WebStorm / AsyncGeneratorMethod syntax highlighting in flow

When i set `JavaScript language version` to `ECMAScript 6`, highlighting is OK

But when I use `Flow`, highlighting breaks down(expecting newline or semilicon)

class SomeIterable {
    async* [Symbol.asyncIterator]() {
        yield await 1;
        yield await 2;
    }

    async* foo() {
        yield await 1;
        yield await 2;
    }
}

 I use WebStorm 2017.2.5