First implementation of the paint slimming update algorithm

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 78 matching lines @@
 
     const PaintList& paintList();
     void add(WTF::PassOwnPtr<DisplayItem>);
     void invalidate(const RenderObject*);
 
 #ifndef NDEBUG
     void showDebugData() const;
 #endif
 
 private:
-    bool isRepaint(PaintList::iterator, const DisplayItem&);
-    // Update m_paintList with any invalidations or new paints.
+    PaintList::iterator findDisplayItem(PaintList::iterator, const DisplayItem&);
+    bool wasInvalidated(const DisplayItem&) const;
     void updatePaintList();
 
     PaintList m_paintList;
+    HashSet<const RenderObject*> m_paintListRenderers;
     HashSet<const RenderObject*> m_invalidated;
     PaintList m_newPaints;
 };
 
 } // namespace blink
 
 #endif // ViewDisplayList_h