The current behavior (removing all outer `FutureOr`s,
then calling *flatten* on the result) was never specified as correct behavior.
Since Dart 2.0, the await has not recursively flattened futures,
so the static analysis behavior did not match run-time behavior.
Change-Id: Ie1da323aedb4b0f51e2c1e3eebe84552576c5f37
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/121846
Commit-Queue: Lasse R.H. Nielsen <lrn@google.com>
Reviewed-by: Leaf Petersen <leafp@google.com>
