When an origin is cleared from the cache, it should also clear out all the cache items that are in the partitions associated with the origins being cleared. <rdar://problem/13008298>
Created attachment 191356 [details] Patch
I don't really think there's a good way to write an automated test for this functionality; it'd require either exposing mechanisms for fiddling with the cache to WKTR or, in different ways, to TestWebKitAPI. It's rather easy to test manually in Safari, however.
Comment on attachment 191356 [details] Patch r=me
Committed r144819: <http://trac.webkit.org/changeset/144819>