[giow] (3) Match reality better. (Turns out parts of the spec already assumed this was defined this way anyway.)
Fixing https://www.w3.org/Bugs/Public/show_bug.cgi?id=20379
Affected topics: DOM APIs

git-svn-id: http://svn.whatwg.org/webapps@7845 340c8d12-0b0e-0410-8428-c7bf67bfef74
(cherry picked from commit a67524f5e7d858db0db8446f9240a66c8fb2216b)

Window's "document" property should return the Window's document and not
"active document"