for await of loops don't call AsyncIterator.return() on early exit

[martinbirks]

Bug Report

🔎 Search Terms

Async return AsyncIterator

🕗 Version & Regression Information

• This changed between versions 4.8.4 and 4.9.5

⏯ Playground Link

Playground link with relevant code

💻 Code

const LIMIT = 3;

const asyncIterable = {
  [Symbol.asyncIterator]() {
    let i = 0;
    return {
      next() {
        const done = i === LIMIT;
        const value = done ? undefined : i++;
        return Promise.resolve({ value, done });
      },
      return() {
        console.log("RETURN");
        // This will be reached if the consumer called 'break' or 'return' early in the loop.
        return { done: true, value: undefined };
      },
    };
  },
};

(async () => {
  for await (const num of asyncIterable) {
    console.log(num);
    break;
  }
})();

🙁 Actual behavior

Outputted "0", the return function of the async iterator was never called.

🙂 Expected behavior

Output "0" and "RETURN" to the log. This would show that the return() function was called.

[fatcerberus]

Possibly related to #50525