这样分配对象属性。怎么回事，我不明白（还）

Question

以下是MDN的代码段：

class Person {
      constructor(first, last, age, gender, interests) {
        this.name = {  //I don't understand these lines
          first,       //I don't understand these lines
          last         //I don't understand these lines
        };
        this.age = age;
        this.gender = gender;
        this.interests = interests;
      }

我理解这一点：

this.name = {  
   first: first,     
   last: last     
}

但不是第一个。有人可以对我解释一下吗？