migrate projects:branches:new to static bundle

app/assets/javascripts/dispatcher.js

@@ -48,16 +48,6 @@ var Dispatcher;
         case 'projects:issues:show':
           shortcut_handler = true;
           break;
-        case 'projects:branches:new':
-          import('./pages/projects/branches/new')
-            .then(callDefault)
-            .catch(fail);
-          break;
-        case 'projects:branches:create':
-          import('./pages/projects/branches/new')
-            .then(callDefault)
-            .catch(fail);
-          break;
         case 'projects:branches:index':
           import('./pages/projects/branches/index')
             .then(callDefault)

app/assets/javascripts/pages/projects/branches/new/index.js

 import NewBranchForm from '~/new_branch_form';
 
-export default () => new NewBranchForm($('.js-create-branch-form'), JSON.parse(document.getElementById('availableRefs').innerHTML));
+document.addEventListener('DOMContentLoaded', () => (
+  new NewBranchForm($('.js-create-branch-form'), JSON.parse(document.getElementById('availableRefs').innerHTML))
+));