Await and skip a missed broken expectation (#3253)
Await and skip a missed broken expectation (#3253)

These expectations can fail as an unhandled async error and the
exception lost because of the error handling zone running the `Builder`.
The test should have been failing, add a `skip` for now instead of
silently failing the test.

dart-lang/build,dart-lang/build,dart-lang/build,dart-lang/build