The "@compile-error" comment is an old not-great way of defining static
error tests.
Also fix a test to use a mixin declaration instead of a class for declaring a mixin. This was
broken by class modifiers but the breakage was masked by @compile-error treating a test as
passing if any compile error, even an unrelated one, is reported.
See: https://github.com/dart-lang/sdk/issues/45634
Change-Id: I5d1d387002d886cb87340e2559bf8ed01c3f2d6a
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/296409
Commit-Queue: Bob Nystrom <rnystrom@google.com>
Auto-Submit: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Nate Bosch <nbosch@google.com>
