appDisplay: Don't use icons in results for settings

The search results are not necessarily improved by including icons, so don't.

https://bugzilla.gnome.org/show_bug.cgi?id=681797

js/ui/appDisplay.js

@@ -383,9 +383,7 @@ const SettingsSearchProvider = new Lang.Class({
             let pref = prefs[i];
             metas.push({ 'id': pref,
                          'name': pref.get_name(),
-                         'createIcon': function(size) {
-                             return pref.create_icon_texture(size);
-                         }
+                         'createIcon': function() { return null; }
                        });
         }
         callback(metas);