Make dart2js_info work again after partial migration to null-safety
Make dart2js_info work again after partial migration to null-safety

Change-Id: I09b87ce1d6978f2b8aed65ecefe55557dd7b5784
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/246581
Reviewed-by: Nate Biggs <4bdbe5a28604b503f0b7346ee4d58c334975887b@google.com>
Reviewed-by: Alexander Thomas <29642742b6693024c89de8232f2e2542cf7eedf7@google.com>
Commit-Queue: Ilya Yanok <1dfd2cc24bb9137848337da02847927c89a2cde5@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk