[giow] (3) Attempt to actually define what Referer headers are used f…

…or a whole host of things that were poorly defined. Also: cleanup of a bunch of editorial mistakes I found from past such attempts. Mark every fetch algorithm use for sanity in the future. Block data:, javascript:, and about:blank referrers. Note: This relies on not-yet-done changes to CORS and XHR.

Affected topics: DOM APIs, HTML, Offline Web Applications, Server-Sent Events, Video Text Tracks, Video and Audio, Web Workers

git-svn-id: http://svn.whatwg.org/webapps@7341 340c8d12-0b0e-0410-8428-c7bf67bfef74