Re: [RDFa] ISSUE-9: nested LINK and META, link to ISSUE-12

> "LINK and META appear only in HEAD with no changes to content model"

Note that if we resolve this issue as above, which looks likely, then
this will also address ISSUE-12, which was a point about the RDFa syntax
not mentioning the nested META use case.

Note that I will mark ISSUE-12 as "postponed" to take into account
possible XHTML2 changes.

-Ben