[gnome-documents] preview: Don't invert preview in Books

[Bastien Nocera <hadess src gnome org>]

commit 723a1e69b612039e0b0a5e1c027733b73892f379
Author: Bastien Nocera <hadess hadess net>
Date:   Fri Sep 18 18:22:05 2015 +0200

    preview: Don't invert preview in Books
    
    In gnome-books, don't invert the colours of the view as they're likely
    not text, but images which really shouldn't be inverted.
    
    See https://bugzilla.gnome.org/show_bug.cgi?id=747132
    
    https://bugzilla.gnome.org/show_bug.cgi?id=755231

 src/preview.js |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/src/preview.js b/src/preview.js
index 3624e96..16c0d0b 100644
--- a/src/preview.js
+++ b/src/preview.js
@@ -572,7 +572,7 @@ const PreviewView = new Lang.Class({
     },
 
     _updateNightMode: function() {
-        if (this._model) {
+        if (this._model && !Application.application.isBooks) {
             let nightMode = Application.settings.get_boolean('night-mode');
             this._model.set_inverted_colors(nightMode);
         }