Asyncstar - exception thrown before yield or await would not get caught

sdk/lib/_internal/compiler/js_lib/js_helper.dart

Index: sdk/lib/_internal/compiler/js_lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_helper.dart b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
index 4f970badadc918199ff78fd7e0cc496384e22483..b45b6c170d15a86b7a329913d5ac5067ac837d31 100644
--- a/sdk/lib/_internal/compiler/js_lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/js_lib/js_helper.dart
@@ -3729,16 +3729,17 @@ class AsyncStarStreamController {
   addError(error, stackTrace) => controller.addError(error, stackTrace);
   close() => controller.close();
 
-  AsyncStarStreamController(helperCallback) {
+  AsyncStarStreamController(body) {
     controller = new StreamController(
       onListen: () {
         scheduleMicrotask(() {
-          JS('', '#(#, null)', helperCallback, async_error_codes.SUCCESS);
+          _wrapJsFunctionForAsync(body,

[floitsch, 2015/02/20 12:16:08]

nit: the "(null)" drowns.
maybe:
Function wrapped = _wrapJs...(
   body, async_error_codes.SUCCESS);
wrapped(null);

?

[sigurdm, 2015/02/23 12:33:49]

Done.

+                                  async_error_codes.SUCCESS)(null);
         });
       },
       onResume: () {
         if (!isAdding) {
-          asyncStarHelper(null, helperCallback, this);
+          asyncStarHelper(null, body, this);
         }
       }, onCancel: () {
         stopRunning = true;
@@ -3746,8 +3747,8 @@ class AsyncStarStreamController {
   }
 }
 
-makeAsyncStarController(helperCallback) {
-  return new AsyncStarStreamController(helperCallback);
+makeAsyncStarController(body) {
+  return new AsyncStarStreamController(body);
 }
 
 class IterationMarker {