message: Printer case for Flow SymbolTypeAnnotation.
diff: @@ -1795,6 +1795,9 @@ function genericPrintNoParens(path: any, options: any, print: any) {
  case "NullTypeAnnotation":
  return fromString("null", options);
  + case "SymbolTypeAnnotation":
  + return fromString("symbol", options);
  +
  // Type Annotations for TypeScript (when using Babylon as parser)
  case "TSType":
  throw new Error("unprintable type: " + JSON.stringify(n.type));
  