[gtk/global-coords] Remove a misleading comment

[Matthias Clasen <matthiasc src gnome org>]

commit 4849091c76687a70c217118497e8a9cc5ef55f86
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed May 29 15:18:15 2019 +0000

    Remove a misleading comment
    
    We don't have windowed widgets anymore, and
    gdk_surface_move_resize is about to go away.

 gtk/gtkwidget.c | 4 ----
 1 file changed, 4 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 2c2a823c83..a90dddbc16 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -3909,10 +3909,6 @@ gtk_widget_unrealize (GtkWidget *widget)
   g_object_unref (widget);
 }
 
-/*
- * Returns the values you're supposed to pass to gdk_surface_move_resize
- * for a windowed widget.
- */
 void
 gtk_widget_get_surface_allocation (GtkWidget     *widget,
                                   GtkAllocation *allocation)