diff --git a/core/lib/Drupal/Core/Controller/HtmlFormController.php b/core/lib/Drupal/Core/Controller/HtmlFormController.php
index 96530d5..68b6c31 100644
--- a/core/lib/Drupal/Core/Controller/HtmlFormController.php
+++ b/core/lib/Drupal/Core/Controller/HtmlFormController.php
@@ -57,10 +57,12 @@ public function content(Request $request, $_form) {
     $request->attributes->set('form', array());
     $request->attributes->set('form_state', $form_state);
     $args = $this->container->get('controller_resolver')->getArguments($request, array($form_object, 'buildForm'));
-    unset($args[0], $args[1]);
     $request->attributes->remove('form');
     $request->attributes->remove('form_state');
-    $form_state['build_info']['args'] = $args;
+
+    // Remove $form and $form_state from the arguments, and re-index them.
+    unset($args[0], $args[1]);
+    $form_state['build_info']['args'] = array_values($args);
 
     $form_id = _drupal_form_id($form_object, $form_state);
     $form = drupal_build_form($form_id, $form_state);
diff --git a/core/modules/color/color.module b/core/modules/color/color.module
index a11e035..2203133 100644
--- a/core/modules/color/color.module
+++ b/core/modules/color/color.module
@@ -37,7 +37,7 @@ function color_theme() {
  * Implements hook_form_FORM_ID_alter().
  */
 function color_form_system_theme_settings_alter(&$form, &$form_state) {
-  if (isset($form_state['build_info']['args'][2]) && ($theme = $form_state['build_info']['args'][2]) && color_get_info($theme) && function_exists('gd_info')) {
+  if (isset($form_state['build_info']['args'][0]) && ($theme = $form_state['build_info']['args'][0]) && color_get_info($theme) && function_exists('gd_info')) {
     $form['color'] = array(
       '#type' => 'details',
       '#title' => t('Color scheme'),
diff --git a/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php b/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
index 26e8142..903c4f5 100644
--- a/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
+++ b/core/modules/system/lib/Drupal/system/Form/ThemeSettingsForm.php
@@ -21,14 +21,21 @@
 class ThemeSettingsForm extends SystemConfigFormBase {
 
   /**
-   * The module handler
+   * The module handler.
    *
-   * @var \Drupal\Core\Extension\ModuleHandler
+   * @var \Drupal\Core\Extension\ModuleHandlerInterface
    */
   protected $moduleHandler;
 
   /**
-   * {@inheritdoc}
+   * Constructs a ThemeSettingsForm object.
+   *
+   * @param \Drupal\Core\Config\ConfigFactory $config_factory
+   *   The factory for configuration objects.
+   * @param \Drupal\Core\Config\Context\ContextInterface $context
+   *   The configuration context to use.
+   * @param Drupal\Core\Extension\ModuleHandlerInterface
+   *   The module handler instance to use.
    */
   public function __construct(ConfigFactory $config_factory, ContextInterface $context, ModuleHandlerInterface $module_handler) {
     parent::__construct($config_factory, $context);
@@ -92,15 +99,15 @@ public function buildForm(array $form, array &$form_state, $theme_name = '') {
 
     // Toggle settings
     $toggles = array(
-      'logo'                      => t('Logo'),
-      'name'                      => t('Site name'),
-      'slogan'                    => t('Site slogan'),
-      'node_user_picture'         => t('User pictures in posts'),
-      'comment_user_picture'      => t('User pictures in comments'),
+      'logo' => t('Logo'),
+      'name' => t('Site name'),
+      'slogan' => t('Site slogan'),
+      'node_user_picture' => t('User pictures in posts'),
+      'comment_user_picture' => t('User pictures in comments'),
       'comment_user_verification' => t('User verification status in comments'),
-      'favicon'                   => t('Shortcut icon'),
-      'main_menu'                 => t('Main menu'),
-      'secondary_menu'            => t('Secondary menu'),
+      'favicon' => t('Shortcut icon'),
+      'main_menu' => t('Main menu'),
+      'secondary_menu' => t('Secondary menu'),
     );
 
     // Some features are not always available