lib/index.esm.js
function PromiseCapability(C) {
  var resolve, reject;
  this.promise = new C(function ($$resolve, $$reject) {
    if (resolve !== undefined || reject !== undefined) throw TypeError('Bad Promise constructor');
    resolve = $$resolve;
    reject = $$reject;
  });
  this.resolve = _aFunction(resolve);
  this.reject = _aFunction(reject);
}
function PromiseCapability(C) {
  var resolve, reject;
  this.promise = new C(function ($$resolve, $$reject) {
    if (resolve !== undefined || reject !== undefined) throw TypeError('Bad Promise constructor');
    resolve = $$resolve;
    reject = $$reject;
  });
  this.resolve = _aFunction(resolve);
  this.reject = _aFunction(reject);
}
25.4.1.5 NewPromiseCapability(C)