Clean up forward declarations in WebKit/Source

Source/platform/graphics/paint/DrawingRecorder.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DrawingRecorder_h
 #define DrawingRecorder_h
 
 #include "platform/PlatformExport.h"
 
 #include "platform/geometry/FloatRect.h"
 #include "platform/graphics/paint/DisplayItem.h"
 
 #ifndef NDEBUG
 #include "wtf/text/WTFString.h"
 #endif
 
 namespace blink {
 
 class GraphicsContext;
-class RenderObject;
 
 class PLATFORM_EXPORT DrawingRecorder {
 public:
     explicit DrawingRecorder(GraphicsContext*, const DisplayItemClient, DisplayItem::Type, const FloatRect& bounds);
 
     ~DrawingRecorder();
 
     bool canUseCachedDrawing() const { return m_canUseCachedDrawing; }
 
 #ifndef NDEBUG
     void setClientDebugString(const WTF::String&);
 #endif
 
 private:
     GraphicsContext* m_context;
     DisplayItemClient m_displayItemClient;
     const DisplayItem::Type m_displayItemType;
     const FloatRect m_bounds;
     bool m_canUseCachedDrawing;
 #ifndef NDEBUG
     WTF::String m_clientDebugString;
 #endif
 };
 
 } // namespace blink
 
 #endif // DrawingRecorder_h