diff -u b/core/includes/theme.inc b/core/includes/theme.inc
--- b/core/includes/theme.inc
+++ b/core/includes/theme.inc
@@ -364,7 +364,7 @@
  *
  * You use this method in theme functions to ensure that the result is safe for
  * output inside HTML fragments.
- * This mimics the behavior of the auto-escape fucntionality in Twig.
+ * This mimics the behavior of the auto-escape functionality in Twig.
  *
  * @param mixed $arg
  *   The string, object, or render array to escape if needed.
reverted:
--- b/core/tests/Drupal/KernelTests/Core/Theme/ThemeAutoescapeTest.php
+++ /dev/null
@@ -1,86 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\KernelTests\Core\Theme\ThemeAutoescapeTest.
- */
-
-namespace Drupal\KernelTests\Core\Theme;
-
-use Drupal\Component\Utility\Html;
-use Drupal\Core\Link;
-use Drupal\Core\Render\RenderContext;
-use Drupal\Core\Render\SafeString;
-use Drupal\Core\Url;
-use Drupal\KernelTests\KernelTestBase;
-
-/**
- * Tests the TranslatableString class.
- *
- * @group StringTranslation
- */
-class ThemeAutoescapeTest extends KernelTestBase {
-
-  /**
-   * {@inheritdoc}
-   */
-  public static $modules = ['system'];
-
-  /**
-   * {@inheritdoc}
-   */
-  protected function setUp() {
-    parent::setUp();
-
-    $this->installSchema('system', 'router');
-    \Drupal::service('router.builder')->rebuild();
-  }
-
-  /**
-   * Tests automatic escaping.
-   *
-   * @dataProvider providerTestThemeEscapeAndRender
-   */
-  public function testThemeEscapeAndRender($arg, $expected) {
-    if (is_array($arg) && isset($arg['#type']) && $arg['#type'] === 'link') {
-      $arg = Link::createFromRoute($arg['#title'], $arg['#url']);
-    }
-
-    /** @var \Drupal\Core\Render\RendererInterface $renderer */
-    $renderer = \Drupal::service('renderer');
-    $context = new RenderContext();
-    $renderer->executeInRenderContext($context, function () use ($expected, $arg) {
-      $this->assertSame($expected, theme_escape_and_render($arg));
-    });
-  }
-
-  /**
-   * Provide test examples.
-   */
-  public function providerTestThemeEscapeAndRender() {
-    return [
-      ['', ''],
-      ['a', 'a'],
-      ['>', '&gt;'],
-      [SafeString::create('<em>hi</em>'), '<em>hi</em>'],
-      [SafeString::create('<script>hi</script>'), '<script>hi</script>'],
-      ['<em>hi</em>', Html::escape('<em>hi</em>')],
-      [['#type' => 'link', '#title' => 'Text', '#url' => '<none>'], '<a href="">Text</a>'],
-      [['#markup' => '<em>hi</em>'], '<em>hi</em>'],
-      [
-        '<script>alert(123)</script>',
-        Html::escape('<script>alert(123)</script>')
-      ],
-    ];
-  }
-
-  /**
-   * @expectedException \Exception
-   */
-  public function testThemeEscapeAndRenderNotPrintable() {
-    theme_escape_and_render(new NonPrintable());
-  }
-
-}
-
-class NonPrintable { }
diff -u b/core/themes/engines/phptemplate/phptemplate.engine b/core/themes/engines/phptemplate/phptemplate.engine
--- b/core/themes/engines/phptemplate/phptemplate.engine
+++ b/core/themes/engines/phptemplate/phptemplate.engine
@@ -6,11 +6,11 @@
  *
  * Note: The PHP template engine is highly problematic, because each individual
  * template needs to take care of escaping for each variable manually, so using
- * it, makes it really hard to provide safe output. Instead its highly
- * encouraged to use the twig template engine instead.
+ * it makes it really hard to provide safe output. Instead it's highly
+ * encouraged to use the Twig template engine instead.
  *
  * @deprecated in Drupal 8.0.0, will be removed before Drupal 9.0.0.
- *   The phptemplate engine is deprecated and replaced with the twig template
+ *   The phptemplate engine is deprecated and replaced with the Twig template
  *   engine.
  */
 
@@ -20,7 +20,7 @@
  * Implements hook_init().
  */
 function phptemplate_init(Extension $theme) {
-  trigger_error('The php template engine is deprecated and should no longer be used. Use the twig template engine instead.', E_USER_DEPRECATED);
+  trigger_error('The php template engine is deprecated and should no longer be used. Use the Twig template engine instead.', E_USER_DEPRECATED);
   $theme->load();
 }