Clean up unused includes

Some late spring cleaning ...

js/ui/docDisplay.js

@@ -1,10 +1,7 @@
 /* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
 
 const Clutter = imports.gi.Clutter;
-const Gio = imports.gi.Gio;
-const Gtk = imports.gi.Gtk;
 const Lang = imports.lang;
-const Pango = imports.gi.Pango;
 const Shell = imports.gi.Shell;
 const Signals = imports.signals;
 const St = imports.gi.St;