Reduce forward declarations in core/dom

Source/core/dom/SelectorQuery.h

 /*
  * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
  * Copyright (C) 2014 Samsung Electronics. 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.
@@ skipping 22 matching lines @@
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicStringHash.h"
 
 namespace WebCore {
 
 class CSSSelector;
 class ContainerNode;
 class Document;
 class Element;
 class ExceptionState;
-class Node;
-class SimpleNodeList;
 class StaticNodeList;
-class SpaceSplitString;
 
 class SelectorDataList {
 public:
     void initialize(const CSSSelectorList&);
     bool matches(Element&) const;
     PassRefPtrWillBeRawPtr<StaticNodeList> queryAll(ContainerNode& rootNode) const;
     PassRefPtrWillBeRawPtr<Element> queryFirst(ContainerNode& rootNode) const;
 
 private:
     bool canUseFastQuery(const ContainerNode& rootNode) const;
@@ skipping 49 matching lines @@
     SelectorQuery* add(const AtomicString&, const Document&, ExceptionState&);
     void invalidate();
 
 private:
     HashMap<AtomicString, OwnPtr<SelectorQuery> > m_entries;
 };
 
 }
 
 #endif