Explicit notification and removal of lifecycle observers.

Source/platform/LifecycleNotifier.h

Index: Source/platform/LifecycleNotifier.h
diff --git a/Source/platform/LifecycleNotifier.h b/Source/platform/LifecycleNotifier.h
index 57d684f009aa4b463b3ac7e83c32ac36dabbf581..f75d3cfccf7017b07b36210fcc9ca59186228864 100644
--- a/Source/platform/LifecycleNotifier.h
+++ b/Source/platform/LifecycleNotifier.h
@@ -64,6 +64,8 @@ protected:
     {
     }
 
+    virtual void removeAndNotifyAllObservers();
+
     Context* context() const { return m_context; }
 
     enum IterationType {
@@ -86,7 +88,7 @@ private:
 };
 
 template<typename T>
-inline LifecycleNotifier<T>::~LifecycleNotifier()
+inline void LifecycleNotifier<T>::removeAndNotifyAllObservers()
 {
     TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverAll);
     for (typename ObserverSet::iterator it = m_observers.begin(); it != m_observers.end(); it = m_observers.begin()) {
@@ -98,6 +100,12 @@ inline LifecycleNotifier<T>::~LifecycleNotifier()
 }
 
 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);