[gnome-shell] LayoutManager: add missing constant

[Giovanni Campagna <gcampagna src gnome org>]

commit e4af954a95373539f045df06dde1eccd2e98e334
Author: Giovanni Campagna <gcampagna src gnome org>
Date:   Wed Feb 20 02:17:55 2013 +0100

    LayoutManager: add missing constant
    
    https://bugzilla.gnome.org/show_bug.cgi?id=694227

 js/ui/layout.js |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/js/ui/layout.js b/js/ui/layout.js
index ca3c3e0..a0fbbc8 100644
--- a/js/ui/layout.js
+++ b/js/ui/layout.js
@@ -20,6 +20,7 @@ const Tweener = imports.ui.tweener;
 const HOT_CORNER_ACTIVATION_TIMEOUT = 0.5;
 const STARTUP_ANIMATION_TIME = 0.5;
 const KEYBOARD_ANIMATION_TIME = 0.15;
+const BACKGROUND_FADE_ANIMATION_TIME = 1.0;
 const DEFAULT_BACKGROUND_COLOR = Clutter.Color.from_pixel(0x2e3436ff);
 
 // The message tray takes this much pressure