Async generator instances should directly extend %AsyncGeneratorPrototype%, not %AsyncIteratorPrototype%

[dead-claudia]

As in, the following should hold when transpiled:

var runtime = require("regenerator-runtime")

async function *foo() {}

var fooPrototype = foo.prototype
var asyncGeneratorPrototype = Object.getPrototypeOf(fooPrototype)
var asyncIteratorPrototype = Object.getPrototypeOf(asyncGeneratorPrototype)

assert.equal(asyncGeneratorPrototype, runtime.AsyncIterator.prototype)

See sections 2.3.10 and 6.4.1 in the proposal.

[benjamn]

Might you have time to submit a pull request for this? I suspect it will be analogous to #264.

[dead-claudia]

I've got other things on my plate, and I don't hardly use async iterators ATM, either.