.../system/lib/Drupal/system/Controller/SystemController.php    |    7 +------
 .../Drupal/system/Tests/System/DefaultMobileMetaTagsTest.php    |    6 +++---
 2 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/core/modules/system/lib/Drupal/system/Controller/SystemController.php b/core/modules/system/lib/Drupal/system/Controller/SystemController.php
index 259ef66..a51ae40 100644
--- a/core/modules/system/lib/Drupal/system/Controller/SystemController.php
+++ b/core/modules/system/lib/Drupal/system/Controller/SystemController.php
@@ -183,14 +183,9 @@ public function themeSetDefault() {
    *   The updated renderable array.
    */
   public static function setLinkActiveClass(array $element, array $context) {
-    // Ensure we only manipulate HTML markup.
-    if (strpos($element['#markup'], '<!DOCTYPE') !== 0) {
-      return $element;
-    }
-
     // If none of the HTML in the current page contains even just the current
     // page's attribute, return early.
-    if (strpos($element['#markup'], 'data-drupal-link-system-path="' . $context['path'] . '"') === FALSE && (!$context['front'] || strpos($element['#markup'], 'data-drupal-link-system-path="<front>"') === FALSE)) {
+    if (strpos($element['#markup'], 'data-drupal-link-system-path="' . $context['path'] . '"') === FALSE && (!$context['front'] || strpos($element['#markup'], 'data-drupal-link-system-path="&lt;front&gt;"') === FALSE)) {
       return $element;
     }
 
diff --git a/core/modules/system/lib/Drupal/system/Tests/System/DefaultMobileMetaTagsTest.php b/core/modules/system/lib/Drupal/system/Tests/System/DefaultMobileMetaTagsTest.php
index aaaf2bd..ba0889f 100644
--- a/core/modules/system/lib/Drupal/system/Tests/System/DefaultMobileMetaTagsTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/System/DefaultMobileMetaTagsTest.php
@@ -22,9 +22,9 @@ public static function getInfo() {
   function setUp() {
     parent::setUp();
     $this->default_metatags = array(
-      'MobileOptimized' => '<meta name="MobileOptimized" content="width"',
-      'HandheldFriendly' => '<meta name="HandheldFriendly" content="true"',
-      'viewport' => '<meta name="viewport" content="width=device-width"',
+      'MobileOptimized' => '<meta name="MobileOptimized" content="width" />',
+      'HandheldFriendly' => '<meta name="HandheldFriendly" content="true" />',
+      'viewport' => '<meta name="viewport" content="width=device-width" />',
     );
   }