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

samples/sample_extension/test/sample_extension_test.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.
 //
 // Dart test program for testing native extensions.
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
@@ skipping 21 matching lines @@
     case 'macos':
       return join(buildDirectory, 'libsample_extension.dylib');
     case 'windows':
       return join(buildDirectory, 'sample_extension.dll');
     default:
       Expect.fail('Unknown operating system ${Platform.operatingSystem}');
   }
 }
 
 void main() {
+  String scriptDirectory = dirname(Platform.script);
   String buildDirectory = dirname(Platform.executable);
   Directory tempDirectory =
       Directory.systemTemp.createTempSync('sample_extension_');
   String testDirectory = tempDirectory.path;
-  String sourceDirectory = Platform.script.resolve('..').toFilePath();
+  String sourceDirectory = join(scriptDirectory, '..');
 
   // Copy sample_extension shared library, sample_extension dart files and
   // sample_extension tests to the temporary test directory.
   copyFileToDirectory(getNativeLibraryPath(buildDirectory), testDirectory)
   .then((_) => Future.forEach(['sample_synchronous_extension.dart',
                                'sample_asynchronous_extension.dart',
                                'test_sample_synchronous_extension.dart',
                                'test_sample_asynchronous_extension.dart'],
     (file) => copyFileToDirectory(join(sourceDirectory, file), testDirectory)
   ))
 
   .then((_) => Future.forEach(['test_sample_synchronous_extension.dart',
                                'test_sample_asynchronous_extension.dart'],
     (test) => Process.run(Platform.executable, [join(testDirectory, test)])
     .then((ProcessResult result) {
       if (result.exitCode != 0) {
         print('Failing test: ${join(sourceDirectory, test)}');
         print('Failing process stdout: ${result.stdout}');
         print('Failing process stderr: ${result.stderr}');
         print('End failing process stderr');
         Expect.fail('Test failed with exit code ${result.exitCode}');
       }
     })
   ))
   .whenComplete(() => tempDirectory.deleteSync(recursive: true));
 }