Update to Drupal 8.1.2. For more information, see https://www.drupal.org/project/drupal/releases/8.1.2

core/lib/Drupal/Core/Render/Element/MachineName.php

@@ -22,7 +22,10 @@ use Drupal\Core\Language\LanguageInterface;
  * Properties:
  * - #machine_name: An associative array containing:
  *   - exists: A callable to invoke for checking whether a submitted machine
- *     name value already exists. The submitted value is passed as an argument.
+ *     name value already exists. The arguments passed to the callback will be:
+ *     - The submitted value.
+ *     - The element array.
+ *     - The form state object.
  *     In most cases, an existing API or menu argument loader function can be
  *     re-used. The callback is only invoked if the submitted value differs from
  *     the element's #default_value.

core/lib/Drupal/Core/Render/Element/Pager.php

@@ -30,7 +30,7 @@ namespace Drupal\Core\Render\Element;
  *
  * @RenderElement("pager")
  */
-class Pager extends RenderElement{
+class Pager extends RenderElement {
 
   /**
    * {@inheritdoc}

core/lib/Drupal/Core/Render/Element/Textarea.php

@@ -61,4 +61,5 @@ class Textarea extends FormElement {
     }
     return NULL;
   }
+
 }

core/lib/Drupal/Core/Render/Element/VerticalTabs.php

@@ -125,7 +125,7 @@ class VerticalTabs extends RenderElement {
     // form is rendered, e.g. on preview pages or when form validation
     // fails.
     $name = implode('__', $element['#parents']);
-    if ($form_state->hasValue($name . '__active_tab')){
+    if ($form_state->hasValue($name . '__active_tab')) {
       $element['#default_tab'] = $form_state->getValue($name . '__active_tab');
     }
     $element[$name . '__active_tab'] = array(

core/lib/Drupal/Core/Render/HtmlResponseAttachmentsProcessor.php

@@ -442,7 +442,7 @@ class HtmlResponseAttachmentsProcessor implements AttachmentsResponseProcessorIn
    */
   protected function processFeed($attached_feed) {
     $html_head_link = [];
-    foreach($attached_feed as $item) {
+    foreach ($attached_feed as $item) {
       $feed_link = [
         'href' => $item[0],
         'rel' => 'alternate',

core/lib/Drupal/Core/Render/MainContent/MainContentRendererInterface.php

@@ -13,7 +13,7 @@ use Symfony\Component\HttpFoundation\Request;
  * (HTML, JSON …) and/or in a certain decorated manner (e.g. in the case of the
  * default HTML main content renderer: with a page display variant applied).
  */
-interface MainContentRendererInterface  {
+interface MainContentRendererInterface {
 
   /**
    * Renders the main content render array into a response.

core/lib/Drupal/Core/Render/Markup.php

@@ -22,4 +22,5 @@ use Drupal\Component\Render\MarkupTrait;
  */
 final class Markup implements MarkupInterface, \Countable {
   use MarkupTrait;
+
 }

core/lib/Drupal/Core/Render/Placeholder/SingleFlushStrategy.php

@@ -18,4 +18,5 @@ class SingleFlushStrategy implements PlaceholderStrategyInterface {
     // Return all placeholders as is; they should be rendered directly.
     return $placeholders;
   }
+
 }

core/lib/Drupal/Core/Render/RendererInterface.php

@@ -319,8 +319,8 @@ interface RendererInterface {
    *   The rendered HTML.
    *
    * @throws \LogicException
-   *   When called outside of a render context. (i.e. outside of a renderRoot(),
-   *   renderPlain() or executeInRenderContext() call.)
+   *   When called outside of a render context (i.e. outside of a renderRoot(),
+   *   renderPlain() or executeInRenderContext() call).
    * @throws \Exception
    *   If a #pre_render callback throws an exception, it is caught to mark the
    *   renderer as no longer being in a root render call, if any. Then the

core/lib/Drupal/Core/Render/theme.api.php

@@ -1110,7 +1110,8 @@ function hook_page_bottom(array &$page_bottom) {
  *     Template implementations receive each array key as a variable in the
  *     template file (so they must be legal PHP/Twig variable names). Function
  *     implementations are passed the variables in a single $variables function
- *     argument.
+ *     argument. If you are using these variables in a render array, prefix the
+ *     variable names defined here with a #.
  *   - render element: Used for render element items only: the name of the
  *     renderable element or element tree to pass to the theme function. This
  *     name is used as the name of the variable that holds the renderable