[NathanColosimo]

Summary

Fixes #2260. Related: expo/expo#51842 (breaks @orpc/client in Expo apps). The failing code in oRPC is here: https://github.com/middleapi/orpc/blob/f198f7474d5cbea613b5bff7f0656fc4e35a1c2a/packages/client/src/client.ts#L24-L28

async (...[a, b]) => {} fails with error: invalid destructuring target.

Async arrow heads are parsed as a call expression, so the rest parameter arrives in reparseArrowParameters as a SpreadElement. That branch wrapped spread->_argument in a RestElementNode without reparsing it, which left an ArrayExpression/ObjectExpression that SemanticResolver rejects.

The fix reparses the argument with reparseAssignmentPattern(..., /*inDecl*/ true), the same way other arrow parameters and array-pattern rest elements are handled. Side effect: async (...(a)) => {} is now a SyntaxError, matching the sync arrow form and the spec. It was previously accepted.

Test Plan

Added test/hermes/async-arrow-rest-pattern.js, which covers array, object, and nested rest patterns, a leading parameter, and a throwing default that becomes a rejection. It runs with the default, -O, and -lazy.

Repro (repro.js):

var f = async (...[input, options = {}]) => input;
f("ok").then(print);

Before (static_h @ e760a68):

$ build/bin/hermes repro.js
repro.js:1:19: error: invalid destructuring target

After:

$ build/bin/hermes repro.js
ok
$ build/bin/hermes -lazy repro.js
ok

Invalid forms still error: async (...a, b) => 0 (rest parameter must be last), async (...a = 1) => 0, async (...await) => 0. Calls like async(...[1, 2]) are unchanged.

cmake --build build --target check-hermes (Release, macOS arm64): 4126 expected passes, 6 expected failures, 188 unsupported, 0 unexpected failures.

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