Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/http-kernel/Debug/ErrorHandler.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpKernel\Debug;
+
+@trigger_error('The '.__NAMESPACE__.'\ErrorHandler class is deprecated since version 2.3 and will be removed in 3.0. Use the Symfony\Component\Debug\ErrorHandler class instead.', E_USER_DEPRECATED);
+
+use Symfony\Component\Debug\ErrorHandler as DebugErrorHandler;
+
+/**
+ * ErrorHandler.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @deprecated since version 2.3, to be removed in 3.0. Use the same class from the Debug component instead.
+ */
+class ErrorHandler extends DebugErrorHandler
+{
+}