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

core/modules/views/js/views-contextual.js

@@ -0,0 +1,24 @@
+/**
+ * @file
+ * Javascript related to contextual links.
+ */
+
+(function ($) {
+
+  "use strict";
+
+  /**
+   *
+   * @type {Drupal~behavior}
+   */
+  Drupal.behaviors.viewsContextualLinks = {
+    attach: function (context) {
+      var id = $('body').attr('data-views-page-contextual-id');
+
+      $('[data-contextual-id="' + id + '"]')
+        .closest(':has(.view)')
+        .addClass('contextual-region');
+    }
+  };
+
+})(jQuery);