[dconf-editor] Add a style class to close button.

[Arnaud B. <arnaudb src gnome org>]

commit 5e78cfbc02fe1758c2814626ca58db6df3f1a5a8
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Thu Aug 1 14:05:57 2019 +0200

    Add a style class to close button.
    
    Helps with Yaru theme.

 editor/base-headerbar.ui | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/editor/base-headerbar.ui b/editor/base-headerbar.ui
index 6ff6c8f..b18f626 100644
--- a/editor/base-headerbar.ui
+++ b/editor/base-headerbar.ui
@@ -68,6 +68,7 @@
             <property name="action-name">app.quit</property>
             <style>
               <class name="titlebutton"/>
+              <class name="close"/>
             </style>
             <child>
               <object class="GtkImage">