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

Source/modules/push_messaging/PushEventInit.idl

Index: Source/modules/push_messaging/PushEventInit.idl
diff --git a/Source/core/html/HTMLPictureElement.idl b/Source/modules/push_messaging/PushEventInit.idl
similarity index 57%
copy from Source/core/html/HTMLPictureElement.idl
copy to Source/modules/push_messaging/PushEventInit.idl
index 649316cb8a1be19e29c17f14bfbc5b6e10397164..aa921f407c832292ef0b0d034c33029a30d9c54d 100644
--- a/Source/core/html/HTMLPictureElement.idl
+++ b/Source/modules/push_messaging/PushEventInit.idl
@@ -2,9 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// http://picture.responsiveimages.org
-[
-    RuntimeEnabled=Picture
-] interface HTMLPictureElement : HTMLElement {
-};
+// https://w3c.github.io/push-api/#idl-def-PushEvent
 
+dictionary PushEventInit : ExtendableEventInit {
+    PushMessageData data;
+};