原型对象的constructor

Question

function Super(){

    this.name = "this is super";

}

Super.prototype = {

    say:function(){

        console.log(this.name);

    }

}

function Sub(){

    this.name = "this is sub";

}

Sub.prototype = new Super();

var o = new Sub();

o.say(); //this is sub

实例 o 的原型对象的constructor是Super，那么 this.name 应该是Super的构造函数。但是输出是 this is sub