[e] (0) Fix the mess I made of port message queues. I'm pretty sure originally they weren't task sources and I corrupted them at some point to be that without changing what I was putting in them. Anyway at this point it's easier just to say that they're real task sources and thus have tasks, even if those tasks have to now be a little more complicated than ideal.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=27208
Affected topics: DOM APIs

git-svn-id: https://svn.whatwg.org/webapps@8864 340c8d12-0b0e-0410-8428-c7bf67bfef74