Merge branch '2.8' into 3.2

* 2.8:
  [Console] Do not duplicate Helper::strlen() code
  [FrameworkBundle] Adding the extension XML
  [Form] Minor: Fix comment in ChoiceType
  [FrameworkBundle] AbstractConfigCommand: do not try registering bundles twice

Author: fabpot

Command/AbstractConfigCommand.php

@@ -117,7 +117,7 @@ private function initializeBundles()
         // Re-build bundle manually to initialize DI extensions that can be extended by other bundles in their build() method
         // as this method is not called when the container is loaded from the cache.
         $container = $this->getContainerBuilder();
-        $bundles = $this->getContainer()->get('kernel')->registerBundles();
+        $bundles = $this->getContainer()->get('kernel')->getBundles();
         foreach ($bundles as $bundle) {
             if ($extension = $bundle->getContainerExtension()) {
                 $container->registerExtension($extension);

composer.json

@@ -17,6 +17,7 @@
     ],
     "require": {
         "php": ">=5.5.9",
+        "ext-xml": "*",
         "symfony/cache": "~3.2.2|~3.3",
         "symfony/class-loader": "~3.2",
         "symfony/dependency-injection": "~3.2.1|~3.3",