Some of the callbacks for cache partitioning may be passed null values on Mac, which are not currently properly handled. <rdar://problem/16117886>
Created attachment 224921 [details] Patch
Of note: I'm planning to merge some WKSI changes into the final patch, but those changes are API-compatible so it shouldn't cause a problem.
Committed r164516: <http://trac.webkit.org/changeset/164516>