In fastcomp builds, I'm seeing the beginning of the asm module to get these lines:

    var asm = (function(global, env, buffer) {
      'use asm';
      var nan = +env.NaN, inf = +env.Infinity;

whereas in the old compiler, it looked like this:

    var asm = (function(global, env, buffer) {
      'use asm';
      var NaN = +env.NaN;
      var Infinity = +env.Infinity;