Update to drupal-org-drupal 8.0.0-rc2. For more information, see https://www.drupal.org/node/2598668

core/misc/dialog/dialog.ajax.js

@@ -5,7 +5,7 @@
 
 (function ($, Drupal) {
 
-  "use strict";
+  'use strict';
 
   /**
    * Initialize dialogs for Ajax purposes.

core/misc/dialog/dialog.jquery-ui.js

@@ -5,7 +5,7 @@
 
 (function ($) {
 
-  "use strict";
+  'use strict';
 
   $.widget('ui.dialog', $.ui.dialog, {
     options: {

core/misc/dialog/dialog.js

@@ -7,7 +7,7 @@
 
 (function ($, Drupal, drupalSettings) {
 
-  "use strict";
+  'use strict';
 
   /**
    * Default dialog options.

core/misc/dialog/dialog.position.js

@@ -11,7 +11,7 @@
 
 (function ($, Drupal, drupalSettings, debounce, displace) {
 
-  "use strict";
+  'use strict';
 
   // autoResize option will turn off resizable and draggable.
   drupalSettings.dialog = $.extend({autoResize: true, maxHeight: '95%'}, drupalSettings.dialog);