When using option rejectPublicSuffixes: true (the default), trying to set a cookie with Domain=localhost throws the error Cookie has domain set to a public suffix, which I believe is incorrect.

How to reproduce

Run the following code with the latest master of tough-cookie (commit 1b25269)

const { CookieJar } = require("../lib/cookie");
const cookieJar = new CookieJar();
cookieJar.setCookieSync("a=b; Domain=localhost", "http://localhost")  // throws 'Error: Cookie has domain set to a public suffix'

Expected result

I can set cookies with Domain=localhost without an error.

Workaround

Turning off the rejectPublicSuffixes option when creating the CookieJar causes the cookie to be set without errors, as expected.