Allow Windows network share paths for the script path and the package root.

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 "package:expect/expect.dart";
 import "package:path/path.dart";
 import 'dart:async';
 import 'dart:io';
@@ skipping 38 matching lines @@
     var extensionDartFile = join(scriptDirectory, 'test_extension.dart');
     return copyFileToDirectory(extensionDartFile, testDirectory);
   }).then((_) {
     var testExtensionTesterFile =
         join(scriptDirectory, 'test_extension_tester.dart');
     return copyFileToDirectory(testExtensionTesterFile, testDirectory);
   }).then((_) {
     var script = join(testDirectory, 'test_extension_tester.dart');
     return Process.run(Platform.executable, [script]);
   })..then((ProcessResult result) {
+    if (result.exitCode != 0) {

[Søren Gjesse, 2013/11/04 16:15:58]

Debug print.

[Bill Hesse, 2013/11/05 08:52:23]

This is not debug printing, but output of the subprocess stdout and stderr in
the case of a test failure, as we do with other subprocess tests.

+      print('Subprocess failed with exit code ${result.exitCode}');
+      print('stdout:');
+      print('${result.stdout}');
+      print('stderr:');
+      print('${result.stderr}');
+    }
     Expect.equals(0, result.exitCode);
     tempDirectory.deleteSync(recursive: true);
   })..catchError((_) {
     tempDirectory.deleteSync(recursive: true);
   });
 }