Yield delegation fails for class instance of async iterable

[OliverJAsh]

TS 2.3 RC

{
    const iterable: Iterable<number> = {
        [Symbol.iterator]: () => 1 as any as Iterator<number>
    }

    const asyncIterable: AsyncIterable<number> = {
        [Symbol.asyncIterator]: () => 1 as any as AsyncIterator<number>
    }

    class AsyncIterable2 implements AsyncIterable<number> {
        [Symbol.asyncIterator] = () => 1 as any as AsyncIterator<number>
    }

    const asyncIterable2 = new AsyncIterable2()

    const gen = async function*(): AsyncIterator<number> {
        yield 0;
        yield* [1]
        yield* iterable
        yield* asyncIterable
        yield* asyncIterable2 // Error: The type returned by the 'next()' method of an iterator must have a 'value' property.
    }

    gen()
}

I would expect asyncIterable2 to work, but it errors. See code comment above.

I'm using type assertions because the values don't matter so much, just trying to prove the types should fit together.

[rbuckton]

This is a duplicate of #14442.