We have been implementing constructors of Events. CloseEvent has a constructor in JSC (https://bugs.webkit.org/show_bug.cgi?id=68340), but do not have it in V8.
Created attachment 108641 [details] Patch
Comment on attachment 108641 [details] Patch Clearing flags on attachment: 108641 Committed r96061: <http://trac.webkit.org/changeset/96061>
All reviewed patches have been landed. Closing bug.