The HTML spec doesn’t require it, and I prefer to omit it. This has been
bothering me for ages, but I hadn’t gotten round to fixing it yet.
This can cause nominally invalid HTML to be emitted, if `</body>` was
omitted but `</html>` was present, but that’s unlikely to happen, and
this is for development purposes only, and the right thing will happen
anyway in all environments (per browser behaviour and spec).
I don’t think this warrants a changelog entry.
cc01d3f82f