[gnome-shell] main: Fix unsetting of custom stylesheets

[Florian Müllner <fmuellner src gnome org>]

commit ed7649c93ad3d05d844838d4c8e4a2c0f33fa613
Author: Florian Müllner <fmuellner gnome org>
Date:   Thu Nov 27 14:24:49 2014 +0000

    main: Fix unsetting of custom stylesheets
    
    Since moving to a GFile based API in commit 642bf2b7782819,
    setThemeStylesheet() no longer accepts %null to revert to
    the default theme. We should have some way to revert to the
    default and the least intrusive option is to return to the
    old behavior, so do that.

 js/ui/main.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/main.js b/js/ui/main.js
index 9467d56..36d7591 100644
--- a/js/ui/main.js
+++ b/js/ui/main.js
@@ -271,7 +271,7 @@ function getThemeStylesheet() {
  * Set the theme CSS file that the shell will load
  */
 function setThemeStylesheet(cssStylesheet) {
-    _cssStylesheet = Gio.File.new_for_path(cssStylesheet);
+    _cssStylesheet = cssStylesheet ? Gio.File.new_for_path(cssStylesheet) : null;
 }
 
 /**