Fix chicken and egg problem in composited bounds computation

Source/core/rendering/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 306 matching lines @@
     bool hasAncestorClippingLayer = compositor()->clippedByAncestor(m_owningLayer);
     bool clippingAncestorIsScrollParent = m_owningLayer->renderer()->containingBlock()->enclosingLayer() == m_owningLayer->ancestorScrollingLayer();
     if (hasAncestorClippingLayer && clippingAncestorIsScrollParent)
         return false;
 
     return true;
 }
 
 void CompositedLayerMapping::updateCompositedBounds()
 {
+    // We need to know if we draw content in order to update our bounds (this has an effect
+    // on whether or not descendands will paint into our backing). Update this value now.
+    updateDrawsContent(isSimpleContainerCompositingLayer());
+
     IntRect layerBounds = compositor()->calculateCompositedBounds(m_owningLayer, m_owningLayer);
 
     // Clip to the size of the document or enclosing overflow-scroll layer.
     // If this or an ancestor is transformed, we can't currently compute the correct rect to intersect with.
     // We'd need RenderObject::convertContainerToLocalQuad(), which doesn't yet exist.
     if (shouldClipCompositedBounds()) {
         RenderView* view = m_owningLayer->renderer()->view();
         RenderLayer* rootLayer = view->layer();
 
         LayoutRect clippingBounds;
@@ skipping 1665 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore