Hidden Captcha Input Box

I have a page where Image captcha is enabled, but I cannot find the file that contains a display:none for form-item-captcha-respone.

I went into sites/all/modules and sites/all/themes and ran this script in each of the folders:

<?php
foreach (new DirectoryIterator('.') as $file) {
   // if the file is not this file, and does not start with a '.' or '..',
   // then store it for later display
   if ( (!$file->isDot()) && ($file->getFilename() != basename($_SERVER['PHP_SELF'])) ) {
      // if the element is a directory add to the file name "(Dir)"
     if ($file->isDir()===false){
     $fcon=file_get_contents($file->getFilename());
      if (strpos($fcon,"form-item-captcha-response")>-1){
      echo $file->getFilename() . "<br />";
      }
    }    

   }
}

?>

I cannot find this piece of code. Any help would be great on where to go to find this