fix: print borrowed markers once

A whitespace-only <pre> or <textarea>, which tidyrs prints as written
where Prettier formats it, went through Prettier's branch for elements
it prints as written. That branch prints the borrowed markers both on
their own and in the tags, so <b>a</b><textarea> </textarea> gained a
stray >. Those elements now print them once. Prettier's own cases keep
its output, and printing them once there too is raised for sign-off
in deviations.md.