This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Currently the fetch spec is proposing webidl that looks like: typedef (Headers or sequence<sequence<ByteString>> or OpenEndedDictionary<ByteString>) HeadersInit; This is illegal at the moment, however, because Sequence and OpenEndedDictionary are not distinguishable.
In particular, we should try to convert as sequence; if that fails due to non-iterable, then go on to OpenEndedDictionary (or dictionary, for that matter).
Fixed by https://github.com/heycam/webidl/commit/1814384