Merge branch '4.4' into 5.3

* 4.4:
  Don't produce TypeErrors for non-string CSRF tokens
  [HttpKernel] Fix SplFileInfo mock in HttpKernelBrowserTest
  Update NativeSessionStorage docblock to match defaults

Author: derrabus

Session/Storage/NativeSessionStorage.php

@@ -86,7 +86,7 @@ class NativeSessionStorage implements SessionStorageInterface
      * name, "PHPSESSID"
      * referer_check, ""
      * serialize_handler, "php"
-     * use_strict_mode, "0"
+     * use_strict_mode, "1"
      * use_cookies, "1"
      * use_only_cookies, "1"
      * use_trans_sid, "0"