This one is my bad. When I filtered out events with no listeners, I forgot to add support for DOMWindow dispatch. This only effects DOM events that are delivered to window (like 'click'). So we current miss this case: window.addEventListener('click', function(e) { }, false); Patch is ready, I'm about to upload.
Created attachment 42340 [details] Proposed fix.
Comment on attachment 42340 [details] Proposed fix. Clearing flags on attachment: 42340 Committed r50428: <http://trac.webkit.org/changeset/50428>
All reviewed patches have been landed. Closing bug.