reverted:
--- b/core/lib/Drupal/Component/Utility/Html.php
+++ a/core/lib/Drupal/Component/Utility/Html.php
@@ -393,19 +393,4 @@
     return htmlspecialchars($text, ENT_QUOTES | ENT_SUBSTITUTE, 'UTF-8');
   }
 
-  /**
-   * Decodes HTML entities back to characters.
-   *
-   * This method is the opposite of Html::escape().
-   *
-   * @param $text
-   *   The input text.
-   *
-   * @return string
-   *   The text with all HTML entities decoded back to characters.
-   */
-  public static function unescape($text) {
-    return htmlspecialchars_decode($text, ENT_QUOTES | ENT_SUBSTITUTE);
-  }
-
 }
diff -u b/core/modules/views/src/Tests/FieldApiDataTest.php b/core/modules/views/src/Tests/FieldApiDataTest.php
--- b/core/modules/views/src/Tests/FieldApiDataTest.php
+++ b/core/modules/views/src/Tests/FieldApiDataTest.php
@@ -99,7 +99,8 @@
     // Click sort should only be on the primary field.
     $this->assertTrue(empty($data[$revision_table][$field_storage->getName()]['field']['click sortable']), 'Non-primary fields are not click sortable');
 
-    $this->assertEqual($data[$current_table][$field_storage->getName()]['help'], 'Appears in: page, article. Also known as: Content: The giraffe2" label');
+    $help = \Drupal::service('renderer')->renderPlain($data[$current_table][$field_storage->getName()]['help']);
+    $this->assertEqual(1, preg_match('/Appears in: .*page.*article.*\. Also known as: .*Content: The giraffe2" label.*\./', $help), 'Help text has the expected format');
   }
 
 }
diff -u b/core/modules/views/views.views.inc b/core/modules/views/views.views.inc
--- b/core/modules/views/views.views.inc
+++ b/core/modules/views/views.views.inc
@@ -322,9 +322,6 @@
     }
   }
 
-  /** @var \Drupal\Core\Render\RendererInterface $renderer */
-  $renderer = \Drupal::service('renderer');
-
   // Description of the field tables.
   // @todo Generalize this code to make it work with any table layout. See
   //   https://www.drupal.org/node/2079019.
@@ -422,7 +419,17 @@
       'group' => $group,
       'title' => $label,
       'title short' => $label,
-      'help' =>  t('Appears in: @bundles.', array('@bundles' => implode(', ', $bundles_names))),
+      'help' => [
+        [
+          '#markup' => t('Appears in:'),
+          '#suffix' => ' ',
+        ],
+        [
+          '#theme' => 'item_list',
+          '#items' => $bundles_names,
+          '#context' => ['list_style' => 'comma-list'],
+        ]
+      ],
     );
 
     // Go through and create a list of aliases for all possible combinations of
@@ -453,8 +460,18 @@
     }
     if ($aliases) {
       $data[$table_alias][$field_alias]['aliases'] = $aliases;
-      // Decode the entities, as they might have been escaped before.
-      $data[$table_alias][$field_alias]['help'] .= ' ' . t('Also known as: ') . Html::unescape(implode(', ', $also_known));
+      $data[$table_alias][$field_alias]['help'][] = [
+        '#prefix' => '. ',
+        '#markup' => t('Also known as:'),
+        '#suffix' => ' ',
+      ];
+      $data[$table_alias][$field_alias]['help'][] = [
+        '#theme' => 'item_list',
+        '#items' => $also_known,
+        '#context' => ['list_style' => 'comma-list'],
+        '#suffix' => '.',
+      ];
+
     }
 
     $keys = array_keys($field_columns);
@@ -530,7 +547,17 @@
         'group' => $group,
         'title' => $title,
         'title short' => $title_short,
-        'help' =>  t('Appears in: @bundles.', array('@bundles' => implode(', ', $bundles_names))),
+        'help' => [
+          [
+            '#markup' => t('Appears in:'),
+            '#suffix' => ' ',
+          ],
+          [
+            '#theme' => 'item_list',
+            '#context' => ['list_style' => 'comma-list'],
+            '#items' => $bundles_names,
+          ]
+        ],
       );
 
       // Go through and create a list of aliases for all possible combinations of
@@ -555,10 +582,17 @@
       }
       if ($aliases) {
         $data[$table_alias][$column_real_name]['aliases'] = $aliases;
-        // Decode the entities, as they might have been escaped before.
-        $data[$table_alias][$column_real_name]['help'] .= ' ' . t('Also known as: ') . Html::unescape(implode(', ', $also_known));
+        $data[$table_alias][$column_real_name]['help'][] = [
+          '#prefix' => ' ',
+          '#markup' => t('Also known as:'),
+          '#suffix' => ' ',
+        ];
+        $data[$table_alias][$column_real_name]['help'][] = [
+          '#theme' => 'item_list',
+          '#items' => $also_known,
+          '#context' => ['list_style' => 'comma-list'],
+        ];
       }
-
       $data[$table_alias][$column_real_name]['argument'] = array(
         'field' => $column_real_name,
         'table' => $table,
diff -u b/core/modules/views_ui/src/ViewEditForm.php b/core/modules/views_ui/src/ViewEditForm.php
--- b/core/modules/views_ui/src/ViewEditForm.php
+++ b/core/modules/views_ui/src/ViewEditForm.php
@@ -139,14 +139,14 @@
         '#account' => $this->entityManager->getStorage('user')->load($view->lock->owner),
       );
       $lock_message_substitutions = array(
-        '@user' => drupal_render($username),
-        '@age' => $this->dateFormatter->formatTimeDiffSince($view->lock->updated),
+        '!user' => drupal_render($username),
+        '!age' => $this->dateFormatter->formatTimeDiffSince($view->lock->updated),
         '@url' => $view->url('break-lock-form'),
       );
       $form['locked'] = array(
         '#type' => 'container',
         '#attributes' => array('class' => array('view-locked', 'messages', 'messages--warning')),
-        '#children' => $this->t('This view is being edited by user @user, and is therefore locked from editing by others. This lock is @age old. Click here to <a href="@url">break this lock</a>.', $lock_message_substitutions),
+        '#children' => $this->t('This view is being edited by user !user, and is therefore locked from editing by others. This lock is !age old. Click here to <a href="@url">break this lock</a>.', $lock_message_substitutions),
         '#weight' => -10,
       );
     }
reverted:
--- b/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
+++ a/core/tests/Drupal/Tests/Component/Utility/HtmlTest.php
@@ -310,47 +310,4 @@
     $this->assertSame('&lt;em&gt;répété&lt;/em&gt;', $escaped);
   }
 
-  /**
-   * Tests Html::unescape().
-   *
-   * @dataProvider providerUnescape
-   * @covers ::unescape
-   */
-  public function testUnescape($expected, $text) {
-    $this->assertEquals($expected, Html::unescape($text));
-  }
-
-  /**
-   * Data provider for testUnescape().
-   *
-   * @see testUnescape()
-   */
-  public function providerUnescape() {
-    return [
-      ['Drupal', 'Drupal'],
-      ['<script>', '&lt;script&gt;'],
-      ['&lt;script&gt;', '&amp;lt;script&amp;gt;'],
-      ['&#34;', '&amp;#34;'],
-      ['"', '&quot;'],
-      ['&quot;', '&amp;quot;'],
-      ["'", '&#039;'],
-      ['&#039;', '&amp;#039;'],
-      ['©', '©'],
-      ['→', '→'],
-      ['➼', '➼'],
-      ['€', '€'],
-    ];
-  }
-
-  /**
-   * Ensure Html::unescape() is the opposite of Html::escape().
-   *
-   * @covers ::unescape
-   * @covers ::escape
-   */
-  public function testEscapeAndUnescape() {
-    $string = "<em>kittén&eacute;</em>";
-    $this->assertEquals($string, Html::unescape(Html::escape($string)));
-  }
-
 }