Unreviewed, skip flaky tests in the GTK bots, all the
        mathml/presentation tests.
        https://bugs.webkit.org/show_bug.cgi?id=47727

        * platform/gtk/Skipped:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@70383 268f45cc-cd09-0410-ab3c-d52691b4dbfc