- Add getters for the current packageRoot or packageMap.

sdk/lib/io/platform_impl.dart

Index: sdk/lib/io/platform_impl.dart
diff --git a/sdk/lib/io/platform_impl.dart b/sdk/lib/io/platform_impl.dart
index 6380e0d7c92f622495d3c9ca2149db2baafdfda9..b2f3240bd0a7c6c15bb1ce201ae9fe8d6b86b9bc 100644
--- a/sdk/lib/io/platform_impl.dart
+++ b/sdk/lib/io/platform_impl.dart
@@ -28,12 +28,12 @@ class _Platform {
    */
   external static _environment();
   external static List<String> _executableArguments();
-  external static String _packageRoot();
   external static String _version();
 
   static String executable = _executable();
   static String resolvedExecutable = _resolvedExecutable();
-  static String packageRoot = _packageRoot();
+  external static Future<Uri> get packageRoot;
+  external static Future<Map<String,Uri>> get packageMap;
 
   // Cache the OS environemnt. This can be an OSError instance if
   // retrieving the environment failed.