diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/TaxonomyRouteController.php b/core/modules/taxonomy/lib/Drupal/taxonomy/TaxonomyRouteController.php
index 5ca4134..396dbfb 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/TaxonomyRouteController.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/TaxonomyRouteController.php
@@ -7,8 +7,6 @@
 
 namespace Drupal\taxonomy;
 
-use Drupal\taxonomy\Term;
-use Drupal\taxonomy\Vocabulary;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\JsonResponse;
 
@@ -22,13 +20,13 @@ class TaxonomyRouteController {
    *
    * This callback outputs term name suggestions in response to Ajax requests
    * made by the taxonomy autocomplete widget for taxonomy term reference
-   * fields. The output is a JSON object of plain-text term suggestions, keyed by
-   * the user-entered value with the completed term name appended.  Term names
-   * containing commas are wrapped in quotes.
+   * fields. The output is a JSON object of plain-text term suggestions, keyed
+   * by the user-entered value with the completed term name appended.  Term
+   * names containing commas are wrapped in quotes.
    *
-   * For example, suppose the user has entered the string 'red fish, blue' in the
-   * field, and there are two taxonomy terms, 'blue fish' and 'blue moon'. The
-   * JSON output would have the following structure:
+   * For example, suppose the user has entered the string 'red fish, blue' in
+   * the field, and there are two taxonomy terms, 'blue fish' and 'blue moon'.
+   * The JSON output would have the following structure:
    * @code
    *   {
    *     "red fish, blue fish": "blue fish",
@@ -36,9 +34,9 @@ class TaxonomyRouteController {
    *   };
    * @endcode
    *
-   * @param $field_name
+   * @param string $field_name
    *   The name of the term reference field.
-   * @param $tags_typed
+   * @param string $tags_typed
    *   (optional) A comma-separated list of term names entered in the
    *   autocomplete form element. Only the last term is used for autocompletion.
    *   Defaults to '' (an empty string).
@@ -47,22 +45,23 @@ class TaxonomyRouteController {
    * @see taxonomy_field_widget_info()
    */
   public function autocomplete($field_name, $tags_typed = '') {
-    // If the request has a '/' in the search text, then the menu system will have
-    // split it into multiple arguments, recover the intended $tags_typed.
+    // If the request has a '/' in the search text, then the menu system
+    // will have split it into multiple arguments, recover the intended
+    // $tags_typed.
     $args = func_get_args();
     // Shift off the $field_name argument.
-    array_shift($args);
+    unset($args[0]);
     $tags_typed = implode('/', $args);
 
     // Make sure the field exists and is a taxonomy field.
     if (!($field = field_info_field($field_name)) || $field['type'] !== 'taxonomy_term_reference') {
       // Error string. The JavaScript handler will realize this is not JSON and
       // will display it as debugging information.
-      print t('Taxonomy field @field_name not found.', array('@field_name' => $field_name));
-      exit;
+      return new Response(t('Taxonomy field @field_name not found.', array('@field_name' => $field_name)));
     }
 
-    // The user enters a comma-separated list of tags. We only autocomplete the last tag.
+    // The user enters a comma-separated list of tags. We only autocomplete
+    // the last tag.
     $tags_typed = drupal_explode_tags($tags_typed);
     $tag_last = drupal_strtolower(array_pop($tags_typed));