HTTP Content-Language header

Nothing to see here.

Assertion: [html tag] ko
no other language info
The html tag has no language attribute. (for html, html5, xhtmlH)
This HTML file contains xml:lang attributes. (for html)
A tag uses an xml:lang attribute without an associated lang attribute. (for html5, should be an error!, xhtmlH)

Next test
html5 as html