Remove dropzoneInput from global namespace

app/assets/javascripts/blob/blob_file_dropzone.js

 /* eslint-disable func-names, object-shorthand, prefer-arrow-callback */
-/* global Dropzone */
-
+import Dropzone from 'dropzone';
 import '../lib/utils/url_utility';
 import { HIDDEN_CLASS } from '../lib/utils/constants';
 import csrf from '../lib/utils/csrf';

app/assets/javascripts/gl_form.js

-/* global DropzoneInput */
 /* global autosize */
 
 import GfmAutoComplete from './gfm_auto_complete';
+import dropzoneInput from './dropzone_input';
 
 export default class GLForm {
   constructor(form, enableGFM = false) {
@@ -41,7 +41,7 @@ export default class GLForm {
         mergeRequests: this.enableGFM,
         labels: this.enableGFM,
       });
-      new DropzoneInput(this.form); // eslint-disable-line no-new
+      dropzoneInput(this.form);
       autosize(this.textarea);
     }
     // form and textarea event listeners

app/assets/javascripts/notes.js

@@ -13,7 +13,6 @@ import $ from 'jquery';
 import _ from 'underscore';
 import Cookies from 'js-cookie';
 import autosize from 'vendor/autosize';
-import Dropzone from 'dropzone';
 import 'vendor/jquery.caret'; // required by jquery.atwho
 import 'vendor/jquery.atwho';
 import AjaxCache from '~/lib/utils/ajax_cache';
@@ -22,13 +21,11 @@ import CommentTypeToggle from './comment_type_toggle';
 import GLForm from './gl_form';
 import loadAwardsHandler from './awards_handler';
 import './autosave';
-import './dropzone_input';
 import TaskList from './task_list';
 import { ajaxPost, isInViewport, getPagePath, scrollToElement, isMetaKey } from './lib/utils/common_utils';
 import imageDiffHelper from './image_diff/helpers/index';
 
 window.autosize = autosize;
-window.Dropzone = Dropzone;
 
 function normalizeNewlines(str) {
   return str.replace(/\r\n/g, '\n');

app/assets/javascripts/zen_mode.js

@@ -11,8 +11,6 @@ import Dropzone from 'dropzone';
 import 'mousetrap';
 import 'mousetrap/plugins/pause/mousetrap-pause';
 
-window.Dropzone = Dropzone;
-
 //
 // ### Events
 //

spec/javascripts/blob/blob_file_dropzone_spec.js

-import 'dropzone';
 import BlobFileDropzone from '~/blob/blob_file_dropzone';
 
 describe('BlobFileDropzone', () => {

spec/javascripts/zen_mode_spec.js

 /* eslint-disable space-before-function-paren, no-var, one-var, one-var-declaration-per-line, object-shorthand, comma-dangle, no-return-assign, new-cap, max-len */
-/* global Dropzone */
 /* global Mousetrap */
-
+import Dropzone from 'dropzone';
 import ZenMode from '~/zen_mode';
 
 (function() {