Display metadata about out-of-band callbacks in scheduled test errors.

pkg/scheduled_test/lib/scheduled_test.dart

Index: pkg/scheduled_test/lib/scheduled_test.dart
diff --git a/pkg/scheduled_test/lib/scheduled_test.dart b/pkg/scheduled_test/lib/scheduled_test.dart
index 6ae8449c56b0b626b760af07c7417ebc493f9221..a65731ab1792f0eb58db91a0a8abc4a61dfea485 100644
--- a/pkg/scheduled_test/lib/scheduled_test.dart
+++ b/pkg/scheduled_test/lib/scheduled_test.dart
@@ -317,13 +317,13 @@ void _setUpScheduledTest([void setUpFn()]) {
 /// initialized.
 void _ensureInitialized() {
   unittest.ensureInitialized();
-  unittest.wrapAsync = (f, [id = '']) {
+  unittest.wrapAsync = (f, [description]) {
     if (currentSchedule == null) {
       throw new StateError("Unexpected call to wrapAsync with no current "
           "schedule.");
     }
 
-    return currentSchedule.wrapAsync(f);
+    return currentSchedule.wrapAsync(f, description);
   };
 }