Fixed node imports.

src/core/operations/Checksum.js

@@ -124,7 +124,7 @@ const Checksum = {
      * @returns {string}
      */
     runCRC32: function(input, args) {
-        var crcTable = window.crcTable || (window.crcTable = Checksum._genCRCTable()),
+        var crcTable = global.crcTable || (global.crcTable = Checksum._genCRCTable()),
             crc = 0 ^ (-1);
 
         for (var i = 0; i < input.length; i++) {

src/node/index.js

@@ -5,7 +5,7 @@
  * @copyright Crown Copyright 2017
  * @license Apache-2.0
  */
-import "babel-polyfill";
+require("babel-polyfill");
 
 var Chef = require("../core/Chef.js").default;