[gnome-shell] workspacesView: Fix off-by-one error

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

commit 9f0e7632a6e1cb94bb9bf71002d548a8cbb2d558
Author: Florian Müllner <fmuellner gnome org>
Date:   Fri Jan 8 02:14:42 2021 +0100

    workspacesView: Fix off-by-one error
    
    The scroll adjustment's upper value corresponds to the number of
    workspaces, not to the last workspace index. We want the latter
    when mirroring the layout in RTL locales, so subtract 1.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1598>

 js/ui/workspacesView.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/js/ui/workspacesView.js b/js/ui/workspacesView.js
index 865b52b502..12f5ca3a81 100644
--- a/js/ui/workspacesView.js
+++ b/js/ui/workspacesView.js
@@ -300,7 +300,7 @@ class WorkspacesView extends WorkspacesViewBase {
         const vertical = workspaceManager.layout_rows === -1;
         const rtl = this.text_direction === Clutter.TextDirection.RTL;
         const progress = vertical || !rtl
-            ? adj.value : adj.upper - adj.value;
+            ? adj.value : adj.upper - adj.value - 1;
 
         for (const ws of this._workspaces) {
             if (vertical)