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

vendor/symfony/http-kernel/DependencyInjection/ConfigurableExtension.php

@@ -0,0 +1,45 @@
+<?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\DependencyInjection;
+
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+
+/**
+ * This extension sub-class provides first-class integration with the
+ * Config/Definition Component.
+ *
+ * You can use this as base class if you
+ *
+ *    a) use the Config/Definition component for configuration
+ *    b) your configuration class is named "Configuration" and
+ *    c) the configuration class resides in the DependencyInjection sub-folder
+ *
+ * @author Johannes M. Schmitt <schmittjoh@gmail.com>
+ */
+abstract class ConfigurableExtension extends Extension
+{
+    /**
+     * {@inheritdoc}
+     */
+    final public function load(array $configs, ContainerBuilder $container)
+    {
+        $this->loadInternal($this->processConfiguration($this->getConfiguration($configs, $container), $configs), $container);
+    }
+
+    /**
+     * Configures the passed container according to the merged configuration.
+     *
+     * @param array            $mergedConfig
+     * @param ContainerBuilder $container
+     */
+    abstract protected function loadInternal(array $mergedConfig, ContainerBuilder $container);
+}