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

Source/web/WebPageSerializerImpl.cpp

Index: Source/web/WebPageSerializerImpl.cpp
diff --git a/Source/web/WebPageSerializerImpl.cpp b/Source/web/WebPageSerializerImpl.cpp
index 126b38feeb991c2f237563f4dbc836733e834124..28803d4b0731a407fe874bb9371f405b77140812 100644
--- a/Source/web/WebPageSerializerImpl.cpp
+++ b/Source/web/WebPageSerializerImpl.cpp
@@ -303,19 +303,19 @@ void WebPageSerializerImpl::openTagToString(Element* element,
     result.append(element->nodeName().lower());
     // Go through all attributes and serialize them.
     if (element->hasAttributes()) {
-        unsigned numAttrs = element->attributeCount();
-        for (unsigned i = 0; i < numAttrs; i++) {
+        AttributeIteratorAccessor attributes = element->attributesIterator();
+        AttributeConstIterator end = attributes.end();
+        for (AttributeConstIterator it = attributes.begin(); it != end; ++it) {
             result.append(' ');
             // Add attribute pair
-            const Attribute& attribute = element->attributeItem(i);
-            result.append(attribute.name().toString());
+            result.append(it->name().toString());
             result.appendLiteral("=\"");
-            if (!attribute.value().isEmpty()) {
-                const String& attrValue = attribute.value();
+            if (!it->value().isEmpty()) {
+                const String& attrValue = it->value();
 
                 // Check whether we need to replace some resource links
                 // with local resource paths.
-                const QualifiedName& attrName = attribute.name();
+                const QualifiedName& attrName = it->name();
                 if (element->hasLegalLinkAttribute(attrName)) {
                     // For links start with "javascript:", we do not change it.
                     if (attrValue.startsWith("javascript:", false))