WebKit merge 41660:41709 (WebKit side)....

third_party/WebKit/WebCore/css/CSSStyleSheet.cpp

 /*
  * (C) 1999-2003 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2006, 2007 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 164 matching lines @@
     }
     return false;
 }
 
 void CSSStyleSheet::checkLoaded()
 {
     if (isLoading())
         return;
     if (parent())
         parent()->checkLoaded();
+
+    // Avoid |this| being deleted by scripts that run via HTMLTokenizer::executeScriptsWaitingForStylesheets().
+    // See <rdar://problem/6622300>.
+    RefPtr<CSSStyleSheet> protector(this);
     m_loadCompleted = ownerNode() ? ownerNode()->sheetLoaded() : true;
 }
 
 void CSSStyleSheet::styleSheetChanged()
 {
     StyleBase* root = this;
     while (StyleBase* parent = root->parent())
         root = parent;
     Document* documentToUpdate = (root && root->isCSSStyleSheet()) ? static_cast<CSSStyleSheet*>(root)->doc() : 0;
     
@@ skipping 32 matching lines @@
             if (rule->isImportRule()) {
                 if (CSSStyleSheet* ruleStyleSheet = static_cast<CSSImportRule*>(rule)->styleSheet())
                     styleSheetQueue.append(ruleStyleSheet);
             }
             rule->addSubresourceStyleURLs(urls);
         }
     }
 }
 
 }