refactor Star class to ES module syntax

app/assets/javascripts/dispatcher.js

@@ -22,7 +22,6 @@
 /* global ProjectAvatar */
 /* global CompareAutocomplete */
 /* global ProjectNew */
-/* global Star */
 /* global ProjectShow */
 /* global Labels */
 /* global Shortcuts */
@@ -51,6 +50,7 @@ import UsersSelect from './users_select';
 import RefSelectDropdown from './ref_select_dropdown';
 import GfmAutoComplete from './gfm_auto_complete';
 import ShortcutsBlob from './shortcuts_blob';
+import Star from './star';
 import Todos from './todos';
 import TreeView from './tree';
 import UsagePing from './usage_ping';

app/assets/javascripts/star.js

 /* eslint-disable func-names, space-before-function-paren, wrap-iife, no-unused-vars, one-var, no-var, one-var-declaration-per-line, prefer-arrow-callback, no-new, max-len */
 /* global Flash */
 
-class Star {
+export default class Star {
   constructor() {
     $('.project-home-panel .toggle-star').on('ajax:success', function(e, data, status, xhr) {
       var $starIcon, $starSpan, $this, toggleStar;
@@ -24,5 +24,3 @@ class Star {
     });
   }
 }
-
-window.Star = Star;