Fix documentation of path.toUri().
Fix documentation of path.toUri().

R=nweiz@google.com

Review URL: https://codereview.chromium.org//20043004

git-svn-id: d21bfdc9f98bb697a501ab295d9b4211dc860b14@25366 260f80e4-7a28-3924-810f-c04153c831b5

dart-lang/path