message: Fix a lingering rename
diff: import * as bril from './bril';
  import {readStdin, unreachable} from './util';
  -type Env = Map<bril.Ident, bril.ConstValue>;
  +type Env = Map<bril.Ident, bril.Value>;
  function get(env: Env, ident: bril.Ident) {
  let val = env.get(ident);
  