What steps will clearly show the issue / need for enhancement?

1. a lot of Unix based systems use Unix sockets for interprocess communication
2. with dart:io only TCP based communication is possible
3. support for Unix sockets would greatly increase the integration potential of dart server-side apps

What is the current output?
None, not supported

What would you like to see instead?
Success, connected!

What version of the product are you using? On what operating system?
1.7.2 on Arch Linux

Please provide any additional information below.