Add fields to platform library, implement them on runtime dart.

tests/lib/platform/uri_test.dart

Index: tests/lib/platform/uri_test.dart
diff --git a/tests/standalone/io/uri_platform_test.dart b/tests/lib/platform/uri_test.dart
similarity index 89%
copy from tests/standalone/io/uri_platform_test.dart
copy to tests/lib/platform/uri_test.dart
index cc677606eababae1fe6a2fca603a4b04a7f00ad3..7aaf8e0724a6e16a1d780e4d8675cbdda8f17c73 100644
--- a/tests/standalone/io/uri_platform_test.dart
+++ b/tests/lib/platform/uri_test.dart
@@ -1,12 +1,12 @@
-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 import "package:expect/expect.dart";
-import "dart:io";
+import "dart:platform" as platform;
 
 main() {
-  if (Platform.isWindows) {
+  if (platform.isWindows) {
     Expect.equals("a\\b", Uri.parse("a/b").toFilePath());
     Expect.equals("a\\b\\", Uri.parse("a/b/").toFilePath());
     Expect.equals("a b", Uri.parse("a%20b").toFilePath());
@@ -36,7 +36,4 @@ main() {
     Expect.equals("a/b", new Uri.file("a/b").toFilePath());
     Expect.equals("a\\b", new Uri.file("a\\b").toFilePath());
   }
-
-  Expect.equals(Uri.base,
-                new Uri.file(Directory.current.path + Platform.pathSeparator));
 }