Merge branch '2.7' into 2.8

* 2.7:
  [HttpFoundation] Fix transient test
  [HttpFoundation] Add a dependency on the mbstring polyfill
  [2.7] update readme files for new components
  add readme files where missing
  fix lowest TwigBridge deps versions
  [EventDispatcher] fix syntax error
  Don't use reflections when possible
  Don't use reflections when possible
  [Form] Update form tests after the ICU data update
  [Intl] Update tests and the number formatter to match behaviour of the intl extension
  [Intl] Update the ICU data to version 55
  [Intl] Fix the update-data.php script in preparation for ICU 5.5
  [Process] Fix memory issue when using large input streams
  Use constant instead of function call.
  fixed test name
  automatically generate safe fallback filename
  [Console] default to stderr in the console helpers

Conflicts:
	composer.json
	src/Symfony/Bridge/PhpUnit/README.md
	src/Symfony/Bridge/Twig/composer.json
	src/Symfony/Component/Console/Helper/DialogHelper.php
	src/Symfony/Component/Debug/DebugClassLoader.php
	src/Symfony/Component/HttpFoundation/composer.json
	src/Symfony/Component/Security/Acl/README.md
	src/Symfony/Component/Security/Core/README.md
	src/Symfony/Component/Security/Csrf/README.md
	src/Symfony/Component/Security/Http/README.md

Author: nicolas-grekas

DependencyInjection/Compiler/FragmentRendererPass.php

@@ -37,9 +37,8 @@ public function process(ContainerBuilder $container)
             // We must assume that the class value has been correctly filled, even if the service is created by a factory
             $class = $container->getDefinition($id)->getClass();
 
-            $refClass = new \ReflectionClass($class);
             $interface = 'Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface';
-            if (!$refClass->implementsInterface($interface)) {
+            if (!is_subclass_of($class, $interface)) {
                 throw new \InvalidArgumentException(sprintf('Service "%s" must implement interface "%s".', $id, $interface));
             }
 

DependencyInjection/Compiler/LoggingTranslatorPass.php

@@ -36,8 +36,7 @@ public function process(ContainerBuilder $container)
             $definition = $container->getDefinition((string) $translatorAlias);
             $class = $container->getParameterBag()->resolveValue($definition->getClass());
 
-            $refClass = new \ReflectionClass($class);
-            if ($refClass->implementsInterface('Symfony\Component\Translation\TranslatorInterface') && $refClass->implementsInterface('Symfony\Component\Translation\TranslatorBagInterface')) {
+            if (is_subclass_of($class, 'Symfony\Component\Translation\TranslatorInterface') && is_subclass_of($class, 'Symfony\Component\Translation\TranslatorBagInterface')) {
                 $container->getDefinition('translator.logging')->setDecoratedService('translator');
                 $container->getDefinition('translation.warmer')->replaceArgument(0, new Reference('translator.logging.inner'));
             }

README.md

@@ -0,0 +1,10 @@
+FrameworkBundle
+===============
+
+Resources
+---------
+
+  * [Contributing](https://symfony.com/doc/current/contributing/index.html)
+  * [Report issues](https://github.com/symfony/symfony/issues) and
+    [send Pull Requests](https://github.com/symfony/symfony/pulls)
+    in the [main Symfony repository](https://github.com/symfony/symfony)