diff --git a/core/lib/Drupal/Core/Entity/EntityFormController.php b/core/lib/Drupal/Core/Entity/EntityFormController.php
index f384e16..0ab7f93 100644
--- a/core/lib/Drupal/Core/Entity/EntityFormController.php
+++ b/core/lib/Drupal/Core/Entity/EntityFormController.php
@@ -366,7 +366,8 @@ public function buildEntity(array $form, array &$form_state) {
       $entity->set($key, $value);
     }
 
-    // Invoke all specified builders for copying form values to entity properties.
+    // Invoke all specified builders for copying form values to entity
+    // properties.
     if (isset($form['#entity_builders'])) {
       foreach ($form['#entity_builders'] as $function) {
         call_user_func_array($function, array($entity->entityType(), $entity, &$form, &$form_state));
diff --git a/core/lib/Drupal/Core/Entity/EntityManager.php b/core/lib/Drupal/Core/Entity/EntityManager.php
index b0974be..e9808d2 100644
--- a/core/lib/Drupal/Core/Entity/EntityManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityManager.php
@@ -442,14 +442,15 @@ public function getAdminRouteInfo($entity_type, $bundle) {
   }
 
   /**
-   * Gets an array of entity field definitions.
+   * Gets an array of content entity field definitions.
    *
    * If a bundle is passed, fields specific to this bundle are included. Entity
    * fields are always multi-valued, so 'list' is TRUE for each returned field
    * definition.
    *
    * @param string $entity_type
-   *   The entity type to get field definitions for.
+   *   The entity type to get field definitions for. Only entity types that
+   *   implement \Drupal\Core\Entity\ContentEntityInterface are supported.
    * @param string $bundle
    *   (optional) The entity bundle for which to get field definitions. If NULL
    *   is passed, no bundle-specific fields are included. Defaults to NULL.
@@ -477,10 +478,6 @@ public function getFieldDefinitions($entity_type, $bundle = NULL) {
       }
       else {
         $class = $this->factory->getPluginClass($entity_type, $this->getDefinition($entity_type));
-        // @todo: This shouldn't be called...
-        if (!in_array('Drupal\Core\Entity\ContentEntityInterface', class_implements($class))) {
-          return array();
-        }
         $this->entityFieldInfo[$entity_type] = array(
           'definitions' => $class::baseFieldDefinitions($entity_type),
           // Contains definitions of optional (per-bundle) fields.
diff --git a/core/modules/content_translation/content_translation.module b/core/modules/content_translation/content_translation.module
index 66567fd..003ec3f 100644
--- a/core/modules/content_translation/content_translation.module
+++ b/core/modules/content_translation/content_translation.module
@@ -8,7 +8,6 @@
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityFormControllerInterface;
 use Drupal\Core\Entity\EntityInterface;
-use Drupal\Core\Entity\ContentEntityBase;
 use Drupal\Core\Language\Language;
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\TypedData\TranslatableInterface;
@@ -269,7 +268,6 @@ function _content_translation_menu_strip_loaders($path) {
  *   The entity whose translation overview should be displayed.
  */
 function content_translation_translate_access(EntityInterface $entity) {
-  $entity_type = $entity->entityType();
   return $entity instanceof ContentEntityInterface && empty($entity->getUntranslated()->language()->locked) && language_multilingual() && $entity->isTranslatable() &&
     (user_access('create content translations') || user_access('update content translations') || user_access('delete content translations'));
 }
@@ -591,7 +589,7 @@ function content_translation_permission() {
  * Implements hook_form_alter().
  */
 function content_translation_form_alter(array &$form, array &$form_state) {
-  if (($form_controller = content_translation_form_controller($form_state)) && ($entity = $form_controller->getEntity()) && !$entity->isNew() && $entity instanceof TranslatableInterface && $entity->isTranslatable()) {
+  if (($form_controller = content_translation_form_controller($form_state)) && ($entity = $form_controller->getEntity()) && !$entity->isNew() && $entity instanceof ContentEntityInterface && $entity->isTranslatable()) {
     $controller = content_translation_controller($entity->entityType());
     $controller->entityFormAlter($form, $form_state, $entity);
 
@@ -602,7 +600,7 @@ function content_translation_form_alter(array &$form, array &$form_state) {
 
     // Handle fields shared between translations when there is at least one
     // translation available or a new one is being created.
-    if ($entity instanceof ContentEntityInterface && !$entity->isNew() && (!isset($translations[$form_langcode]) || count($translations) > 1)) {
+     if (!$entity->isNew() && (!isset($translations[$form_langcode]) || count($translations) > 1)) {
       foreach ($entity->getPropertyDefinitions() as $property_name => $definition) {
         if (isset($form[$property_name])) {
           $form[$property_name]['#multilingual'] = !empty($definition['translatable']);
diff --git a/core/modules/editor/editor.module b/core/modules/editor/editor.module
index 26d18af..8282d07 100644
--- a/core/modules/editor/editor.module
+++ b/core/modules/editor/editor.module
@@ -541,7 +541,7 @@ function _editor_get_file_uuids_by_field(EntityInterface $entity) {
  * @return array
  *   The names of the fields on this entity that have text processing enabled.
  */
-function _editor_get_processed_text_fields(EntityInterface $entity) {
+function _editor_get_processed_text_fields(ContentEntityInterface $entity) {
   $properties = $entity->getPropertyDefinitions();
   if (empty($properties)) {
     return array();
diff --git a/core/modules/field/lib/Drupal/field/Plugin/field/field_type/LegacyConfigFieldItem.php b/core/modules/field/lib/Drupal/field/Plugin/field/field_type/LegacyConfigFieldItem.php
index da813a9..f5febd5 100644
--- a/core/modules/field/lib/Drupal/field/Plugin/field/field_type/LegacyConfigFieldItem.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/field/field_type/LegacyConfigFieldItem.php
@@ -50,8 +50,7 @@ public function isEmpty() {
     // properties.
     $item = $this->getValue(TRUE);
     // The previous hook was never called on an empty item, but
-    // ContentEntityBase always
-    // creates a FieldItem element for an empty field.
+    // ContentEntityBase always creates a FieldItem element for an empty field.
     return empty($item) || $callback($item, $this->getFieldDefinition()->getFieldType());
   }
 
diff --git a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
index dbd8065..e95eb01 100644
--- a/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
+++ b/core/modules/menu_link/lib/Drupal/menu_link/MenuLinkFormController.php
@@ -255,7 +255,8 @@ public function validate(array $form, array &$form_state) {
    * {@inheritdoc}
    */
   public function buildEntity(array $form, array &$form_state) {
-    // @todo: Remove this when menu links are content entities.
+    // @todo: Remove this when menu links are converted to content entities in
+    //   http://drupal.org/node/1842858.
     $entity = clone $this->entity;
     // If you submit a form, the form state comes from caching, which forces
     // the controller to be the one before caching. Ensure to have the
diff --git a/core/modules/toolbar/toolbar.module b/core/modules/toolbar/toolbar.module
index c9c9d7a..6644fbb 100644
--- a/core/modules/toolbar/toolbar.module
+++ b/core/modules/toolbar/toolbar.module
@@ -655,7 +655,7 @@ function toolbar_modules_disabled($modules) {
  * Implements hook_ENTITY_TYPE_update().
  */
 function toolbar_menu_link_update(MenuLinkInterface $menu_link) {
-  if ($menu_link->get('menu_name') === 'admin') {
+  if ($menu_link->menu_name === 'admin') {
     _toolbar_clear_user_cache();
   }
 }