Crashing Safari on OS X, too. Or rather, the tab hangs.
It produces an "TypeError: 'undefined' is not an object (evaluating 'a[Ra]')" and "TypeError: 'undefined' is not an object (evaluating 'b.count')". The console was a bit hard to get to with webkit2 taking up 100% of a cpu and all that.
I suppose, if you see it. I just looked in Firefox, Chrome, Chromium, Safari and Opera and while there was such a box originally, I do not currently see it on the page.