[gtk/wip/baedert/for-master] scrolledwindow: Remove an unnecessary cast

[Timm Bäder <baedert src gnome org>]

commit 9013305554b6a356ddf9e3872c39b733b15e8157
Author: Timm Bäder <mail baedert org>
Date:   Sun Feb 23 16:08:23 2020 +0100

    scrolledwindow: Remove an unnecessary cast

 gtk/gtkscrolledwindow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/gtk/gtkscrolledwindow.c b/gtk/gtkscrolledwindow.c
index 3a90ca7595..6debc150ae 100644
--- a/gtk/gtkscrolledwindow.c
+++ b/gtk/gtkscrolledwindow.c
@@ -3486,7 +3486,7 @@ gtk_scrolled_window_add (GtkContainer *container,
   GtkAdjustment *hadj, *vadj;
 
   bin = GTK_BIN (container);
-  g_return_if_fail (gtk_bin_get_child (GTK_BIN (scrolled_window)) == NULL);
+  g_return_if_fail (gtk_bin_get_child (bin) == NULL);
 
   /* gtk_scrolled_window_set_[hv]adjustment have the side-effect
    * of creating the scrollbars