Optimize / clean up hasTagName() call sites

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 107 matching lines @@
         namespaceHash.set(xmlAtom, XMLNames::xmlNamespaceURI);
         namespaces = &namespaceHash;
     }
 
     serializeNodesWithNamespaces(targetNode, childrenOnly, namespaces, tagNamesToSkip);
     return m_markup.toString();
 }
 
 void MarkupAccumulator::serializeNodesWithNamespaces(Node& targetNode, EChildrenOnly childrenOnly, const Namespaces* namespaces, Vector<QualifiedName>* tagNamesToSkip)
 {
-    if (tagNamesToSkip) {
+    if (tagNamesToSkip && targetNode.isElementNode()) {
         for (size_t i = 0; i < tagNamesToSkip->size(); ++i) {
-            if (targetNode.hasTagName(tagNamesToSkip->at(i)))
+            if (toElement(targetNode).hasTagName(tagNamesToSkip->at(i)))
                 return;
         }
     }
 
     Namespaces namespaceHash;
     if (namespaces)
         namespaceHash = *namespaces;
 
     if (!childrenOnly)
         appendStartTag(targetNode, &namespaceHash);
@@ skipping 420 matching lines @@
 }
 
 bool MarkupAccumulator::serializeAsHTMLDocument(const Node& node) const
 {
     if (m_serializationType == ForcedXML)
         return false;
     return node.document().isHTMLDocument();
 }
 
 }