window.open.length should be 0 as all its parameters are optional:
It is 2 in WebKit. Firefox and Chrome agree with the specification and return 0.
Created attachment 284826 [details]
Comment on attachment 284826 [details]
Clearing flags on attachment: 284826
Committed r203849: <http://trac.webkit.org/changeset/203849>
All reviewed patches have been landed. Closing bug.