Custom attributes to javascript tags

I am afraid this is impossible. The markup is hard coded in /wp-includes/class.wp-scripts.php:

if ( $this->do_concat )
    $this->print_html .= "<script type="text/javascript" src="https://wordpress.stackexchange.com/questions/70184/$src"></script>\n";
else
    echo "<script type="text/javascript" src="https://wordpress.stackexchange.com/questions/70184/$src"></script>\n";