This CL changes the Dart grammar in Dart.g such that it contains all
the grammar changes applied to the patterns proposal since the previous
update of Dart.g.
Change-Id: I9b5f0d9a092d30ce0055db99da5fdbe3b9b1d5dc
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/275002
Reviewed-by: William Hesse <whesse@google.com>
Auto-Submit: Erik Ernst <eernst@google.com>
Commit-Queue: Erik Ernst <eernst@google.com>
