2.4.16.4 Properties of the Enumerator Prototype Object

The Enumerator prototype object is itself an Enumerator object with a [[Collection]] property of undefined, and which does not have an [[EnumerationState]] property.

The value of the internal [[Prototype]] internal property of the Enumerator prototype object is the Object prototype object ([ECMA-262/5] Section 15.2.3.1).