[DependencyInjection] added public attribute when dumping a container to XML

src/Symfony/Component/DependencyInjection/Dumper/XmlDumper.php

@@ -122,6 +122,9 @@ class XmlDumper extends Dumper
         if (ContainerInterface::SCOPE_CONTAINER !== $scope = $definition->getScope()) {
             $service->setAttribute('scope', $scope);
         }
+        if (!$definition->isPublic()) {
+            $service->setAttribute('public', 'false');
+        }
 
         foreach ($definition->getTags() as $name => $tags) {
             foreach ($tags as $attributes) {