Default constructor for dart:io Path now handles native Windows paths. Path() now does the same as…

tests/standalone/io/test_extension_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.
 //
 // Dart test program for testing native extensions.
 
 import 'dart:async';
 import 'dart:io';
 import 'dart:isolate';
 
@@ skipping 20 matching lines @@
     case 'windows':
       return buildDirectory.append('test_extension.dll');
     default:
       Expect.fail('Unknown operating system ${Platform.operatingSystem}');
   }
 }
 
 void main() {
   Options options = new Options();
 
-  Path scriptDirectory = new Path.fromNative(options.script).directoryPath;
-  Path buildDirectory = new Path.fromNative(options.executable).directoryPath;
+  Path scriptDirectory = new Path(options.script).directoryPath;
+  Path buildDirectory = new Path(options.executable).directoryPath;
   Directory tempDirectory = new Directory('').createTempSync();
-  Path testDirectory = new Path.fromNative(tempDirectory.path);
+  Path testDirectory = new Path(tempDirectory.path);
 
   // Copy test_extension shared library, test_extension.dart and
   // test_extension_tester.dart to the temporary test directory.
   copyFileToDirectory(getExtensionPath(buildDirectory),
                       testDirectory).then((_) {
     Path extensionDartFile = scriptDirectory.append('test_extension.dart');
     return copyFileToDirectory(extensionDartFile, testDirectory);
   }).then((_) {
     Path testExtensionTesterFile =
         scriptDirectory.append('test_extension_tester.dart');
     return copyFileToDirectory(testExtensionTesterFile, testDirectory);
   }).then((_) {
     Path script = testDirectory.append('test_extension_tester.dart');
     return Process.run(options.executable, [script.toNativePath()]);
   })..then((ProcessResult result) {
     Expect.equals(0, result.exitCode);
     tempDirectory.deleteSync(recursive: true);
   })..catchError((_) {
     tempDirectory.deleteSync(recursive: true);
   });
 }