Oilpan: make DOMWindowProperty a GC mixin.

Source/modules/crypto/DOMWindowCrypto.cpp

 /*
  * Copyright (C) 2013 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 23 matching lines @@
 #include "core/frame/LocalDOMWindow.h"
 #include "modules/crypto/Crypto.h"
 
 namespace blink {
 
 DOMWindowCrypto::DOMWindowCrypto(LocalDOMWindow& window)
     : DOMWindowProperty(window.frame())
 {
 }
 
-DOMWindowCrypto::~DOMWindowCrypto()
-{
-}
+DEFINE_EMPTY_DESTRUCTOR_WILL_BE_REMOVED(DOMWindowCrypto);
 
 const char* DOMWindowCrypto::supplementName()
 {
     return "DOMWindowCrypto";
 }
 
 DOMWindowCrypto& DOMWindowCrypto::from(LocalDOMWindow& window)
 {
     DOMWindowCrypto* supplement = static_cast<DOMWindowCrypto*>(WillBeHeapSupplement<LocalDOMWindow>::from(window, supplementName()));
     if (!supplement) {
@@ skipping 12 matching lines @@
 {
     if (!m_crypto && frame())
         m_crypto = Crypto::create();
     return m_crypto.get();
 }
 
 void DOMWindowCrypto::trace(Visitor* visitor)
 {
     visitor->trace(m_crypto);
     WillBeHeapSupplement<LocalDOMWindow>::trace(visitor);
+    DOMWindowProperty::trace(visitor);
 }
 
 } // namespace blink