We should fallback to the default storage session in WebKit1 and WebKit2 without NetworkProcess when we have a null private browsing session so as to make our behavior consistent with the analogous behavior in WebKit2 with NetworkProcess.
Created attachment 228771 [details]
I didn't include a test for this change because it's not obvious to me how to write a test that disables private browsing via WebKit preferences and starts a load before WebKit notifies WebCore of the preference change ([-WebView _preferencesChanged] is called in WebKit1) such that we update the session ID of the page. I am open to suggestions.
Committed r166928: <http://trac.webkit.org/changeset/166928>