Fixing IndexedDB Dartium Checked Mode tests

sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart

Index: sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
diff --git a/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart b/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
index ba92d54dda7380b5f0e248ac422741021e7a7454..ec89509124662f3ae9696670f41da9de9388c4b3 100644
--- a/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
+++ b/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
@@ -780,7 +780,7 @@ class ObjectStore native "*IDBObjectStore" {
     // TODO: need to guarantee that the controller provides the values
     // immediately as waiting until the next tick will cause the transaction to
     // close.
-    var controller = new StreamController<Cursor>();
+    var controller = new StreamController();
 
     request.onError.listen((e) {
       //TODO: Report stacktrace once issue 4061 is resolved.