Protecting against other possible uses of invalid V8 execution context.

Source/modules/indexeddb/IDBDatabase.cpp

 /*
  * Copyright (C) 2010 Google 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
@@ skipping 361 matching lines @@
     ASSERT(executionContext());
     EventQueue* eventQueue = executionContext()->eventQueue();
     event->setTarget(this);
     eventQueue->enqueueEvent(event.get());
     m_enqueuedEvents.append(event);
 }
 
 bool IDBDatabase::dispatchEvent(PassRefPtr<Event> event)
 {
     IDB_TRACE("IDBDatabase::dispatchEvent");
+    if (m_contextStopped || !executionContext())
+        return false;
     ASSERT(event->type() == EventTypeNames::versionchange || event->type() == EventTypeNames::close);
     for (size_t i = 0; i < m_enqueuedEvents.size(); ++i) {
         if (m_enqueuedEvents[i].get() == event.get())
             m_enqueuedEvents.remove(i);
     }
     return EventTarget::dispatchEvent(event.get());
 }
 
 int64_t IDBDatabase::findObjectStoreId(const String& name) const
 {
@@ skipping 30 matching lines @@
 {
     return EventTargetNames::IDBDatabase;
 }
 
 ExecutionContext* IDBDatabase::executionContext() const
 {
     return ActiveDOMObject::executionContext();
 }
 
 } // namespace WebCore