Isabelle/HOL translation: syntax aliases incorrectly translated

[lukaszcz]

Example:

Name : Type := Nat;

syntax alias T := Name;

type RR := mkRR {
  x : T
};

gives

type_synonym Name = nat

record RR =
  x :: nat

fun x :: "RR \<Rightarrow> T" where
  "x (| RR.x = x' |) = x'"