this picture does show differently in Chrome and Safari, but if I analyze it using the methods you did I arrive at a different result - I don't see an iHDR chunk there, instead I see a gAMA chunk and if I remove it with pngcrush it shows normally in Chrome.
maybe you linked a different picture?
that was quick, i edited the wayback cache of the image in like i lamented i couldn't in the orginal, i'm such a pessimist :-)