[slotchange-events.html]
[Moving default content into a slot fires 'slotchange' event]
expected: FAIL
[Moving default content out of a slot fires 'slotchange' event]
expected: FAIL
[Moving a slottable into and out out of a custom element fires 'slotchange' event]
expected: FAIL
[Moving a slot runs the assign slottables algorithm]
expected: FAIL