[gnome-control-center] display: Stop night light dialog being destroyed twice

[Robert Ancell <rancell src gnome org>]

commit 044eeb0d064cda35d103d7bf5b57f77b140eb84d
Author: Robert Ancell <robert ancell canonical com>
Date:   Fri Oct 12 10:58:40 2018 +1300

    display: Stop night light dialog being destroyed twice
    
    The night light dialog is both marked as "destroy_with_parent" and explicitly
    destroyed in the panel. Drop one of these.
    
    Causes the warning after opening the dialog then closing the app:
    (gnome-control-center:19887): Gtk-CRITICAL **: 11:00:01.370: gtk_widget_destroy: assertion 'GTK_IS_WIDGET 
(widget)' failed
    
    This bug was introduced in ed36688c58c4f676b79fcd7a248a98d63bdc0129

 panels/display/cc-night-light-dialog.ui | 1 -
 1 file changed, 1 deletion(-)
---
diff --git a/panels/display/cc-night-light-dialog.ui b/panels/display/cc-night-light-dialog.ui
index e4a32a4e7..5ec19dd6b 100644
--- a/panels/display/cc-night-light-dialog.ui
+++ b/panels/display/cc-night-light-dialog.ui
@@ -4,7 +4,6 @@
     <property name="can_focus">False</property>
     <property name="resizable">False</property>
     <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" 
/>
     <child internal-child="vbox">