Partial html test

Seeing some buggy behavior around using trumpet against partial HTML snippets. It's tough to see the actual output (I think I'm using `tap` wrong maybe?) but it scoots the original `<script>` tag backwards a ways, usually obliterating the previous tag.

Trumpet's complicated enough that I haven't made much headway on just why that happens. Maybe trumpet was just never intended to work with unbalanced/partial HTML structures?

Hopefully this is useful!