Update to Drupal 8.2.6. For more information, see https://www.drupal.org/project/drupal/releases/8.2.6

vendor/symfony/css-selector/XPath/Extension/NodeExtension.php

@@ -50,7 +50,7 @@ class NodeExtension extends AbstractExtension
      * @param int  $flag
      * @param bool $on
      *
-     * @return NodeExtension
+     * @return $this
      */
     public function setFlag($flag, $on)
     {

vendor/symfony/css-selector/XPath/Translator.php

@@ -70,9 +70,6 @@ class Translator implements TranslatorInterface
      */
     private $attributeMatchingTranslators = array();
 
-    /**
-     * Constructor.
-     */
     public function __construct(ParserInterface $parser = null)
     {
         $this->mainParser = $parser ?: new Parser();
@@ -149,7 +146,7 @@ class Translator implements TranslatorInterface
      *
      * @param Extension\ExtensionInterface $extension
      *
-     * @return Translator
+     * @return $this
      */
     public function registerExtension(Extension\ExtensionInterface $extension)
     {
@@ -185,7 +182,7 @@ class Translator implements TranslatorInterface
      *
      * @param ParserInterface $shortcut
      *
-     * @return Translator
+     * @return $this
      */
     public function registerParserShortcut(ParserInterface $shortcut)
     {
@@ -268,9 +265,9 @@ class Translator implements TranslatorInterface
      * @param string    $attribute
      * @param string    $value
      *
-     * @throws ExpressionErrorException
-     *
      * @return XPathExpr
+     *
+     * @throws ExpressionErrorException
      */
     public function addAttributeMatching(XPathExpr $xpath, $operator, $attribute, $value)
     {

vendor/symfony/css-selector/XPath/XPathExpr.php

@@ -66,7 +66,7 @@ class XPathExpr
     /**
      * @param $condition
      *
-     * @return XPathExpr
+     * @return $this
      */
     public function addCondition($condition)
     {
@@ -84,7 +84,7 @@ class XPathExpr
     }
 
     /**
-     * @return XPathExpr
+     * @return $this
      */
     public function addNameTest()
     {
@@ -97,7 +97,7 @@ class XPathExpr
     }
 
     /**
-     * @return XPathExpr
+     * @return $this
      */
     public function addStarPrefix()
     {
@@ -112,7 +112,7 @@ class XPathExpr
      * @param string    $combiner
      * @param XPathExpr $expr
      *
-     * @return XPathExpr
+     * @return $this
      */
     public function join($combiner, XPathExpr $expr)
     {