[gnome-shell] st/scroll-view: Remove scrollbars references on dispose

[Florian Müllner <fmuellner src gnome org>]

commit aa9031d8e7692e41b442534a2e473ef4f2f67f14
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Fri Aug 3 19:06:47 2018 +0200

    st/scroll-view: Remove scrollbars references on dispose
    
    As we're destroying the scrollbars on destruction, we should remove any
    reference of it, not to cause multiple-calls to disposal to unreference them
    again.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/190

 src/st/st-scroll-view.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
---
diff --git a/src/st/st-scroll-view.c b/src/st/st-scroll-view.c
index 029e4a356d..79af3ca13a 100644
--- a/src/st/st-scroll-view.c
+++ b/src/st/st-scroll-view.c
@@ -250,11 +250,8 @@ st_scroll_view_dispose (GObject *object)
       priv->fade_effect = NULL;
     }
 
-  if (priv->vscroll)
-    clutter_actor_destroy (priv->vscroll);
-
-  if (priv->hscroll)
-    clutter_actor_destroy (priv->hscroll);
+  g_clear_pointer (&priv->vscroll, clutter_actor_destroy);
+  g_clear_pointer (&priv->hscroll, clutter_actor_destroy);
 
   /* For most reliable freeing of memory, an object with signals
    * like StAdjustment should be explicitly disposed. Since we own