Issue #3019706 by hchonov, jibran: Functional JS Tests are broken if XDEBUG_CONFIG is set as an env variable

(cherry picked from commit 6248e44)

Author: alexpott

tests/Drupal/Tests/BrowserTestBase.php

@@ -239,6 +239,11 @@ protected function initMink() {
     ]);
     $session = new Session($driver, $selectors_handler);
     $cookies = $this->extractCookiesFromRequest(\Drupal::request());
+    // If there are any cookies, then first start the session before setting
+    // them.
+    if ($cookies && !$session->isStarted()) {
+      $session->start();
+    }
     foreach ($cookies as $cookie_name => $values) {
       foreach ($values as $value) {
         $session->setCookie($cookie_name, $value);