diff -u b/core/lib/Drupal/Core/Theme/Registry.php b/core/lib/Drupal/Core/Theme/Registry.php
--- b/core/lib/Drupal/Core/Theme/Registry.php
+++ b/core/lib/Drupal/Core/Theme/Registry.php
@@ -236,7 +236,7 @@
   public function getRuntime() {
     $this->init($this->themeName);
     if (!isset($this->runtimeRegistry)) {
-      $this->runtimeRegistry = new ThemeRegistry($this->cache, $this->lock, array('theme_registry'), $this->moduleHandler->isLoaded());
+      $this->runtimeRegistry = new ThemeRegistry($this->cache, $this->lock, $this->theme, array('theme_registry'), $this->moduleHandler->isLoaded());
     }
     return $this->runtimeRegistry;
   }
diff -u b/core/lib/Drupal/Core/Utility/ThemeRegistry.php b/core/lib/Drupal/Core/Utility/ThemeRegistry.php
--- b/core/lib/Drupal/Core/Utility/ThemeRegistry.php
+++ b/core/lib/Drupal/Core/Utility/ThemeRegistry.php
@@ -12,6 +12,7 @@
 use Drupal\Core\Cache\CacheCollector;
 use Drupal\Core\DestructableInterface;
 use Drupal\Core\Lock\LockBackendInterface;
+use Drupal\Core\Theme\ActiveTheme;
 
 /**
  * Builds the run-time theme registry.
@@ -40,7 +41,14 @@
   /**
    * Whether all modules have already been loaded.
    */
-  protected $modules_loaded;
+  protected $modulesLoaded;
+
+  /**
+   * The theme object representing the active theme for this registry.
+   *
+   * @var \Drupal\Core\Theme\ActiveTheme
+   */
+  protected $theme;
 
   /**
    * Constructs a ThemeRegistry object.
@@ -49,16 +57,19 @@
    *   The cache backend.
    * @param \Drupal\Core\Lock\LockBackendInterface $lock
    *   The lock backend.
+   * @param \Drupal\Core\Theme\ActiveTheme $theme
+   *   The theme object representing the active theme for this registry. 
    * @param array $tags
    *   (optional) The tags to specify for the cache item.
    * @param bool $modules_loaded
    *   Whether all modules have already been loaded.
    */
-  function __construct(CacheBackendInterface $cache, LockBackendInterface $lock, $tags = array(), $modules_loaded = FALSE) {
+  function __construct(CacheBackendInterface $cache, LockBackendInterface $lock, ActiveTheme $theme, $tags = array(), $modules_loaded = FALSE) {
     $this->cache = $cache;
     $this->lock = $lock;
     $this->tags = $tags;
-    $this->modules_loaded;
+    $this->theme = $theme;
+    $this->modulesLoaded = $modules_loaded;
   }
 
   /**
@@ -79,7 +90,7 @@
    */
   protected function getPersistable() {
     if ($this->persistable === NULL) {
-      $this->persistable = $this->modules_loaded && \Drupal::hasRequest() && \Drupal::request()->isMethod('GET');
+      $this->persistable = $this->modulesLoaded && \Drupal::hasRequest() && \Drupal::request()->isMethod('GET');
     }
 
     return $this->persistable;