9c34ff75db
When a post-feature library implements a pre-feature library declaration that has a final core library class as a super declaration, it should not produce a base/final/sealed transitivity error. Subclasses of a base core library class will still emit this error. Otherwise, if base/sealed/final is omitted in a non-implement case, we want to report these errors. Bug: https://github.com/dart-lang/sdk/issues/52315 Change-Id: Icdd4f63f69b061be5eabc7fd30b703d0358018a7 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/302365 Commit-Queue: Kallen Tu <kallentu@google.com> Reviewed-by: Konstantin Shcheglov <scheglov@google.com>