cleanup: Use Function.prototype.bind()

When not using arrow notation with anonymous functions, we use Lang.bind()
to bind `this` to named callbacks. However since ES5, this functionality
is already provided by Function.prototype.bind() - in fact, Lang.bind()
itself uses it when no extra arguments are specified. Just use the built-in
function directly where possible, and use arrow notation in the few places
where we pass additional arguments.

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

js/ui/appFavorites.js

@@ -51,7 +51,7 @@ var AppFavorites = new Lang.Class({
 
     _init() {
         this._favorites = {};
-        global.settings.connect('changed::' + this.FAVORITE_APPS_KEY, Lang.bind(this, this._onFavsChanged));
+        global.settings.connect('changed::' + this.FAVORITE_APPS_KEY, this._onFavsChanged.bind(this));
         this.reload();
     },