diff --git a/core/includes/theme.inc b/core/includes/theme.inc
index d8f3136..f481902 100644
--- a/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -492,27 +492,14 @@ function template_preprocess_datetime_form(&$variables) {
  *
  * @param array $variables
  *   An associative array containing:
- *   - element: An associative array containing the properties of the element.
- *     Properties used: #title, #children, #required, #attributes.
+ *   - title: The title text.
+ *   - title_attributes: An Attribute object for the title element.
+ *   - description: The help text description of the field.
+ *   - required: A required boolean state for the date field.
+ *   - children: The form element content.
  */
 function template_preprocess_datetime_wrapper(&$variables) {
-  $element = $variables['element'];
-
-  if (!empty($element['#title'])) {
-    $variables['title'] = $element['#title'];
-  }
-
-  if (!empty($element['#description'])) {
-    $variables['description'] = $element['#description'];
-  }
-
-  $variables['required'] = FALSE;
-  // For required datetime fields a 'form-required' class is appended to the
-  // label attributes.
-  if (!empty($element['#required'])) {
-    $variables['required'] = TRUE;
-  }
-  $variables['content'] = $element['#children'];
+  $variables['content'] = $variables['children'];
 }
 
 /**
@@ -1222,8 +1209,6 @@ function _template_preprocess_default_variables() {
   // Variables that don't depend on a database connection.
   $variables = array(
     'attributes' => array(),
-    'title_attributes' => array(),
-    'content_attributes' => array(),
     'title_prefix' => array(),
     'title_suffix' => array(),
     'db_is_active' => !defined('MAINTENANCE_MODE'),
@@ -1584,6 +1569,9 @@ function template_preprocess_field(&$variables, $hook) {
     $variables['items'][$delta]['attributes'] = !empty($element['#items'][$delta]->_attributes) ? new Attribute($element['#items'][$delta]->_attributes) : clone($default_attributes);
     $delta++;
   }
+
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : clone $default_attributes;
+  $variables['content_attributes'] = isset($variables['content_attributes']) ? new Attribute($variables['content_attributes']) : clone $default_attributes;
 }
 
 /**
@@ -1734,9 +1722,15 @@ function drupal_common_theme() {
     'datetime_form' => array(
       'render element' => 'element',
     ),
-    'datetime_wrapper' => array(
-      'render element' => 'element',
-    ),
+    'datetime_wrapper' => [
+      'variables' => [
+        'title' => '',
+        'title_attributes' => new Attribute(),
+        'description' => '',
+        'required' => FALSE,
+        'children' => '',
+      ],
+    ],
     'status_messages' => array(
       'variables' => ['status_headings' => [], 'message_list' => NULL],
     ),
diff --git a/core/lib/Drupal/Core/Theme/ThemeManager.php b/core/lib/Drupal/Core/Theme/ThemeManager.php
index 6850fcb..aa8ed7c 100644
--- a/core/lib/Drupal/Core/Theme/ThemeManager.php
+++ b/core/lib/Drupal/Core/Theme/ThemeManager.php
@@ -355,15 +355,13 @@ protected function theme($hook, $variables = array()) {
       if (!isset($default_attributes)) {
         $default_attributes = new Attribute();
       }
-      foreach (array('attributes', 'title_attributes', 'content_attributes') as $key) {
-        if (isset($variables[$key]) && !($variables[$key] instanceof Attribute)) {
-          if ($variables[$key]) {
-            $variables[$key] = new Attribute($variables[$key]);
-          }
-          else {
-            // Create empty attributes.
-            $variables[$key] = clone $default_attributes;
-          }
+      if (isset($variables['attributes']) && !($variables['attributes'] instanceof Attribute)) {
+        if ($variables['attributes']) {
+          $variables['attributes'] = new Attribute($variables['attributes']);
+        }
+        else {
+          // Create empty attributes.
+          $variables['attributes'] = clone $default_attributes;
         }
       }
 
diff --git a/core/modules/aggregator/aggregator.theme.inc b/core/modules/aggregator/aggregator.theme.inc
index ab6c3dc..b7b6f73 100644
--- a/core/modules/aggregator/aggregator.theme.inc
+++ b/core/modules/aggregator/aggregator.theme.inc
@@ -7,6 +7,7 @@
 
 use Drupal\Component\Utility\SafeMarkup;
 use Drupal\Core\Render\Element;
+use Drupal\Core\Template\Attribute;
 
 /**
  * Prepares variables for aggregator item templates.
@@ -27,6 +28,7 @@ function template_preprocess_aggregator_item(&$variables) {
 
   $variables['url'] = check_url($item->getLink());
   $variables['title'] = SafeMarkup::checkPlain($item->label());
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : new Attribute();
 }
 
 /**
@@ -47,4 +49,5 @@ function template_preprocess_aggregator_feed(&$variables) {
   }
   $variables['full'] = $variables['elements']['#view_mode'] == 'full';
   $variables['title'] = SafeMarkup::checkPlain($feed->label());
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : new Attribute();
 }
diff --git a/core/modules/block/block.module b/core/modules/block/block.module
index e65d07a..3456dc4 100644
--- a/core/modules/block/block.module
+++ b/core/modules/block/block.module
@@ -13,6 +13,7 @@
 use Drupal\language\ConfigurableLanguageInterface;
 use Drupal\system\Entity\Menu;
 use Drupal\block\Entity\Block;
+use Drupal\Core\Template\Attribute;
 
 /**
  * Implements hook_help().
@@ -258,6 +259,8 @@ function template_preprocess_block(&$variables) {
     $variables['attributes']['aria-describedby'] = $variables['title_attributes']['id'];
   }
 
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : new Attribute();
+  $variables['content_attributes'] = isset($variables['content_attributes']) ? new Attribute($variables['content_attributes']) : new Attribute();
 }
 
 /**
diff --git a/core/modules/comment/comment.module b/core/modules/comment/comment.module
index ad82046..60999ab 100644
--- a/core/modules/comment/comment.module
+++ b/core/modules/comment/comment.module
@@ -24,6 +24,7 @@
 use Drupal\Core\Entity\Display\EntityViewDisplayInterface;
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Render\Element;
+use Drupal\Core\Template\Attribute;
 use Drupal\Core\Url;
 use Drupal\field\Entity\FieldStorageConfig;
 use Drupal\field\FieldConfigInterface;
@@ -708,6 +709,8 @@ function template_preprocess_comment(&$variables) {
 
   // Add comment author user ID. Necessary for the comment-by-viewer library.
   $variables['attributes']['data-comment-user-id'] = $comment->getOwnerId();
+  $variables['content_attributes'] = isset($variables['content_attributes']) ? new Attribute($variables['content_attributes']) : new Attribute();
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : new Attribute();
 }
 
 /**
diff --git a/core/modules/node/node.module b/core/modules/node/node.module
index aa26ce4..de83d5b 100644
--- a/core/modules/node/node.module
+++ b/core/modules/node/node.module
@@ -613,6 +613,9 @@ function template_preprocess_node(&$variables) {
 
   // Add article ARIA role.
   $variables['attributes']['role'] = 'article';
+
+  $variables['title_attributes'] = isset($variables['title_attributes']) ? new Attribute($variables['title_attributes']) : new Attribute();
+  $variables['content_attributes'] = isset($variables['content_attributes']) ? new Attribute($variables['content_attributes']) : new Attribute();
 }
 
 /**
diff --git a/core/modules/search/search.module b/core/modules/search/search.module
index 462e4db..afe514d 100644
--- a/core/modules/search/search.module
+++ b/core/modules/search/search.module
@@ -11,6 +11,7 @@
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\Template\Attribute;
 
 /**
  * Matches all 'N' Unicode character classes (numbers)
@@ -103,7 +104,12 @@ function search_help($route_name, RouteMatchInterface $route_match) {
 function search_theme() {
   return array(
     'search_result' => array(
-      'variables' => array('result' => NULL, 'plugin_id' => NULL),
+      'variables' => [
+        'result' => NULL,
+        'plugin_id' => NULL,
+        'title_attributes' => new Attribute(),
+        'content_attributes' => new Attribute(),
+      ],
       'file' => 'search.pages.inc',
     ),
   );