Coffeescript code block which produces different output on firefox and chrome

gistfile1.txt

# http://jsfiddle.net/YwqsV/
fromAngleAxis = (angle, axis, dest) ->
  axis = normalize axis
  halfAngle = angle / 2
  s = Math.sin halfAngle

  dest[0] = axis[0] * s
  dest[1] = axis[1] * s
  dest[2] = axis[2] * s
  dest[3] = Math.cos halfAngle

  return dest

magnitudeSquared = (u) ->
  sum = 0
  for i in [0..3]
    sum += u[i] * u[i]
  return sum

magnitude = (u) ->
  return Math.sqrt(magnitudeSquared(u))

normalize = (u) ->
  mag = magnitude(u)
  return u if mag == 0
  length = 1 / mag
  for i in [0..3]
    u[i] *= length
  return u

mult = (u, v, dest) ->
  # [x, y, z] are the imaginary parts and w is the real part.
  ux = u[0]
  uy = u[1]
  uz = u[2]
  uw = u[3]
  vx = v[0]
  vy = v[1]
  vz = v[2]
  vw = v[3]

  dest[0] = ux * vw + uw * vx + uy * vz - uz * vy
  dest[1] = uy * vw + uw * vy + uz * vx - ux * vz
  dest[2] = uz * vw + uw * vz + ux * vy - uy * vx
  dest[3] = uw * vw - ux * vx - uy * vy - uz * vz

  return dest

q1 = []
q2 = []
q3 = []
fromAngleAxis(20, [0, 0, 1], q1)
fromAngleAxis(20, [0, 0, 1], q2)
mult(q1, q2, q3)
console.log q3[0], q3[1], q3[2], q3[3]