Update to Drupal 8.0.0-rc3. For more information, see https://www.drupal.org/node/2608078

core/modules/shortcut/shortcut.api.php

@@ -26,7 +26,7 @@
  *
  * @param $account
  *   The user account whose default shortcut set is being requested.
- * @return
+ * @return string
  *   The name of the shortcut set that this module recommends for that user, if
  *   there is one.
  */

core/modules/shortcut/src/ShortcutSetStorage.php

@@ -35,8 +35,6 @@ class ShortcutSetStorage extends ConfigEntityStorage implements ShortcutSetStora
    *   The entity info for the entity type.
    * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
    *   The config factory service.
-   * @param \Drupal\Core\Config\StorageInterface $config_storage
-   *   The config storage service.
    * @param \Drupal\Component\Uuid\UuidInterface $uuid_service
    *   The UUID service.
    * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler