This is because poison initialization may depend on options.
<rdar://problem/36629138>
Created attachment 331649 [details] proposed patch.
Comment on attachment 331649 [details] proposed patch. r=me.
Comment on attachment 331649 [details] proposed patch. Clearing flags on attachment: 331649 Committed r227159: <https://trac.webkit.org/changeset/227159>
All reviewed patches have been landed. Closing bug.