[2] 「pair」構文は >>1 で MapClass の削除により不要となり、削除されました。
[3] Allow extended attributes to apply to types (#286) (domenic著, ) https://github.com/heycam/webidl/commit/faaaaa9ffb548a303db362a09e4b1504c4605e0c
[4] Fix Web IDL extended attribute usage for recent changes (domenic著, ) https://github.com/whatwg/html/commit/793ace83447c9420a4dbc14f9bb14d3c35550f0a
[5] 24116 – Add additional form of Extended Attribute () https://www.w3.org/Bugs/Public/show_bug.cgi?id=24116
[6] Stop using extended attributes for constructors by Ms2ger · Pull Request #700 · heycam/webidl () https://github.com/heycam/webidl/pull/700