The http/tests/appcache/404-resource-with-slow-main-resource.php layout test timing out since it was added on r178937 (https://trac.webkit.org/changeset/r178937).
Some commit in the range [r204842-r204851] made this test to start passing on the GTK+ port.
But it don't passes always, sometimes fails with the following diff:
Updated expectations at https://trac.webkit.org/changeset/212890
It's flaky because of the console output. Fixing it according to https://bugs.webkit.org/show_bug.cgi?id=185431 .