Clean up forward declarations in Source/core/html

Source/core/html/imports/HTMLImport.h

 /*
  * 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 20 matching lines @@
 #ifndef HTMLImport_h
 #define HTMLImport_h
 
 #include "core/html/imports/HTMLImportState.h"
 #include "platform/heap/Handle.h"
 #include "wtf/TreeNode.h"
 
 namespace blink {
 
 class Document;
-class LocalFrame;
-class HTMLImportChild;
 class HTMLImportLoader;
-class HTMLImportsController;
-class KURL;
 
 //
 // # Basic Data Structure and Algorithms of HTML Imports implemenation.
 //
 // ## The Import Tree
 //
 // HTML Imports form a tree:
 //
 // * The root of the tree is HTMLImportTreeRoot.
 //
@@ skipping 81 matching lines @@
 #endif
 
 private:
     HTMLImportState m_state;
     unsigned m_sync : 1;
 };
 
 } // namespace blink
 
 #endif // HTMLImport_h