Remove include of RetainPtr.h in Image.h.

Source/platform/graphics/Image.h

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006 Apple Computer, 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
@@ skipping 20 matching lines @@
 #include "platform/geometry/IntRect.h"
 #include "platform/graphics/Color.h"
 #include "platform/graphics/GraphicsTypes.h"
 #include "platform/graphics/ImageAnimationPolicy.h"
 #include "platform/graphics/ImageOrientation.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "wtf/Assertions.h"
 #include "wtf/PassRefPtr.h"
 #include "wtf/RefCounted.h"
 #include "wtf/RefPtr.h"
-#include "wtf/RetainPtr.h"
 #include "wtf/text/WTFString.h"
 
 class SkBitmap;
 class SkImage;
 
 namespace blink {
 
 class FloatPoint;
 class FloatRect;
 class FloatSize;
@@ skipping 103 matching lines @@
     RefPtr<SharedBuffer> m_encodedImageData;
     ImageObserver* m_imageObserver;
 };
 
 #define DEFINE_IMAGE_TYPE_CASTS(typeName) \
     DEFINE_TYPE_CASTS(typeName, Image, image, image->is##typeName(), image.is##typeName())
 
 } // namespace blink
 
 #endif