migrate projects:merge_requests:edit to static bundle

app/assets/javascripts/dispatcher.js

@@ -49,12 +49,7 @@ var Dispatcher;
         case 'projects:issues:new':
         case 'projects:issues:edit':
         case 'projects:merge_requests:creations:diffs':
-          shortcut_handler = true;
-          break;
         case 'projects:merge_requests:edit':
-          import('./pages/projects/merge_requests/edit')
-            .then(callDefault)
-            .catch(fail);
           shortcut_handler = true;
           break;
         case 'projects:tags:new':

app/assets/javascripts/pages/projects/merge_requests/edit/index.js

 import initMergeRequest from '~/pages/projects/merge_requests/init_merge_request';
 
-export default initMergeRequest;
+document.addEventListener('DOMContentLoaded', initMergeRequest);