Clearing a registration should null out its workers before setting their state to "redundant". This seems to match Firefox and Chrome.
Created attachment 332933 [details]
Created attachment 332934 [details]
Comment on attachment 332934 [details]
Clearing flags on attachment: 332934
Committed r228015: <https://trac.webkit.org/changeset/228015>
All reviewed patches have been landed. Closing bug.