[CSS Blending] Implement mix-blend-mode in software.

Source/core/rendering/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 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 1568 matching lines @@
     if (layer->isRootLayer()
         || layer->transform() // note: excludes perspective and transformStyle3D.
         || requiresCompositingForVideo(renderer)
         || requiresCompositingForCanvas(renderer)
         || requiresCompositingForPlugin(renderer)
         || requiresCompositingForFrame(renderer)
         || requiresCompositingForBackfaceVisibilityHidden(renderer)
         || requiresCompositingForAnimation(renderer)
         || requiresCompositingForTransition(renderer)
         || requiresCompositingForFilters(renderer)
-        || requiresCompositingForBlending(renderer)
         || requiresCompositingForPosition(renderer, layer)
         || requiresCompositingForOverflowScrolling(layer)
         || requiresCompositingForOverflowScrollingParent(layer)
         || requiresCompositingForOutOfFlowClipping(layer)
         || renderer->isTransparent()
         || renderer->hasMask()
         || renderer->hasReflection()
         || renderer->hasFilter())
         return true;
 
@@ skipping 38 matching lines @@
 
     if (requiresCompositingForFilters(renderer))
         directReasons |= CompositingReasonFilters;
 
     if (requiresCompositingForPosition(renderer, layer))
         directReasons |= renderer->style()->position() == FixedPosition ? CompositingReasonPositionFixed : CompositingReasonPositionSticky;
 
     if (requiresCompositingForOverflowScrolling(layer))
         directReasons |= CompositingReasonOverflowScrollingTouch;
 
-    if (requiresCompositingForBlending(renderer))
-        directReasons |= CompositingReasonBlending;
-
     if (requiresCompositingForOverflowScrollingParent(layer))
         directReasons |= CompositingReasonOverflowScrollingParent;
 
     if (requiresCompositingForOutOfFlowClipping(layer))
         directReasons |= CompositingReasonOutOfFlowClipping;
 
     return directReasons;
 }
 
 CompositingReasons RenderLayerCompositor::reasonsForCompositing(const RenderLayer* layer) const
@@ skipping 302 matching lines @@
 }
 
 bool RenderLayerCompositor::requiresCompositingForFilters(RenderObject* renderer) const
 {
     if (!(m_compositingTriggers & ChromeClient::FilterTrigger))
         return false;
 
     return renderer->hasFilter();
 }
 
-bool RenderLayerCompositor::requiresCompositingForBlending(RenderObject* renderer) const
-{
-    return renderer->hasBlendMode();
-}
-
 bool RenderLayerCompositor::requiresCompositingForOverflowScrollingParent(const RenderLayer* layer) const
 {
     if (!layer->compositorDrivenAcceleratedScrollingEnabled())
         return false;
 
     // A layer scrolls with its containing block. So to find the overflow scrolling layer
     // that we scroll with respect to, we must ascend the layer tree until we reach the
     // first overflow scrolling div at or above our containing block. I will refer to this
     // layer as our 'scrolling ancestor'.
     //
@@ skipping 746 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "Frame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore