modern-media-controls LayoutTests are flaky
This started to affect all media tests (see https://bugs.webkit.org/show_bug.cgi?id=165432).
Skipping all tests in the media/modern-media-controls directory until the flakiness can be resolved: https://trac.webkit.org/r209406
All subtasks were completed. There are still several bugs open that didn't get marked as subtasks, but clearly this bug is not useful any more, closing.