KeywordToken: Change keyword field to a getter over type

[gmpassos]

Reduce KeywordToken memory usage by changing the keyword field to a getter over type as Keyword.

---

• [✅] I’ve reviewed the contributor guide and applied the relevant portions to this PR.

[copybara-service]

Thank you for your contribution! This project uses Gerrit for code reviews. Your pull request has automatically been converted into a code review at:

https://dart-review.googlesource.com/c/sdk/+/379980

Please wait for a developer to review your code review at the above link; you can speed up the review if you sign into Gerrit and manually add a reviewer that has recently worked on the relevant code. See CONTRIBUTING.md to learn how to upload changes to Gerrit directly.

Additional commits pushed to this PR will update both the PR and the corresponding Gerrit CL. After the review is complete on the CL, your reviewer will merge the CL (automatically closing this PR).

[mraleph]

Please see https://logs.chromium.org/logs/dart/buildbucket/cr-buildbucket/8739802134420221793/+/u/analyze_pkg_/stdout for a build failure which blocked landing.

[copybara-service]

https://dart-review.googlesource.com/c/sdk/+/379980 has been updated with the latest commits from this pull request.

[gmpassos]

... a build failure which blocked landing.

Fixed analyzer warning (now using super parameters) 👍

[kevmoo]

Nice find, @gmpassos !

[gmpassos]

@kevmoo

I'm conducting some optimization experiments with the analyzer and analysis_server packages, BTW:
https://github.com/gmpassos/sdk/tree/optimize-analyzer

If I achieve any significant improvements, I will submit a PR.

Thanks, everyone, for the quick merge!

[gmpassos]

@kevmoo @mraleph

FYI:
https://github.com/gmpassos/sdk/tree/optimize-analyzer

I'm still validating the optimizations with real world projects.