YamlDumper should dump Definition::getFactoryClass() setting

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

@@ -102,6 +102,10 @@ class YamlDumper extends Dumper
             $code .= sprintf("        synchronized: true\n");
         }
 
+        if ($definition->getFactoryClass()) {
+            $code .= sprintf("        factory_class: %s\n", $definition->getFactoryClass());
+        }
+
         if ($definition->getFactoryMethod()) {
             $code .= sprintf("        factory_method: %s\n", $definition->getFactoryMethod());
         }

src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services9.yml

@@ -9,6 +9,7 @@ services:
         tags:
             - { name: foo, foo: foo }
             - { name: foo, bar: bar }
+        factory_class: FooClass
         factory_method: getInstance
         arguments: [foo, '@foo.baz', { '%foo%': 'foo is %foo%', foobar: '%foo%' }, true, '@service_container']
         properties: { foo: bar, moo: '@foo.baz' }
@@ -23,6 +24,7 @@ services:
         configurator: ['@foo.baz', configure]
     foo.baz:
         class: %baz_class%
+        factory_class: %baz_class%
         factory_method: getInstance
         configurator: ['%baz_class%', configureStatic1]
     foo_bar: