message: Declare "Flow" and "FlowType" as unprintable AST node types.
diff: @@ -1389,7 +1389,9 @@ function genericPrintNoParens(path, options, print) {
  case "Declaration":
  case "Specifier":
  case "NamedSpecifier":
  - case "Comment": // Supertype of Block and Line.
  + case "Comment": // Supertype of Block and Line
  + case "Flow": // Supertype of all Flow AST node types
  + case "FlowType": // Supertype of all Flow types
  case "MemberTypeAnnotation": // Flow
  case "Type": // Flow
  case "TSHasOptionalTypeParameters":
  