Update code-prettify dart highlighting

[parlough]

I noticed there were a lot of old and new keywords missing or highlighted wrong on the website, so I went ahead and added everyone I found to be missing. I made this PR on the code-prettify repository as well, but it seems maintenance is quite slow over there, so I made it here as well. I'll make any requested changes in both locations and can always update again when upstream changes are made.

You can find the other PR here with some more information: googlearchive/code-prettify#592

[kwalrath]

Thank you so much, @parlough! This looks great to me, but I should get a DPE to take a look, just to be sure.

[johnpryan]

LGTM. Thanks for the contribution!

[ycvzyl-star]

2025-08-05T12:24:49.800Z | | | | -- defaults@1.0.4 2025-08-05T12:24:49.802Z | | | | -- clone@1.0.4
2025-08-05T12:24:49.804Z | | | +-- run-async@2.4.1
2025-08-05T12:24:49.806Z | | | +-- rxjs@7.8.2
2025-08-05T12:24:49.808Z | | | | -- tslib@2.8.1 deduped 2025-08-05T12:24:49.810Z | | | +-- string-width@4.2.3 2025-08-05T12:24:49.812Z | | | | +-- emoji-regex@8.0.0 2025-08-05T12:24:49.814Z | | | | +-- is-fullwidth-code-point@3.0.0 2025-08-05T12:24:49.816Z | | | | -- strip-ansi@6.0.1 deduped
2025-08-05T12:24:49.817Z | | | +-- strip-ansi@6.0.1
2025-08-05T12:24:49.819Z | | | | -- ansi-regex@5.0.1 2025-08-05T12:24:49.821Z | | | +-- through@2.3.8 2025-08-05T12:24:49.823Z | | | -- wrap-ansi@6.2.0
2025-08-05T12:24:49.825Z | | | +-- ansi-styles@4.3.0 deduped