Make iterator for Element's attributes more lightweight

Source/core/dom/Element.idl

 /*
  * Copyright (C) 2006, 2007, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2006 Samuel Weinig <sam.weinig@gmail.com>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 16 matching lines @@
     [TreatReturnedNullStringAs=Null] readonly attribute DOMString tagName;
 
     [TreatReturnedNullStringAs=Null] DOMString getAttribute(DOMString name);
     [RaisesException, CustomElementCallbacks] void setAttribute(DOMString name, DOMString value);
     [CustomElementCallbacks] void removeAttribute(DOMString name);
     [MeasureAs=ElementGetAttributeNode] Attr getAttributeNode([Default=Undefined] optional DOMString name); // Removed from DOM4.
     [RaisesException, CustomElementCallbacks, MeasureAs=ElementSetAttributeNode] Attr setAttributeNode([Default=Undefined, TypeChecking=Nullable] optional Attr newAttr); // Removed from DOM4.
     [RaisesException, CustomElementCallbacks, MeasureAs=ElementRemoveAttributeNode] Attr removeAttributeNode([Default=Undefined, TypeChecking=Nullable] optional Attr oldAttr); // Removed from DOM4.
     HTMLCollection getElementsByTagName(DOMString name);
 
-    [PerWorldBindings] readonly attribute NamedNodeMap     attributes;
+    [PerWorldBindings, ImplementedAs=attributesForBindings] readonly attribute NamedNodeMap     attributes;
     [MeasureAs=HasAttributes] boolean hasAttributes();
 
     // DOM Level 2 Core
 
     [TreatReturnedNullStringAs=Null] DOMString getAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
     [RaisesException, CustomElementCallbacks] void setAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString qualifiedName, DOMString value);
     [CustomElementCallbacks] void removeAttributeNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
     HTMLCollection getElementsByTagNameNS([TreatNullAs=NullString] DOMString namespaceURI, DOMString localName);
     [MeasureAs=ElementGetAttributeNodeNS] Attr getAttributeNodeNS([TreatNullAs=NullString, Default=Undefined] optional DOMString namespaceURI,
                                                                   [Default=Undefined] optional DOMString localName); // Removed from DOM4.
@@ skipping 91 matching lines @@
     [RuntimeEnabled=Touch] attribute EventHandler ontouchend;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchmove;
     [RuntimeEnabled=Touch] attribute EventHandler ontouchstart;
     attribute EventHandler onwebkitfullscreenchange;
     attribute EventHandler onwebkitfullscreenerror;
     [LogActivity=SetterOnly] attribute EventHandler onwheel;
 };
 
 Element implements ParentNode;
 Element implements ChildNode;