Remove the certificate management methods from dart:io

tests/standalone/io/certificate_test_client_database.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.  This client tests that addCertificate works if a certificate
-// database has been specified.
-
-import 'dart:io';
-
-void main() {
-  int port = int.parse(new Options().arguments[0]);
-  String certificate = new Options().arguments[1];
-  String database = new Options().arguments[2];
-  SecureSocket.initialize(database: database,
-                          password: 'dartdart',
-                          readOnly: false);
-  SecureSocket.removeCertificate('localhost_cert');
-  SecureSocket.removeCertificate('myauthority_cert');
-  var mycert = new File(certificate).readAsBytesSync();
-  SecureSocket.addCertificate(mycert,
-                              SecureSocket.TRUST_ISSUE_SERVER_CERTIFICATES);
-  if (null != SecureSocket.getCertificate('myauthority_cert')) {
-    throw "Expected getCertificate to return null";
-  }
-  SecureSocket.connect('localhost', port).then((SecureSocket socket) {
-    socket.writeln('hello world');
-    socket.listen((data) { });
-    return socket.close();
-  }).then((_) {
-    // The certificate is only in the in-memory cache, so cannot be removed.
-    try {
-      SecureSocket.removeCertificate('myauthority_cert');
-    } catch (e) {
-      if (e is! CertificateException) throw "error $e";
-    }
-  }).then((_) {
-    print('SUCCESS');  // Checked by parent process.
-  });
-}