Revert "Extract ContextLifecycleNotifier from ScriptExecutionContext."

Source/core/dom/ContextDestructionObserver.h

Index: Source/core/dom/ContextDestructionObserver.h
diff --git a/Source/core/dom/ContextDestructionObserver.h b/Source/core/dom/ContextDestructionObserver.h
index 1254a0ad8cd5fc7dc46897344a81f288943028b7..ca956abc8d20a23147b1942b5464851769f93591 100644
--- a/Source/core/dom/ContextDestructionObserver.h
+++ b/Source/core/dom/ContextDestructionObserver.h
@@ -33,20 +33,14 @@ class ScriptExecutionContext;
 
 class ContextDestructionObserver {
 public:
-    enum Type {
-        ActiveDOMObjectType,
-        DocumentLifecycleObserverType,
-        GenericType
-    };
-
-    explicit ContextDestructionObserver(ScriptExecutionContext*, Type = GenericType);
+    explicit ContextDestructionObserver(ScriptExecutionContext*);
     virtual void contextDestroyed();
 
     ScriptExecutionContext* scriptExecutionContext() const { return m_scriptExecutionContext; }
 
 protected:
     virtual ~ContextDestructionObserver();
-    void observeContext(ScriptExecutionContext*, Type);
+    void observeContext(ScriptExecutionContext*);
 
     ScriptExecutionContext* m_scriptExecutionContext;
 };