This adds a single new method, which acts like sendAsyncMessage, but
also returns a promise. This promise is fulfilled when the promise
returned from the receiveMessage callback is resolved.
```
partial interface JSWindowActor {
[Throws]
Promise<any> sendQuery(DOMString messageName,
optional any obj,
optional any transfers);
}
```
Differential Revision: https://phabricator.services.mozilla.com/D27809
--HG--
extra : moz-landing-system : lando