[mattdawson]

FWIW, this is also the way O'Reilly's JS Pocket Reference explains it.

[leetrout]

Thanks, that's what I had read.

I also found this set of tests http://jsperf.com/asi-versus-msi

My results on Opera Next (v15) http://imgur.com/hkAopfX shows MSI fastest FWIW.