Remove var not used due to returning early (introduced in 8982c32)

Author: Dave Hulbert

src/Symfony/Component/HttpFoundation/Request.php

@@ -476,7 +476,6 @@ public function __clone()
      */
     public function __toString()
     {
-        $content = '';
         try {
             $content = $this->getContent();
         } catch (\LogicException $e) {