This moves pattern variable assignments of fully matched expressions into the case body. This will help backends (dart2js in particular) to reason about the code flow.
Closes#54115
Change-Id: I598a384a829f16e91ab2d6a309499cf20b9cc121
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/339122
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Johnni Winther