Issue #3420391 by dench0: Fix test failures

Closes #3420391

tests/src/Functional/LoadTest.php

@@ -34,7 +34,7 @@ class LoadTest extends BrowserTestBase {
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'stable';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}