Implement async/await for bytecode VM with code review fixes (§3.3)
Add full async/await support: parser recognizes async functions, arrows,
methods, and await expressions; compiler emits MakeAsyncFunction/Await
opcodes; runtime reuses generator suspension with Promise-based
auto-advancement via microtask queue. All await resumptions go through
microtasks per ECMAScript §27.7.5.3 for correct ordering. Includes
adversarial code review fixes (18 issues: correct await precedence,
async_depth leak guard, rejection type preservation, compiler-level
await validation, typed async resume detection). 27 integration tests
in tests/js_async.rs cover all acceptance criteria. Demotes 125
pre-existing false-positive Test262 full-suite entries.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
b43cd2d58b