使用pretotype，call实现完美继承
父类：
fuction Animal(name){
this.name=name||"Animal";
this.sleep=function(){
console.log(this.name + '正在睡觉！');
}
}
Animal.prototype.eat=function(food){
console.log(this.name + '正在吃：'+ food);
}
寄生组合继承：
function Cat(name){
Animal.call(this);
this.name=name||"Tom";
}
(function{
var Super=fuction(){};
Super.prototype=Animal.Pretotype;
Cat.prototype=new Super();
})();
var cat=new Cat();
console.log(cat.name);
console.log(cat.sleep());
console.log(cat instanceof Animal);