That's the AppleWin port which relies on non-redistributable libraries, using the iTunes compatibility libraries.
There's also upstream the WinCairo port, which is redistributable. (can be downloaded from Buildbot at https://trac.webkit.org/wiki/BuildingCairoOnWindows#Download...)
It's just that Apple doesn't want to make Safari as a whole available on Windows, while making it easy for others to develop browsers using that same engine - even on Windows.
(WebKit isn't enough; I often need to test Safari behavior specifically)
That's the AppleWin port which relies on non-redistributable libraries, using the iTunes compatibility libraries.
There's also upstream the WinCairo port, which is redistributable. (can be downloaded from Buildbot at https://trac.webkit.org/wiki/BuildingCairoOnWindows#Download...)
It's just that Apple doesn't want to make Safari as a whole available on Windows, while making it easy for others to develop browsers using that same engine - even on Windows.