[gtk+] assistant: Avoid tripping template tests

[Matthias Clasen <matthiasc src gnome org>]

commit 88c3456d2fed626448059272b2a0db3f06db6e70
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Jan 27 12:57:58 2016 -0500

    assistant: Avoid tripping template tests
    
    We need to unset the titlebar manually before chaining up
    in destroy, otherwise we trigger the template invariant
    checking - GtkWindow would eventually unset it, but too late
    for the invariants checking code in gtk_widget_destroy.

 gtk/gtkassistant.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkassistant.c b/gtk/gtkassistant.c
index c66bc0f..d8d7329 100644
--- a/gtk/gtkassistant.c
+++ b/gtk/gtkassistant.c
@@ -303,7 +303,7 @@ apply_use_header_bar (GtkAssistant *assistant)
   gtk_widget_set_visible (priv->headerbar, priv->use_header_bar);
   if (!priv->use_header_bar)
     gtk_window_set_titlebar (GTK_WINDOW (assistant), NULL);
-  if (priv->use_header_bar)
+  else
     g_signal_connect (priv->action_area, "add", G_CALLBACK (add_cb), assistant);
 }
 
@@ -1365,6 +1365,7 @@ gtk_assistant_destroy (GtkWidget *widget)
       priv->visited_pages = NULL;
     }
 
+  gtk_window_set_titlebar (GTK_WINDOW (widget), NULL);
   GTK_WIDGET_CLASS (gtk_assistant_parent_class)->destroy (widget);
 }