cleanup: Use arrow notation for anonymous functions

Arrow notation is great, use it consistently through-out the code base
to bind `this` to anonymous functions, replacing the more overbose
Lang.bind(this, function() {}).

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/23

js/ui/edgeDragAction.js

@@ -22,9 +22,7 @@ var EdgeDragAction = new Lang.Class({
         this._allowedModes = allowedModes;
         this.set_n_touch_points(1);
 
-        global.display.connect('grab-op-begin', Lang.bind(this, function() {
-            this.cancel();
-        }));
+        global.display.connect('grab-op-begin', () => { this.cancel(); });
     },
 
     _getMonitorRect(x, y) {