Test262 #2: RegExp prototype is missing Symbol.match/replace/split/search/matchAll dispatch (~290 tests)

[nickna]

Motivation

Surfaced during the #69 RegExp folder rollout (commit b968a9e). Test262's RegExp/prototype/Symbol.{match, replace, split, search, matchAll}/* directories test the well-known-symbol-keyed protocol methods that ECMA-262 §22.2.5 mandates on RegExp.prototype.

In SharpTS, r[Symbol.match](...), r[Symbol.replace](...), etc. either runtime-error (interpreter) or produce wrong values (compiler). The named-method API (r.exec(...), 'foo'.replace(/./, ...)) works; the symbol-keyed protocol does not.

Sample failing tests

• test/built-ins/RegExp/prototype/Symbol.match/builtin-coerce-lastindex.js:

  var r = /./y;
  r.lastIndex = '1.9';
  result = r[Symbol.match]('abc');   // RuntimeError: Symbol.match not on RegExp prototype

• test/built-ins/RegExp/prototype/Symbol.replace/arg-1-coerce.js:

  /./[Symbol.replace](arg, 'x');     // RuntimeError

Impact

Bucket	Symbol.match	Symbol.replace	Symbol.split	Symbol.matchAll	Symbol.search	Total
Interp RuntimeError	39	39	29	15	11	133
Compile Fail	35	52	35	15	18	155

Total: ~290 tests across both modes.

Suggested approach

1. Implement the four Symbol-keyed methods on RegExp.prototype per ECMA-262:
   • RegExp.prototype[Symbol.match] (§22.2.5.7)
   • RegExp.prototype[Symbol.replace] (§22.2.5.10)
   • RegExp.prototype[Symbol.search] (§22.2.5.11)
   • RegExp.prototype[Symbol.split] (§22.2.5.13)
   • RegExp.prototype[Symbol.matchAll] (§22.2.5.8)
2. Each must dispatch through RegExpExec so lastIndex coercion works (current named methods may already do this — wire the symbols to the same code path).
3. Compile mode emits the same dispatch — verify the IL path for obj[Symbol.X](...) properly resolves the symbol-keyed slot rather than falling through to a string-keyed lookup.

Acceptance

• All 290 tests above flip out of RuntimeError/Fail to Pass or to a more specific bucket.
• String.prototype.{match, replace, search, split, matchAll} continue to delegate through the symbol protocol on a regex argument (existing behavior preserved).
• No regressions in String/prototype/* or RegExp/prototype/* baselines.

Related

Part of #69. Sibling cluster issues filed concurrently.