Changed property descriptor for Array.includes polyfill (#1134)

* changed property descriptor for Array.includes polyfill

* replaced defineProperty with shim

* removed Array.includes existance checking

Author: zwug

lib/polyfills.js

@@ -1,9 +1,8 @@
 'use strict';
 
 /* polyfills for Node 4.8.x users */
-/* eslint no-extend-native: off, global-require: off */
 
 // [email protected] uses [].includes
-if (!Array.prototype.includes) {
-  Array.prototype.includes = require('array-includes');
-}
+const includes = require('array-includes');
+
+includes.shim();