Make root-zone handleUncaughtError rethrow with the correct stack.

runtime/lib/async_patch.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "dart:_internal";
 
 // We need to pass the value as first argument and leave the second and third
 // arguments empty (used for error handling).
 // See vm/ast_transformer.cc for usage.
 Function _asyncThenWrapperHelper(continuation) {
@@ skipping 164 matching lines @@
     if (controller.isClosed) {
       return null;
     }
     if (cancellationCompleter == null) {
       cancellationCompleter = new Completer();
       scheduleGenerator();
     }
     return cancellationCompleter.future;
   }
 }
+
+patch void _rethrow(Object error, StackTrace stackTrace) native "Zone_rethrow";

[Ivan Posva, 2015/10/02 23:40:39]

Strictly speaking this native should be named "Async_rethrow" since it is a
top-level method in the async library and not a method in the Zone class.

Any particular reason why it has to be a top-level method?

[Lasse Reichstein Nielsen, 2015/10/05 06:18:49]

Renamed to Async_rethrow.
It's top-level because it's called from another top-level function. There isn't
any class that it would obviously belong to.
I considered Error, but it's in a different library, so it would have to be
public, and then we would have to implement it in JavaScript too, which isn't
obvious to me how to do (even though having the functionality public would be
awesome!)