Simplify ContextLifecycleNotifier's handling of ActiveDOMObjects.

Source/core/frame/DOMWindowLifecycleNotifier.cpp

Index: Source/core/frame/DOMWindowLifecycleNotifier.cpp
diff --git a/Source/core/frame/DOMWindowLifecycleNotifier.cpp b/Source/core/frame/DOMWindowLifecycleNotifier.cpp
index dc23a6abcda7fc58a0fcbe0d8d17c8e2d2ef2e31..9ea2188f952b06b1e68d27c5381a16c404d1a14d 100644
--- a/Source/core/frame/DOMWindowLifecycleNotifier.cpp
+++ b/Source/core/frame/DOMWindowLifecycleNotifier.cpp
@@ -57,14 +57,14 @@ void DOMWindowLifecycleNotifier::notifyRemoveEventListener(LocalDOMWindow* windo
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     for (DOMWindowLifecycleObserver* observer : m_observers)
-        static_cast<DOMWindowLifecycleObserver*>(observer)->didRemoveEventListener(window, eventType);
+        observer->didRemoveEventListener(window, eventType);
 }
 
 void DOMWindowLifecycleNotifier::notifyRemoveAllEventListeners(LocalDOMWindow* window)
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     for (DOMWindowLifecycleObserver* observer : m_observers)
-        static_cast<DOMWindowLifecycleObserver*>(observer)->didRemoveAllEventListeners(window);
+        observer->didRemoveAllEventListeners(window);
 }
 
 } // namespace blink