fixes for core/tests

Closes #3503741

core/tests/Drupal/FunctionalTests/Asset/AssetOptimizationTest.php

@@ -23,6 +23,8 @@ class AssetOptimizationTest extends BrowserTestBase {
 
   /**
    * The file assets path settings value.
+   *
+   * @var string
    */
   protected $fileAssetsPath;