Following the fix for https://bugs.webkit.org/show_bug.cgi?id=179236, two WPT tests are flaky due to failing with unexpected time values which vary from test run to test run based on when the test samples the timeline.
https://bugs.webkit.org/show_bug.cgi?id=178932 makes http/wpt/web-animations/interfaces/Animation/startTime.html flaky, we'll need to address that one as well.
These tests do not exist anymore.