idna: update from x/text

CL 359634: use nontransitional processing in Go 1.18
CL 317731: fix int32 overflows

Updates golang/go#46001
Updates golang/go#47510
Updates golang/go#28233

Change-Id: I2d9cdf5caa44f7c9b2834a256e7464b6edaae9ef
Reviewed-on: https://go-review.googlesource.com/c/net/+/360381
Trust: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

Author: neild

idna/example_test.go

@@ -1,5 +1,3 @@
-// Code generated by running "go generate" in golang.org/x/text. DO NOT EDIT.
-
 // Copyright 2017 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
@@ -15,27 +13,26 @@ import (
 func ExampleProfile() {
 	// Raw Punycode has no restrictions and does no mappings.
 	fmt.Println(idna.ToASCII(""))
-	fmt.Println(idna.ToASCII("*.faß.com"))
-	fmt.Println(idna.Punycode.ToASCII("*.faß.com"))
+	fmt.Println(idna.ToASCII("*.GÖPHER.com"))
+	fmt.Println(idna.Punycode.ToASCII("*.GÖPHER.com"))
 
-	// Rewrite IDN for lookup. This (currently) uses transitional mappings to
-	// find a balance between IDNA2003 and IDNA2008 compatibility.
+	// Rewrite IDN for lookup.
 	fmt.Println(idna.Lookup.ToASCII(""))
-	fmt.Println(idna.Lookup.ToASCII("www.faß.com"))
+	fmt.Println(idna.Lookup.ToASCII("www.GÖPHER.com"))
 
-	// Convert an IDN to ASCII for registration purposes. This changes the
-	// encoding, but reports an error if the input was illformed.
-	fmt.Println(idna.Registration.ToASCII(""))
-	fmt.Println(idna.Registration.ToASCII("www.faß.com"))
+	// Convert an IDN to ASCII for registration purposes.
+	// This reports an error if the input was illformed.
+	fmt.Println(idna.Registration.ToASCII("www.GÖPHER.com"))
+	fmt.Println(idna.Registration.ToASCII("www.göpher.com"))
 
 	// Output:
 	//  <nil>
-	// *.xn--fa-hia.com <nil>
-	// *.xn--fa-hia.com <nil>
+	// *.xn--GPHER-1oa.com <nil>
+	// *.xn--GPHER-1oa.com <nil>
 	//  <nil>
-	// www.fass.com <nil>
-	//  idna: invalid label ""
-	// www.xn--fa-hia.com <nil>
+	// www.xn--gpher-jua.com <nil>
+	// www.xn--GPHER-1oa.com idna: disallowed rune U+0047
+	// www.xn--gpher-jua.com <nil>
 }
 
 func ExampleNew() {