Oilpan: have WebPerformance use transition types.

Source/web/WebPerformance.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:
  *
  *     * 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 150 matching lines @@
 double WebPerformance::loadEventStart() const
 {
     return millisecondsToSeconds(m_private->timing()->loadEventStart());
 }
 
 double WebPerformance::loadEventEnd() const
 {
     return millisecondsToSeconds(m_private->timing()->loadEventEnd());
 }
 
-WebPerformance::WebPerformance(const PassRefPtr<Performance>& performance)
+WebPerformance::WebPerformance(const PassRefPtrWillBeRawPtr<Performance>& performance)
     : m_private(performance)
 {
 }
 
-WebPerformance& WebPerformance::operator=(const PassRefPtr<Performance>& performance)
+WebPerformance& WebPerformance::operator=(const PassRefPtrWillBeRawPtr<Performance>& performance)
 {
     m_private = performance;
     return *this;
 }
 
-WebPerformance::operator PassRefPtr<Performance>() const
-{
-    return m_private.get();
-}
-
 } // namespace blink