fs.readdir seems broken since Node 10.10.0

[kibertoad]

"fs.readdir" -> "lists nested directory contents" test is timing out in Node.js 10.10.0 and this seems consistent with what we are seeing in Knex.js tests that rely on mock-fs.

[maxwellgerber]

This is caused by the addition of fs.Dirent objects in 10.10.0, which changed the API of binding.readDir. See: https://github.com/nodejs/node/blob/master/lib/fs.js#L789 https://nodejs.org/api/fs.html#fs_class_fs_dirent