N°2651 rollback gitignore for lib tests dirs

Too dangerous ! We'll work properly on this but for 2.8

lib/symfony/http-kernel/Tests/Fixtures/ResettableService.php

@@ -0,0 +1,13 @@
+<?php
+
+namespace Symfony\Component\HttpKernel\Tests\Fixtures;
+
+class ResettableService
+{
+    public static $counter = 0;
+
+    public function reset()
+    {
+        ++self::$counter;
+    }
+}