Clean up forward declarations in Source/platform

Source/platform/graphics/CrossfadeGeneratedImage.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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 #define CrossfadeGeneratedImage_h
 
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GeneratedImage.h"
 #include "platform/graphics/Image.h"
 #include "platform/graphics/ImageObserver.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
-class CSSCrossfadeValue;
-
 class PLATFORM_EXPORT CrossfadeGeneratedImage : public GeneratedImage {
 public:
     static PassRefPtr<CrossfadeGeneratedImage> create(Image* fromImage, Image* toImage, float percentage, IntSize crossfadeSize, const IntSize& size)
     {
         return adoptRef(new CrossfadeGeneratedImage(fromImage, toImage, percentage, crossfadeSize, size));
     }
 
     virtual void setContainerSize(const IntSize&) OVERRIDE { }
     virtual bool usesContainerSize() const OVERRIDE { return false; }
     virtual bool hasRelativeWidth() const OVERRIDE { return false; }
@@ skipping 16 matching lines @@
     Image* m_fromImage;
     Image* m_toImage;
 
     float m_percentage;
     IntSize m_crossfadeSize;
 };
 
 } // namespace blink
 
 #endif