[epiphany] Fix spacing in fonts preferences tab

[Michael Catanzaro <mcatanzaro src gnome org>]

commit f413e5512e253ba7570563f8da5d1a63e245412e
Author: Jan-Michael Brummer <jan brummer tabos org>
Date:   Tue Apr 9 23:14:12 2019 +0200

    Fix spacing in fonts preferences tab
    
    Fixes: https://gitlab.gnome.org/GNOME/epiphany/issues/620

 src/resources/gtk/prefs-dialog.ui | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/resources/gtk/prefs-dialog.ui b/src/resources/gtk/prefs-dialog.ui
index 4effa5f5c..68ac7bf46 100644
--- a/src/resources/gtk/prefs-dialog.ui
+++ b/src/resources/gtk/prefs-dialog.ui
@@ -440,6 +440,7 @@
                   <object class="GtkBox">
                     <property name="visible">True</property>
                     <property name="orientation">vertical</property>
+                    <property name="spacing">6</property>
                     <child>
                       <object class="GtkLabel">
                         <property name="visible">True</property>