Merge branch '2.3' into 2.7

* 2.3:
  [Process] Remove a misleading comment
  Improve the phpdoc of SplFileInfo methods
  [Process] Use stream based storage to avoid memory issues
  Fixed the documentation of VoterInterface::supportsAttribute
  Remove useless duplicated tests
  [FrameworkBundle] Optimize framework extension tests
  Use is_subclass_of instead of Reflection when possible

Author: fabpot

Normalizer/CustomNormalizer.php

@@ -59,8 +59,6 @@ public function supportsNormalization($data, $format = null)
      */
     public function supportsDenormalization($data, $type, $format = null)
     {
-        $class = new \ReflectionClass($type);
-
-        return $class->isSubclassOf('Symfony\Component\Serializer\Normalizer\DenormalizableInterface');
+        return is_subclass_of($type, 'Symfony\Component\Serializer\Normalizer\DenormalizableInterface');
     }
 }