Perf: Avoid creation of intermediary array when iterating over style rules

[eoghanmurray]

Discovered there's a second mapFn argument of Array.from

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from

[changeset-bot]

🦋 Changeset detected

Latest commit: 9c4c5fe

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 8 packages

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rrweb-snapshot	Patch
rrweb	Patch
rrdom	Patch
rrdom-nodejs	Patch
rrweb-player	Patch
@rrweb/types	Patch
@rrweb/web-extension	Patch
rrvideo	Patch

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[JonasBa]

🥇

[Juice10]

I'm happy to merge this once we have benchmarks running on CI

[JonasBa]

@Juice10 If you plan on doing that in github actions just note that performance may vary quite a lot there. We (sentry) collect performance data and profiles from a lot of our CI runs and we see numbers vary about 30% for the same runners.

[Juice10]

@JonasBa I'm hoping we can do relative benchmarking (more info https://labs.quansight.org/blog/2021/08/github-actions-benchmarks ) to help with this. But it's definitely a valid concern.

I'm not sure if there are any companies like https://buildjet.com that offer dedicated resources for benchmarking.

[JonasBa]

@JonasBa I'm hoping we can do relative benchmarking (more info https://labs.quansight.org/blog/2021/08/github-actions-benchmarks ) to help with this. But it's definitely a valid concern.

I'm not sure if there are any companies like https://buildjet.com that offer dedicated resources for benchmarking.

@Juice10 yes, that is a good approach if you plan on using github's runners as your benchmarking infra. I would probably invest into seeing if it's possible to have an automated workflow that re-runs the benchmarks a few times so that they hopefully run on different runners - this could help improve the signal to noise ratio.

[eoghanmurray]

To note: MooTools versions less than 1.6 add an Array.from to the Array prototype, which doesn't have the second argument; they symptoms are

<style>
[object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSStyleRule][object CSSS

I don't know if we should guard against this similar to #1196 ...