Layer squashing prototype

Source/WebCore/rendering/RenderLayerBacking.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1362 matching lines @@
     if (!m_backgroundLayer)
         phase |= GraphicsLayerPaintBackground;
     if (!m_foregroundLayer)
         phase |= GraphicsLayerPaintForeground;
     if (!m_overlapLayer)
         phase |= GraphicsLayerPaintOverlap;
     if (!m_maskLayer)
         phase |= GraphicsLayerPaintMask;
 
     if (m_scrollingContentsLayer) {
-        phase &= ~(GraphicsLayerPaintForeground & GraphicsLayerPaintOverlap);

[shawnsingh, 2013/03/21 05:01:02]

Actually I think this should be bitwise OR |  instead of AND &.

+        phase &= ~(GraphicsLayerPaintForeground | GraphicsLayerPaintOverlap);
         phase |= GraphicsLayerPaintCompositedScroll;
     }
 
     return static_cast<GraphicsLayerPaintingPhase>(phase);
 }
 
 float RenderLayerBacking::compositingOpacity(float rendererOpacity) const
 {
     float finalOpacity = rendererOpacity;
 ····
@@ skipping 961 matching lines @@
     info.addMember(m_layerForHorizontalScrollbar, "layerForHorizontalScrollbar");
     info.addMember(m_layerForVerticalScrollbar, "layerForVerticalScrollbar");
     info.addMember(m_layerForScrollCorner, "layerForScrollCorner");
     info.addMember(m_scrollingLayer, "scrollingLayer");
     info.addMember(m_scrollingContentsLayer, "scrollingContentsLayer");
 }
 
 } // namespace WebCore
 
 #endif // USE(ACCELERATED_COMPOSITING)