Trace base class Event in SpeechRecognitionError.

Source/modules/speech/SpeechRecognitionError.h

 /*
  * Copyright (C) 2012 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 copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 46 matching lines @@
 
     static PassRefPtrWillBeRawPtr<SpeechRecognitionError> create(ErrorCode, const String&);
     static PassRefPtrWillBeRawPtr<SpeechRecognitionError> create();
     static PassRefPtrWillBeRawPtr<SpeechRecognitionError> create(const AtomicString&, const SpeechRecognitionErrorInit&);
 
     const String& error() { return m_error; }
     const String& message() { return m_message; }
 
     virtual const AtomicString& interfaceName() const OVERRIDE;
 
-    virtual void trace(Visitor*) OVERRIDE { }
+    virtual void trace(Visitor* visitor) OVERRIDE
+    {
+        Event::trace(visitor);
+    }
 
 private:
     SpeechRecognitionError(const String&, const String&);
     SpeechRecognitionError(const AtomicString&, const SpeechRecognitionErrorInit&);
 
     String m_error;
     String m_message;
 };
 
 } // namespace WebCore
 
 #endif // SpeechRecognitionError_h