Remove outdated comment

Author: marijnh

acorn/src/expression.js

@@ -46,10 +46,12 @@ pp.checkPropClash = function(prop, propHash, refDestructuringErrors) {
  if (name === "__proto__" && kind === "init") {
  if (propHash.proto) {
  if (refDestructuringErrors) {
- if (refDestructuringErrors.doubleProto < 0)
+ if (refDestructuringErrors.doubleProto < 0) {
  refDestructuringErrors.doubleProto = key.start
- // Backwards-compat kludge. Can be removed in version 6.0
- } else this.raiseRecoverable(key.start, "Redefinition of __proto__ property")
+ }
+ } else {
+ this.raiseRecoverable(key.start, "Redefinition of __proto__ property")
+ }
  }
  propHash.proto = true
  }