[giow] (1) Always allow a browsing context to navigate itself.
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=23857
Affected topics: HTML, Security

git-svn-id: http://svn.whatwg.org/webapps@8301 340c8d12-0b0e-0410-8428-c7bf67bfef74