diff -u b/core/lib/Drupal/Component/Utility/Html.php b/core/lib/Drupal/Component/Utility/Html.php
--- b/core/lib/Drupal/Component/Utility/Html.php
+++ b/core/lib/Drupal/Component/Utility/Html.php
@@ -396,6 +396,8 @@
   /**
    * Decodes HTML entities back to characters.
    *
+   * This method is the opposite of Html::escape().
+   *
    * @param $text
    *   The input text
    *
reverted:
--- b/core/modules/views/src/ViewsData.php
+++ a/core/modules/views/src/ViewsData.php
@@ -10,7 +10,6 @@
 use Drupal\Component\Utility\NestedArray;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheBackendInterface;
-use Drupal\Core\Cache\NullBackend;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Language\LanguageManagerInterface;
only in patch2:
unchanged:
--- a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
+++ b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
@@ -310,4 +310,36 @@ public function testDecodeEntitiesAndEscape() {
     $this->assertSame('<em>répété</em>', $escaped);
   }
 
+  /**
+   * Tests Html::descape().
+   *
+   * @dataProvider providerDescape
+   * @covers ::descape
+   */
+  public function testDescape($expected, $text) {
+    $this->assertEquals($expected, Html::descape($text));
+  }
+
+  /**
+   * Data provider for testDescape().
+   *
+   * @see testDescape()
+   */
+  public function providerDescape() {
+    return array(
+      array('Drupal', 'Drupal'),
+      array('<script>', '&lt;script&gt;'),
+      array('&lt;script&gt;', '&amp;lt;script&amp;gt;'),
+      array('&#34;', '&amp;#34;'),
+      array('"', '&quot;'),
+      array('&quot;', '&amp;quot;'),
+      array("'", '&#039;'),
+      array('&#039;', '&amp;#039;'),
+      array('©', '©'),
+      array('→', '→'),
+      array('➼', '➼'),
+      array('€', '€'),
+    );
+  }
+
 }