Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/modules/system/templates/datetime-form.html.twig

@@ -0,0 +1,17 @@
+{#
+/**
+ * @file
+ * Default theme implementation of a datetime form element.
+ *
+ * Available variables:
+ * - attributes: HTML attributes for the datetime form element.
+ * - content: The datelist form element to be output.
+ *
+ * @see template_preprocess_datetime_form()
+ *
+ * @ingroup themeable
+ */
+#}
+<div{{ attributes }}>
+  {{ content }}
+</div>