Check for loading state before adding event listener for transitionEnded event in options_page.js. During loading, no transitionEnded event fires as the transition duration is set to 0s.

BUG=308829

Review URL: https://codereview.chromium.org/28873008

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@229817 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 229817