Remove Babel (#1074)

* Test helpers no longer rely on Babel.

* Behaviours are no longer imported.

* Removed Babel dependency.

* Fixed linter errors.

test/helpers/sign.js

@@ -1,22 +1,28 @@
-import utils from 'ethereumjs-util';
+const utils = require('ethereumjs-util');
 
 /**
  * Hash and add same prefix to the hash that ganache use.
  * @param {string} message the plaintext/ascii/original message
  * @return {string} the hash of the message, prefixed, and then hashed again
  */
-export const hashMessage = (message) => {
+function hashMessage (message) {
   const messageHex = Buffer.from(utils.sha3(message).toString('hex'), 'hex');
   const prefix = utils.toBuffer('\u0019Ethereum Signed Message:\n' + messageHex.length.toString());
   return utils.bufferToHex(utils.sha3(Buffer.concat([prefix, messageHex])));
-};
+}
 
 // signs message using web3 (auto-applies prefix)
-export const signMessage = (signer, message = '', options = {}) => {
+function signMessage (signer, message = '', options = {}) {
   return web3.eth.sign(signer, web3.sha3(message, options));
-};
+}
 
 // signs hex string using web3 (auto-applies prefix)
-export const signHex = (signer, message = '') => {
+function signHex (signer, message = '') {
   return signMessage(signer, message, { encoding: 'hex' });
+}
+
+module.exports = {
+  hashMessage,
+  signMessage,
+  signHex,
 };