LayoutTest media/modern-media-controls/pip-support/pip-support-click.html is timing out on El Capitan https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=media/modern-media-controls/pip-support/pip-support-click.html
We have designed an iOS-specific test for this, so this particular test is skipped on iOS with good reason.
Oops, wrong conclusion. This was a Mac timeout. Anyway, hasn't been an issue since turning modern media controls back on.