Oilpan: Ensure that classes with virtual trace methods always have vtables for their left-most base…

Source/core/workers/AbstractWorker.h

 /*
  * 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 40 matching lines @@
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(AbstractWorker);
 public:
     // EventTarget APIs
     virtual ExecutionContext* executionContext() const OVERRIDE FINAL { return ActiveDOMObject::executionContext(); }
 
     DEFINE_STATIC_ATTRIBUTE_EVENT_LISTENER(error);
 
     AbstractWorker(ExecutionContext*);
     virtual ~AbstractWorker();
 
+    virtual void trace(Visitor* visitor)
+    {
+        EventTargetWithInlineData::trace(visitor);
+    }
+
 protected:
     // Helper function that converts a URL to an absolute URL and checks the result for validity.
     KURL resolveURL(const String& url, ExceptionState&);
 };
 
 } // namespace blink
 
 #endif // AbstractWorker_h