Add a DOCTYPE to the stream if the <html> tag is rendered (#21680)

This makes it a lot easier to render the whole document using React without
needing to patch into the stream.

We expect that currently people will still have to patch into the stream
to do advanced things but eventually the goal is that you shouldn't
need to.

Sebastian Markbåge committed 5y ago

bd45ad05dc4fe05f289d482bfd0111bee5d09ef4

Parent: a8f5e77

Committed by GitHub <noreply@github.com> on 6/14/2021, 8:57:17 PM