Add iterator object to iterate efficiently over an Element's attributes

Source/core/editing/MarkupAccumulator.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009, 2010 Google 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.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 367 matching lines @@
     result.append(' ');
     result.append(data);
     result.appendLiteral("?>");
 }
 
 void MarkupAccumulator::appendElement(StringBuilder& result, Element& element, Namespaces* namespaces)
 {
     appendOpenTag(result, element, namespaces);
 
     if (element.hasAttributes()) {
-        unsigned length = element.attributeCount();
-        for (unsigned i = 0; i < length; i++)
-            appendAttribute(result, element, element.attributeItem(i), namespaces);
+        AttributeIteratorAccessor attributes = element.attributesIterator();
+        AttributeConstIterator end = attributes.end();
+        for (AttributeConstIterator it = attributes.begin(); it != end; ++it)
+            appendAttribute(result, element, **it, namespaces);
     }
 
     // Give an opportunity to subclasses to add their own attributes.
     appendCustomAttributes(result, element, namespaces);
 
     appendCloseTag(result, element);
 }
 
 static String nodeNamePreservingCase(const Element& element)
 {
@@ skipping 158 matching lines @@
 }
 
 bool MarkupAccumulator::serializeAsHTMLDocument(const Node& node) const
 {
     if (m_serializationType == ForcedXML)
         return false;
     return node.document().isHTMLDocument();
 }
 
 }