co19 tests - add tests for super-parameters

[devoncarew]

See dart-lang/sdk#48055 for the main tracking issue.

[devoncarew]

cc @lrhn @athomas

[a-siva]

Should this issue be filed in https://github.com/dart-lang/co19

[devoncarew]

Yup, will do.

[sgrekhov]

Super parameters co19 tests can be found at https://github.com/dart-lang/co19/tree/master/LanguageFeatures/Super-parameters