message: Add printer cases for unprintable TSHasOptionalType{Parameters,Annotation}.
diff: @@ -1345,6 +1345,8 @@ function genericPrintNoParens(path, options, print) {
  case "MemberTypeAnnotation": // Flow
  case "TupleTypeAnnotation": // Flow
  case "Type": // Flow
  + case "TSHasOptionalTypeParameters":
  + case "TSHasOptionalTypeAnnotation":
  throw new Error("unprintable type: " + JSON.stringify(n.type));
  case "CommentBlock": // Babel block comment.
  