Update to Drupal 8.1.1. For more information, see https://www.drupal.org/node/2718713

core/themes/bartik/bartik.theme

@@ -5,6 +5,7 @@
  * Functions to support theming in the Bartik theme.
  */
 
+use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Template\Attribute;
 
 /**
@@ -113,7 +114,7 @@ function bartik_theme_suggestions_form_alter(array &$suggestions, array $variabl
 /**
  * Implements hook_form_alter() to add classes to the search form.
  */
-function bartik_form_alter(&$form, \Drupal\Core\Form\FormStateInterface $form_state, $form_id) {
+function bartik_form_alter(&$form, FormStateInterface $form_state, $form_id) {
   if (in_array($form_id, ['search_block_form', 'search_form'])) {
     $key = ($form_id == 'search_block_form') ? 'actions' : 'basic';
     if (!isset($form[$key]['submit']['#attributes'])) {

core/themes/bartik/templates/node.html.twig

@@ -5,9 +5,16 @@
  *
  * Available variables:
  * - node: The node entity with limited access to object properties and methods.
-     Only "getter" methods (method names starting with "get", "has", or "is")
-     and a few common methods such as "id" and "label" are available. Calling
-     other methods (such as node.delete) will result in an exception.
+ *   Only method names starting with "get", "has", or "is" and a few common
+ *   methods such as "id", "label", and "bundle" are available. For example:
+ *   - node.getCreatedTime() will return the node creation timestamp.
+ *   - node.hasField('field_example') returns TRUE if the node bundle includes
+ *     field_example. (This does not indicate the presence of a value in this
+ *     field.)
+ *   - node.isPublished() will return whether the node is published or not.
+ *   Calling other methods, such as node.delete(), will result in an exception.
+ *   See \Drupal\node\Entity\Node for a full list of public properties and
+ *   methods for the node object.
  * - label: The title of the node.
  * - content: All node items. Use {{ content }} to print them all,
  *   or print a subset such as {{ content.field_example }}. Use

core/themes/classy/templates/content/node.html.twig

@@ -5,9 +5,16 @@
  *
  * Available variables:
  * - node: The node entity with limited access to object properties and methods.
-     Only "getter" methods (method names starting with "get", "has", or "is")
-     and a few common methods such as "id" and "label" are available. Calling
-     other methods (such as node.delete) will result in an exception.
+ *   Only method names starting with "get", "has", or "is" and a few common
+ *   methods such as "id", "label", and "bundle" are available. For example:
+ *   - node.getCreatedTime() will return the node creation timestamp.
+ *   - node.hasField('field_example') returns TRUE if the node bundle includes
+ *     field_example. (This does not indicate the presence of a value in this
+ *     field.)
+ *   - node.isPublished() will return whether the node is published or not.
+ *   Calling other methods, such as node.delete(), will result in an exception.
+ *   See \Drupal\node\Entity\Node for a full list of public properties and
+ *   methods for the node object.
  * - label: The title of the node.
  * - content: All node items. Use {{ content }} to print them all,
  *   or print a subset such as {{ content.field_example }}. Use

core/themes/stable/templates/content/node.html.twig

@@ -5,9 +5,16 @@
  *
  * Available variables:
  * - node: The node entity with limited access to object properties and methods.
-     Only "getter" methods (method names starting with "get", "has", or "is")
-     and a few common methods such as "id" and "label" are available. Calling
-     other methods (such as node.delete) will result in an exception.
+ *   Only method names starting with "get", "has", or "is" and a few common
+ *   methods such as "id", "label", and "bundle" are available. For example:
+ *   - node.getCreatedTime() will return the node creation timestamp.
+ *   - node.hasField('field_example') returns TRUE if the node bundle includes
+ *     field_example. (This does not indicate the presence of a value in this
+ *     field.)
+ *   - node.isPublished() will return whether the node is published or not.
+ *   Calling other methods, such as node.delete(), will result in an exception.
+ *   See \Drupal\node\Entity\Node for a full list of public properties and
+ *   methods for the node object.
  * - label: The title of the node.
  * - content: All node items. Use {{ content }} to print them all,
  *   or print a subset such as {{ content.field_example }}. Use