Clean up forward declarations in Source/core

Source/core/paint/FilterPainter.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 FilterPainter_h
 #define FilterPainter_h
 
 #include "core/rendering/LayerPaintingInfo.h"
 #include "wtf/OwnPtr.h"
 
 namespace blink {
 
 class ClipRecorder;
 class ClipRect;
-class FloatRect;
 class GraphicsContext;
 class RenderLayer;
 
 class FilterPainter {
 public:
     FilterPainter(RenderLayer&, GraphicsContext*, const LayoutPoint& offsetFromRoot, const ClipRect&, LayerPaintingInfo&, PaintLayerFlags paintFlags, LayoutRect& rootRelativeBounds, bool& rootRelativeBoundsComputed);
     ~FilterPainter();
 
 private:
     bool m_filterInProgress;
     GraphicsContext* m_context;
     OwnPtr<ClipRecorder> m_clipRecorder;
 };
 
 } // namespace blink
 
 #endif // FilterPainter_h