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

tests/lib/platform/number_of_processors_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 for testing binary operations.
-// VMOptions=--verify_implements  --check-function-fingerprints
 
-class BootstrapTest {
+import "dart:platform" as platform;
 
-  static testMain() {
-    var obj = new Object();
-
-    return obj;
-  }
-
-}
+import "package:unittest/unittest.dart";
 
 main() {
-  BootstrapTest.testMain();
+  if (platform.operatingSystem != null) {
+    expect(platform.numberOfProcessors, isPositive);
+  } else {
+    expect(platform.numberOfProcessors, isNull);
+  }
 }