- Fix precompilation test.

tests/standalone/precompilation_dart2js_test.dart

Index: tests/standalone/precompilation_dart2js_test.dart
diff --git a/tests/standalone/precompilation_dart2js_test.dart b/tests/standalone/precompilation_dart2js_test.dart
index 52957d758256258667fbf0b74c4e93937391c5ef..303c95576f1ddf1f2d103891a1be0f208104641c 100644
--- a/tests/standalone/precompilation_dart2js_test.dart
+++ b/tests/standalone/precompilation_dart2js_test.dart
@@ -43,7 +43,8 @@ main(List args) {
     return;
   }
 
-  var abs_package_root = new File(Platform.packageRoot).absolute.path;
+  var pkgRoot = Uri.parse(Platform.packageRoot);
+  var abs_package_root = new File.fromUri(pkgRoot).absolute.path;
   var dart_executable =
       Directory.current.path + Platform.pathSeparator + Platform.executable;
   Directory tmp;