[gnome-boxes] wizard: Fix assumption that installer is Unattended

[Zeeshan Ali Khattak <zeeshanak src gnome org>]

commit 6af5eb9767e90ed93d72e7f5cbc7a5cb72ccbff6
Author: Zeeshan Ali (Khattak) <zeeshanak gnome org>
Date:   Fri Jun 8 03:38:20 2012 +0300

    wizard: Fix assumption that installer is Unattended
    
    https://bugzilla.gnome.org/show_bug.cgi?id=677666

 src/wizard.vala |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/src/wizard.vala b/src/wizard.vala
index 25e24e8..efc2671 100644
--- a/src/wizard.vala
+++ b/src/wizard.vala
@@ -253,12 +253,14 @@ private class Boxes.Wizard: Boxes.UI {
             return true;
 
         return_if_fail (install_media != null);
+        // Setup only needed for Unattended installers
+        if (!(install_media is UnattendedInstaller))
+            return true;
 
         foreach (var child in setup_vbox.get_children ())
             setup_vbox.remove (child);
 
-        var installer = install_media as UnattendedInstaller;
-        installer.populate_setup_vbox (setup_vbox);
+        (install_media as UnattendedInstaller).populate_setup_vbox (setup_vbox);
         setup_vbox.show_all ();
 
         return true;