diff --git a/core/modules/simpletest/src/TestServiceProvider.php b/core/modules/simpletest/src/TestServiceProvider.php
index 5a1a398..5aa9c8b 100644
--- a/core/modules/simpletest/src/TestServiceProvider.php
+++ b/core/modules/simpletest/src/TestServiceProvider.php
@@ -12,7 +12,7 @@
 use Drupal\Core\DependencyInjection\ServiceProviderInterface;
 use Symfony\Component\DependencyInjection\Definition;
 
-class TestServiceProvider implements ServiceProviderInterface, ServiceModifierInterface {
+class TestServiceProvider implements ServiceProviderInterface {
 
   /**
    * @var \Drupal\simpletest\TestBase;
@@ -28,20 +28,4 @@ function register(ContainerBuilder $container) {
     }
   }
 
-  /**
-   * {@inheritdoc}
-   */
-  public function alter(ContainerBuilder $container) {
-    if (static::$currentTest instanceof KernelTestBase) {
-      // While $container->get() does a recursive resolve, getDefinition() does
-      // not, so do it ourselves.
-      foreach (['router.route_provider' => 'RouteProvider'] as $original_id => $class) {
-        for ($id = $original_id; $container->hasAlias($id); $id = (string) $container->getAlias($id));
-        $definition = $container->getDefinition($id);
-        $definition->clearTag('needs_destruction');
-        $container->setDefinition("simpletest.$original_id", $definition);
-        $container->setDefinition($id, new Definition('Drupal\simpletest\\' . $class));
-      }
-    }
-  }
 }