.__proto__.constructor vs .constructor

proto.js

var A = function A() {};
var B = function B() {};
B.prototype = new A();
// B.prototype.constructor = B; // only way I can find to get bi's constructor to be B. Comment or uncomment this line to produce exactly the same output for both tests. It doesn't matter.
// require('util').inherits(B, A); // same here. Comment or uncomment it doesn't make a difference.

var ai = new A();
var bi = new B();

console.log('Test 1: constructor directly');
console.log(ai.constructor.name);
console.log(bi.constructor.name);
console.log('');
console.log('Test 2: constructor through __proto__');
console.log(ai.__proto__.constructor.name);
console.log(bi.__proto__.constructor.name);