Index: core/modules/block/lib/Drupal/block/BlockFormController.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- core/modules/block/lib/Drupal/block/BlockFormController.php	(revision ea72375a15290f9f42d144652590ee78751186f8)
+++ core/modules/block/lib/Drupal/block/BlockFormController.php	(revision )
@@ -14,6 +14,7 @@
 use Drupal\Core\Entity\Query\QueryFactory;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Language\LanguageManager;
+use Drupal\Core\StringTranslation\TranslationManager;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -179,9 +180,9 @@
       $languages = language_list(Language::STATE_ALL);
       $langcodes_options = array();
       foreach ($languages as $language) {
-        // @todo $language->name is not wrapped with t(), it should be replaced
-        //   by CMI translation implementation.
-        $langcodes_options[$language->id] = $language->name;
+        $t = new TranslationManager();
+        $lang = $t->translate($language->name);
+        $langcodes_options[$language->id] = $lang;
       }
       $form['visibility']['language'] = array(
         '#type' => 'details',