diff --git a/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinition.php b/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinition.php
index 0ed2eef..222949d 100644
--- a/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinition.php
+++ b/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinition.php
@@ -112,8 +112,17 @@ public function getBundles() {
   /**
    * {@inheritdoc}
    */
-  public function setBundles(array $bundles) {
-    return $this->addConstraint('Bundle', $bundles);
+  public function setBundles(array $bundles = NULL) {
+    if (isset($bundles)) {
+      $this->addConstraint('Bundle', $bundles);
+    }
+    else {
+      // Remove the constraint.
+      $constraints = $this->getConstraints();
+      unset($constraints['Bundle']);
+      $this->setConstraints($constraints);
+    }
+    return $this;
   }
 
 }
diff --git a/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinitionInterface.php b/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinitionInterface.php
index 9b57384..933d3a3 100644
--- a/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinitionInterface.php
+++ b/core/lib/Drupal/Core/Entity/TypedData/EntityDataDefinitionInterface.php
@@ -37,19 +37,18 @@ public function setEntityTypeId($entity_type_id);
    * Returns the array of possible entity bundles.
    *
    * @return array|null
-   *   The array of possible bundles, or NULL if the bundle is unknown or the
-   *   entity type does not have bundles.
+   *   The array of possible bundles, or NULL for any.
    */
   public function getBundles();
 
   /**
    * Sets the array of possible entity bundles.
    *
-   * @param array $bundles
-   *   The bundles to set.
+   * @param array|null $bundles
+   *   The array of possible bundles, or NULL for any.
    *
    * @return static
    *   The object itself for chaining.
    */
-  public function setBundles(array $bundles);
+  public function setBundles(array $bundles = NULL);
 }
diff --git a/core/lib/Drupal/Core/Field/FieldDefinitionInterface.php b/core/lib/Drupal/Core/Field/FieldDefinitionInterface.php
index 39fdc83..c182231 100644
--- a/core/lib/Drupal/Core/Field/FieldDefinitionInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldDefinitionInterface.php
@@ -103,22 +103,6 @@ public function getSettings();
   public function getSetting($setting_name);
 
   /**
-   * Returns the names of the field's subproperties.
-   *
-   * A field is a list of items, and each item can contain one or more
-   * properties. All items for a given field contain the same property names,
-   * but the values can be different for each item.
-   *
-   * For example, an email field might just contain a single 'value' property,
-   * while a link field might contain 'title' and 'url' properties, and a text
-   * field might contain 'value', 'summary', and 'format' properties.
-   *
-   * @return array
-   *   The property names.
-   */
-  public function getPropertyNames();
-
-  /**
    * Returns whether the field is translatable.
    *
    * @return bool
@@ -276,6 +260,22 @@ public function getPropertyDefinition($name);
   public function getPropertyDefinitions();
 
   /**
+   * Returns the names of the field's subproperties.
+   *
+   * A field is a list of items, and each item can contain one or more
+   * properties. All items for a given field contain the same property names,
+   * but the values can be different for each item.
+   *
+   * For example, an email field might just contain a single 'value' property,
+   * while a link field might contain 'title' and 'url' properties, and a text
+   * field might contain 'value', 'summary', and 'format' properties.
+   *
+   * @return array
+   *   The property names.
+   */
+  public function getPropertyNames();
+
+  /**
    * Returns the name of the main property, if any.
    *
    * Some field items consist mainly of one main property, e.g. the value of a
diff --git a/core/lib/Drupal/Core/Field/FieldItemBase.php b/core/lib/Drupal/Core/Field/FieldItemBase.php
index 8efa994..403dc25 100644
--- a/core/lib/Drupal/Core/Field/FieldItemBase.php
+++ b/core/lib/Drupal/Core/Field/FieldItemBase.php
@@ -26,7 +26,7 @@
   /**
    * {@inheritdoc}
    */
-  public static function getMainPropertyName() {
+  public static function mainPropertyName() {
     return 'value';
   }
 
@@ -37,7 +37,7 @@ public function __construct(DataDefinitionInterface $definition, $name = NULL, T
     parent::__construct($definition, $name, $parent);
     // Initialize computed properties by default, such that they get cloned
     // with the whole item.
-    foreach ($this->getPropertyDefinitions() as $name => $definition) {
+    foreach ($this->definition->getPropertyDefinitions() as $name => $definition) {
       if ($definition->isComputed()) {
         $this->properties[$name] = \Drupal::typedDataManager()->getPropertyInstance($this, $name);
       }
@@ -98,7 +98,7 @@ public function setValue($values, $notify = TRUE) {
     // Treat the values as property value of the first property, if no array is
     // given.
     if (isset($values) && !is_array($values)) {
-      $keys = array_keys($this->getPropertyDefinitions());
+      $keys = array_keys($this->definition->getPropertyDefinitions());
       $values = array($keys[0] => $values);
     }
     $this->values = $values;
diff --git a/core/lib/Drupal/Core/Field/FieldItemInterface.php b/core/lib/Drupal/Core/Field/FieldItemInterface.php
index b6a9653..899fbad 100644
--- a/core/lib/Drupal/Core/Field/FieldItemInterface.php
+++ b/core/lib/Drupal/Core/Field/FieldItemInterface.php
@@ -46,7 +46,7 @@ public static function propertyDefinitions(FieldDefinitionInterface $field_defin
    *
    * @see \Drupal\Core\Field\FieldDefinition
    */
-  public static function getMainPropertyName();
+  public static function mainPropertyName();
 
   /**
    * Returns the schema for the field.
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
index ce449af..f83c427 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/EntityReferenceItem.php
@@ -71,7 +71,7 @@ public static function propertyDefinitions(FieldDefinitionInterface $field_defin
   /**
    * {@inheritdoc}
    */
-  public static function getMainPropertyName() {
+  public static function mainPropertyName() {
     return 'target_id';
   }
 
diff --git a/core/lib/Drupal/Core/TypedData/ComplexDataDefinitionBase.php b/core/lib/Drupal/Core/TypedData/ComplexDataDefinitionBase.php
index ac70ef5..1fa5dab 100644
--- a/core/lib/Drupal/Core/TypedData/ComplexDataDefinitionBase.php
+++ b/core/lib/Drupal/Core/TypedData/ComplexDataDefinitionBase.php
@@ -16,14 +16,17 @@
    * An array of data definitions.
    *
    * @var \Drupal\Core\TypedData\DataDefinitionInterface[]
-   *
-   * @see ComplexDataDefinitionBase::getPropertyDefinitions()
    */
   protected $propertyDefinitions;
 
   /**
    * {@inheritdoc}
    */
+  abstract public function getPropertyDefinitions();
+
+  /**
+   * {@inheritdoc}
+   */
   public function getPropertyDefinition($name) {
     if (!isset($this->propertyDefinitions)) {
       $this->getPropertyDefinitions();
@@ -36,16 +39,6 @@ public function getPropertyDefinition($name) {
   /**
    * {@inheritdoc}
    */
-  public function __sleep() {
-    // Do not serialize the cached property definitions.
-    $vars = get_object_vars($this);
-    unset($vars['propertyDefinitions']);
-    return array_keys($vars);
-  }
-
-  /**
-   * {@inheritdoc}
-   */
   public function getMainPropertyName() {
     return NULL;
   }
@@ -53,6 +46,11 @@ public function getMainPropertyName() {
   /**
    * {@inheritdoc}
    */
-  abstract public function getPropertyDefinitions();
+  public function __sleep() {
+    // Do not serialize the cached property definitions.
+    $vars = get_object_vars($this);
+    unset($vars['propertyDefinitions']);
+    return array_keys($vars);
+  }
 
 }
diff --git a/core/lib/Drupal/Core/TypedData/DataDefinition.php b/core/lib/Drupal/Core/TypedData/DataDefinition.php
index dd1d400..a902ef0 100644
--- a/core/lib/Drupal/Core/TypedData/DataDefinition.php
+++ b/core/lib/Drupal/Core/TypedData/DataDefinition.php
@@ -43,11 +43,11 @@ public static function createFromDataType($type) {
   /**
    * Constructs a new data definition object.
    *
-   * @param array $definition
-   *   (optional) If given, a data definition represented as array.
+   * @param array $values
+   *   (optional) If given, an array of initial values to set on the definition.
    */
-  public function __construct(array $definition = array()) {
-    $this->definition = $definition;
+  public function __construct(array $values = array()) {
+    $this->definition = $values;
   }
 
   /**
diff --git a/core/lib/Drupal/Core/TypedData/ListDataDefinition.php b/core/lib/Drupal/Core/TypedData/ListDataDefinition.php
index 412803e..75e93e8 100644
--- a/core/lib/Drupal/Core/TypedData/ListDataDefinition.php
+++ b/core/lib/Drupal/Core/TypedData/ListDataDefinition.php
@@ -52,8 +52,8 @@ public static function createFromItemType($item_type) {
   /**
    * {@inheritdoc}
    */
-  public function __construct(array $definition = array(), DataDefinitionInterface $item_definition = NULL) {
-    $this->definition = $definition;
+  public function __construct(array $values = array(), DataDefinitionInterface $item_definition = NULL) {
+    $this->definition = $values;
     $this->itemDefinition = $item_definition;
   }
 
diff --git a/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
index 30ac403..d895632 100644
--- a/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
+++ b/core/lib/Drupal/Core/TypedData/Plugin/DataType/Map.php
@@ -7,7 +7,6 @@
 
 namespace Drupal\Core\TypedData\Plugin\DataType;
 
-use Drupal\Core\TypedData\MapDataDefinition;
 use Drupal\Core\TypedData\TypedData;
 use Drupal\Core\TypedData\ComplexDataInterface;
 
@@ -154,7 +153,7 @@ public function set($property_name, $value, $notify = TRUE) {
    */
   public function getProperties($include_computed = FALSE) {
     $properties = array();
-    foreach ($this->getPropertyDefinitions() as $name => $definition) {
+    foreach ($this->definition->getPropertyDefinitions() as $name => $definition) {
       if ($include_computed || !$definition->isComputed()) {
         $properties[$name] = $this->get($name);
       }
diff --git a/core/modules/config_translation/tests/Drupal/config_translation/Tests/ConfigMapperManagerTest.php b/core/modules/config_translation/tests/Drupal/config_translation/Tests/ConfigMapperManagerTest.php
index 5f4afe5..860941b 100644
--- a/core/modules/config_translation/tests/Drupal/config_translation/Tests/ConfigMapperManagerTest.php
+++ b/core/modules/config_translation/tests/Drupal/config_translation/Tests/ConfigMapperManagerTest.php
@@ -164,7 +164,7 @@ public function providerTestHasTranslatable() {
   protected function getElement(array $definition) {
     $element = $this->getMock('Drupal\Core\TypedData\TypedDataInterface');
     $element->expects($this->any())
-      ->method('getDefinition')
+      ->method('getDataDefinition')
       ->will($this->returnValue($definition));
     return $element;
   }
diff --git a/core/modules/editor/editor.module b/core/modules/editor/editor.module
index fde8db0..3841820 100644
--- a/core/modules/editor/editor.module
+++ b/core/modules/editor/editor.module
@@ -628,14 +628,14 @@ function _editor_get_file_uuids_by_field(EntityInterface $entity) {
  *   The names of the fields on this entity that have text processing enabled.
  */
 function _editor_get_processed_text_fields(ContentEntityInterface $entity) {
-  $fields = $entity->getFieldDefinitions();
-  if (empty($fields)) {
+  $field_definitions = $entity->getFieldDefinitions();
+  if (empty($field_definitions)) {
     return array();
   }
 
   // Find all configurable fields, because only they could have a
   // text_processing setting.
-  $configurable_fields = array_keys(array_filter($fields, function ($definition) {
+  $configurable_fields = array_keys(array_filter($field_definitions, function ($definition) {
     return $definition->isConfigurable();
   }));
   if (empty($configurable_fields)) {
diff --git a/core/modules/field/lib/Drupal/field/Entity/Field.php b/core/modules/field/lib/Drupal/field/Entity/Field.php
index aceb2f7..96ba183 100644
--- a/core/modules/field/lib/Drupal/field/Entity/Field.php
+++ b/core/modules/field/lib/Drupal/field/Entity/Field.php
@@ -453,8 +453,7 @@ public static function postDelete(EntityStorageControllerInterface $storage_cont
   public function getSchema() {
     if (!isset($this->schema)) {
       // Get the schema from the field item class.
-      $definition = \Drupal::service('plugin.manager.field.field_type')->getDefinition($this->type);
-      $class = $definition['class'];
+      $class = $this->getFieldItemClass();
       $schema = $class::schema($this);
       // Fill in default values for optional entries.
       $schema += array('indexes' => array(), 'foreign keys' => array());
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
index 65fb4ab..eece832 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityFieldTest.php
@@ -7,8 +7,6 @@
 
 namespace Drupal\system\Tests\Entity;
 
-use Drupal\Core\Entity\TypedData\EntityDataDefinition;
-use Drupal\Core\Entity\TypedData\EntityDataDefinitionInterface;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Field\FieldDefinition;
 use Drupal\Core\Field\FieldDefinitionInterface;
diff --git a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTypedDataDefinitionTest.php b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTypedDataDefinitionTest.php
index 7fae753..3e0fe10 100644
--- a/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTypedDataDefinitionTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/Entity/EntityTypedDataDefinitionTest.php
@@ -67,8 +67,7 @@ public function testFields() {
     $this->assertEqual($field_item_definition->getMainPropertyName(), 'value');
     $this->assertNull($field_item_definition->getPropertyDefinition('invalid'));
 
-    // To ease access of field item property metadata, field definitions make
-    // metadata about field item properties on the field level as well.
+    // Test accessing field item property metadata via the field definition.
     $this->assertTrue($field_definition instanceof FieldDefinitionInterface);
     $this->assertEqual(array_keys($field_definition->getPropertyDefinitions()), array('value'));
     $this->assertEqual($field_definition->getPropertyDefinition('value')->getDataType(), 'integer');
@@ -76,12 +75,12 @@ public function testFields() {
     $this->assertNull($field_definition->getPropertyDefinition('invalid'));
 
     // Test using the definition factory for field item lists and field items.
-    $field_item2 = $this->typedDataManager->createDataDefinition('field_item:integer');
-    $this->assertFalse($field_item2 instanceof ListDataDefinitionInterface);
-    $this->assertTrue($field_item2 instanceof ComplexDataDefinitionInterface);
+    $field_item = $this->typedDataManager->createDataDefinition('field_item:integer');
+    $this->assertFalse($field_item instanceof ListDataDefinitionInterface);
+    $this->assertTrue($field_item instanceof ComplexDataDefinitionInterface);
     // Comparison should ignore the internal static cache, so compare the
     // serialized objects instead.
-    $this->assertEqual(serialize($field_item_definition), serialize($field_item2));
+    $this->assertEqual(serialize($field_item_definition), serialize($field_item));
 
     $field_definition2 = $this->typedDataManager->createListDataDefinition('field_item:integer');
     $this->assertTrue($field_definition2 instanceof ListDataDefinitionInterface);
@@ -111,7 +110,7 @@ public function testEntities() {
     $this->assertTrue($entity_definition2 instanceof ComplexDataDefinitionInterface);
     $this->assertEqual(serialize($entity_definition), serialize($entity_definition2));
 
-    // Test that definition factory creates the right definitions for all
+    // Test that the definition factory creates the right definitions for all
     // entity data types variants.
     $this->assertEqual($this->typedDataManager->createDataDefinition('entity'), EntityDataDefinition::create());
     $this->assertEqual($this->typedDataManager->createDataDefinition('entity:node'), EntityDataDefinition::create('node'));
@@ -128,7 +127,7 @@ public function testEntityReferences() {
     $this->assertEqual($reference_definition->getTargetDefinition()->getDataType(), 'entity');
     $this->assertTrue($reference_definition->getTargetDefinition() instanceof \Drupal\Core\Entity\TypedData\EntityDataDefinitionInterface);
 
-    // Test using the definition factory.
+    // Test that the definition factory creates the right definition object.
     $reference_definition2 = $this->typedDataManager->createDataDefinition('entity_reference');
     $this->assertTrue($reference_definition2 instanceof DataReferenceDefinitionInterface);
     $this->assertEqual($reference_definition2, $reference_definition);
diff --git a/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataDefinitionTest.php b/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataDefinitionTest.php
index 57a7bd6..aa9d3c1 100644
--- a/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataDefinitionTest.php
+++ b/core/modules/system/lib/Drupal/system/Tests/TypedData/TypedDataDefinitionTest.php
@@ -57,8 +57,8 @@ public function testLists() {
     $this->assertTrue($list_definition2 instanceof ListDataDefinitionInterface);
     $this->assertEqual($list_definition, $list_definition2);
 
-    // Test creating a single list item, which is the same as a list of any
-    // items.
+    // Test creating the definition of data with type 'list', which is the same
+    // as creating a definition of a list of items of type 'any'.
     $list_definition = $this->typedDataManager->createDataDefinition('list');
     $this->assertTrue($list_definition instanceof ListDataDefinitionInterface);
     $this->assertEqual($list_definition->getDataType(), 'list');
diff --git a/core/modules/text/lib/Drupal/text/Plugin/Field/FieldType/TextItemBase.php b/core/modules/text/lib/Drupal/text/Plugin/Field/FieldType/TextItemBase.php
index 340e98b..9cac637 100644
--- a/core/modules/text/lib/Drupal/text/Plugin/Field/FieldType/TextItemBase.php
+++ b/core/modules/text/lib/Drupal/text/Plugin/Field/FieldType/TextItemBase.php
@@ -66,7 +66,7 @@ public function getCacheData() {
     // the sanitized value in the filter cache separately.
     $text_processing = $this->getSetting('text_processing');
     if (!$text_processing || filter_format_allowcache($this->get('format')->getValue())) {
-      foreach ($this->getPropertyDefinitions() as $property => $definition) {
+      foreach ($this->definition->getPropertyDefinitions() as $property => $definition) {
         if ($definition->getClass() == '\Drupal\text\TextProcessed') {
           $data[$property] = $this->get($property)->getValue();
         }
@@ -85,7 +85,7 @@ public function onChange($property_name) {
     }
 
     // Unset processed properties that are affected by the change.
-    foreach ($this->getPropertyDefinitions() as $property => $definition) {
+    foreach ($this->definition->getPropertyDefinitions() as $property => $definition) {
       if ($definition->getClass() == '\Drupal\text\TextProcessed') {
         if ($property_name == 'format' || ($definition->getSetting('text source') == $property_name)) {
           $this->set($property, NULL, FALSE);