Even with a warmup, the unwrapped version is more than 3x faster.
Largely, the use modern javascript and proper benchmarking made the results more consistent with the benchmark posted.
This included
1) avoiding the use of "var" (using let for scoped iterator variables and const for unchanging references)
2) using proper warmup (10% of runs)
3) isolating the benchmarked code into a function that can be invoked within a loop
4) reseting the values of the arrays being added between benchmarks (to prevent any NaNs/infinities from cropping up)
Inserting the loop into a function really speeds it up in Chrome. Also, I have noticed, that for Float32Array, the rolled / unrolled performance is almost identical, but for Uint32Array, unrolled is about 30% faster: https://jsfiddle.net/aq06p94f/