[gnome-control-center] night-light: Uncomment signal handler

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 6c28263e6b31e6ae324a3c63ac45653b92216a66
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Jul 23 11:36:39 2018 -0300

    night-light: Uncomment signal handler
    
    This was mistakenly introduced ed36688c and was causing
    a crash when opening the Night Light dialog multiple times.

 panels/display/cc-night-light-dialog.ui | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/panels/display/cc-night-light-dialog.ui b/panels/display/cc-night-light-dialog.ui
index 55594a5b3..e4a32a4e7 100644
--- a/panels/display/cc-night-light-dialog.ui
+++ b/panels/display/cc-night-light-dialog.ui
@@ -6,7 +6,7 @@
     <property name="modal">True</property>
     <property name="destroy_with_parent">True</property>
     <property name="type_hint">dialog</property>
-    <!-- <signal name="delete-event" handler="gtk_widget_hide_on_delete" object="CcNightLightDialog" 
swapped="no" /> -->
+    <signal name="delete-event" handler="gtk_widget_hide_on_delete" object="CcNightLightDialog" swapped="no" 
/>
     <child internal-child="vbox">
       <object class="GtkBox">
         <property name="can_focus">False</property>