message: Support optional catch parameters.
diff: @@ -1030,13 +1030,22 @@ function genericPrintNoParens(path, options, print) {
  return concat(parts);
  case "CatchClause":
  - parts.push("catch (", path.call(print, "param"));
  + parts.push("catch ");
  - if (n.guard)
  + if (n.param) {
  + parts.push("(", path.call(print, "param"));
  + }
  +
  + if (n.guard) {
  // Note: esprima does not recognize conditional catch clauses.
  parts.push(" if ", path.call(print, "guard"));
  + }
  - parts.push(") ", path.call(print, "body"));
  + if (n.param) {
  + parts.push(") ");
  + }
  +
  + parts.push(path.call(print, "body"));
  return concat(parts);
  