lang="" vs HTTP
Test passes if you see green below, and no message to ignore it.
This test is only valid if the user agent recognises the HTTP and html lang declarations, and :lang works.
|Ignore this test. (:lang not supported)|
Assertion: If the HTTP header contains a language declaration but the html element uses an empty lang attribute, the UA will not recognize the language declared in the HTTP header.
Red means the HTTP declared language was used.