7c0e4d67c7
- Remove unsound platform .dill files from the packaged SDK. - Throw and error referencing the sound null safety requirements of Dart 3 when compiling with `--no-sound-null-safety` and an unsound platform .dill file is not found. Change-Id: I703a446e3e92c76a6b48168577fc0161eea83854 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/289280 Commit-Queue: Nate Biggs <natebiggs@google.com> Reviewed-by: Sigmund Cherem <sigmund@google.com>