[Class modifiers] Syntax highlighters implementation

[itsjustkevin]

Cobbling together the list from past issues:

• https://github.com/dart-lang/dart-syntax-highlight/ (@DanTup)
  • Support modifiers + patterns dart-syntax-highlight#38
• https://github.com/highlightjs/highlight.js (@srawlins)
  • issue: [Request] support new Dart language keywords highlightjs/highlight.js#3725
  • PR: enh(dart) Add base, interface, sealed, and when keywords highlightjs/highlight.js#3726
• https://github.com/codemirror/CodeMirror/ (@domesticmouse)

[srawlins]

A note for tracking: These features are completed "out-of-band": they do not require changes to the Dart SDK or the Flutter repositories, so they can be landed after the Beta 3 deadline. I think it is still good to track them with the Beta 3 milestone for now.

[itsjustkevin]

See #49752

[leafpetersen]

Any updates here?

[vsmenon]

@domesticmouse - per checklist above - is there any work here you were planning on? And anything blocking?

[vsmenon]

ping

@domesticmouse @itsjustkevin - do we have anything left here? I don't think this would block a release. Should we move to cleanup?

[domesticmouse]

I believe CodeMirror is ready for this release. I added the appropriate keywords, and I think it's been through CodeMirror's monthly release cycle.

[vsmenon]

Thanks, I will go ahead and close this one.