Merge branch '4.4'

* 4.4:
  fixed CS
  fixed CS
  fixed CS
  fixed CS
  Do not log or call the proxy function when the locale is the same
  Added missing required dependencies on psr/cache and psr/container in symfony/cache-contracts and symfony/service-contracts respectively.
  [HttpClient] fix closing debug stream prematurely
  [Mailer] made code more robust
  Restore compatibility with php 5.5
  fixed sender/recipients in SMTP Envelope
  collect called listeners information only once
  [HttpClient] add HttplugClient for compat with libs that need httplug v1 or v2
  [HttpKernel] Remove TestEventDispatcher.

Test/Fixtures/web/index.php

@@ -80,7 +80,7 @@
     case '/post':
         $output = json_encode($_POST + ['REQUEST_METHOD' => $vars['REQUEST_METHOD']], JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);
         header('Content-Type: application/json', true);
-        header('Content-Length: '.\strlen($output));
+        header('Content-Length: '.strlen($output));
         echo $output;
         exit;