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/kbdA11yDialog.js

@@ -18,7 +18,7 @@ var KbdA11yDialog = new Lang.Class({
 
         let deviceManager = Clutter.DeviceManager.get_default();
         deviceManager.connect('kbd-a11y-flags-changed',
-                              Lang.bind(this, this._showKbdA11yDialog));
+                              this._showKbdA11yDialog.bind(this));
     },
 
     _showKbdA11yDialog(deviceManager, newFlags, whatChanged) {