He would have to break the cryptographic algo to see the salt. Good luck with that. Sure that is possible for the NSA with weak encryption. But most hackers wont be able to do this. The salt does not give a slightly different hash but a totally different hash. Also, using salt (your own or server based) should protect you from some kind of rainbow table attacks.
But just use a PW manager (e.g. enpass.io ) I am very happy with it but I don't use the autofill plug-ins. You can never be paranoid enough.