Remove dead statement

Author: tvdijen

src/XML/SignableElementTrait.php

@@ -34,7 +34,6 @@ private function toSignedXML(XMLSecurityKey $signingKey, array $certificates, DO
 
         if ($insertBefore !== null) {
             XMLSecurityUtils::insertSignature($signingKey, $certificates, $root, $insertBefore);
-            $doc = clone $root->ownerDocument;
         } else {
             $signature = new Signature($signingKey->getAlgorithm(), $certificates, $signingKey);
             $signature->toXML($root);