[Null-aware elements] co19 Tests

[chloestefantsova]

This is the tracking issue for co19 tests for the feature. Feature spec: https://github.com/dart-lang/language/blob/main/working/0323-null-aware-elements/feature-specification.md

[chloestefantsova]

/cc @eernstg @sgrekhov

[sgrekhov]

I don't know how the right approach should be but now we have two duplicated issues. There is co19 issue that I'm working on now dart-lang/co19#2694. May be it makes sense convert this issue into co19 issue and I'll close dart-lang/co19#2694 as a duplicate of this one?

[eernstg]

It looks like there is a shared implementation issue that keeps track of all the implementation work associated with null-aware elements: #55949.

If nobody else refers to this issue, but various references to dart-lang/co19#2694 already exist then we should probably update that link such that it points to dart-lang/co19#2694, and then close this one.

(I've seen references to issues in non-sdk repos previously, so that should already be an accepted practice. For example, #47451.)

@chloestefantsova, would that cause any inconveniences for you?

[sgrekhov]

As an option I can go on work on dart-lang/co19#2694 and when complete (hopefully it'll be soon) then close this issue as well

[eernstg]

Sounds good, working on dart-lang/co19#2694 would then be the next step, no matter what. ;-)

[sgrekhov]

Closed as completed. See dart-lang/co19#2694