Release 2.2.0

 - export the native window API so native plugins can detect when
   games are listening for events on the window object

   ```
   import devkit.native.Window as nativeWindow;

   nativeWindow.on('newListener', function (type, cb) {
   	 console.log("new native listener for", type);
   });

   window.addEventListener("devicemotion", function () { ... });
   ```

src/clientapi/native/Window.js

@@ -14,24 +14,22 @@
  * along with the Game Closure SDK.  If not, see <http://mozilla.org/MPL/2.0/>.
  */
 
-"use import";
-
 import lib.PubSub;
 
-var _evts = new lib.PubSub();
+module.exports = new lib.PubSub();
 
 window.open = window.open || window.setLocation;
 
 window.addEventListener = function (evtName, cb, isBubble) {
-	_evts.subscribe(evtName, window, cb);
+  module.exports.on(evtName, cb);
 }
 
 window.removeEventListener = function (evtName, cb, isBubble) {
-	_evts.unsubscribe(evtName, window, cb);
+  module.exports.removeListener(evtName, cb);
 }
 
 window.__fireEvent = function (name, evt) {
-	if (!evt) { evt = {}; }
-	evt.type = name;
-	_evts.publish(name, evt);
+  if (!evt) { evt = {}; }
+  evt.type = name;
+  module.exports.publish(name, evt);
 }