Add support for inline classes

[DanTup]

See dart-lang/sdk#49734 and https://github.com/dart-lang/language/blob/master/accepted/future-releases/inline-classes/feature-specification.md.

Inline is only detected as part of class, since the spec says:

The token inline is not made a built-in identifier: the reserved word class that occurs right after inline serves to disambiguate the inline class declaration with a fixed lookahead.

[kevmoo]

Thanks, @DanTup !

[devoncarew]

🎉

[devoncarew]

@DanTup - can you resolve the change conflict here? And, you now have write access to this repo, so will be able to merge your own PRs (after review).

[DanTup]

@devoncarew thanks! I've rebased and updated the version/date. I presume it's reasonable to land this now even if inline classes may be a little way off (it's just the single keyword)?

[devoncarew]

I presume it's reasonable to land this now even if inline classes may be a little way off (it's just the single keyword)?

Ah, good question. It may be better to hold off on that until more things start landing / we have a better sense of how far out it is.

[DanTup]

sgtm, I'll leave it here for now and update the version/date as appropriate when things might be clearer. Thanks!

[DanTup]

@devoncarew @jwren based on discussions it sounds like it's reasonable to merge this?

I've updated the date in changelog, though the version is still the same as nothing else has been committed since I first did this. Let me know if you've happy for me to merge (seems like I have merge access here now 👍).

[jwren]

Yes, do merge, if there are any other syntax changes we can always follow up.