[sp332]

It runs, but running in the normal JS engine is slow. If code validates as asm.js code, you can compile it with fewer checks and no garbage collection, so that it would run a lot faster. https://en.wikipedia.org/wiki/Asm.js#Performance

Chrome already provides some speedup on asm.js code https://hacks.mozilla.org/2015/03/asm-speedups-everywhere/