Fix use-after-free in geolocation layout test code introduced in r175404.

Source/modules/geolocation/GeolocationController.cpp

 /*
  * Copyright (C) 2009 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 163 matching lines @@
         return m_lastPosition.get();
 
     if (!m_client)
         return 0;
 
     return m_client->lastPosition();
 }
 
 void GeolocationController::setClientForTest(GeolocationClient* client)
 {
+    if (m_hasClientForTest)
+        m_client->controllerForTestRemoved(this);
     m_client = client;
     m_hasClientForTest = true;
 
     client->controllerForTestAdded(this);
 }
 
 void GeolocationController::pageVisibilityChanged()
 {
     if (m_observers.isEmpty() || !m_client)
         return;
 
     if (page() && page()->visibilityState() == PageVisibilityStateVisible)
         startUpdatingIfNeeded();
     else
         stopUpdatingIfNeeded();
 }
 
 const char* GeolocationController::supplementName()
 {
     return "GeolocationController";
 }
 
 void provideGeolocationTo(LocalFrame& frame, GeolocationClient* client)
 {
     Supplement<LocalFrame>::provideTo(frame, GeolocationController::supplementName(), GeolocationController::create(frame, client));
 }
 
 } // namespace WebCore