[giow] (2) Make sure that we say that enabling audio tracks and selecting video tracks is all synchronised with the event loop
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=25574
Affected topics: HTML, Video and Audio

git-svn-id: http://svn.whatwg.org/webapps@8673 340c8d12-0b0e-0410-8428-c7bf67bfef74
Merge remote branch 'origin/master' into whatwg