Use event init dictionaries in modules/{notifications,push_messaging,serviceworkers}

Source/modules/notifications/NotificationEvent.h

Index: Source/modules/notifications/NotificationEvent.h
diff --git a/Source/modules/notifications/NotificationEvent.h b/Source/modules/notifications/NotificationEvent.h
index 048c098f45bef2a29ac8d3165801746e79f18b13..eb6d985d838ab4901a6d788288366d8d252d7b94 100644
--- a/Source/modules/notifications/NotificationEvent.h
+++ b/Source/modules/notifications/NotificationEvent.h
@@ -7,17 +7,12 @@
 
 #include "modules/EventModules.h"
 #include "modules/notifications/Notification.h"
+#include "modules/notifications/NotificationEventInit.h"
 #include "modules/serviceworkers/ExtendableEvent.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
-struct NotificationEventInit : public ExtendableEventInit {
-    NotificationEventInit();
-
-    Member<Notification> notification;
-};
-
 class NotificationEvent final : public ExtendableEvent {
     DEFINE_WRAPPERTYPEINFO();
 public: