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

sdk/lib/_internal/lib/platform_patch.dart

Index: sdk/lib/_internal/lib/platform_patch.dart
diff --git a/sdk/lib/_internal/lib/platform_patch.dart b/sdk/lib/_internal/lib/platform_patch.dart
index 8df6d946c9c5d72ba154d01612807fdee14cbe56..11d18917a4e38226adb413508b4832607e18ecc3 100644
--- a/sdk/lib/_internal/lib/platform_patch.dart
+++ b/sdk/lib/_internal/lib/platform_patch.dart
@@ -2,3 +2,31 @@
 // 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.
 

[ahe, 2013/10/25 11:34:04]

In follow-up CL:

import 'dart:_js_helper' show Primitives;

Then add additional primitives if needed.

+patch int get numberOfProcessors => null;
+
+patch String get pathSeparator => '/';
+
+patch String get operatingSystem => null;
+
+patch String get localHostname => null;
+
+patch String get version => null;
+
+patch Map<String, String> get environment => null;
+
+patch String get executable => null;
+
+patch Uri get script => null;
+
+patch List<String> get executableArguments => new List<String>(0);

[ahe, 2013/10/25 11:34:04]

Add comment that this is unmodifiable.

[Bill Hesse, 2013/10/25 17:50:00]

Done.

+
+patch String get packageRoot => null;
+
+patch bool get isLinux => false;
+
+patch bool get isMacOS => false;
+
+patch bool get isWindows => false;
+
+patch bool get isAndroid => false;
+