Change dart:io Platform.script to return a URI. Change all uses of Platform.script to work with th…

pkg/scheduled_test/test/metatest.dart

Index: pkg/scheduled_test/test/metatest.dart
diff --git a/pkg/scheduled_test/test/metatest.dart b/pkg/scheduled_test/test/metatest.dart
index 0c7725d41d64dbf7770da1c8651b86a87ccd91e2..d2ed92fe3259f447f9ecc8d9aaa34fac2803d330 100644
--- a/pkg/scheduled_test/test/metatest.dart
+++ b/pkg/scheduled_test/test/metatest.dart
@@ -119,7 +119,7 @@ void initMetatest(message) {
 /// describing the results of that test run.
 Future<Map> _runInIsolate(String description) {
   var replyPort = new ReceivePort();
-  return Isolate.spawnUri(Uri.parse(Platform.script), [], {
+  return Isolate.spawnUri(Platform.script, [], {
     'testToRun': description,
     'replyTo': replyPort.sendPort
   }).then((_) {