Remove all event listeners during window's frame destruction step.

Source/core/frame/DOMWindowLifecycleObserver.h

Index: Source/core/frame/DOMWindowLifecycleObserver.h
diff --git a/Source/core/frame/DOMWindowLifecycleObserver.h b/Source/core/frame/DOMWindowLifecycleObserver.h
index 33f6c9b0d574f072b6f1460ba5df08e483bbd9be..60a8cc26ac404f3c6c50767c02b8dfe2dab5870e 100644
--- a/Source/core/frame/DOMWindowLifecycleObserver.h
+++ b/Source/core/frame/DOMWindowLifecycleObserver.h
@@ -37,11 +37,6 @@ class DOMWindowLifecycleNotifier;
 
 class DOMWindowLifecycleObserver : public LifecycleObserver<LocalDOMWindow, DOMWindowLifecycleObserver, DOMWindowLifecycleNotifier> {
 public:
-    virtual void contextDestroyed()
-    {
-        didRemoveAllEventListeners(lifecycleContext());
-        LifecycleObserver<LocalDOMWindow, DOMWindowLifecycleObserver, DOMWindowLifecycleNotifier>::contextDestroyed();
-    }
     virtual void didAddEventListener(LocalDOMWindow*, const AtomicString&) { }
     virtual void didRemoveEventListener(LocalDOMWindow*, const AtomicString&) { }
     virtual void didRemoveAllEventListeners(LocalDOMWindow*) { }