Remove Babel (#1074)

* Test helpers no longer rely on Babel.

* Behaviours are no longer imported.

* Removed Babel dependency.

* Fixed linter errors.

test/helpers/expectEvent.js

@@ -1,6 +1,6 @@
 const should = require('chai').should();
 
-const inLogs = async (logs, eventName, eventArgs = {}) => {
+async function inLogs (logs, eventName, eventArgs = {}) {
   const event = logs.find(e => e.event === eventName);
   should.exist(event);
   for (const [k, v] of Object.entries(eventArgs)) {
@@ -8,12 +8,12 @@ const inLogs = async (logs, eventName, eventArgs = {}) => {
     event.args[k].should.eq(v);
   }
   return event;
-};
+}
 
-const inTransaction = async (tx, eventName, eventArgs = {}) => {
+async function inTransaction (tx, eventName, eventArgs = {}) {
   const { logs } = await tx;
   return inLogs(logs, eventName, eventArgs);
-};
+}
 
 module.exports = {
   inLogs,