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

DataCollector/ConfigDataCollector.php

@@ -75,7 +75,7 @@ public function collect(Request $request, Response $response, \Exception $except
             'wincache_enabled' => extension_loaded('wincache') && ini_get('wincache.ocenabled'),
             'zend_opcache_enabled' => extension_loaded('Zend OPcache') && ini_get('opcache.enable'),
             'bundles' => array(),
-            'sapi_name' => php_sapi_name(),
+            'sapi_name' => PHP_SAPI,
         );
 
         if (isset($this->kernel)) {

DependencyInjection/FragmentRendererPass.php

@@ -52,9 +52,9 @@ public function process(ContainerBuilder $container)
                 throw new \InvalidArgumentException(sprintf('The service "%s" must not be abstract as fragment renderer are lazy-loaded.', $id));
             }
 
-            $refClass = new \ReflectionClass($container->getParameterBag()->resolveValue($def->getClass()));
+            $class = $container->getParameterBag()->resolveValue($def->getClass());
             $interface = 'Symfony\Component\HttpKernel\Fragment\FragmentRendererInterface';
-            if (!$refClass->implementsInterface($interface)) {
+            if (!is_subclass_of($class, $interface)) {
                 throw new \InvalidArgumentException(sprintf('Service "%s" must implement interface "%s".', $id, $interface));
             }