Spec-correct CSS Flexbox §4.5 auto-min-size opt-in on YGConfig (re-land) (#57015)

[adityasharat]

Summary:
X-link: facebook/yoga#1968

Re-land of D105720159, originally reverted (revert: 0e642b96c7e2) due to a latent NPE in ReactProgressBarViewManager.kt and Instagram-internal ReactSwitchManager.kt — both fixed in the prior diffs in this stack. Crash and broken e2e tests reported in T273821098 / P2359486686.

This re-land additionally fixes a correctness gap in the original D105720159 design: it claimed "Default configs carry the bit (preserves today's behaviour); existing trees see no change" — but LayoutConformance::Strict in YogaLayoutableShadowNode::resolveErrata returned YGErrataNone, which clears every errata bit including the new MinSizeUndefinedInsteadOfAuto (bit 8). Since react-strict-dom sets experimental_layoutConformance="strict" on every native View, this implicitly opts every RSD-using surface into the new auto-min probe. That's the exact path Airwave's tests took to hit the original NPE.

Change: LayoutConformance::Strict now returns YGErrataMinSizeUndefinedInsteadOfAuto instead of YGErrataNone. Strict mode keeps every other CSS conformance behavior intact; only the new auto-min feature stays opt-in via explicit YGConfig setup. This matches the design pattern Litho uses in the child diff (ComponentsConfiguration.useAutoMinSize flag, gated independently of any strict-mode plumbing).

Original summary follows:

X-link: facebook/yoga#1966

Implements CSS Flexbox §4.5 automatic minimum sizing in Yoga. When opted in on a YGConfig, every flex item whose main-axis min-{width,height} is undefined receives a content-derived floor — min(min-content, specified-size, max-size) plus any aspect-ratio-transferred lower bound — so it cannot shrink below the size CSS browsers would honor.

How to opt in: clear the new YGErrataMinSizeUndefinedInsteadOfAuto errata bit on the config. Default configs carry the bit (preserves today's behaviour); existing trees see no change. The bit is added to YGErrataClassic so consumers using that constant continue to get the same default. LayoutConformance::Strict also keeps the bit set — the new feature is strictly opt-in, not inferred from strict-mode CSS conformance.

See D105720159 for full details on precedence rules, container recursion semantics, and per-item opt-outs.

Changelog:
[General][Added] - Add CSS Flexbox §4.5 automatic minimum sizing. Opt in by clearing the new YGErrataMinSizeUndefinedInsteadOfAuto errata bit on YGConfig.

Differential Revision: D107183851

[meta-codesync]

@adityasharat has exported this pull request. If you are a Meta employee, you can view the originating Diff in D107183851.

[meta-codesync]

This pull request has been merged in b766986.

[react-native-bot]

This pull request was successfully merged by @adityasharat in b766986

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