diff -u b/core/modules/system/lib/Drupal/system/Controller/ThemeListingController.php b/core/modules/system/lib/Drupal/system/Controller/ThemeListingController.php
--- b/core/modules/system/lib/Drupal/system/Controller/ThemeListingController.php
+++ b/core/modules/system/lib/Drupal/system/Controller/ThemeListingController.php
@@ -9,7 +9,7 @@
 
 use Drupal\Core\Controller\ControllerInterface;
 use Drupal\Core\Config\Config;
-use Drupal\Core\Extension\ModuleHandler;
+use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\StringTranslation\TranslationManager;
 use Drupal\Core\Access\CsrfTokenGenerator;
 use Symfony\Component\DependencyInjection\ContainerInterface;
@@ -30,12 +30,12 @@
   /**
    * The module handler service.
    *
-   * @var \Drupal\Core\Extension\ModuleHandler
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
    */
   protected $moduleHandler;
 
   /**
-   * The translation manager service.
+   * The translation service.
    *
    * @var \Drupal\Core\StringTranslation\TranslationManager
    */
@@ -53,14 +53,14 @@
    *
    * @param \Drupal\Core\Config\Config $config
    *  The system.theme config object.
-   * @param \Drupal\Core\Extension\ModuleHandler $module_handler
+   * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
    *  The module handler service.
    * @param \Drupal\Core\StringTranslation\TranslationManager $translation
    *  The translation manager service.
    * @param \Drupal\Core\Access\CsrfTokenGenerator
    *  The Csrf token generator.
    */
-  public function __construct(Config $config, ModuleHandler $module_handler, TranslationManager $translation, CsrfTokenGenerator $token_generator) {
+  public function __construct(Config $config, ModuleHandlerInterface $module_handler, TranslationManager $translation, CsrfTokenGenerator $token_generator) {
     $this->config = $config;
     $this->moduleHandler = $module_handler;
     $this->translation = $translation;
@@ -127,12 +127,12 @@
         // Ensure this theme is compatible with this version of core.
         // Require the 'content' region to make sure the main page
         // content has a common place in all themes.
-        $theme->incompatible_core = !isset($theme->info['core']) || ($theme->info['core'] != DRUPAL_CORE_COMPATIBILITY) || (!isset($theme->info['regions']['content']));
+        $theme->incompatible_core = !isset($theme->info['core']) || ($theme->info['core'] != DRUPAL_CORE_COMPATIBILITY) || !isset($theme->info['regions']['content']);
         $theme->incompatible_php = version_compare(phpversion(), $theme->info['php']) < 0;
         // Confirmed that the base theme is available.
-        $theme->incompatible_base = (isset($theme->info['base theme']) && !isset($themes[$theme->info['base theme']]));
+        $theme->incompatible_base = isset($theme->info['base theme']) && !isset($themes[$theme->info['base theme']]);
         // Confirm that the theme engine is available.
-        $theme->incompatible_engine = (isset($theme->info['engine']) && !isset($theme->owner));
+        $theme->incompatible_engine = isset($theme->info['engine']) && !isset($theme->owner);
       }
       $query['token'] = $this->tokenGenerator->get('system-theme-operation-link');
       $theme->operations = array();