There are (still!) old [multitests](https://github.com/dart-lang/sdk/blob/main/docs/Testing.md#multitests) in co19 tests. Replace them by [static error tests](https://github.com/dart-lang/sdk/blob/main/docs/Testing.md#static-error-tests)
There are (still!) old multitests in co19 tests. Replace them by static error tests