Fix & clarify some comments in compositing. Rename clippedByAncestor to more accurately

Source/core/rendering/compositing/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 1191 matching lines @@
     // FIXME: We disable accelerated compositing for elements in a RenderFlowThread as it doesn't work properly.
     // See http://webkit.org/b/84900 to re-enable it.
     return m_hasAcceleratedCompositing && layer->isSelfPaintingLayer() && layer->renderer()->flowThreadState() == RenderObject::NotInsideFlowThread;
 }
 
 // Return true if the given layer has some ancestor in the RenderLayer hierarchy that clips,
 // up to the enclosing compositing ancestor. This is required because compositing layers are parented
 // according to the z-order hierarchy, yet clipping goes down the renderer hierarchy.
 // Thus, a RenderLayer can be clipped by a RenderLayer that is an ancestor in the renderer hierarchy,
 // but a sibling in the z-order hierarchy.
-bool RenderLayerCompositor::clippedByAncestor(const RenderLayer* layer) const
+bool RenderLayerCompositor::clippedByNonAncestorInStackingTree(const RenderLayer* layer) const
 {
     if (!layer->hasCompositedLayerMapping() || !layer->parent())
         return false;
 
     const RenderLayer* compositingAncestor = layer->ancestorCompositingLayer();
     if (!compositingAncestor)
         return false;
 
     RenderObject* clippingContainer = layer->renderer()->clippingContainer();
     if (!clippingContainer)
@@ skipping 494 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore