diff -u b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
--- b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
+++ b/core/tests/Drupal/Tests/Core/Render/Element/HtmlTagTest.php
@@ -85,25 +85,19 @@
     );
     $tags[] = array($element, "<p&gt;&lt;script&gt;alert()&lt;/script&gt;&lt;p>value</p&gt;&lt;script&gt;alert()&lt;/script&gt;&lt;p>\n");
 
-    // Ensure that #value, #value_prefix and #value_suffix are not filtered if
-    // they marked as safe.
+    // Ensure that #value is not filtered if it is marked as safe.
     $element = array(
       '#tag' => 'p',
       '#value' => SafeString::create('<script>value</script>'),
-      '#value_prefix' => SafeString::create('<script>alert()</script>'),
-      '#value_suffix' => SafeString::create('<script>alert()</script>'),
     );
-    $tags[] = array($element, "<p><script>alert()</script><script>value</script><script>alert()</script></p>\n");
+    $tags[] = array($element, "<p><script>value</script></p>\n");
 
-    // Ensure that #value, #value_prefix and #value_suffix are filtered if they
-    // are not safe.
+    // Ensure that #value is filtered if they are not safe.
     $element = array(
       '#tag' => 'p',
       '#value' => '<script>value</script>',
-      '#value_prefix' => '<script>alert()</script>',
-      '#value_suffix' => '<script>alert()</script>',
     );
-    $tags[] = array($element, "<p>alert()valuealert()</p>\n");
+    $tags[] = array($element, "<p>value</p>\n");
 
     return $tags;
   }