lib/reflect.js
function makeUnwrapping0ArgMethod(primitive) {
  return function builtin() {
    var vHandler = safeWeakMapGet(directProxies, this);
    if (vHandler !== undefined) {
      return builtin.call(vHandler.target);
    } else {
      return primitive.call(this);
    }
  }
}
function makeUnwrapping0ArgMethod(primitive) {
  return function builtin() {
    var vHandler = safeWeakMapGet(directProxies, this);
    if (vHandler !== undefined) {
      return builtin.call(vHandler.target);
    } else {
      return primitive.call(this);
    }
  }
}
returns a new function of zero arguments that recursively unwraps any proxies specified as the |this|-value. The primitive is assumed to be a zero-argument method that uses its |this|-binding.