Make Notification override hasPendingActivity() to prolong its lifetime while async op is running

Source/platform/AsyncMethodRunner.h

Index: Source/platform/AsyncMethodRunner.h
diff --git a/Source/platform/AsyncMethodRunner.h b/Source/platform/AsyncMethodRunner.h
index f5168b0be8f595c6909875b36a6056928ee60ca3..da86ed3ca3d7e8b14faab4d356a4a03d6e7ac8bf 100644
--- a/Source/platform/AsyncMethodRunner.h
+++ b/Source/platform/AsyncMethodRunner.h
@@ -110,6 +110,11 @@ public:
             m_timer.stop();
     }
 
+    bool isActive() const
+    {
+        return m_timer.isActive();
+    }
+
 private:
     void fired(Timer<AsyncMethodRunner<TargetClass> >*) { (m_object->*m_method)(); }