?
Firefox is used as a baseline on both, so the ratio is adjusted for Firefox (as the baseline)
The actual speed of the javascript benchmark is not shown, but the adjustment is to make Firefox as the baseline, and then a ratio is shown, comparing the other browsers. The results shows that Safari has a faster javascript performance, compared to browsers on both platforms.
As the actual speeds are not shown - other than "It's faster!", and no test of Safari natively on Windows (no current Windows version of Safari), I'm not sure that you can draw a conclusion that Safari is faster than browsers on both platform.
But - a moot point, anyway -- that info is out of date, so today's result from the same testing could be very different.