diff --git a/core/modules/system/system.module b/core/modules/system/system.module
index 67b25fe..10b3a03 100644
--- a/core/modules/system/system.module
+++ b/core/modules/system/system.module
@@ -1491,6 +1491,117 @@ function system_rebuild_module_data() {
  */
 function _system_rebuild_theme_data() {
   return \Drupal::service('theme_handler')->rebuildThemeData();
+  // Find themes
+  $themes = drupal_system_listing('/^' . DRUPAL_PHP_FUNCTION_PATTERN . '\.info.yml$/', 'themes');
+  // Allow modules to add further themes.
+  if ($module_themes = Drupal::moduleHandler()->invokeAll('system_theme_info')) {
+    foreach ($module_themes as $name => $uri) {
+      // @see file_scan_directory()
+      $themes[$name] = (object) array(
+        'uri' => $uri,
+        'filename' => pathinfo($uri, PATHINFO_FILENAME),
+        'name' => $name,
+      );
+    }
+  }
+
+  // Find theme engines
+  $engines = drupal_system_listing('/^' . DRUPAL_PHP_FUNCTION_PATTERN . '\.engine$/', 'themes/engines');
+
+  // Set defaults for theme info.
+  $defaults = array(
+    'engine' => 'twig',
+    'name' => 'MISSING THEME NAME',
+    'regions' => array(
+      'sidebar_first' => 'Left sidebar',
+      'sidebar_second' => 'Right sidebar',
+      'content' => 'Content',
+      'header' => 'Header',
+      'footer' => 'Footer',
+      'highlighted' => 'Highlighted',
+      'help' => 'Help',
+      'page_top' => 'Page top',
+      'page_bottom' => 'Page bottom',
+    ),
+    'description' => '',
+    'features' => _system_default_theme_features(),
+    'screenshot' => 'screenshot.png',
+    'php' => DRUPAL_MINIMUM_PHP,
+    'stylesheets' => array(),
+    'scripts' => array(),
+  );
+
+  $sub_themes = array();
+  // Read info files for each theme
+  foreach ($themes as $key => $theme) {
+    $themes[$key]->filename = $theme->uri;
+    $themes[$key]->info = drupal_parse_info_file($theme->uri) + $defaults;
+
+    // Skip this extension if its type is not theme.
+    if (!isset($themes[$key]->info['type']) || $themes[$key]->info['type'] != 'theme') {
+      unset($themes[$key]);
+      continue;
+    }
+
+    // Add the info file modification time, so it becomes available for
+    // contributed modules to use for ordering theme lists.
+    $themes[$key]->info['mtime'] = filemtime($theme->uri);
+
+    // Invoke hook_system_info_alter() to give installed modules a chance to
+    // modify the data in the .info.yml files if necessary.
+    $type = 'theme';
+    drupal_alter('system_info', $themes[$key]->info, $themes[$key], $type);
+
+    if (!empty($themes[$key]->info['base theme'])) {
+      $sub_themes[] = $key;
+    }
+
+    $engine = $themes[$key]->info['engine'];
+    if (isset($engines[$engine])) {
+      $themes[$key]->owner = $engines[$engine]->uri;
+      $themes[$key]->prefix = $engines[$engine]->name;
+      $themes[$key]->template = TRUE;
+    }
+
+    // Prefix stylesheets and scripts with module path.
+    $path = dirname($theme->uri);
+    $theme->info['stylesheets'] = _system_info_add_path($theme->info['stylesheets'], $path);
+    $theme->info['scripts'] = _system_info_add_path($theme->info['scripts'], $path);
+
+    // Give the screenshot proper path information.
+    if (!empty($themes[$key]->info['screenshot'])) {
+      $themes[$key]->info['screenshot'] = $path . '/' . $themes[$key]->info['screenshot'];
+    }
+  }
+
+  // Now that we've established all our master themes, go back and fill in data
+  // for subthemes.
+  foreach ($sub_themes as $key) {
+    $themes[$key]->base_themes = drupal_find_base_themes($themes, $key);
+    // Don't proceed if there was a problem with the root base theme.
+    if (!current($themes[$key]->base_themes)) {
+      continue;
+    }
+    $base_key = key($themes[$key]->base_themes);
+    foreach (array_keys($themes[$key]->base_themes) as $base_theme) {
+      $themes[$base_theme]->sub_themes[$key] = $themes[$key]->info['name'];
+    }
+    // Copy the 'owner' and 'engine' over if the top level theme uses a theme
+    // engine.
+    if (isset($themes[$base_key]->owner)) {
+      if (isset($themes[$base_key]->info['engine'])) {
+        $themes[$key]->info['engine'] = $themes[$base_key]->info['engine'];
+        $themes[$key]->owner = $themes[$base_key]->owner;
+        $themes[$key]->prefix = $themes[$base_key]->prefix;
+      }
+      else {
+        $themes[$key]->prefix = $key;
+      }
+    }
+  }
+
+  return $themes;
+>>>>>>> Applyin patch from issue 619542
 }
 
 /**