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

Source/core/css/SelectorChecker.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 2004-2005 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2006, 2007 Nicholas Shanks (webkit@nickshanks.com)
  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alexey Proskuryakov <ap@webkit.org>
  * Copyright (C) 2007, 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008, 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  * Copyright (C) Research In Motion Limited 2011. All rights reserved.
@@ skipping 482 matching lines @@
 
     // Synchronize the attribute in case it is lazy-computed.
     // Currently all lazy properties have a null namespace, so only pass localName().
     element.synchronizeAttribute(selectorAttr.localName());
 
     if (!element.hasAttributesWithoutUpdate())
         return false;
 
     const AtomicString& selectorValue =  selector.value();
 
-    unsigned attributeCount = element.attributeCount();
-    for (size_t i = 0; i < attributeCount; ++i) {
-        const Attribute& attributeItem = element.attributeItem(i);
+    AttributeIteratorAccessor attributes = element.attributesIterator();
+    AttributeConstIterator end = attributes.end();
+    for (AttributeConstIterator it = attributes.begin(); it != end; ++it) {
+        const Attribute& attributeItem = **it;
 
         if (!attributeItem.matches(selectorAttr))
             continue;
 
         if (attributeValueMatches(attributeItem, match, selectorValue, true))
             return true;
 
         // Case sensitivity for attribute matching is looser than hasAttribute or
         // Element::shouldIgnoreAttributeCase() for now. Unclear if that's correct.
         bool caseSensitive = !element.document().isHTMLDocument() || HTMLDocument::isCaseSensitiveAttribute(selectorAttr);
@@ skipping 632 matching lines @@
     return element.focused() && isFrameFocused(element);
 }
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const DOMSiblingTraversalStrategy&, MatchResult*) const;
 
 template
 SelectorChecker::Match SelectorChecker::match(const SelectorCheckingContext&, const ShadowDOMSiblingTraversalStrategy&, MatchResult*) const;
 
 }