[Aura] Apply NTP fix to app list webui.

Fix potential app list crash similar to NTP crash bug http://crbug.com/104059.

BUG=none.
TEST=After drag-n-drop is supported in aura, drag an app in app list window should not crash.


Review URL: http://codereview.chromium.org/8555015

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@109952 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/aura/app_list/app_list.js

@@ -49,7 +49,7 @@ cr.define('appList', function() {
   }
 
   function getAppsPageIndex(page) {
-    appsView.getAppsPageIndex(page);
+    return appsView.getAppsPageIndex(page);
   }
 
   function getCardSlider() {