imported/w3c/web-platform-tests/html/semantics/links/linktypes/alternate-css.html [ Timeout Pass ] It just happened like 4 or 5 times, but the test may timeout in the first run. There aren't more details about what's happening there.
The test filed under this bug has been passing consistently in the last 4000 revisions. The test was removed from expectations in r262797. Closing bug. Committed r262811: <https://trac.webkit.org/changeset/262811>