0db6545b51
Extends the illegal return type check for async functions to cover illegal return types for functions marked async* or sync* as well. Adds new error messages for illegal return types of functions marked async, async*, and sync*. These error messages conform with those produced by the analyzer. Closes https://github.com/dart-lang/sdk/issues/33068 Bug: www.dartbug.com/33068 Change-Id: I6d8690537139d3d094a4e295fcac9de4f4a7f0af Reviewed-on: https://dart-review.googlesource.com/69581 Commit-Queue: Daniel Hillerström <hillerstrom@google.com> Reviewed-by: Aske Simon Christensen <askesc@google.com>