[gnome-shell] AllView: prevent accessing a NULL effect

[Rui Matos <rtcm src gnome org>]

commit 7bdd1c625c982c43847d5dbbe2c5250ac1726586
Author: Rui Matos <tiagomatos gmail com>
Date:   Wed Jun 10 16:05:41 2015 +0200

    AllView: prevent accessing a NULL effect
    
    In some cases we might be allocated a size such that
    this._grid.topPadding and this._grid.bottomPadding are both 0 which
    means that the ScrollView fade effect gets removed. In that case don't
    try to access the effect since it will be NULL.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=750714

 js/ui/appDisplay.js |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
---
diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index c938e1f..37cc5eb 100644
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -753,7 +753,8 @@ const AllView = new Lang.Class({
         let fadeOffset = Math.min(this._grid.topPadding,
                                   this._grid.bottomPadding);
         this._scrollView.update_fade_effect(fadeOffset, 0);
-        this._scrollView.get_effect('fade').fade_edges = true;
+        if (fadeOffset > 0)
+            this._scrollView.get_effect('fade').fade_edges = true;
 
         if (this._availWidth != availWidth || this._availHeight != availHeight || oldNPages != 
this._grid.nPages()) {
             this._adjustment.value = 0;