Remove ActiveDOMObject::willStop, and introduce WorkerGlobalScope::TerminationObserver.

Source/core/dom/ContextLifecycleNotifier.cpp

Index: Source/core/dom/ContextLifecycleNotifier.cpp
diff --git a/Source/core/dom/ContextLifecycleNotifier.cpp b/Source/core/dom/ContextLifecycleNotifier.cpp
index 9a585d8ed1ce1735b88d4b7506666c354e1a1a5a..048978c735435f9f54fe8aaa07f7e51944ee6664 100644
--- a/Source/core/dom/ContextLifecycleNotifier.cpp
+++ b/Source/core/dom/ContextLifecycleNotifier.cpp
@@ -86,17 +86,6 @@ void ContextLifecycleNotifier::notifySuspendingActiveDOMObjects()
     }
 }
 
-void ContextLifecycleNotifier::notifyWillStopActiveDOMObjects()
-{
-    TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverActiveDOMObjects);
-    ActiveDOMObjectSet::iterator activeObjectsEnd = m_activeDOMObjects.end();
-    for (ActiveDOMObjectSet::iterator iter = m_activeDOMObjects.begin(); iter != activeObjectsEnd; ++iter) {
-        ASSERT((*iter)->executionContext() == context());
-        ASSERT((*iter)->suspendIfNeededCalled());
-        (*iter)->willStop();
-    }
-}
-
 void ContextLifecycleNotifier::notifyStoppingActiveDOMObjects()
 {
     TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverActiveDOMObjects);