clutter: Remove window scaling feature

Window scaling is a clutter feature used to enable automatic scaling of
stage windows when running under as an application in windowing system.
Clutter in mutter does not support running as a stand-alone application
toolkit, so lets remove this unused feature.

https://bugzilla.gnome.org/show_bug.cgi?id=777732

src/backends/meta-backend.c

@@ -948,7 +948,6 @@ meta_init_backend (GType backend_gtype)
 void
 meta_clutter_init (void)
 {
-  ClutterSettings *clutter_settings;
   GSource *source;
 
   clutter_set_custom_backend_func (meta_get_clutter_backend);
@@ -959,13 +958,6 @@ meta_clutter_init (void)
       exit (1);
     }
 
-  /*
-   * XXX: We cannot handle high dpi scaling yet, so fix the scale to 1
-   * for now.
-   */
-  clutter_settings = clutter_settings_get_default ();
-  g_object_set (clutter_settings, "window-scaling-factor", 1, NULL);
-
   source = g_source_new (&event_funcs, sizeof (GSource));
   g_source_attach (source, NULL);
   g_source_unref (source);