[gnome-documents] preview: Simplify the PreviewNavButtons show/hide code

[Debarshi Ray <debarshir src gnome org>]

commit 894d8e7d379f4ccfa7402562742cba2944fce331
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Dec 23 17:46:36 2013 +0100

    preview: Simplify the PreviewNavButtons show/hide code
    
    We could just call _updateVisibility instead of fading it in and out
    ourself.
    
    In fact, it would be more correct to do so because otherwise show will
    always fade in both widgets -- which is wrong. The reason it works
    correctly now is that show is called before setModel. So the call to
    _fadeInButton from show aborts because this._model is null. This is
    due to the particular order in which _onLoadFinished is called in
    PreviewView and Embed.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=720985

 src/preview.js |    6 ++----
 1 files changed, 2 insertions(+), 4 deletions(-)
---
diff --git a/src/preview.js b/src/preview.js
index 2cc40e2..1436354 100644
--- a/src/preview.js
+++ b/src/preview.js
@@ -796,14 +796,12 @@ const PreviewNavButtons = new Lang.Class({
 
     show: function() {
         this._visible = true;
-        this._fadeInButton(this.prev_widget);
-        this._fadeInButton(this.next_widget);
+        this._updateVisibility();
     },
 
     hide: function() {
         this._visible = false;
-        this._fadeOutButton(this.prev_widget);
-        this._fadeOutButton(this.next_widget);
+        this._updateVisibility();
     }
 });