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

core/modules/action/src/ActionEditForm.php

@@ -0,0 +1,15 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\action\ActionEditForm.
+ */
+
+namespace Drupal\action;
+
+/**
+ * Provides a form for action edit forms.
+ */
+class ActionEditForm extends ActionFormBase {
+
+}