diff -u b/core/modules/language/src/Tests/LanguageSwitchingTest.php b/core/modules/language/src/Tests/LanguageSwitchingTest.php
--- b/core/modules/language/src/Tests/LanguageSwitchingTest.php
+++ b/core/modules/language/src/Tests/LanguageSwitchingTest.php
@@ -129,11 +129,11 @@
     // Assert that only the current language is marked as active.
     list($language_switcher) = $this->xpath('//div[@id=:id]', array(':id' => 'block-test-language-block'));
     $links = array(
-      'is-active' => array(),
+      'active' => array(),
       'inactive' => array(),
     );
     $anchors = array(
-      'is-active' => array(),
+      'active' => array(),
       'inactive' => array(),
     );
     $labels = array();
@@ -141,22 +141,22 @@
       $classes = explode(" ", (string) $link['class']);
       list($langcode) = array_intersect($classes, array('en', 'fr'));
       if (in_array('is-active', $classes)) {
-        $links['is-active'][] = $langcode;
+        $links['active'][] = $langcode;
       }
       else {
         $links['inactive'][] = $langcode;
       }
       $anchor_classes = explode(" ", (string) $link->a['class']);
       if (in_array('is-active', $anchor_classes)) {
-        $anchors['is-active'][] = $langcode;
+        $anchors['active'][] = $langcode;
       }
       else {
         $anchors['inactive'][] = $langcode;
       }
       $labels[] = (string) $link->a;
     }
-    $this->assertIdentical($links, array('is-active' => array('en'), 'inactive' => array('fr')), 'Only the current language list item is marked as active on the language switcher block.');
-    $this->assertIdentical($anchors, array('is-active' => array('en'), 'inactive' => array('fr')), 'Only the current language anchor is marked as active on the language switcher block.');
+    $this->assertIdentical($links, array('active' => array('en'), 'inactive' => array('fr')), 'Only the current language list item is marked as active on the language switcher block.');
+    $this->assertIdentical($anchors, array('active' => array('en'), 'inactive' => array('fr')), 'Only the current language anchor is marked as active on the language switcher block.');
     $this->assertIdentical($labels, array('English', 'français'), 'The language links labels are in their own language on the language switcher block.');
   }