baf740ee92
Option --null-safety was replaced with --sound-null-safety (in https://dart-review.googlesource.com/c/sdk/+/153660). This change cleans up obsolete option from the VM and kernel compilers. Issue: https://github.com/dart-lang/sdk/issues/41853 Change-Id: I605703bd5bf526391b21704b842bb9e6ca452061 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/155020 Reviewed-by: Régis Crelier <regis@google.com> Commit-Queue: Alexander Markov <alexmarkov@google.com>