
+    `// Reflection methods should return these exports alphabetically sorted.
+     export var b = 2;
+     export var a = 1;`
 );
 
 let b = moduleRepo['b'] = parseModule(
@@ -35,11 +45,16 @@ b.evaluation();
 testHasNames(getModuleEnvironmentNames(b), ["ns", "x"]);
 let ns = getModuleEnvironmentValue(b, "ns");
 testHasNames(Object.keys(ns), ["a", "b"]);
+assertEq(ns.a, 1);
+assertEq(ns.b, 2);
+assertEq(ns.c, undefined);
 assertEq(getModuleEnvironmentValue(b, "x"), 3);
 
 // Test module namespace internal methods as defined in 9.4.6
 assertEq(Object.getPrototypeOf(ns), null);
-assertThrowsInstanceOf(() => Object.setPrototypeOf(ns, null), TypeError);
+assertEq(Reflect.setPrototypeOf(ns, null), true);
+assertEq(Reflect.setPrototypeOf(ns, Object.prototype), false);
+assertThrowsInstanceOf(() => Object.setPrototypeOf(ns, {}), TypeError);
 assertThrowsInstanceOf(function() { ns.foo = 1; }, TypeError);
 assertEq(Object.isExtensible(ns), false);
 Object.preventExtensions(ns);
@@ -59,29 +74,15 @@ desc = Object.getOwnPropertyDescriptor(ns, Symbol.toStringTag);
 assertEq(desc.value, "Module");
 assertEq(desc.writable, false);
 assertEq(desc.enumerable, false);
-assertEq(desc.configurable, true);
+assertEq(desc.configurable, false);
 assertEq(typeof desc.get, "undefined");
 assertEq(typeof desc.set, "undefined");
 assertEq(Object.prototype.toString.call(ns), "[object Module]");
 
-// Test @@iterator method.
-let iteratorFun = ns[Symbol.iterator];
-assertEq(iteratorFun.name, "[Symbol.iterator]");
-
-let iterator = ns[Symbol.iterator]();
-assertEq(iterator[Symbol.iterator](), iterator);
-assertIteratorNext(iterator, "a");
-assertIteratorNext(iterator, "b");
-assertIteratorDone(iterator);
-
-// The iterator's next method can only be called on the object it was originally
-// associated with.
-iterator = ns[Symbol.iterator]();
-let iterator2 = ns[Symbol.iterator]();
-assertThrowsInstanceOf(() => iterator.next.call({}), TypeError);
-assertThrowsInstanceOf(() => iterator.next.call(iterator2), TypeError);
-assertEq(iterator.next.call(iterator).value, "a");
-assertEq(iterator2.next.call(iterator2).value, "a");
+// Test [[OwnPropertyKeys]] internal method.
+testEqualArrays(Reflect.ownKeys(ns), ["a", "b", Symbol.toStringTag]);
+testEqualArrays(Object.getOwnPropertyNames(ns), ["a", "b"]);
+testEqualArrays(Object.getOwnPropertySymbols(ns), [Symbol.toStringTag]);
 
 // Test cyclic namespace import and access in module evaluation.
 let c = moduleRepo['c'] =
diff --git a/js/src/jit/InlinableNatives.h b/js/src/jit/InlinableNatives.h
index 18535389a..23d3143a7 100644
--- a/js/src/jit/InlinableNatives.h
+++ b/js/src/jit/InlinableNatives.h
@@ -120,7 +120,6 @@
     _(IntrinsicGuardToArrayIterator) \
     _(IntrinsicGuardToMapIterator)  \
     _(IntrinsicGuardToSetIterator)  \
-    _(IntrinsicIsListIterator)      \
     _(IntrinsicGuardToStringIterator) \
                                     \
     _(IntrinsicGuardToMapObject)    \
diff --git a/js/src/jit/MCallOptimize.cpp b/js/src/jit/MCallOptimize.cpp
index 01755094a..736c6c892 100644
--- a/js/src/jit/MCallOptimize.cpp
+++ b/js/src/jit/MCallOptimize.cpp
@@ -288,8 +288,6 @@ IonBuilder::inlineNativeCall(CallInfo& callInfo, JSFunction* target)
         return inlineGuardToClass(callInfo, &SetIteratorObject::class_);
       case InlinableNative::IntrinsicGuardToStringIterator:
         return inlineGuardToClass(callInfo, &StringIteratorObject::class_);
-      case InlinableNative::IntrinsicIsListIterator:
-        return inlineHasClass(callInfo, &ListIteratorObject::class_);
       case InlinableNative::IntrinsicDefineDataProperty:
         return inlineDefineDataProperty(callInfo);
       case InlinableNative::IntrinsicObjectHasPrototype:
diff --git a/js/src/jsiter.cpp b/js/src/jsiter.cpp
index c1ae5dc15..59893fa98 100644
--- a/js/src/jsiter.cpp
+++ b/js/src/jsiter.cpp
@@ -1157,18 +1157,6 @@ static const JSFunctionSpec string_iterator_methods[] = {
     JS_FS_END
 };
 
-enum {
-    ListIteratorSlotIteratedObject,
-    ListIteratorSlotNextIndex,
-    ListIteratorSlotNextMethod,
-    ListIteratorSlotCount
-};
-
-const Class ListIteratorObject::class_ = {
-    "List Iterator",
-    JSCLASS_HAS_RESERVED_SLOTS(ListIteratorSlotCount)
-};
-
 JSObject*
 js::ValueToIterator(JSContext* cx, unsigned flags, HandleValue vp)
 {
diff --git a/js/src/jsiter.h b/js/src/jsiter.h
index f11f09b55..a3035ddd0 100644
--- a/js/src/jsiter.h
+++ b/js/src/jsiter.h
@@ -151,12 +151,6 @@ class StringIteratorObject : public JSObject
     static const Class class_;
 };
 
-class ListIteratorObject : public JSObject
-{
-  public:
-    static const Class class_;
-};
-
 bool
 GetIterator(JSContext* cx, HandleObject obj, unsigned flags, MutableHandleObject objp);
 
diff --git a/js/src/vm/EnvironmentObject.cpp b/js/src/vm/EnvironmentObject.cpp
index 34c39eabf..9b20c2b9c 100644
--- a/js/src/vm/EnvironmentObject.cpp
+++ b/js/src/vm/EnvironmentObject.cpp
@@ -491,7 +491,7 @@ ModuleEnvironmentObject::createImportBinding(JSContext* cx, HandleAtom importNam
 {
     RootedId importNameId(cx, AtomToId(importName));
     RootedId localNameId(cx, AtomToId(localName));
-    RootedModuleEnvironmentObject env(cx, module->environment());
+    RootedModuleEnvironmentObject env(cx, &module->initialEnvironment());
     if (!importBindings().putNew(cx, importNameId, env, localNameId)) {
         ReportOutOfMemory(cx);
         return false;
diff --git a/js/src/vm/SelfHosting.cpp b/js/src/vm/SelfHosting.cpp
index 08670c833..3e7baccad 100644
--- a/js/src/vm/SelfHosting.cpp
+++ b/js/src/vm/SelfHosting.cpp
@@ -857,37 +857,6 @@ intrinsic_NewStringIterator(JSContext* cx, unsigned argc, Value* vp)
 }
 
 static bool
-intrinsic_NewListIterator(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    MOZ_ASSERT(args.length() == 0);
-
-    RootedObject proto(cx, GlobalObject::getOrCreateIteratorPrototype(cx, cx->global()));
-    if (!proto)
-        return false;
-
-    RootedObject iterator(cx);
-    iterator = NewObjectWithGivenProto(cx, &ListIteratorObject::class_, proto);
-    if (!iterator)
-        return false;
-
-    args.rval().setObject(*iterator);
-    return true;
-}
-
-static bool
-intrinsic_ActiveFunction(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    MOZ_ASSERT(args.length() == 0);
-
-    ScriptFrameIter iter(cx);
-    MOZ_ASSERT(iter.isFunctionFrame());
-    args.rval().setObject(*iter.callee(cx));
-    return true;
-}
-
-static bool
 intrinsic_SetCanonicalName(JSContext* cx, unsigned argc, Value* vp)
 {
     CallArgs args = CallArgsFromVp(argc, vp);
@@ -2306,11 +2275,6 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_FN("CallArrayIteratorMethodIfWrapped",
           CallNonGenericSelfhostedMethod<Is<ArrayIteratorObject>>,      2,0),
 
-    JS_FN("NewListIterator",         intrinsic_NewListIterator,         0,0),
-    JS_FN("CallListIteratorMethodIfWrapped",
-          CallNonGenericSelfhostedMethod<Is<ListIteratorObject>>,       2,0),
-    JS_FN("ActiveFunction",          intrinsic_ActiveFunction,          0,0),
-
     JS_FN("_SetCanonicalName",       intrinsic_SetCanonicalName,        2,0),
 
     JS_INLINABLE_FN("GuardToArrayIterator",
@@ -2325,9 +2289,6 @@ static const JSFunctionSpec intrinsic_functions[] = {
     JS_INLINABLE_FN("GuardToStringIterator",
                     intrinsic_GuardToBuiltin<StringIteratorObject>, 1,0,
                     IntrinsicGuardToStringIterator),
-    JS_INLINABLE_FN("IsListIterator",
-                    intrinsic_IsInstanceOfBuiltin<ListIteratorObject>,  1,0,
-                    IntrinsicIsListIterator),
 
     JS_FN("_CreateMapIterationResultPair", intrinsic_CreateMapIterationResultPair, 0, 0),
     JS_INLINABLE_FN("_GetNextMapEntryForIterator", intrinsic_GetNextMapEntryForIterator, 2,0,
@@ -2549,7 +2510,6 @@ static const JSFunctionSpec intrinsic_functions[] = {
           intrinsic_InstantiateModuleFunctionDeclarations, 1, 0),
     JS_FN("SetModuleState", intrinsic_SetModuleState, 1, 0),
     JS_FN("EvaluateModule", intrinsic_EvaluateModule, 1, 0),
-    JS_FN("IsModuleNamespace", intrinsic_IsInstanceOfBuiltin<ModuleNamespaceObject>, 1, 0),
     JS_FN("NewModuleNamespace", intrinsic_NewModuleNamespace, 2, 0),
     JS_FN("AddModuleNamespaceBinding", intrinsic_AddModuleNamespaceBinding, 4, 0),
     JS_FN("ModuleNamespaceExports", intrinsic_ModuleNamespaceExports, 1, 0),
diff --git a/modules/libpref/init/all.js b/modules/libpref/init/all.js
index beab06aff..bee38d6c4 100644
--- a/modules/libpref/init/all.js
+++ b/modules/libpref/init/all.js
@@ -5453,3 +5453,6 @@ pref("dom.storageManager.enabled", false);
 // be blocked (automatically canceled) for that page. The counter resets
 // when the page is reloaded. To turn this feature off, just set the limit to 0.
 pref("prompts.authentication_dialog_abuse_limit", 3);
+
+// Whether module scripts (<script type="module">) are enabled for content.
+pref("dom.moduleScripts.enabled", false);