In the new type system, allow native types that have a "peer" on
the Dart side to use that Dart type as their reified type.
This matches the semantics of the old type system for these types.
Change-Id: I62bf6cb1654d33549a6ea2c757e7e65fa81677a4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/313700
Reviewed-by: Srujan Gaddam <srujzs@google.com>
Reviewed-by: Sigmund Cherem <sigmund@google.com>
Commit-Queue: Nicholas Shahan <nshahan@google.com>
