Introduce ES6 iterator for DOM objects.

Source/core/testing/Internals.h

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  * Copyright (C) 2013 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 41 matching lines @@
 class DocumentMarker;
 class Element;
 class ExceptionState;
 class ExecutionContext;
 class GCObservation;
 class HTMLElement;
 class HTMLMediaElement;
 class InternalProfilers;
 class InternalRuntimeFlags;
 class InternalSettings;
+class Iterator;
 class LayerRectList;
 class LocalFrame;
 class Node;
 class Page;
 class PagePopupController;
 class PrivateScriptTest;
 class Range;
 class SerializedScriptValue;
 class ShadowRoot;
 template <typename NodeType> class StaticNodeTypeList;
@@ skipping 239 matching lines @@
     void setNetworkStateNotifierTestOnly(bool);
     // Test must call setNetworkStateNotifierTestOnly(true) before calling setNetworkConnectionInfo.
     void setNetworkConnectionInfo(const String&, ExceptionState&);
     String serializeNavigationMarkup();
     void hideAllTransitionElements();
 
     unsigned countHitRegions(CanvasRenderingContext2D*);
 
     void forcePluginPlaceholder(HTMLElement* plugin, const String& htmlSource, ExceptionState&);
 
+    Iterator* iterator(ScriptState*, ExceptionState&);
+
 private:
     explicit Internals(Document*);
     Document* contextDocument() const;
     LocalFrame* frame() const;
     Vector<String> iconURLs(Document*, int iconTypesMask) const;
     PassRefPtrWillBeRawPtr<ClientRectList> annotatedRegions(Document*, bool draggable, ExceptionState&);
 
     DocumentMarker* markerAt(Node*, const String& markerType, unsigned index, ExceptionState&);
     RefPtrWillBeMember<InternalRuntimeFlags> m_runtimeFlags;
     RefPtrWillBeMember<InternalProfilers> m_profilers;
 };
 
 } // namespace blink
 
 #endif