Simplify CompositedLayerMapping's hasVisibleNonCompositingDescendant

Source/core/rendering/compositing/CompositedLayerMapping.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 1585 matching lines @@
 
         if (hasBoxDecorationsOrBackgroundImage(style))
             return false;
     }
 
     return true;
 }
 
 static bool hasVisibleNonCompositingDescendant(RenderLayer* parent)
 {
+    if (!parent->hasVisibleDescendant())
+        return false;
+
     // FIXME: We shouldn't be called with a stale z-order lists. See bug 85512.
     parent->stackingNode()->updateLayerListsIfNeeded();
 
 #if !ASSERT_DISABLED
     LayerListMutationDetector mutationChecker(parent->stackingNode());
 #endif
 
-    RenderLayerStackingNodeIterator normalFlowIterator(*parent->stackingNode(), NormalFlowChildren);
+    RenderLayerStackingNodeIterator normalFlowIterator(*parent->stackingNode(), AllChildren);
     while (RenderLayerStackingNode* curNode = normalFlowIterator.next()) {
         RenderLayer* curLayer = curNode->layer();
-        if (!curLayer->hasCompositedLayerMapping()
-            && (curLayer->hasVisibleContent() || hasVisibleNonCompositingDescendant(curLayer)))
+        if (curLayer->hasCompositedLayerMapping())
+            continue;
+        if (curLayer->hasVisibleContent() || hasVisibleNonCompositingDescendant(curLayer))
             return true;
     }
 
-    if (!parent->hasVisibleDescendant())
-        return false;
-
-    RenderLayerStackingNodeIterator zOrderIterator(*parent->stackingNode(), NegativeZOrderChildren | PositiveZOrderChildren);
-    while (RenderLayerStackingNode* curNode = zOrderIterator.next()) {
-        RenderLayer* curLayer = curNode->layer();
-        if (!curLayer->hasCompositedLayerMapping()
-            && (curLayer->hasVisibleContent() || hasVisibleNonCompositingDescendant(curLayer)))
-            return true;
-    }
-
     return false;
 }
 
 // FIXME: By name the implementation is correct. But the code that uses this function means something
 // very slightly different - the implementation needs to also include composited descendants that
 // don't paint into their own backing, and instead paint into this backing.
 bool CompositedLayerMapping::hasVisibleNonCompositingDescendantLayers() const
 {
     return hasVisibleNonCompositingDescendant(m_owningLayer);
 }
@@ skipping 522 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore