Make new StreamController be async by default.

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 99346e1cff5be5ea21b8f3e723e02cca488c5b83..ba4acd20a442c215dacfd454880b1895ded55f47 100644
--- a/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
+++ b/sdk/lib/indexed_db/dart2js/indexed_db_dart2js.dart
@@ -158,7 +158,7 @@ class Cursor native "IDBCursor" {
     }
   }
 
-  
+
   @DomName('IDBCursor.direction')
   @DocsEditable
   final String direction;
@@ -585,7 +585,7 @@ class Index native "IDBIndex" {
     return ObjectStore._cursorStreamFromResult(request, autoAdvance);
   }
 
-  
+
   @DomName('IDBIndex.keyPath')
   @DocsEditable
   final dynamic keyPath;
@@ -1016,7 +1016,7 @@ 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();
+    var controller = new StreamController(sync: true);
 
     request.onError.listen((e) {
       //TODO: Report stacktrace once issue 4061 is resolved.