[whatwg] Use <b> instead of <m>

[Simon Pieters]

Hi,

I think that we should use <b> instead of <m>[1]. It will stand for marked 
or highlighted. The reason for this is backwards compability. I think it's 
ok, given that we have <dl> to stand for "unordered association list", while 
we havn't given it the name <ual> (or simular).

If we use <b>, Google is already (partially) compliant. ;-)

[1] http://whatwg.org/specs/web-apps/current-work/#the-m

Regards,
Simon Pieters