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

Dumper/AbstractDumper.php

@@ -35,7 +35,7 @@ abstract class AbstractDumper implements DataDumperInterface, DumperInterface
     protected $indentPad = '  ';
     protected $flags;
 
-    private $charset;
+    private $charset = '';
 
     /**
      * @param callable|resource|string|null $output  A line dumper callable, an opened stream or an output path, defaults to static::$defaultOutput