面试题两则，求指教。。

Question

// ES5

var randy = new Person('Randy', 1995)

console.log(randy) // => {name: "Randy", birth: 1995}

randy.say('Hello') // => 'Randy: Hello'

// es6

var randy = new Person('Randy', 1995)

console.log(randy) // => {name: "Randy", birth: 1995}

randy.say('Hello') // => 'Randy: Hello'

console.log(randy.age) // => 22

randy.birth = 1998

console.log(randy.age) // => 19

分别用es5跟es6实现上面两个类