diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
index 210e259..d2f26f7 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityBase.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\Config\Entity;
 
-use Drupal\Component\Plugin\ConfigurablePluginInterface;
 use Drupal\Component\Utility\String;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Config\Schema\SchemaIncompleteException;
@@ -23,7 +22,7 @@
  *
  * @ingroup entity_api
  */
-abstract class ConfigEntityBase extends Entity implements ConfigEntityInterface {
+abstract class ConfigEntityBase extends Entity implements ConfigEntityInterface, \Serializable {
 
   use PluginDependencyTrait {
     addDependency as addDependencyTrait;
@@ -372,4 +371,21 @@ public function getConfigDependencyName() {
     return $this->getEntityType()->getConfigPrefix() . '.' . $this->id();
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function serialize() {
+    $values = $this->toArray();
+    $values['entityTypeID'] = $this->getEntityTypeId();
+    return serialize($values);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function unserialize($serialized) {
+    $values = unserialize($serialized);
+    return $this->__construct($values, $values['entityTypeID']);
+  }
+
 }
diff --git a/core/modules/entity/src/Entity/EntityFormDisplay.php b/core/modules/entity/src/Entity/EntityFormDisplay.php
index 6457e23..3e88d0a 100644
--- a/core/modules/entity/src/Entity/EntityFormDisplay.php
+++ b/core/modules/entity/src/Entity/EntityFormDisplay.php
@@ -225,23 +225,4 @@ public function validateFormValues(ContentEntityInterface $entity, array &$form,
     }
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function __sleep() {
-    // Only store the definition, not external objects or derived data.
-    $keys = array_keys($this->toArray());
-    $keys[] = 'entityTypeId';
-    return $keys;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __wakeup() {
-    // Run the values from self::toArray() through __construct().
-    $values = array_intersect_key($this->toArray(), get_object_vars($this));
-    $this->__construct($values, $this->entityTypeId);
-  }
-
 }
diff --git a/core/modules/field/src/Entity/FieldInstanceConfig.php b/core/modules/field/src/Entity/FieldInstanceConfig.php
index 8ce7afa..bfd9806 100644
--- a/core/modules/field/src/Entity/FieldInstanceConfig.php
+++ b/core/modules/field/src/Entity/FieldInstanceConfig.php
@@ -617,30 +617,6 @@ public function targetBundle() {
     return $this->bundle;
   }
 
-  /*
-   * Implements the magic __sleep() method.
-   *
-   * Using the Serialize interface and serialize() / unserialize() methods
-   * breaks entity forms in PHP 5.4.
-   * @todo Investigate in https://drupal.org/node/2074253.
-   */
-  public function __sleep() {
-    // Only serialize properties from self::toArray().
-    $properties = array_keys(array_intersect_key($this->toArray(), get_object_vars($this)));
-    // Serialize $entityTypeId property so that toArray() works when waking up.
-    $properties[] = 'entityTypeId';
-    return $properties;
-  }
-
-  /**
-   * Implements the magic __wakeup() method.
-   */
-  public function __wakeup() {
-    // Run the values from self::toArray() through __construct().
-    $values = array_intersect_key($this->toArray(), get_object_vars($this));
-    $this->__construct($values);
-  }
-
   /**
    * {@inheritdoc}
    */
diff --git a/core/modules/field/src/Entity/FieldStorageConfig.php b/core/modules/field/src/Entity/FieldStorageConfig.php
index dcae40b..0133b1b 100644
--- a/core/modules/field/src/Entity/FieldStorageConfig.php
+++ b/core/modules/field/src/Entity/FieldStorageConfig.php
@@ -635,30 +635,6 @@ public function hasData() {
   }
 
   /**
-   * Implements the magic __sleep() method.
-   *
-   * Using the Serialize interface and serialize() / unserialize() methods
-   * breaks entity forms in PHP 5.4.
-   * @todo Investigate in https://drupal.org/node/2074253.
-   */
-  public function __sleep() {
-    // Only serialize properties from self::toArray().
-    $properties = array_keys(array_intersect_key($this->toArray(), get_object_vars($this)));
-    // Serialize $entityTypeId property so that toArray() works when waking up.
-    $properties[] = 'entityTypeId';
-    return $properties;
-  }
-
-  /**
-   * Implements the magic __wakeup() method.
-   */
-  public function __wakeup() {
-    // Run the values from self::toArray() through __construct().
-    $values = array_intersect_key($this->toArray(), get_object_vars($this));
-    $this->__construct($values);
-  }
-
-  /**
    * {@inheritdoc}
    */
   public function getConstraints() {
diff --git a/core/modules/tour/tests/src/Entity/TourTest.php b/core/modules/tour/tests/src/Entity/TourTest.php
index 7b5f943..adb45ad 100644
--- a/core/modules/tour/tests/src/Entity/TourTest.php
+++ b/core/modules/tour/tests/src/Entity/TourTest.php
@@ -31,8 +31,17 @@ class TourTest extends UnitTestCase {
    * @dataProvider routeProvider
    */
   public function testHasMatchingRoute($routes, $route_name, $route_params, $result) {
-    $tour = $this->getMockBuilder('\Drupal\tour\Entity\Tour')
+    // Tour::__construct() pulls the plugin.manager.tour.tip service from the
+    // container. Mock it and and place it there.
+    $tip_manager = $this->getMockBuilder('Drupal\tour\TipPluginManager')
       ->disableOriginalConstructor()
+      ->getMock();
+    $container = new ContainerBuilder();
+    $container->set('plugin.manager.tour.tip', $tip_manager);
+    \Drupal::setContainer($container);
+
+    $tour = $this->getMockBuilder('\Drupal\tour\Entity\Tour')
+      ->setConstructorArgs(array(array(), 'tour'))
       ->setMethods(array('getRoutes'))
       ->getMock();