Use new is*Element() helper functions in DOM code

Source/core/dom/StyleSheetCandidate.cpp

 /*
  * Copyright (C) 2013 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 86 matching lines @@
 
     return true;
 }
 
 StyleSheetCandidate::Type StyleSheetCandidate::typeOf(Node& node)
 {
     if (node.nodeType() == Node::PROCESSING_INSTRUCTION_NODE)
         return Pi;
 
     if (node.isHTMLElement()) {
-        if (node.hasTagName(linkTag))
+        if (isHTMLLinkElement(node))
             return HTMLLink;
-        if (node.hasTagName(styleTag))
+        if (isHTMLStyleElement(node))
             return HTMLStyle;
 
         ASSERT_NOT_REACHED();
         return HTMLStyle;
     }
 
-    if (node.isSVGElement() && node.hasTagName(SVGNames::styleTag))
+    if (isSVGStyleElement(node))
         return SVGStyle;
 
     ASSERT_NOT_REACHED();
     return HTMLStyle;
 }
 
 StyleSheet* StyleSheetCandidate::sheet() const
 {
     switch (m_type) {
     case HTMLLink:
         return toHTMLLinkElement(m_node).sheet();
     case HTMLStyle:
         return toHTMLStyleElement(m_node).sheet();
     case SVGStyle:
         return toSVGStyleElement(m_node).sheet();
     case Pi:
         return toProcessingInstruction(m_node).sheet();
     }
 
     ASSERT_NOT_REACHED();
     return 0;
 }
 
 }