[mutter] window: Fix typo

[Florian Müllner <fmuellner src gnome org>]

commit 482a97466d30972f4affe4b5d82c6ba488a01849
Author: Florian Müllner <fmuellner gnome org>
Date:   Sat Sep 27 03:58:33 2014 +0200

    window: Fix typo

 src/core/window.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/core/window.c b/src/core/window.c
index 06fb210..d4c1018 100644
--- a/src/core/window.c
+++ b/src/core/window.c
@@ -4297,7 +4297,7 @@ meta_window_focus (MetaWindow  *window,
  *  - workspace->windows is a list of windows that is located on
  *    that workspace.
  *
- *  - If the window is on_all_workspaces, then then
+ *  - If the window is on_all_workspaces, then
  *    window->workspace == NULL, but workspace->windows contains
  *    the window.
  */