Merge branch 'add-missing-gl-dropdown' into 'master'

Explicitly import gl_dropdown

See merge request gitlab-org/gitlab!16907

app/assets/javascripts/blob/template_selector.js

 /* eslint-disable class-methods-use-this */
 
 import $ from 'jquery';
+import '~/gl_dropdown';
 
 export default class TemplateSelector {
   constructor({ dropdown, data, pattern, wrapper, editor, $input } = {}) {

app/assets/javascripts/create_item_dropdown.js

 import _ from 'underscore';
+import '~/gl_dropdown';
 
 export default class CreateItemDropdown {
   /**

app/assets/javascripts/namespace_select.js

 /* eslint-disable func-names, no-else-return, prefer-template, prefer-arrow-callback */
 
 import $ from 'jquery';
+import '~/gl_dropdown';
 import Api from './api';
 import { mergeUrlParams } from './lib/utils/url_utility';
 import { parseBoolean } from '~/lib/utils/common_utils';

app/assets/javascripts/pages/dashboard/todos/index/todos.js

 /* eslint-disable class-methods-use-this, no-unneeded-ternary */
 
 import $ from 'jquery';
+import '~/gl_dropdown';
 import { visitUrl } from '~/lib/utils/url_utility';
 import UsersSelect from '~/users_select';
 import { isMetaClick } from '~/lib/utils/common_utils';

app/assets/javascripts/pages/search/show/search.js

 import $ from 'jquery';
+import '~/gl_dropdown';
 import Flash from '~/flash';
 import Api from '~/api';
 import { __ } from '~/locale';

app/assets/javascripts/ref_select_dropdown.js

 import $ from 'jquery';
+import '~/gl_dropdown';
 
 class RefSelectDropdown {
   constructor($dropdownButton, availableRefs) {

app/assets/javascripts/sidebar/lib/sidebar_move_issue.js

 import $ from 'jquery';
+import '~/gl_dropdown';
 import _ from 'underscore';
 import { __ } from '~/locale';