Debug Panels computed too early if c.write is used

[RandalSchwartz]

It looks like this section of the code:

        my $content = $self->renderer->($vars);
        return sub {
            my $chunk = shift;
            return unless defined $chunk;
            $chunk =~ s!(?=</body>)!$content!i;
            return $chunk;
        };

will freeze the content of the debug panels the first time some streaming content comes back. In our app, we're using c.write to get Time-To-First-Byte down, and therefore the panels are frozen at that time, and don't contain data that would have been accumulated throughout the rendering of the page. Would it be possible to compute $content only when </body> is seen instead, so that the debug panels are computed after the full page render?