[FrameworkBundle] fixed typos (patch from Dennis.Verspuij)

src/Symfony/Bundle/FrameworkBundle/Templating/Form/Field.php

@@ -56,7 +56,7 @@ class Field extends BaseField
         ));
     }
 
-    public function label($label, $template = null)
+    public function label($label = false, $template = null)
     {
         if (null === $template) {
             $template = 'FrameworkBundle:Form:label.php';

src/Symfony/Bundle/FrameworkBundle/Templating/HtmlGenerator.php

@@ -121,7 +121,7 @@ class HtmlGenerator implements HtmlGeneratorInterface
             if (is_array($option)) {
                 $options[] = $this->contentTag(
                     'optgroup',
-                    "\n".renderChoices($option, $selected)."\n",
+                    "\n".$this->doChoices($option, $selected)."\n",
                     array('label' => $this->escape($key))
                 );
             } else {