range: Don't use an abstract role

This snuck through, because the range wasn't
setting any role at all, it just ends up using
the initial, abstract role of widget.

gtk/gtkrange.c

@@ -441,6 +441,7 @@ gtk_range_class_init (GtkRangeClass *class)
   g_object_class_install_properties (gobject_class, LAST_PROP, properties);
 
   gtk_widget_class_set_css_name (widget_class, I_("range"));
+  gtk_widget_class_set_accessible_role (widget_class, GTK_ACCESSIBLE_ROLE_GENERIC);
 }
 
 static gboolean