Oilpan: have Navigator and its supplements be on the heap by default.

Source/core/frame/LocalDOMWindow.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * 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
@@ skipping 245 matching lines @@
 
     mutable PersistentWillBeMember<Screen> m_screen;
     mutable PersistentWillBeMember<History> m_history;
     mutable RefPtrWillBeMember<BarProp> m_locationbar;
     mutable RefPtrWillBeMember<BarProp> m_menubar;
     mutable RefPtrWillBeMember<BarProp> m_personalbar;
     mutable RefPtrWillBeMember<BarProp> m_scrollbars;
     mutable RefPtrWillBeMember<BarProp> m_statusbar;
     mutable RefPtrWillBeMember<BarProp> m_toolbar;
     mutable PersistentWillBeMember<Console> m_console;
-    mutable RefPtrWillBeMember<Navigator> m_navigator;
+    mutable PersistentWillBeMember<Navigator> m_navigator;
     mutable RefPtrWillBeMember<StyleMedia> m_media;
 
     String m_status;
     String m_defaultStatus;
 
     mutable RefPtrWillBeMember<ApplicationCache> m_applicationCache;
 
     mutable RefPtrWillBeMember<DOMWindowCSS> m_css;
 
     RefPtrWillBeMember<DOMWindowEventQueue> m_eventQueue;
@@ skipping 10 matching lines @@
 }
 
 inline String LocalDOMWindow::defaultStatus() const
 {
     return m_defaultStatus;
 }
 
 } // namespace blink
 
 #endif // LocalDOMWindow_h