If you do not want your FF or Flock browser to bite the dust within 20 seconds, go there with NoScript installed, in that case nothing happens: http://lcamtuf.coredump.cx/ffoxdie_orig.html
It does not hurt the browser, it just nukes it. It has been around quite some time now, and the coders did not come up with a fix, and their eyes are filled with shameful tears. It is a pointer that confuses the browser kernel. It should be cured with traverse code in NsINode, but no-one has come up with that up to now…