Add fast path for tag#id selector queries

Source/core/dom/SelectorQuery.h

 /*
  * Copyright (C) 2011 Apple 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 50 matching lines @@
     void collectElementsByClassName(Node& rootNode, const AtomicString& className, Vector<RefPtr<Node> >&) const;
     Element* findElementByClassName(Node& rootNode, const AtomicString& className) const;
     void collectElementsByTagName(Node& rootNode, const QualifiedName& tagName, Vector<RefPtr<Node> >&) const;
     Element* findElementByTagName(Node& rootNode, const QualifiedName& tagName) const;
     PassOwnPtr<SimpleNodeList> findTraverseRoots(Node& rootNode, bool& matchTraverseRoots) const;
     void executeSlowQueryAll(Node& rootNode, Vector<RefPtr<Node> >& matchedElements) const;
     void executeQueryAll(Node& rootNode, Vector<RefPtr<Node> >& matchedElements) const;
     Node* findTraverseRoot(Node& rootNode, bool& matchTraverseRoot) const;
     Element* executeSlowQueryFirst(Node& rootNode) const;
     Element* executeQueryFirst(Node& rootNode) const;
+    const CSSSelector* selectorForIdLookup(const CSSSelector*) const;
 
     Vector<SelectorData> m_selectors;
 };
 
 class SelectorQuery {
     WTF_MAKE_NONCOPYABLE(SelectorQuery);
     WTF_MAKE_FAST_ALLOCATED;
 public:
     explicit SelectorQuery(const CSSSelectorList&);
     bool matches(Element&) const;
@@ skipping 10 matching lines @@
     SelectorQuery* add(const AtomicString&, const Document&, ExceptionState&);
     void invalidate();
 
 private:
     HashMap<AtomicString, OwnPtr<SelectorQuery> > m_entries;
 };
 
 }
 
 #endif