Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

core/themes/classy/templates/content-edit/file-managed-file.html.twig

@@ -10,6 +10,7 @@
  * @see template_preprocess_file_managed_file()
  */
 #}
+{{ attach_library('classy/file') }}
 {%
   set classes = [
     'js-form-managed-file',

core/themes/classy/templates/content-edit/file-widget.html.twig

@@ -10,6 +10,7 @@
  * @see template_preprocess_file_widget()
  */
 #}
+{{ attach_library('classy/file') }}
 <div{{ attributes }}>
   {{ element }}
 </div>

core/themes/classy/templates/content-edit/filter-caption.html.twig

@@ -12,7 +12,7 @@
  * - string classes: The classes of the captioned HTML tag.
  */
 #}
-<figure class="caption caption-{{ tag }}{%- if classes %} {{ classes }}{%- endif %}">
+<figure role="group" class="caption caption-{{ tag }}{%- if classes %} {{ classes }}{%- endif %}">
 {{ node }}
 <figcaption>{{ caption }}</figcaption>
 </figure>

core/themes/classy/templates/content-edit/image-widget.html.twig

@@ -10,6 +10,7 @@
  * @see template_preprocess_image_widget()
  */
 #}
+{{ attach_library('classy/image-widget') }}
 <div{{ attributes }}>
   {% if data.preview %}
     <div class="image-preview">

core/themes/classy/templates/content-edit/text-format-wrapper.html.twig

@@ -13,7 +13,7 @@
  * @see template_preprocess_text_format_wrapper()
  */
 #}
-<div class="js-text-format-wrapper text-format-wrapper form-item">
+<div class="js-text-format-wrapper text-format-wrapper js-form-item form-item">
   {{ children }}
   {% if description %}
     {%