Merge 123128 - Crash in WebCore::StyleResolver::collectMatchingRulesForList

Source/WebCore/dom/ProcessingInstruction.cpp

 /*
  * Copyright (C) 2000 Peter Kelly (pmk@post.com)
  * Copyright (C) 2006, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 294 matching lines @@
         return;
     
     document()->removeStyleSheetCandidateNode(this);
 
     if (m_sheet) {
         ASSERT(m_sheet->ownerNode() == this);
         m_sheet->clearOwnerNode();
         m_sheet = 0;
     }
 
-    if (m_cachedSheet)
+    // If we're in document teardown, then we don't need to do any notification of our sheet's removal.
+    if (document()->renderer())
         document()->styleResolverChanged(DeferRecalcStyle);
 }
 
 void ProcessingInstruction::finishParsingChildren()
 {
     m_createdByParser = false;
     Node::finishParsingChildren();
 }
 
 } // namespace