Fix client certificate sorting order for network configuration.

Certificates were ordered from early expiration to late expiration and the first matching cert was selected.
This was exactly the wrong order. This change reverses the order to select a certificate with the latest expiration date.

BUG=327389
R=dconnelly@chromium.org

Review URL: https://codereview.chromium.org/107653003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@240273 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 240273