Implement Permissions.query() and static PermissionStatus.

Source/modules/permissions/Permissions.idl

 // 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.
 
 // Specification at:
 // https://w3c.github.io/permissions/
 
 enum PermissionName {
     "geolocation",
     "notifications",
-    "push"
+    "push-notifications",
+    "midi-sysex"
 };
 
 [
     Exposed=(Window,Worker),
     GarbageCollected,
     RuntimeEnabled=Permissions
 ] interface Permissions {
     [CallWith=ScriptState] static Promise<PermissionStatus> query(PermissionName permission);
 };