diff --git a/core/lib/Drupal/Core/Template/TwigEnvironment.php b/core/lib/Drupal/Core/Template/TwigEnvironment.php
index a126b398a9..05a66dd581 100644
--- a/core/lib/Drupal/Core/Template/TwigEnvironment.php
+++ b/core/lib/Drupal/Core/Template/TwigEnvironment.php
@@ -36,10 +36,13 @@ class TwigEnvironment extends \Twig_Environment {
    */
   protected $templateClasses;
 
+  /**
+   * The template cache filename prefix.
+   *
+   * @var string
+   */
   protected $twigCachePrefix = '';
 
-  protected $templateClassPrefix = '__TwigTemplate_';
-
   /**
    * Constructs a TwigEnvironment object and stores cache and storage
    * internally.
diff --git a/core/lib/Drupal/Core/Template/TwigTransTokenParser.php b/core/lib/Drupal/Core/Template/TwigTransTokenParser.php
index 4c1741ba5e..a7c0c785d2 100644
--- a/core/lib/Drupal/Core/Template/TwigTransTokenParser.php
+++ b/core/lib/Drupal/Core/Template/TwigTransTokenParser.php
@@ -54,6 +54,9 @@ public function parse(\Twig_Token $token) {
 
   /**
    * Detect a 'plural' switch or the end of a 'trans' tag.
+   *
+   * @param \Twig_Token $token
+   *   The token to check to detect the start of subparsing.
    */
   public function decideForFork(\Twig_Token $token) {
     return $token->test(['plural', 'endtrans']);
@@ -61,6 +64,9 @@ public function decideForFork(\Twig_Token $token) {
 
   /**
    * Detect the end of a 'trans' tag.
+   *
+   * @param \Twig_Token $token
+   *   The token to check to detect the end of a 'trans' tag.
    */
   public function decideForEnd(\Twig_Token $token) {
     return $token->test('endtrans');
diff --git a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
index ddd38b8fc2..f255e4c907 100644
--- a/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
+++ b/core/tests/Drupal/Tests/Core/Template/TwigExtensionTest.php
@@ -10,20 +10,6 @@
 use Drupal\Core\Template\TwigExtension;
 use Drupal\Core\Url;
 use Drupal\Tests\UnitTestCase;
-/*
-if (!function_exists(__NAMESPACE__ . 't')) {
-
-  function t($string, array $args = []) {
-    return strtr($string, $args);
-  }
-
-}
-if (!function_exists(__NAMESPACE__ . 'file_create_url')) {
-
-  function file_create_url() {
-  }
-
-}*/
 
 /**
  * Tests the twig extension.