This adds an ExperimentalFeatures interface to make the parser able to know which experimental feature is currently supported. This generalizes the existing dependency on patterns and enhanced parts, and facilitates reporting of unsupported features directly within the parser, avoid the need for duplicate handling of this within analyzer+CFE.
Change-Id: If1752745ee4d753e4b463f2017f440223cd98737
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/455700
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Johnni Winther
70a453f55f