Platform.operatingSystemVersion returns uname-like string on iOS

[fwagner]

When reading Platform.operatingSystemVersion from dart:io a uname-like string (darwin 19.3.0 darwin kernel version 19.3.0: the jan 9 21:11:03pst 2020; root:xnu-6153.82.3~1/release_arm64/t8015) is returned on iOS instead of the iOS system version (e.g. 13.4.5).

Essentially it is a clone of this issue, just for iOS (and looking at https://github.com/dart-lang/sdk/blob/master/runtime/bin/platform_macos.cc#L119 probably also for MacOS. I would also expect the system version there instead of the kernel version.): #36625.

• Dart version: 2.7.2
• Platform: iOS (MacOS)