This was added to Gecko 20.0, but it isn't part of the specs. V8 doesn't support it: http://code.google.com/p/v8/issues/detail?id=2455 http://code.google.com/p

This was added to Gecko 20.0, but it isn't part of the specs. V8 doesn't support it: http://code.google.com/p/v8/issues/detail?id=2455 http://code.google.com/p/v8/issues/detail?id=2455