Make NotificationEvent constructable.

Source/modules/notifications/NotificationEvent.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NotificationEvent_h
 #define NotificationEvent_h
 
 #include "modules/EventModules.h"
 #include "modules/notifications/Notification.h"
 #include "modules/serviceworkers/ExtendableEvent.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
-struct NotificationEventInit : public EventInit {
+struct NotificationEventInit : public ExtendableEventInit {
     NotificationEventInit();
 
     Member<Notification> notification;
 };
 
 class NotificationEvent final : public ExtendableEvent {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static PassRefPtrWillBeRawPtr<NotificationEvent> create()
     {
         return adoptRefWillBeNoop(new NotificationEvent);
     }
+    static PassRefPtrWillBeRawPtr<NotificationEvent> create(const AtomicString& type, const NotificationEventInit& initializer)
+    {
+        return adoptRefWillBeNoop(new NotificationEvent(type, initializer));
+    }
     static PassRefPtrWillBeRawPtr<NotificationEvent> create(const AtomicString& type, const NotificationEventInit& initializer, WaitUntilObserver* observer)
     {
         return adoptRefWillBeNoop(new NotificationEvent(type, initializer, observer));
     }
 
     ~NotificationEvent() override;
 
     Notification* notification() const { return m_notification.get(); }
 
     const AtomicString& interfaceName() const override;
 
     void trace(Visitor*) override;
 
 private:
     NotificationEvent();
+    NotificationEvent(const AtomicString& type, const NotificationEventInit&);
     NotificationEvent(const AtomicString& type, const NotificationEventInit&, WaitUntilObserver*);
 
     PersistentWillBeMember<Notification> m_notification;
 };
 
 } // namespace blink
 
 #endif // NotificationEvent_h