There are several instances where print layout can show up - and even remain! - on screen with WebKit2. Patch forthcoming.
Created attachment 81314 [details] proposed patch
One case where print layout can still show up is during window resizing. That's not a regression from WebKit1 - the whole window would turn blank in the same circumstances before, including window chrome!
Committed <http://trac.webkit.org/changeset/77701>.