[Gtk-3.20] Remove deprecated GtkStatusbar:shadow-type. Fixes #506

Author: megax

gtk-3.20/scss/widgets/_base.scss

@@ -3,7 +3,6 @@
 ***************/
 
 * {
-    -GtkStatusbar-shadow-type: none;
     -GtkWindow-resize-grip-height: 0;
     -GtkWindow-resize-grip-width: 0;
     -WnckTasklist-fade-overlay-rect: 0;