Merge branch '3.1'

* 3.1:
  [VarDumper] Fix dumping jsons casted as arrays
  PassConfig::getMergePass is not an array
  Revert "bug #19114 [HttpKernel] Dont close the reponse stream in debug (nicolas-grekas)"
  [Serializer] Include the format in the cache key
  Fix the retrieval of the last username when using forwarding
  [Yaml] Fix PHPDoc of the Yaml class
  [HttpFoundation] Add OPTIONS and TRACE to the list of safe methods
  Update getAbsoluteUri() for query string uris

Conflicts:
	src/Symfony/Component/DependencyInjection/Compiler/PassConfig.php
	src/Symfony/Component/HttpFoundation/Tests/RequestTest.php

Author: nicolas-grekas

Kernel.php

@@ -134,14 +134,6 @@ public function terminate(Request $request, Response $response)
         }
 
         if ($this->getHttpKernel() instanceof TerminableInterface) {
-            if (!$this->debug) {
-                if (function_exists('fastcgi_finish_request')) {
-                    fastcgi_finish_request();
-                } elseif ('cli' !== PHP_SAPI) {
-                    Response::closeOutputBuffers(0, true);
-                }
-            }
-
             $this->getHttpKernel()->terminate($request, $response);
         }
     }