0007 — async/await and generators as stackless frames
Choice. Each async function (and generator) becomes a heap frame struct holding its parameters, locals and awaited
promises; step() is the body wrapped in switch (state) with a case after each await/yield (Duff’s device). All
locals live in the frame, so no declaration is jumped over. Awaiting always yields through the microtask queue,
which reproduces Node’s ordering on the conformance suite.
Consequences. No per-coroutine stacks (fits 2 MB consoles). Awaits must appear as statements, initializers, assignments or returns (not in loop conditions or short-circuit branches); the compiler reports the others.