Some notes.
1. `Token.next` is `Token?` because there are null(s) for comment tokens.
But I think that it is never `null` in code, because there is at
least EOF token. So, lots of `!` null checks.
2. `Link.tail` is never null when `isNotEmpty`, but the type system
cannot express it. So, some number of `!` null checks.
3. I keep assert(s) for now, and use comment
`// ignore: unnecessary_null_comparison`.
4. I disabled `can_get_rid_of_nnbd_issue_error`, I think it fails
because of changes in `_fe_analyzer_shared` language version.
Smoke test in google3 looks green.
https://test.corp.google.com/ui#id=OCL:346825148:BASE:346841611:1607632317129:6e87bf7
I have not tried yet full TAP, will do in the evening.
I have not tried yet Golem, or looked at benchmarks.
Change-Id: I651301e5d3a851dd77d73af960dac779cb0fc991
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/175620
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Paul Berry <paulberry@google.com>
Konstantin Shcheglov
3d67e6f998