[e] (0) Make the EventSource processing model a mite more generic to allow other user agent types to implement this spec.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23693
Affected topics: HTML

git-svn-id: http://svn.whatwg.org/webapps@8475 340c8d12-0b0e-0410-8428-c7bf67bfef74