While this is true, there isn't really a common browser distribution that uses that setup for non-OS X platforms, though. Chrome/Chromium/Opera use Blink now.
For all practical purposes, Safari is an OS X-only browser.
For all practical purposes, Safari is an OS X-only browser.
Whether it's popular on Windows is also irrelevant with regard to the fact that it does, indeed, work on Windows.
Windows Phone uses Trident + Chakra for its IE deployment, as well, so if we're going to make that argument, then IE is multiplatform, as well :P
1. Within reason, of course. It's not on my router (but maybe it could be)