diff -r 000000000000 -r 6474c204b198 js/src/builtin/Iterator.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/builtin/Iterator.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,86 @@
+/* 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/. */
+
+function IteratorIdentity() {
+    return this;
+}
+
+var LegacyIteratorWrapperMap = new std_WeakMap();
+
+function LegacyIteratorNext(arg) {
+    var iter = callFunction(std_WeakMap_get, LegacyIteratorWrapperMap, this);
+    try {
+        return { value: iter.next(arg), done: false };
+    } catch (e) {
+        if (e instanceof std_StopIteration)
+            return { value: undefined, done: true };
+        throw e;
+    }
+}
+
+function LegacyIteratorThrow(exn) {
+    var iter = callFunction(std_WeakMap_get, LegacyIteratorWrapperMap, this);
+    try {
+        return { value: iter.throw(exn), done: false };
+    } catch (e) {
+        if (e instanceof std_StopIteration)
+            return { value: undefined, done: true };
+        throw e;
+    }
+}
+
+function LegacyIterator(iter) {
+    callFunction(std_WeakMap_set, LegacyIteratorWrapperMap, this, iter);
+}
+
+function LegacyGeneratorIterator(iter) {
+    callFunction(std_WeakMap_set, LegacyIteratorWrapperMap, this, iter);
+}
+
+var LegacyIteratorsInitialized = std_Object_create(null);
+
+function InitLegacyIterators() {
+    var props = std_Object_create(null);
+
+    props.next = std_Object_create(null);
+    props.next.value = LegacyIteratorNext;
+    props.next.enumerable = false;
+    props.next.configurable = true;
+    props.next.writable = true;
+
+    props[std_iterator] = std_Object_create(null);
+    props[std_iterator].value = IteratorIdentity;
+    props[std_iterator].enumerable = false;
+    props[std_iterator].configurable = true;
+    props[std_iterator].writable = true;
+
+    var LegacyIteratorProto = std_Object_create(GetIteratorPrototype(), props);
+    MakeConstructible(LegacyIterator, LegacyIteratorProto);
+
+    props.throw = std_Object_create(null);
+    props.throw.value = LegacyIteratorThrow;
+    props.throw.enumerable = false;
+    props.throw.configurable = true;
+    props.throw.writable = true;
+
+    var LegacyGeneratorIteratorProto = std_Object_create(GetIteratorPrototype(), props);
+    MakeConstructible(LegacyGeneratorIterator, LegacyGeneratorIteratorProto);
+
+    LegacyIteratorsInitialized.initialized = true;
+}
+
+function NewLegacyIterator(iter, wrapper) {
+    if (!LegacyIteratorsInitialized.initialized)
+        InitLegacyIterators();
+
+    return new wrapper(iter);
+}
+
+function LegacyIteratorShim() {
+    return NewLegacyIterator(ToObject(this), LegacyIterator);
+}
+
+function LegacyGeneratorIteratorShim() {
+    return NewLegacyIterator(ToObject(this), LegacyGeneratorIterator);
+}