Remove jshint esnext: http://jshint.com/docs/options/#esnext and use esversion: 6

.jshintrc

@@ -0,0 +1,3 @@
+{
+  "esversion": 6
+}

assets/scripts/App.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import { APP_NAME, $document, $pjaxWrapper } from './utils/environment';
 
 import globals from './globals';

assets/scripts/globals.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import TransitionManager from './transitions/TransitionManager';
 
 export default function(firstBlood) {

assets/scripts/modules.js

@@ -1,2 +1 @@
-/* jshint esnext: true */
 export {default as Example} from './modules/Example';

assets/scripts/modules/AbstractModule.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 let uid = 0;
 
 /**

assets/scripts/modules/Example.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import { APP_NAME } from '../utils/environment';
 import AbstractModule from './AbstractModule';
 

assets/scripts/transitions/TransitionManager.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import { APP_NAME, $document, $html, isDebug, $pjaxWrapper, $window } from '../utils/environment';
 import { EVENT as APP_EVENT } from '../App';
 

assets/scripts/utils/scrollTo.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import { isNumeric } from './is'
 
 let isAnimating = false;

assets/scripts/utils/visibility.js

@@ -1,4 +1,3 @@
-/* jshint esnext: true */
 import { isFunction } from './is';
 import { arrayContains, findByKeyValue, removeFromArray } from './array';
 import { $document, $window, $html, $body } from './environment';