Currently they are owned by RuleData. Several RuleData objects can refer to the same StyleRule, requiring recompilation. Compiled selectors are context-independent so they can be shared between all clients.
Created attachment 333373 [details]
Created attachment 333455 [details]
Comment on attachment 333455 [details]
Clearing flags on attachment: 333455
Committed r228313: <https://trac.webkit.org/changeset/228313>
All reviewed patches have been landed. Closing bug.