[e] (0) Better reference CSS for parsing according to CSS.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=26208
Affected topics: Canvas, HTML

git-svn-id: https://svn.whatwg.org/webapps@8793 340c8d12-0b0e-0410-8428-c7bf67bfef74