Performance: cache browserSelection by resolved browserslist

[thoughtspile]

Stylelint is very slow in our projects (1m10s for 1300 files, 8m 3200 files) when using https://github.com/RJWadley/stylelint-no-unsupported-browser-features. After some research, we isolated the issue to doiuse.

I see @cmrn added missingSupportCache in #182 — however, when options.browsers is not provided (the default), CSS file path is used as the cache key, so the cache is not actually shared between files. The benchmark linked master...RJWadley:doiuse:benchmark-2 explictly passses browsers, so it likely mismeasures the perf impact.

browserslist had a similar caching issue, which we just fixed in v4.24.4 with browserslist#862 browserslist#864, so the config resolution should be fine now.

Building upon these enhancements, we can simplify caching: browserslist caches config resolution on its side, and doiuse only caches compileBrowserSupport.

This change speeds up stylelint 8x in our case, from 1m10s to 9s. @cmrn I see you have access to more benchmarks, maybe you could check them as well?

[thoughtspile]

We could also bump browserslist depedendency to ^4.24.4 to ensure latest caching, but it's optional.

[thoughtspile]

Hey @clshortfuse could you take a look?

[clshortfuse]

Hi, thanks for the commit! It would be clearer, though not functionally different, if the cache were part of the class as a static: eg: static #browserSupportCache = new Map();.

[thoughtspile]

✅

[thoughtspile]

Cool, thanks for merging! Could we release this, or do you want to add something?

[thoughtspile]

@clshortfuse would be great to release this!