implement the `new` keyword

JavScript new.js

function myNew(constructor, ...args) {
  const self = {};
  self.__proto__ = constructor.prototype;
  const obj = constructor.apply(self, args);
  // 构造函数返回对象或者函数时，直接返回
  if (typeof obj === 'object' || typeof obj === 'function') {
    return obj;
  }
  return self;
}