Don't be so CRASH happy in the bindings layer.

WebCore/bindings/js/WorkerScriptController.h

 /*
  * Copyright (C) 2008 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 49 matching lines @@
         void evaluate(const ScriptSourceCode&, ScriptValue* exception);
 
         void setException(ScriptValue);
 
         // Async request to terminate a JS run execution. Eventually causes termination
         // exception raised during JS execution, if the worker thread happens to run JS.
         // After JS execution was terminated in this way, the Worker thread has to use
         // forbidExecution()/isExecutionForbidden() to guard against reentry into JS.
         // Can be called from any thread.
         void scheduleExecutionTermination();
+        bool isExecutionTerminating() const;
 
         // Called on Worker thread when JS exits with termination exception caused by forbidExecution() request,
         // or by Worker thread termination code to prevent future entry into JS.
         void forbidExecution();
         bool isExecutionForbidden() const;
 
         void disableEval();
 
         JSC::JSGlobalData* globalData() { return m_globalData.get(); }
 
     private:
         void initScriptIfNeeded()
         {
             if (!m_workerContextWrapper)
                 initScript();
         }
         void initScript();
 
         RefPtr<JSC::JSGlobalData> m_globalData;
         WorkerContext* m_workerContext;
         JSC::Strong<JSWorkerContext> m_workerContextWrapper;
         bool m_executionForbidden;
+        mutable Mutex m_scheduledTerminationMutex;
     };
 
 } // namespace WebCore
 
 #endif // ENABLE(WORKERS)
 
 #endif // WorkerScriptController_h