Merge branch '3.4' into 4.3

* 3.4: (21 commits)
  [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
  [Routing] Fix return type declarations
  ...

Author: nicolas-grekas

Client.php

@@ -153,9 +153,9 @@ public function setServerParameter($key, $value)
      * Gets single server parameter for specified key.
      *
      * @param string $key     A key of the parameter to get
-     * @param string $default A default value when key is undefined
+     * @param mixed  $default A default value when key is undefined
      *
-     * @return string A value of the parameter
+     * @return mixed A value of the parameter
      */
     public function getServerParameter($key, $default = '')
     {

Request.php

@@ -107,7 +107,7 @@ public function getServer()
     /**
      * Gets the request raw body data.
      *
-     * @return string The request raw body data
+     * @return string|null The request raw body data
      */
     public function getContent()
     {