* required is a modifier when followed by [record type] `?`.
* Parse record type as record type if followed by `super` or `?` `super`
or `?` `this`.
* Typedef with record type follow by `?`.
* Parse record type as record type in get/set with async/sync/sync*.
* Parse record type as record type when followed by `>>=` or `>>>=`
(for weird formatted use in typedefs).
Change-Id: I19e208497e28780fb1505139c488e943751cce25
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/263123
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Jens Johansen <jensj@google.com>
Jens Johansen
b3dbaadc83