When I landed the JIT support for Unicode Regular Expressions in https://trac.webkit.org/changeset/221052, I didn't turn it on for match only expressions.
<rdar://problem/34866122>
Created attachment 323056 [details] Patch
Comment on attachment 323056 [details] Patch r=me
Comment on attachment 323056 [details] Patch Clearing flags on attachment: 323056 Committed r223010: <http://trac.webkit.org/changeset/223010>
All reviewed patches have been landed. Closing bug.