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: https://build.webkit.org/results/GTK%20Linux%2064-bit%20Release%20%28Tests%29/r212883%20%2821059%29/http/tests/appcache/404-resource-with-slow-main-resource-pretty-diff.html Its flaky.
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 .
<rdar://problem/40599743>