Pipe the stack traces of errors through Future operations.

corelib/src/implementation/future_implementation.dart

Index: corelib/src/implementation/future_implementation.dart
diff --git a/corelib/src/implementation/future_implementation.dart b/corelib/src/implementation/future_implementation.dart
index 21ee08f26d01b5118749cc8b4ed67c1b0c838c85..58d78433a059fb005f9dc620449624e7b51a7f33 100644
--- a/corelib/src/implementation/future_implementation.dart
+++ b/corelib/src/implementation/future_implementation.dart
@@ -172,7 +172,7 @@ class FutureImpl<T> implements Future<T> {
   Future transform(Function transformation) {
     final completer = new Completer();
     handleException((e) {
-      completer.completeException(e);
+      completer.completeException(e, this.stackTrace);
       return true;
     });
     then((v) {
@@ -191,7 +191,7 @@ class FutureImpl<T> implements Future<T> {
   Future chain(Function transformation) {
     final completer = new Completer();
     handleException((e) {
-      completer.completeException(e);
+      completer.completeException(e, this.stackTrace);
       return true;
     });
     then((v) {
@@ -203,7 +203,7 @@ class FutureImpl<T> implements Future<T> {
         return;
       }
       future.handleException((e) {
-        completer.completeException(e);
+        completer.completeException(e, future.stackTrace);
         return true;
       });
       future.then((b) => completer.complete(b));