main: Drop the use of EggListBox

Now that all panels have been ported, we no longer need to do
g_type_ensure.

https://bugzilla.gnome.org/show_bug.cgi?id=702164

shell/main.c

@@ -24,7 +24,6 @@
 #include <stdlib.h>
 #include <glib/gi18n.h>
 #include <gtk/gtk.h>
-#include <egg-list-box.h>
 
 #ifdef GDK_WINDOWING_X11
 #include <X11/Xlib.h>
@@ -46,8 +45,6 @@ main (int argc, char **argv)
   XInitThreads ();
 #endif
 
-  g_type_ensure (egg_list_box_get_type ());
-
   application = cc_application_new ();
   status = g_application_run (G_APPLICATION (application), argc, argv);