"Cross-browser". Why exactly is it asm.js cross-browser? Because they just said they'd put it in V8? The argument is moot since if Mozilla said that first about PNaCl (that they'd adopt it) it would be PNaCl that would be the cross-browser solution.
No, I don't care about backwards-compatibility. I care about the solution leveraging existing infrastructure and not being a hack.
asm.js is, at its heart, nothing more than a compiler hint. It tells the runtime that the JavaScript you're writing in this function follows some conventions that happen to be easy to optimize, but it's still JavaScript code. A browser that doesn't support asm.js will pause for a few nanoseconds to wonder what the heck that strange string at the start of the function is, then go on to execute the JavaScript code the same way it always does, with the same result as if it had known what asm.js is.
As far as I can tell they haven't said they'd put it in V8. One member of the chromium team, who doesn't work in that area, has opened up a feature request.
This seems to be much ado about nothing unless and until it's accepted and assigned.
No, I don't care about backwards-compatibility. I care about the solution leveraging existing infrastructure and not being a hack.