Remove need to instantiate Platform and make methods static.

runtime/bin/platform.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// 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.
 
 /**
  * The [Platform] class exposes details of the machine and operating
  * system.
  */
-interface Platform default _Platform {
-  /**
-   * Create a Platform object.
-   */
-  Platform();
-
+class Platform {
   /**
    * Get the number of processors of the machine.
    */
-  int numberOfProcessors();
+  static int numberOfProcessors() => _Platform.numberOfProcessors();
 
   /**
    * Get the path separator used by the operating system to separate
    * components in file paths.
    */
-  String pathSeparator();
+  static String pathSeparator() => _Platform.pathSeparator();
 
   /**
    * Get a string ('macos', 'windows', 'linux') representing the
    * operating system.
    */
-  String operatingSystem();
+  static String operatingSystem() => _Platform.operatingSystem();
 
   /**
    * Get the local hostname for the system.
    */
-  String localHostname();
+  static String localHostname() => _Platform.localHostname();
 
   /**
    * Get the environment for this process.
    */
-  Map<String, String> environment();
+  static Map<String, String> environment() => _Platform.environment();
 }