[Slimming Paint] Add *FilterDisplayItem type for slimming paint

Source/core/paint/ViewDisplayList.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 ViewDisplayList_h
 #define ViewDisplayList_h
 
 #include "core/rendering/PaintPhase.h"
 #include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
@@ skipping 29 matching lines @@
         ClipLayerFragmentFloat = 18,
         ClipLayerFragmentForeground = 19,
         ClipLayerFragmentChildOutline = 20,
         ClipLayerFragmentOutline = 21,
         ClipLayerFragmentMask = 22,
         ClipLayerFragmentClippingMask = 23,
         ClipLayerFragmentParent = 24,
         ClipLayerFragmentSelection = 25,
         ClipLayerFragmentChildBlockBackgrounds = 26,
         EndClip = 27,
+        BeginFilter = 28,
+        EndFilter = 29
     };
 
     virtual ~DisplayItem() { }
 
     virtual void replay(GraphicsContext*) = 0;
 
     const RenderObject* renderer() const { return m_id.renderer; }
     Type type() const { return m_id.type; }
     bool idsEqual(const DisplayItem& other) const { return m_id.renderer == other.m_id.renderer && m_id.type == other.m_id.type; }
 
@@ skipping 41 matching lines @@
 
     PaintList m_paintList;
     HashSet<const RenderObject*> m_paintListRenderers;
     HashSet<const RenderObject*> m_invalidated;
     PaintList m_newPaints;
 };
 
 } // namespace blink
 
 #endif // ViewDisplayList_h