widget: Changing the scale does no longer require a redraw

It doesn't require one generally anyway, because only the root can
change scale and when that happens the root will queue a redraw.

But even if the root doesn't queue a redraw, render nodes (the only
thing discarded by queue_draw()) are scale-independant.

gtk/gtkwidget.c

@@ -6856,8 +6856,6 @@ _gtk_widget_scale_changed (GtkWidget *widget)
 
   g_object_notify_by_pspec (G_OBJECT (widget), widget_props[PROP_SCALE_FACTOR]);
 
-  gtk_widget_queue_draw (widget);
-
   gtk_widget_forall (widget, (GtkCallback)_gtk_widget_scale_changed, NULL);
 }