reverted:
--- b/core/lib/Drupal/Core/Template/TwigExtension.php
+++ a/core/lib/Drupal/Core/Template/TwigExtension.php
@@ -76,7 +76,6 @@
       new \Twig_SimpleFunction('path', array($this, 'getPath'), array('is_safe_callback' => array($this, 'isUrlGenerationSafe'))),
       new \Twig_SimpleFunction('url_from_path', array($this, 'getUrlFromPath'), array('is_safe_callback' => array($this, 'isUrlGenerationSafe'))),
       new \Twig_SimpleFunction('link', array($this, 'getLink')),
-      new \Twig_SimpleFunction('file_url', 'file_create_url'),
     );
   }
 
reverted:
--- b/core/modules/system/src/Tests/Theme/EngineTwigTest.php
+++ a/core/modules/system/src/Tests/Theme/EngineTwigTest.php
@@ -65,7 +65,7 @@
   }
 
   /**
+   * Tests the link_generator twig functions.
-   * Tests the link_generator Twig functions.
    */
   public function testTwigLinkGenerator() {
     $this->drupalGet('twig-theme-test/link-generator');
@@ -83,13 +83,4 @@
     }
   }
 
-  /**
-   * Tests the file url Twig functions.
-   */
-  public function testTwigFileUrls() {
-    $this->drupalGet('/twig-theme-test/file-url');
-    $filepath = file_create_url('core/assets/vendor/jquery/jquery.js');
-    $this->assertRaw('<div>file_url: ' . $filepath . '</div>');
-  }
-
 }
reverted:
--- b/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php
+++ a/core/modules/system/tests/modules/twig_theme_test/src/TwigThemeTestController.php
@@ -49,13 +49,4 @@
     );
   }
 
-  /**
-   * Renders for testing file_create_url functions in a Twig template.
-   */
-  public function fileUrlRender() {
-    return array(
-      '#theme' => 'twig_theme_test_file_url',
-    );
-  }
-
 }
reverted:
--- b/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.module
+++ a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.module
@@ -33,10 +33,6 @@
     'variables' => array('test_url' => NULL),
     'template' => 'twig_theme_test.link_generator',
   );
-  $items['twig_theme_test_file_url'] = array(
-    'variables' => array(),
-    'template' => 'twig_theme_test.file_url',
-  );
   return $items;
 }
 
reverted:
--- b/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml
+++ a/core/modules/system/tests/modules/twig_theme_test/twig_theme_test.routing.yml
@@ -25,10 +25,3 @@
     _controller: '\Drupal\twig_theme_test\TwigThemeTestController::linkGeneratorRender'
   requirements:
     _access: 'TRUE'
-
-twig_theme_test_file_url:
-  path: '/twig-theme-test/file-url'
-  defaults:
-    _controller: '\Drupal\twig_theme_test\TwigThemeTestController::fileUrlRender'
-  requirements:
-    _access: 'TRUE'