Add support for the `late` modifier on fields and local variables in
CFE, and `required` on named parameters When using the option
--enable-experiment=non-nullable the `isLate` and `isRequired` flags will be set
accordingly on Field and VariableDeclaration nodes.
Closes#37686Closes#37684
Change-Id: If37fc93defdabc5cc974f3f068f57752a665f4cb
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/113036
Commit-Queue: Johnni Winther <johnniwinther@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Jens Johansen <jensj@google.com>
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>