Some changes are coming to the dart.io Path class constructor that will help make Windows paths platform agnostic. William Hesse gives us the details:
I have finally changed the new Path(String path) constructor to automatically convert Windows paths into platform-independent paths, the way that new Path.fromNative(String path) does now. I found no cases where code needed to create a path without doing this conversion on the Windows platform, so we thought we should make it the default. It is fine if this conversion is done more than once to a path, since it has no effect the second time.