GetPrototypeOf fails for arrow functions

[calebboyd]

Arrow functions do not have a prototype so this will fail when they are reflected upon.

//GetPrototypeOf
// When O = () => 'abc' this fails
let prototype = O.prototype; //undefined
let prototypeProto = Object.getPrototypeOf(prototype); // throws Uncaught TypeError: Cannot convert undefined or null to object(…)
if (prototypeProto == null || prototypeProto === Object.prototype) {
    return proto;
}

Found when attempting to use an arrow function in and angular2 project with: provide(SomeToken, { useFactory: () => 'abc' })
I'd send a PR but I can't seem to get the tests running.