Add NotificationOptions.actions so websites can provide buttons (blink)

Source/modules/notifications/NotificationAction.idl

Index: Source/modules/notifications/NotificationAction.idl
diff --git a/Source/modules/notifications/GetNotificationOptions.idl b/Source/modules/notifications/NotificationAction.idl
similarity index 56%
copy from Source/modules/notifications/GetNotificationOptions.idl
copy to Source/modules/notifications/NotificationAction.idl
index 7ed11aaa37b4cbfe28ddabed476bd21526da63af..bce87e73532c31ded718b6aea05459bda2b206d6 100644
--- a/Source/modules/notifications/GetNotificationOptions.idl
+++ b/Source/modules/notifications/NotificationAction.idl
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// https://notifications.spec.whatwg.org/#service-worker-api
+// https://notifications.spec.whatwg.org/#dictdef-notificationaction
 
-dictionary GetNotificationOptions {
-    DOMString tag = "";
+dictionary NotificationAction {
+    required DOMString title;
 };