Replace bogus html lang=en with lang="" (helps built-in Translate)
Sites seem to default to lang="en" during site creation.
If you are an English user, Firefox is lazy and won't check the contents of a page for a different language if html says lang="en".
Updates:
0.2 reduce breakage on sites by including lang="" instead of removing
0.3 reduce breakage on sites by changing only top document
