[giow] (3) Make sure newly created <video> and <audio> elements with a src='' attribute actually load the media.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=24325
Affected topics: HTML, Video and Audio

git-svn-id: http://svn.whatwg.org/webapps@8422 340c8d12-0b0e-0410-8428-c7bf67bfef74