Merge branch '3.4'

* 3.4:
  [Yaml] Recommend using quotes instead of PARSE_KEYS_AS_STRINGS
  [DependencyInjection] Deprecate autowiring service auto-registration
  Removed useless argument $definition
  [DI] Generate shorter method names for class-based ids
  Fix comment
  [Config] Fix checking class existence freshness
  bumped Symfony version to 3.3.7
  updated VERSION for 3.3.6
  updated CHANGELOG for 3.3.6
  Autoconfigure instances of ArgumentValueResolverInterface
  Deprecate Filesystem/LockHandler
  improve sql explain table display
  Bump minimal PHP version to ^5.5.9|>=7.0.8

Author: nicolas-grekas

Loader/YamlFileLoader.php

@@ -15,7 +15,6 @@
 use Symfony\Component\Translation\Exception\LogicException;
 use Symfony\Component\Yaml\Parser as YamlParser;
 use Symfony\Component\Yaml\Exception\ParseException;
-use Symfony\Component\Yaml\Yaml;
 
 /**
  * YamlFileLoader loads translations from Yaml files.
@@ -40,7 +39,7 @@ protected function loadResource($resource)
         }
 
         try {
-            $messages = $this->yamlParser->parse(file_get_contents($resource), Yaml::PARSE_KEYS_AS_STRINGS);
+            $messages = $this->yamlParser->parse(file_get_contents($resource));
         } catch (ParseException $e) {
             throw new InvalidResourceException(sprintf('Error parsing YAML, invalid file "%s"', $resource), 0, $e);
         }