Update to Drupal 8.2.0. For more information, see https://www.drupal.org/project/drupal/releases/8.2.0

core/lib/Drupal/Component/Serialization/YamlSymfony.php

@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\Component\Serialization;
+
+use Drupal\Component\Serialization\Exception\InvalidDataTypeException;
+use Symfony\Component\Yaml\Parser;
+use Symfony\Component\Yaml\Dumper;
+
+/**
+ * Default serialization for YAML using the Symfony component.
+ */
+class YamlSymfony implements SerializationInterface {
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function encode($data) {
+    try {
+      $yaml = new Dumper();
+      $yaml->setIndentation(2);
+      return $yaml->dump($data, PHP_INT_MAX, 0, TRUE, FALSE);
+    }
+    catch (\Exception $e) {
+      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function decode($raw) {
+    try {
+      $yaml = new Parser();
+      // Make sure we have a single trailing newline. A very simple config like
+      // 'foo: bar' with no newline will fail to parse otherwise.
+      return $yaml->parse($raw, TRUE, FALSE);
+    }
+    catch (\Exception $e) {
+      throw new InvalidDataTypeException($e->getMessage(), $e->getCode(), $e);
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getFileExtension() {
+    return 'yml';
+  }
+
+}