BREWMP sets ENABLE(SINGLE_THREADED), so it uses isMainThread from ThreadingNone.cpp.
Created attachment 56551 [details] Patch
Comment on attachment 56551 [details] Patch OK.
Comment on attachment 56551 [details] Patch Clearing flags on attachment: 56551 Committed r59920: <http://trac.webkit.org/changeset/59920>
All reviewed patches have been landed. Closing bug.