Remove duplicate "validationError" function

Author: mariusschulz

lib/es6-promise/enumerator.js

@@ -20,10 +20,6 @@ import originalResolve from './promise/resolve';
 import originalThen from './then';
 import { makePromise, PROMISE_ID } from './-internal';
 
-function validationError() {
-  return new Error('Array Methods must be provided an Array');
-}
-
 function validationError() {
   return new Error('Array Methods must be provided an Array');
 };