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

Source/core/css/SelectorChecker.cpp

Index: Source/core/css/SelectorChecker.cpp
diff --git a/Source/core/css/SelectorChecker.cpp b/Source/core/css/SelectorChecker.cpp
index 015bda730c7d0c8e77308efb4a7501bc624a78f0..8f8b1c845bc35570498fd1168b272a0016998921 100644
--- a/Source/core/css/SelectorChecker.cpp
+++ b/Source/core/css/SelectorChecker.cpp
@@ -500,9 +500,10 @@ static bool anyAttributeMatches(Element& element, CSSSelector::Match match, cons
 
     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;