Merge 93382 - REGRESSION(r90971): Null pointer dereference with placeholder and webkit-scrollbar-...

Source/WebCore/rendering/RenderObjectChildList.cpp

 /*
  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) Research In Motion Limited 2010. 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
@@ skipping 66 matching lines @@
     }
 
     // If we have a line box wrapper, delete it.
     if (oldChild->isBox())
         toRenderBox(oldChild)->deleteLineBoxWrapper();
 
     if (!owner->documentBeingDestroyed() && fullRemove) {
         // if we remove visible child from an invisible parent, we don't know the layer visibility any more
         RenderLayer* layer = 0;
         if (owner->style()->visibility() != VISIBLE && oldChild->style()->visibility() == VISIBLE && !oldChild->hasLayer()) {
-            layer = owner->enclosingLayer();
-            layer->dirtyVisibleContentStatus();
+            if ((layer = owner->enclosingLayer()))
+                layer->dirtyVisibleContentStatus();
         }
 
          // Keep our layer hierarchy updated.
         if (oldChild->firstChild() || oldChild->hasLayer()) {
             if (!layer)
                 layer = owner->enclosingLayer();
             oldChild->removeLayers(layer);
         }
 
         if (oldChild->isListItem())
@@ skipping 366 matching lines @@
             }
             if (generatedContentContainer->isChildAllowed(renderer, pseudoElementStyle))
                 generatedContentContainer->addChild(renderer);
             else
                 renderer->destroy();
         }
     }
 }
 
 } // namespace WebCore