The following layout test frequently times out on Mac WK2 (Mavericks and Mountain Lion, Debug and Release): editing/selection/5057506.html See http://webkit-test-results.appspot.com/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=editing%2Fselection%2F5057506.html Many of the runs are 80+ second timeouts :( But when it runs fine, it runs in 1 second or less...
Also interesting to note, when it times out, the image results mismatch with text antialiasing differences.
Flaky timeout'd in http://trac.webkit.org/changeset/159361
editing/selection/5057506-2.html has exactly the same behavior.
Marked the second test as flaky timeout in <http://trac.webkit.org/r160999>.
This doesn't seem to happen any more.