Handle lifetime value 0 for form_key cookie

0 should not be interpreted as a duration.

Author: ekuusela

app/code/Magento/PageCache/Observer/RegisterFormKeyFromCookie.php

@@ -88,7 +88,10 @@ private function updateCookieFormKey($formKey)
             ->createPublicCookieMetadata();
         $cookieMetadata->setDomain($this->sessionConfig->getCookieDomain());
         $cookieMetadata->setPath($this->sessionConfig->getCookiePath());
-        $cookieMetadata->setDuration($this->sessionConfig->getCookieLifetime());
+        $lifetime = $this->sessionConfig->getCookieLifetime();
+        if ($lifetime !== 0) {
+            $cookieMetadata->setDuration($lifetime);
+        }
 
         $this->cookieFormKey->set(
             $formKey,