Only expose Notification.requestPermission() on the Window global.

Source/modules/notifications/Notification.cpp

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 293 matching lines @@
 {
     SecurityOrigin* origin = context->securityOrigin();
     ASSERT(origin);
 
     return notificationManager()->checkPermission(WebSecurityOrigin(origin));
 }
 
 ScriptPromise Notification::requestPermission(ScriptState* scriptState, NotificationPermissionCallback* deprecatedCallback)
 {
     ExecutionContext* context = scriptState->executionContext();
-    NotificationPermissionClient* permissionClient = NotificationPermissionClient::from(context);
-    if (!permissionClient) {
-        // TODO(peter): Assert that this code-path will only be reached for Document environments when Blink
-        // supports [Exposed] annotations on class members in IDL definitions. See https://crbug.com/442139.
-        return ScriptPromise::cast(scriptState, v8String(scriptState->isolate(), permission(context)));
-    }
+    if (NotificationPermissionClient* permissionClient = NotificationPermissionClient::from(context))
+        return permissionClient->requestPermission(scriptState, deprecatedCallback);
 
-    return permissionClient->requestPermission(scriptState, deprecatedCallback);
+    // The context has been detached. Return a promise that will never settle.
+    ASSERT(context->activeDOMObjectsAreStopped());
+    return ScriptPromise();
 }
 
 size_t Notification::maxActions()
 {
     // Returns a fixed number for unit tests, which run without the availability of the Platform object.
     if (!notificationManager())
         return 2;
 
     return notificationManager()->maxActions();
 }
@@ skipping 23 matching lines @@
     return m_state == NotificationStateShowing || m_asyncRunner.isActive();
 }
 
 DEFINE_TRACE(Notification)
 {
     RefCountedGarbageCollectedEventTargetWithInlineData<Notification>::trace(visitor);
     ActiveDOMObject::trace(visitor);
 }
 
 } // namespace blink