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

Source/modules/push_messaging/PushEvent.idl

Index: Source/modules/push_messaging/PushEvent.idl
diff --git a/Source/modules/push_messaging/PushEvent.idl b/Source/modules/push_messaging/PushEvent.idl
index 0c852a20757afebd54ad9bdc080aa51498d0ab2a..229793e3882191a4ad744db40206da5af5891298 100644
--- a/Source/modules/push_messaging/PushEvent.idl
+++ b/Source/modules/push_messaging/PushEvent.idl
@@ -2,10 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+// https://w3c.github.io/push-api/#idl-def-PushEvent
+
 [
-    EventConstructor,
     Exposed=ServiceWorker,
     RuntimeEnabled=PushMessaging,
+    Constructor(DOMString type, optional PushEventInit eventInitDict),
 ] interface PushEvent : ExtendableEvent {
-    [InitializedByEventConstructor] readonly attribute PushMessageData data;
+    readonly attribute PushMessageData data;
 };