Rework dispatchEvent so it is consistent for isTrusted support.

Source/modules/notifications/Notification.h

Index: Source/modules/notifications/Notification.h
diff --git a/Source/modules/notifications/Notification.h b/Source/modules/notifications/Notification.h
index 0b6d3df0236518c4de6866310567be8a9be55252..e922eb9227fbdd6c7178da3884fdc23287de9b70 100644
--- a/Source/modules/notifications/Notification.h
+++ b/Source/modules/notifications/Notification.h
@@ -105,7 +105,6 @@ public:
 
     // EventTarget interface.
     ExecutionContext* executionContext() const final { return ActiveDOMObject::executionContext(); }
-    bool dispatchEvent(PassRefPtrWillBeRawPtr<Event>) final;
     const AtomicString& interfaceName() const override;
 
     // ActiveDOMObject interface.
@@ -114,6 +113,10 @@ public:
 
     DECLARE_VIRTUAL_TRACE();
 
+protected:
+    // EventTarget interface.
+    bool dispatchEventInternal(PassRefPtrWillBeRawPtr<Event>) final;
+
 private:
     Notification(const String& title, ExecutionContext*);