Change dart:io Platform.script to return a Uri.

tests/standalone/io/secure_builtin_roots_test.dart

 // Copyright (c) 2012, 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.
 
 import "dart:io";
 import "dart:async";
 
 import "package:async_helper/async_helper.dart";
 import "package:expect/expect.dart";
 import "package:path/path.dart";
 
 void main(List<String> args) {
   if (!args.contains('--child')) {
     runAllTestsInChildProcesses();
   } else {
     InitializeSSL(useDatabase: args.contains('--database'),
                   useBuiltinRoots: args.contains('--builtin-roots'));
     testGoogleUrl(args.contains('--builtin-roots'));
   }
 }
 
 void InitializeSSL({bool useDatabase, bool useBuiltinRoots}) {
   // If the built-in root certificates aren't loaded, the connection
   // should signal an error.  Even when an external database is loaded,
   // they should not be loaded.
   if (useDatabase) {
-    var certificateDatabase = join(dirname(Platform.script), 'pkcert');
+    var certificateDatabase = Platform.script.resolve('pkcert').toFilePath();
     SecureSocket.initialize(database: certificateDatabase,
                             password: 'dartdart',
                             useBuiltinRoots: useBuiltinRoots);
   } else {
     SecureSocket.initialize(useBuiltinRoots: useBuiltinRoots);
   }
 }
 
 void testGoogleUrl(bool expectSuccess) {
   // We need to use an external server that is backed by a
@@ skipping 21 matching lines @@
     // Lookup failed.
     Expect.isTrue(e is SocketException);
     print('SUCCESS');
   });
 }
 
 void runAllTestsInChildProcesses() {
   Future runChild(List<String> scriptArguments) {
     return Process.run(Platform.executable,
                        []..addAll(Platform.executableArguments)
-                         ..add(Platform.script)
+                         ..add(Platform.script.toFilePath())
                          ..addAll(scriptArguments))
     .then((ProcessResult result) {
       if (result.exitCode != 0 || !result.stdout.contains('SUCCESS')) {
         print("Client failed");
         print("  stdout:");
         print(result.stdout);
         print("  stderr:");
         print(result.stderr);
         Expect.fail('Client subprocess exit code: ${result.exitCode}');
       }
     });
   }
 
   asyncStart();
   Future.wait([runChild(['--child']),
                runChild(['--child', '--database']),
                runChild(['--child', '--builtin-roots']),
                runChild(['--child', '--builtin-roots', '--database'])])
       .then((_) => asyncEnd());
   }