Add a timeout expectation to media/track/track-prefer-captions.html after
r146380 on GTK+. The failure is tracked by http://webkit.org/b/113127

* platform/gtk/TestExpectations:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146714 268f45cc-cd09-0410-ab3c-d52691b4dbfc