st: Remove custom text direction stuff

Clutter has its own built-in system for managing text directions, like GTK+.
Convert over to use this.

https://bugzilla.gnome.org/show_bug.cgi?id=670034

js/ui/environment.js

@@ -48,11 +48,6 @@ function init() {
     window.C_ = Gettext.pgettext;
     window.ngettext = Gettext.ngettext;
 
-    // Set the default direction for St widgets (this needs to be done before any use of St)
-    if (Gtk.Widget.get_default_direction() == Gtk.TextDirection.RTL) {
-        St.Widget.set_default_direction(St.TextDirection.RTL);
-    }
-
     // Miscellaneous monkeypatching
     _patchContainerClass(St.BoxLayout);
     _patchContainerClass(St.Table);