use HTML::TokeParser::Simple;

# time passes...

my $parser = HTML::TokeParser::Simple->new( string => $original_html );
while (my $token = $parser->get_token) {
  $token->rewrite_tag;
  if ($token->is_text) {
    my $t = $token->as_is;
    $t =~ s/"/&quote;/g;
    print $t;
  }
  elsif ($token->is_start_tag("script")) {
    # Embedded JavaScript, do not mess up!
    print $token->as_is;
    while ($token = $parser->get_token) {
      print $token->as_is;
      if ($token->is_tag("script") and not $token->is_start_tag) {
        last; # done with JavaScript
      }
    }
  }
  else {
    print $token->as_is;
  }
}