Remove the certificate management methods from dart:io

tests/standalone/io/certificate_test_client.dart

-// Copyright (c) 2013, the Dart project authors. Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-//
-// Client that tests that a certificate authority certificate loaded
-// at runtime can be used to verify a certificate chain. The server it
-// connects to uses localhost_cert, signed by myauthority_cert, to connect
-// securely.
-
-import 'dart:io';
-
-void main() {
-  int port = int.parse(new Options().arguments[0]);
-  String certificate = new Options().arguments[1];
-  SecureSocket.initialize();
-  var mycert = new File(certificate).readAsBytesSync();
-  bool threw = false;
-  try {
-    SecureSocket.addCertificate("I am not a cert".codeUnits,
-                                SecureSocket.TRUST_ISSUE_SERVER_CERTIFICATES);
-  } on CertificateException catch (e) {
-    threw = true;
-  }
-  if (!threw) throw "Expected bad certificate to throw";
-
-  threw = false;
-  try {
-    SecureSocket.addCertificate(mycert, "Trust me, I'm a string");
-  } on CertificateException catch (e) {
-    threw = true;
-  }
-  if (!threw) throw "Expected bad trust string to throw";
-
-  SecureSocket.addCertificate(mycert,
-                              SecureSocket.TRUST_ISSUE_SERVER_CERTIFICATES);
-
-  SecureSocket.connect('localhost', port).then((SecureSocket socket) {
-    socket.writeln('hello world');
-    socket.listen((data) { });
-    return socket.close();
-  }).then((_) {
-    SecureSocket.changeTrust('myauthority_cert', ',,');
-    return SecureSocket.connect('localhost', port);
-  }).then((_) {
-    throw "Expected untrusted authority to stop connection";
-  }, onError: (e) {
-    if (e is! CertificateException) throw e;
-  }).then((_) {
-    SecureSocket.changeTrust('myauthority_cert', 'C,,');
-    return SecureSocket.connect('localhost', port);
-  }).then((SecureSocket socket) {
-    socket.writeln('hello world');
-    socket.listen((data) { });
-    return socket.close();
-  }).then((_) {
-    SecureSocket.removeCertificate('myauthority_cert');
-    return SecureSocket.connect('localhost', port);
-  }).then((_) {
-    throw "Expected untrusted root to stop connection";
-  }, onError: (e) {
-    if (e is! CertificateException) throw e;
-  }).then((_) {
-    print('SUCCESS');  // Checked by parent process.
-  });
-}