Issue #2239241 by Berdir, mr.baileys | tstoeckler: DateItem is completely broken, remove it.

core/lib/Drupal/Core/Field/Plugin/Field/FieldType/DateItem.php

-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Entity\Plugin\Field\FieldType\DateItem.
- */
-
-namespace Drupal\Core\Field\Plugin\Field\FieldType;
-
-use Drupal\Core\Field\FieldItemBase;
-use Drupal\Core\Field\FieldStorageDefinitionInterface;
-use Drupal\Core\TypedData\DataDefinition;
-
-/**
- * Defines the 'date' entity field type.
- *
- * @FieldType(
- *   id = "date",
- *   label = @Translation("Date"),
- *   description = @Translation("An entity field containing a date value."),
- *   no_ui = TRUE
- * )
- */
-class DateItem extends FieldItemBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
-    $properties['value'] = DataDefinition::create('date')
-      ->setLabel(t('Date value'));
-
-    return $properties;
-  }
-
-  /**
-   * {@inheritdoc}
-   */
-  public static function schema(FieldStorageDefinitionInterface $field_definition) {
-    return array(
-      'columns' => array(
-        'value' => array(
-          'type' => 'varchar',
-          'length' => 20,
-          'not null' => FALSE,
-        ),
-      ),
-    );
-  }
-
-}