feat(css-parser): CSS Parser: parse starting-style at rule #1478

[denbezrukov]

Summary

Close #1478

https://drafts.csswg.org/css-transitions-2/#at-ruledef-starting-style

@starting-style {
    rulesets
  }

selector {
 @starting-style {
   declarations
 }
}

Test Plan

cargo test

[netlify]

✅ Deploy Preview for biomejs canceled.

Name	Link
🔨 Latest commit	bed0aa1
🔍 Latest deploy log	https://app.netlify.com/sites/biomejs/deploys/659f0b3e82bbd30008d55f82

[github-actions]

Parser conformance results on

js/262

Test result	main count	This PR count	Difference
Total	49701	49701	0
Passed	48721	48721	0
Failed	980	980	0
Panics	0	0	0
Coverage	98.03%	98.03%	0.00%

jsx/babel

Test result	main count	This PR count	Difference
Total	40	40	0
Passed	37	37	0
Failed	3	3	0
Panics	0	0	0
Coverage	92.50%	92.50%	0.00%

symbols/microsoft

Test result	main count	This PR count	Difference
Total	6322	6322	0
Passed	2036	2036	0
Failed	4286	4286	0
Panics	0	0	0
Coverage	32.20%	32.20%	0.00%

ts/babel

Test result	main count	This PR count	Difference
Total	662	662	0
Passed	592	592	0
Failed	70	70	0
Panics	0	0	0
Coverage	89.43%	89.43%	0.00%

ts/microsoft

Test result	main count	This PR count	Difference
Total	17646	17646	0
Passed	13452	13452	0
Failed	4192	4192	0
Panics	2	2	0
Coverage	76.23%	76.23%	0.00%

[codspeed-hq]

CodSpeed Performance Report

Merging #1518 will not alter performance

_{⚠️ No base runs were found}

_{Falling back to comparing feat/css-starting-style (bed0aa1) with main (352b87d)}

Summary

✅ 93 untouched benchmarks