6265bis has a bunch of references to browsing context and its active document. There were some big changes to HTML recently in whatwg/html#6315 that should have broken some of those.

Note that a lot of this could be solved through adding more accurate layering as described in #2084, but if we wanted to publish a new cookies RFC before that change happens, it may still be worth adding the correct terminology and references.

cc @annevk @domenic @sbingler