[giow] (2) Make :enabled not match <a href>
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=26622
Affected topics: CSS, HTML

git-svn-id: https://svn.whatwg.org/webapps@8818 340c8d12-0b0e-0410-8428-c7bf67bfef74