Remove duplicated headers from core/

Source/core/platform/graphics/skia/OpaqueRegionSkia.cpp

 /*
  * Copyright (c) 2012, Google 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 
 #include "core/platform/graphics/skia/OpaqueRegionSkia.h"
 
 #include "core/platform/graphics/GraphicsContext.h"
 
-#include "SkCanvas.h"
 #include "SkColorFilter.h"
 #include "SkShader.h"
 
 namespace WebCore {
 
 OpaqueRegionSkia::OpaqueRegionSkia()
     : m_opaqueRect(SkRect::MakeEmpty())
 {
 }
 
@@ skipping 376 matching lines @@
     opaqueRect.setEmpty();
 }
 
 SkRect& OpaqueRegionSkia::currentTrackingOpaqueRect()
 {
     // If we are drawing into a canvas layer, then track the opaque rect in that layer.
     return m_canvasLayerStack.isEmpty() ? m_opaqueRect : m_canvasLayerStack.last().opaqueRect;
 }
 
 } // namespace WebCore