JSImmutableButterfly should assert m_header is adjacent to the data
Created attachment 343005 [details] Patch
r=me
Comment on attachment 343005 [details] Patch Clearing flags on attachment: 343005 Committed r232954: <https://trac.webkit.org/changeset/232954>
All reviewed patches have been landed. Closing bug.
<rdar://problem/41252313>