[dart2js] New RTI typechecking for generic functions.
[dart2js] New RTI typechecking for generic functions.

Change-Id: I3bb0a789aa8709907a1590e173f2d24ef8c5ce3b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/111991
Reviewed-by: Stephen Adams <60cb5b73b7e0cb7dcda53302da4fab6ecfc7fa8b@google.com>

dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-lang/sdk,dart-archive/dart-sdk