The problem is that the guesses returned by enchant, which are UTF-8 encoded, are passed to WebCore without converting them to UTF-16.
Created attachment 193464 [details] Patch
Comment on attachment 193464 [details] Patch Clearing flags on attachment: 193464 Committed r146010: <http://trac.webkit.org/changeset/146010>
All reviewed patches have been landed. Closing bug.