Merge branch '4.4'

* 4.4: (28 commits)
  fix merge
  [SecurityBundle] fix return type declarations
  [BrowserKit] fix return type declarations
  [PropertyInfo] fix return type declarations
  [Bridge/Doctrine] fix return type declarations
  [Form] fix return type declarations
  [Console] fix return type declarations
  [Intl] fix return type declarations
  [Templating] fix return type declarations
  [DomCrawler] fix return type declarations
  [Validator] fix return type declarations
  [Process] fix return type declarations
  [Workflow] fix return type declarations
  [Cache] fix return type declarations
  [Serializer] fix return type declarations
  [Translation] fix return type declarations
  [DI] fix return type declarations
  [Config] fix return type declarations
  [HttpKernel] Fix return type declarations
  [Security] Fix return type declarations
  ...

Process.php

@@ -69,7 +69,7 @@ class Process implements \IteratorAggregate
     private $status = self::STATUS_READY;
     private $incrementalOutputOffset = 0;
     private $incrementalErrorOutputOffset = 0;
-    private $tty;
+    private $tty = false;
     private $pty;
 
     private $useFileHandles = false;
@@ -891,7 +891,7 @@ public function getStatus()
      * @param int|float $timeout The timeout in seconds
      * @param int       $signal  A POSIX signal to send in case the process has not stop at timeout, default is SIGKILL (9)
      *
-     * @return int The exit-code of the process
+     * @return int|null The exit-code of the process or null if it's not running
      */
     public function stop(float $timeout = 10, int $signal = null)
     {