[e] (0) Remove some last traces of XBL.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24261
Affected topics: Canvas, DOM APIs, HTML, Rendering

git-svn-id: http://svn.whatwg.org/webapps@8395 340c8d12-0b0e-0410-8428-c7bf67bfef74