原型链在Chrome和Mozilla中的印刷方式不同

Question

我有一个示例程序，我测试三个对象的原型链。当我在Mozilla中输入脚本时，它会给出预期的输出：

Object { constructor: John() }
Object { constructor: Employee() }
Object { run: Person.prototype.run(), … }
Object { … }

Chrome中的相同程序会提供此输出：

Employee {constructor: ƒ}
Person {constructor: ƒ}
{run: ƒ, constructor: ƒ}
{constructor: ƒ, __defineGetter__: ƒ, __defineSetter__: ƒ, hasOwnProperty: ƒ, __lookupGetter__: ƒ, …}

为什么会出现这种差异？究竟发生了什么？这是代码：

function Person() {
    this.age = 15;
    this.year_born = 1996;
}

Person.prototype.run = function () {
    console.log("running");

}

function Employee() {
    Person.call(this);
    this.salary = 600;
}

Employee.prototype = Object.create(Person.prototype);
Employee.prototype.constructor = Employee;

function John() {
    Employee.call(this);
    this.wife = "Jenny";
}

John.prototype = Object.create(Employee.prototype);
John.prototype.constructor = John;

var per = new Person();
var emp = new Employee();
var john = new John();

for (var prot = Object.getPrototypeOf(john); prot != null; prot = Object.getPrototypeOf(prot)) {
    console.log(prot);
}