[gnome-shell] keyboard: Fix fallback layout when using variants

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit d29e5765badbca21a6ef8b40087a8e3587b15dd4
Author: Florian Müllner <fmuellner gnome org>
Date:   Mon Mar 23 16:14:47 2020 +0100

    keyboard: Fix fallback layout when using variants
    
    Commit c1ec7b2ff meant to fall back to the base layout in case
    a variant like `fr+oss` is set up, but as we are checking for
    '+' on the array rather than the layout name, the fallback only
    "works" for a layout that is literally called '+', whoops.
    
    https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/2471

 js/ui/keyboard.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/keyboard.js b/js/ui/keyboard.js
index 635d9b12e5..7d56ef9c8f 100644
--- a/js/ui/keyboard.js
+++ b/js/ui/keyboard.js
@@ -498,7 +498,7 @@ var Key = GObject.registerClass({
 var KeyboardModel = class {
     constructor(groupName) {
         let names = [groupName];
-        if (names.includes('+'))
+        if (groupName.includes('+'))
             names.push(groupName.replace(/\+.*/, ''));
         names.push('us');