[gnome-shell] lightbox: Do not assume GLSL is available

[Adel Gadllah <agadllah src gnome org>]

commit 9a05aea76f593afa8977abdfe0e4e7df720158e3
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Thu Jul 24 15:40:19 2014 +0200

    lightbox: Do not assume GLSL is available
    
    Some hardware does not support it causing crashes in cogl during paint.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=733623

 js/ui/lightbox.js |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/js/ui/lightbox.js b/js/ui/lightbox.js
index 4b07deb..2188b23 100644
--- a/js/ui/lightbox.js
+++ b/js/ui/lightbox.js
@@ -105,8 +105,8 @@ const Lightbox = new Lang.Class({
         this._container = container;
         this._children = container.get_children();
         this._fadeFactor = params.fadeFactor;
-        this._radialEffect = params.radialEffect;
-        if (params.radialEffect)
+        this._radialEffect = Clutter.feature_available(Clutter.FeatureFlags.SHADERS_GLSL) && 
params.radialEffect;
+        if (this._radialEffect)
             this.actor = new RadialShaderQuad({ x: 0,
                                                 y: 0,
                                                 reactive: params.inhibitEvents });