diff --git a/core/includes/install.core.inc b/core/includes/install.core.inc
index 554ad06..8c6e47e 100644
--- a/core/includes/install.core.inc
+++ b/core/includes/install.core.inc
@@ -93,14 +93,6 @@
  * @see install_state_defaults()
  */
 function install_drupal($class_loader, $settings = array()) {
-  // Support the old way of calling this function with just a settings array.
-  // @todo Remove this when Drush is updated in the Drupal testing
-  //   infrastructure in https://www.drupal.org/node/2389243
-  if (is_array($class_loader) && $settings === array()) {
-    $settings = $class_loader;
-    $class_loader = require __DIR__ . '/../../autoload.php';
-  }
-
   global $install_state;
   // Initialize the installation state with the settings that were passed in,
   // as well as a boolean indicating whether or not this is an interactive
diff --git a/core/modules/simpletest/src/BrowserTestBase.php b/core/modules/simpletest/src/BrowserTestBase.php
index 2fc4a95..068bdc3 100644
--- a/core/modules/simpletest/src/BrowserTestBase.php
+++ b/core/modules/simpletest/src/BrowserTestBase.php
@@ -875,7 +875,7 @@ public function installDrupal() {
 
     // Execute the non-interactive installer.
     require_once DRUPAL_ROOT . '/core/includes/install.core.inc';
-    install_drupal($parameters);
+    install_drupal($this->classLoader, $parameters);
 
     // Import new settings.php written by the installer.
     Settings::initialize(DRUPAL_ROOT, $directory, $this->classLoader);