Fix for crash on nested navigation to the same origin

BUG=346632
R=creis@chromium.org

Review URL: https://codereview.chromium.org/177363005

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@254191 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 254191