Always give RenderParts a RenderLayer.

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 131 matching lines @@
     return m_compositing;
 }
 
 void RenderLayerCompositor::setCompositingModeEnabled(bool enable)
 {
     if (enable == m_compositing)
         return;
 
     m_compositing = enable;
 
+    // RenderPart::requiresAcceleratedCompositing is used to determine self-paintingness
+    // and bases it's return value for frames on the m_compositing bit here.
+    if (HTMLFrameOwnerElement* ownerElement = m_renderView.document().ownerElement()) {
+        if (RenderPart* renderer = ownerElement->renderPart())
+            renderer->layer()->updateSelfPaintingLayer();
+    }
+
     if (m_compositing)
         ensureRootLayer();
     else
         destroyRootLayer();
 
     notifyIFramesOfCompositingChange();
 }
 
 void RenderLayerCompositor::enableCompositingModeIfNeeded()
 {
@@ skipping 1256 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore