[polari] Replace Gdk.Screen

[Marge Bot <marge-bot src gnome org>]

commit fa9c2add437b511e1eea7cc497353013c8834966
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Sep 25 00:46:31 2020 +0200

    Replace Gdk.Screen
    
    It's gone in GTK4.
    
    Part-of: <https://gitlab.gnome.org/GNOME/polari/-/merge_requests/228>

 src/application.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/application.js b/src/application.js
index bb123b2e..a720c05e 100644
--- a/src/application.js
+++ b/src/application.js
@@ -399,7 +399,7 @@ export default GObject.registerClass({
             console.warn('Failed to add application style');
             console.debug(e);
         }
-        Gtk.StyleContext.add_provider_for_screen(Gdk.Screen.get_default(),
+        Gtk.StyleContext.add_provider_for_display(Gdk.Display.get_default(),
             provider,
             Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION);
     }