media/event-attributes.html is quite flaky on WK1, sometimes timing out, and other times failing with a text diff.
Note that there is another bug for WebKit2, where the test fails every time.
The diff is:
@@ -5,7 +5,7 @@
-EXPECTED (progressEventCount >= '1') OK
+EXPECTED (progressEventCount >= '1'), OBSERVED '0' FAIL
*** starting playback
Marked as flaky in <http://trac.webkit.org/r167506>.