My comment in https://bugs.webkit.org/show_bug.cgi?id=63216#c7 was wrong. m_webViewHost should be deleted at first.
Created attachment 98672 [details] Patch
Comment on attachment 98672 [details] Patch Auch. Thanks for this fix.
Comment on attachment 98672 [details] Patch Clearing flags on attachment: 98672 Committed r89802: <http://trac.webkit.org/changeset/89802>
All reviewed patches have been landed. Closing bug.