Clean up forward declarations in Source/core/html

Source/core/html/HTMLFormControlElement.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 12 matching lines @@
 
 #ifndef HTMLFormControlElement_h
 #define HTMLFormControlElement_h
 
 #include "core/html/FormAssociatedElement.h"
 #include "core/html/LabelableElement.h"
 
 namespace blink {
 
 class FormDataList;
-class HTMLFieldSetElement;
 class HTMLFormElement;
-class HTMLLegendElement;
 class ValidationMessageClient;
-class ValidityState;
 
 // HTMLFormControlElement is the default implementation of FormAssociatedElement,
 // and form-associated element implementations should use HTMLFormControlElement
 // unless there is a special reason.
 class HTMLFormControlElement : public LabelableElement, public FormAssociatedElement {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(HTMLFormControlElement);
 
 public:
     virtual ~HTMLFormControlElement();
     virtual void trace(Visitor*) OVERRIDE;
@@ skipping 142 matching lines @@
 {
     return element.isFormControlElement();
 }
 
 DEFINE_HTMLELEMENT_TYPE_CASTS_WITH_FUNCTION(HTMLFormControlElement);
 DEFINE_TYPE_CASTS(HTMLFormControlElement, FormAssociatedElement, control, control->isFormControlElement(), control.isFormControlElement());
 
 } // namespace
 
 #endif