The benchmarking tool calculates the population variance rather than the sample variance. Since ...

The benchmarking tool calculates the population variance rather than the sample variance.
Since benchmarking results represent only a sample of the entire population of
results, it would be better to calculate the sample standard deviation, which
is an unbiased estimator of the population variance.  Also, since the Array.avg
function throws out the min and max, this function should not be used when
calculating the variance.

BUG=none
TEST=none
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=88379

[Mike Belshe, 2011-06-08 18:04:58]

LGTM