[giow] (3) Make window.open() match browsers better
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=26830
Affected topics: DOM APIs

git-svn-id: https://svn.whatwg.org/webapps@8816 340c8d12-0b0e-0410-8428-c7bf67bfef74