Support both new and old style package layouts.

utils/pub/sdk_source.dart

 // 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.
 
 #library('sdk_source');
 
 #import('io.dart');
 #import('package.dart');
 #import('pubspec.dart');
 #import('source.dart');
@@ skipping 40 matching lines @@
     // Look in "pkg" first.
     var sourcePath = join(rootDir, "pkg", id.description);
     return exists(sourcePath).chain((found) {
       if (!found) {
         // TODO(rnystrom): Get rid of this when all SDK packages are moved from
         // "lib" to "pkg".
         // Not in "pkg", so try "lib".
         sourcePath = join(rootDir, "lib", id.description);
         return exists(sourcePath).chain((found) {
           if (!found) return new Future<bool>.immediate(false);
-          return createSymlink(sourcePath, destPath).transform((_) => true);
+          return createPackageSymlink(id.name, sourcePath, destPath).transform(
+              (_) => true);
         });
       }
-      return createSymlink(sourcePath, destPath).transform((_) => true);
+
+      return createPackageSymlink(id.name, sourcePath, destPath).transform(
+          (_) => true);
     });
   }
 }