f3bc347448
Introduce runtime checks for BigInt to allow it being used as deeply immutable class. TEST=run_isolate_group_run_test Bug: https://github.com/dart-lang/sdk/issues/61030 Bug: https://github.com/dart-lang/sdk/issues/62601 Change-Id: I343862bdf5603be571d3bf937261dd61aca9ca0e Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/477040 Reviewed-by: Slava Egorov <vegorov@google.com> Commit-Queue: Alexander Aprelev <aam@google.com>