The Tor Browser / file revision

 /* This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 #include "nsISupports.idl"

 [scriptable, uuid(75767928-ecb1-4e6c-9f55-c118b297fcef)]

 interface xpcIJSWeakReference : nsISupports

 {

   /**

    * To be called from JS only.

    *

    * Returns the referenced JS object or null if the JS object has

    * been garbage collected.

    */

   [implicit_jscontext] jsval get();

 };