You cannot set prototype of an object created by Object.create(null)

gistfile1.js

// __proto__ DOES NOT WORK
var foo = Object.create(null);
foo.__proto__ = {
  bar: 'bar'
};
foo;      // { [__proto__]: { bar: 'bar' } }
foo.bar;  // undefined

// __proto__ works
var foo = {};
foo.__proto__ = {
  bar: 'bar'
};
foo;      // { [__proto__]: { bar: 'bar' } }
foo.bar;  // 'bar