remove a test that is not relevant anymore (related to the removed C extension)

test/Twig/Tests/NativeExtensionTest.php

@@ -1,29 +0,0 @@
-<?php
-
-/*
- * This file is part of Twig.
- *
- * (c) Fabien Potencier
- *
- * For the full copyright and license information, please view the LICENSE
- * file that was distributed with this source code.
- */
-
-class Twig_Tests_NativeExtensionTest extends \PHPUnit\Framework\TestCase
-{
-    public function testGetProperties()
-    {
-        $twig = new Twig_Environment(new Twig_Loader_Array(array('index' => '{{ d1.date }}{{ d2.date }}')), array(
-            'debug' => true,
-            'cache' => false,
-            'autoescape' => false,
-        ));
-
-        $d1 = new DateTime();
-        $d2 = new DateTime();
-        $output = $twig->render('index', compact('d1', 'd2'));
-
-        // If it fails, PHP will crash.
-        $this->assertEquals($output, $d1->date.$d2->date);
-    }
-}