[eslint-plugin] Add overflow/overscrollBehavior shorthand expansion to stylex-valid-shorthands

[abhakat]

What changed / motivation ?

Expand overflow and overscrollBehavior two-value shorthands into X/Y longhands.

• overflow: 'hidden scroll' → overflowX: 'hidden' + overflowY: 'scroll'
• overscrollBehavior: 'contain auto' → overscrollBehaviorX: 'contain' + overscrollBehaviorY: 'auto'
• Single values pass through unchanged

Linked PR/Issues

Follow-up to #1553, #1552

Additional Context

Tests covering: single-value passthrough, 2-value X/Y expansion, identical values,
!important propagation.

Pre-flight checklist

• I have read the contributing guidelines
  Contribution Guidelines
• Performed a self-review of my code

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
stylex	Skipped		Apr 6, 2026 6:18pm

[github-actions]

workflow: benchmarks/perf

Comparison of performance test results, measured in operations per second. Larger is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.zVo71UBspS /tmp/tmp.SFDj4H78qR

Results	Base	Patch	Ratio
babel-plugin: stylex.create
· basic create	538	556	1.03	+
· complex create	66	66	1.00
babel-plugin: stylex.createTheme
· basic themes	435	437	1.00	+
· complex themes	34	34	1.00
Done in 0.08s.
Done in 0.32s.

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.
yarn workspace v1.22.22
yarn run v1.22.22
$ node ./compare.js /tmp/tmp.gvymgQLJPd /tmp/tmp.LU84fBhGsx

Results	Base	Patch	Ratio
@stylexjs/stylex/lib/cjs/stylex.js
· compressed	1,441	1,441	1.00
· minified	4,386	4,386	1.00
@stylexjs/stylex/lib/cjs/inject.js
· compressed	1,793	1,793	1.00
· minified	4,915	4,915	1.00
benchmarks/size/.build/bundle.js
· compressed	496,650	496,650	1.00
· minified	4,847,840	4,847,840	1.00
benchmarks/size/.build/stylex.css
· compressed	99,653	99,653	1.00
· minified	747,850	747,850	1.00
Done in 0.08s.
Done in 0.33s.