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

WebCore/bindings/generic/ActiveDOMCallback.h

Index: WebCore/bindings/generic/ActiveDOMCallback.h
===================================================================
--- WebCore/bindings/generic/ActiveDOMCallback.h	(revision 109601)
+++ WebCore/bindings/generic/ActiveDOMCallback.h	(working copy)
@@ -31,26 +31,27 @@
 #ifndef ActiveDOMCallback_h
 #define ActiveDOMCallback_h
 
+#include "ContextDestructionObserver.h"
 #include <wtf/OwnPtr.h>
 
 namespace WebCore {
 
-class ActiveDOMObjectCallbackImpl;
 class ScriptExecutionContext;
 
-// A class that allows callbacks to behave like ActiveDOMObjects, and also
-// be destroyed on the context thread or any other thread.
-class ActiveDOMCallback {
+// A base class that prevents binding callbacks from executing when
+// active dom objects are stopped or suspended, and is used by the
+// generated callback v8 bindings code to avoid erroneously CRASH()'ing
+// after script execution on a worker has been terminated.
+//
+// Should only be created, used, and destroyed on the script execution
+// context thread.
+class ActiveDOMCallback : public ContextDestructionObserver {
 public:
     ActiveDOMCallback(ScriptExecutionContext* context);
-    ~ActiveDOMCallback();
+    virtual ~ActiveDOMCallback();
 
     bool canInvokeCallback() const;
-    ScriptExecutionContext* scriptExecutionContext() const;
-
-private:
-    // The ActiveDOMObject part of the callback.
-    OwnPtr<ActiveDOMObjectCallbackImpl> m_impl;
+    bool isScriptControllerTerminating() const;
 };
 
 } // namespace WebCore