return correct content when not dom_enabled

Fixes [rt.cpan.org #84639].
add TODO test for incorrect content after 302/JS

The "content" method returns the wrong content when the request chain
contains both 302 and JavaScript redirects.  See [rt.cpan.org #84472].
make update_html return the current response

This is necessary because the current response might change as a result
of client-side redirects.  Fixes [rt.cpan.org #84472].
WWW::Scripter 0.030

  - The "content" method no longer fails when "dom_enabled" has been
    unset [rt.cpan.org #84639].

  - The "content" method now returns the correct content when the
    request chain contains both server- and client-side redirects
    [rt.cpan.org #84472].