domenic

var p0 = Promise.cast(null);
var p1 = p0.then(() => remotePromise);
var p2 = p1.invoke("foo");

line 2 calls remotePromise's .then method, like so:
  remotePromise.then(v => { set p1's [[Value]] to v }, r => { set p1's [[Reason]] to r })
it ALSO stores remotePromise in [[Following]]

Once remotePromise settles, i.e. once one of the two above callbacks gets called,
[[Following]] gets cleared.

gist:6399102

// This module uses AP2 as its starting point:
// https://github.com/domenic/promises-unwrapping

var hasOwn = Function.prototype.call.bind(Object.prototype.hasOwnProperty);

function mixin(a, b) {
  Object.keys(b).forEach(function(key) {
    a[key] = b[key];
  });
  return a;