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

vendor/behat/mink-goutte-driver/tests/GoutteConfig.php

@@ -0,0 +1,26 @@
+<?php
+
+namespace Behat\Mink\Tests\Driver;
+
+use Behat\Mink\Driver\GoutteDriver;
+
+class GoutteConfig extends AbstractConfig
+{
+    public static function getInstance()
+    {
+        return new self();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function createDriver()
+    {
+        return new GoutteDriver();
+    }
+
+    protected function supportsJs()
+    {
+        return false;
+    }
+}