Revert of Explicit notification and removal of lifecycle observers.

Source/platform/LifecycleNotifier.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * 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:
  * 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 46 matching lines @@
 
     bool isIteratingOverObservers() const { return m_iterating != IteratingNone; }
 
 protected:
     explicit LifecycleNotifier(Context* context)
         : m_iterating(IteratingNone)
         , m_context(context)
     {
     }
 
-    virtual void removeAndNotifyAllObservers();
-
     Context* context() const { return m_context; }
 
     enum IterationType {
         IteratingNone,
         IteratingOverAll,
         IteratingOverActiveDOMObjects,
         IteratingOverContextObservers,
         IteratingOverDocumentObservers,
         IteratingOverPageObservers,
         IteratingOverDOMWindowObservers
     };
 
     IterationType m_iterating;
 
 private:
     typedef HashSet<Observer*> ObserverSet;
 
     ObserverSet m_observers;
     Context* m_context;
 };
 
 template<typename T>
-inline void LifecycleNotifier<T>::removeAndNotifyAllObservers()
+inline LifecycleNotifier<T>::~LifecycleNotifier()
 {
     TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverAll);
     for (typename ObserverSet::iterator it = m_observers.begin(); it != m_observers.end(); it = m_observers.begin()) {
         Observer* observer = *it;
         m_observers.remove(observer);
         ASSERT(observer->lifecycleContext() == m_context);
         observer->contextDestroyed();
     }
 }
 
 template<typename T>
-inline LifecycleNotifier<T>::~LifecycleNotifier()
-{
-    removeAndNotifyAllObservers();
-}
-
-template<typename T>
 inline void LifecycleNotifier<T>::addObserver(typename LifecycleNotifier<T>::Observer* observer)
 {
     RELEASE_ASSERT(m_iterating != IteratingOverAll);
     m_observers.add(observer);
 }
 
 template<typename T>
 inline void LifecycleNotifier<T>::removeObserver(typename LifecycleNotifier<T>::Observer* observer)
 {
     RELEASE_ASSERT(m_iterating != IteratingOverAll);
     m_observers.remove(observer);
 }
 
 
 
 } // namespace WebCore
 
 #endif // LifecycleNotifier_h