[CMSR] Support for removing formal parameters.

Change-Id: Id04f6c7854dec3d5059009a0a579110690d3eb62
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/310963
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>

https://dart.googlesource.com/sdk/+/fe353626024fea9761a833f8a35d339738219d98