[dconf-editor] Remove a warning.

[Arnaud Bonatti <arnaudb src gnome org>]

commit f2465288366eb3986e12131f211ab99917f343c8
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Thu Dec 14 12:27:47 2017 +0100

    Remove a warning.

 editor/key-list-box-row.vala |    5 ++---
 1 files changed, 2 insertions(+), 3 deletions(-)
---
diff --git a/editor/key-list-box-row.vala b/editor/key-list-box-row.vala
index 1f94c17..3c9d66a 100644
--- a/editor/key-list-box-row.vala
+++ b/editor/key-list-box-row.vala
@@ -133,9 +133,8 @@ private abstract class ClickableListBoxRow : EventBox
                 return;
             }
 
-            ulong popover_closed_handler = ((!) nullable_popover).closed.connect (() => on_popover_disappear 
());
-            ((!) nullable_popover).destroy.connect ((widget) => {
-                    widget.disconnect (popover_closed_handler);
+            ((!) nullable_popover).closed.connect (() => on_popover_disappear ());
+            ((!) nullable_popover).destroy.connect (() => {
                     on_popover_disappear ();
                     nullable_popover = null;
                 });