Clean up forward declarations in Source/core/css

Source/core/css/CSSComputedStyleDeclaration.h

 /*
  * Copyright (C) 2004 Zack Rusin <zack@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2008, 2012 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 24 matching lines @@
 class CSSPrimitiveValue;
 class CSSValueList;
 class ExceptionState;
 class MutableStylePropertySet;
 class Node;
 class RenderObject;
 class RenderStyle;
 class ShadowData;
 class ShadowList;
 class StyleColor;
-class StylePropertySet;
 class StylePropertyShorthand;
 
 enum EUpdateLayout { DoNotUpdateLayout = false, UpdateLayout = true };
 
 class CSSComputedStyleDeclaration FINAL : public CSSStyleDeclaration {
 public:
     static PassRefPtrWillBeRawPtr<CSSComputedStyleDeclaration> create(PassRefPtrWillBeRawPtr<Node> node, bool allowVisitedStyle = false, const String& pseudoElementName = String())
     {
         return adoptRefWillBeNoop(new CSSComputedStyleDeclaration(node, allowVisitedStyle, pseudoElementName));
     }
@@ skipping 63 matching lines @@
     PseudoId m_pseudoElementSpecifier;
     bool m_allowVisitedStyle;
 #if !ENABLE(OILPAN)
     unsigned m_refCount;
 #endif
 };
 
 } // namespace blink
 
 #endif // CSSComputedStyleDeclaration_h