Update to Drupal 8.0.0-beta15. For more information, see: https://www.drupal.org/node/2563023

core/modules/text/migration_templates/text_settings.yml

@@ -0,0 +1,14 @@
+id: text_settings
+label: Drupal teaser length configuration
+migration_tags:
+  - Drupal 6
+  - Drupal 7
+source:
+  plugin: variable
+  variables:
+    - teaser_length
+process:
+  default_summary_length: teaser_length
+destination:
+  plugin: config
+  config_name: text.settings

core/modules/text/src/Plugin/migrate/cckfield/TextField.php

@@ -0,0 +1,74 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\text\Plugin\migrate\cckfield\TextField.
+ */
+
+namespace Drupal\text\Plugin\migrate\cckfield;
+
+use Drupal\migrate\Entity\MigrationInterface;
+use Drupal\migrate_drupal\Plugin\migrate\cckfield\CckFieldPluginBase;
+
+/**
+ * @PluginID("text")
+ */
+class TextField extends CckFieldPluginBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldWidgetMap() {
+    return [
+      'text_textfield' => 'text_textfield',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldFormatterMap() {
+    return [
+      'default' => 'text_default',
+      'trimmed' => 'text_trimmed',
+      'plain' => 'basic_string',
+    ];
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function processCckFieldValues(MigrationInterface $migration, $field_name, $data) {
+    $process = array(
+      array(
+        'plugin' => 'iterator',
+        'source' => $field_name,
+        // See \Drupal\migrate_drupal\Plugin\migrate\source\d6\User::baseFields(),
+        // signature_format for an example of the YAML that represents this
+        // process array.
+        'process' => [
+          'value' => 'value',
+          'format' => [
+            [
+              'plugin' => 'static_map',
+              'bypass' => TRUE,
+              'source' => 'format',
+              'map' => [0 => NULL],
+            ],
+            [
+              'plugin' => 'skip_on_empty',
+              'method' => 'process',
+            ],
+            [
+              'plugin' => 'migration',
+              'migration' => 'd6_filter_format',
+              'source' => 'format',
+            ],
+          ],
+        ],
+      ),
+    );
+    $migration->setProcessOfProperty($field_name, $process);
+  }
+
+}

core/modules/text/src/Tests/Migrate/MigrateTextConfigsTest.php

@@ -0,0 +1,46 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\text\Tests\Migrate\MigrateTextConfigsTest.
+ */
+
+namespace Drupal\text\Tests\Migrate;
+
+use Drupal\config\Tests\SchemaCheckTestTrait;
+use Drupal\migrate_drupal\Tests\d6\MigrateDrupal6TestBase;
+
+/**
+ * Upgrade variables to text.settings.yml.
+ *
+ * @group migrate_drupal_6
+ */
+class MigrateTextConfigsTest extends MigrateDrupal6TestBase {
+
+  use SchemaCheckTestTrait;
+
+  /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = array('text');
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+    $this->executeMigration('text_settings');
+  }
+
+  /**
+   * Tests migration of text variables to text.settings.yml.
+   */
+  public function testTextSettings() {
+    $config = $this->config('text.settings');
+    $this->assertIdentical(456, $config->get('default_summary_length'));
+    $this->assertConfigSchema(\Drupal::service('config.typed'), 'text.settings', $config->get());
+  }
+
+}

core/modules/text/text.js

@@ -11,6 +11,9 @@
    * Auto-hide summary textarea if empty and show hide and unhide links.
    *
    * @type {Drupal~behavior}
+   *
+   * @prop {Drupal~behaviorAttach} attach
+   *   Attaches auto-hide behavior on `text-summary` events.
    */
   Drupal.behaviors.textSummary = {
     attach: function (context, settings) {