perf(css_parser): avoid expensive check when parsing an id

[Conaclos]

Summary

Attempt to improve a hot code path (CSS identifier parsing).

Test Plan

CI should pass.

[github-actions]

Parser conformance results on

js/262

Test result	main count	This PR count	Difference
Total	48504	48504	0
Passed	47313	47313	0
Failed	1191	1191	0
Panics	0	0	0
Coverage	97.54%	97.54%	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	6568	6568	0
Passed	2201	2201	0
Failed	4367	4367	0
Panics	0	0	0
Coverage	33.51%	33.51%	0.00%

ts/babel

Test result	main count	This PR count	Difference
Total	671	671	0
Passed	599	599	0
Failed	72	72	0
Panics	0	0	0
Coverage	89.27%	89.27%	0.00%

ts/microsoft

Test result	main count	This PR count	Difference
Total	18417	18417	0
Passed	14099	14099	0
Failed	4318	4318	0
Panics	0	0	0
Coverage	76.55%	76.55%	0.00%

[codspeed-hq]

CodSpeed Performance Report

Merging #3774 will not alter performance

_{Comparing conaclos/improve-css-id-consumption (411a485) with main (70557f2)}

Summary

✅ 99 untouched benchmarks