[e] (0) Some reference updates, and an example of incumbent vs entry scripts
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=26547
Affected topics: DOM APIs, HTML, HTML Syntax and Parsing, Security, Video and Audio

git-svn-id: https://svn.whatwg.org/webapps@8780 340c8d12-0b0e-0410-8428-c7bf67bfef74