[5] WinIE が実装していました。
[1] Make <body topmargin> win over <iframe marginheight> (#2489)
(zcorpan著, )
https://github.com/whatwg/html/commit/3fc830124986d8fb0aa53cd2d2f2fea12a926e5d
[2] Editorial: fix a typo in Obsolete features
(takenspc著, )
https://github.com/whatwg/html/commit/c3c7d2cb656bea5b8916097e13079b754e329f7c
[3] A typo in 15.2 Non-conforming features · Issue #3602 · whatwg/html
()
https://github.com/whatwg/html/issues/3602
[4] Editorial: fix a typo in Obsolete features by takenspc · Pull Request #3603 · whatwg/html
()
https://github.com/whatwg/html/pull/3603