Merge branch '3.1'

* 3.1:
  [VarDumper] Various minor fixes & cleanups
  Revert "bug #18935 [Form] Consider a violation even if the form is not submitted (egeloen)"
  [Config] Fix DirectoryResourceTest for symlinks
  [HttpKernel] Add missing SsiFragmentRendererTest
  [DoctrineBridge] Fix exception message and tests after misresolved merge
  Fixes the calendar in constructor to handle null

Author: nicolas-grekas

Extension/DumpExtension.php

@@ -69,6 +69,7 @@ public function dump(\Twig_Environment $env, $context)
         }
 
         $dump = fopen('php://memory', 'r+b');
+        $this->dumper->setCharset($env->getCharset());
 
         foreach ($vars as $value) {
             $this->dumper->dump($this->cloner->cloneVar($value), $dump);