Properly capture and pass the stack trace in Future exceptions.

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..9b6c12c80a05a1224a074f91e67213c84d366e21 100644
--- a/corelib/src/implementation/future_implementation.dart
+++ b/corelib/src/implementation/future_implementation.dart
@@ -172,14 +172,14 @@ 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) {
       var transformed = null;
       try {
         transformed = transformation(v);
-      } catch (final ex, final stackTrace) {
+      } catch (Exception ex, final stackTrace) {

[Siggi Cherem (dart-lang), 2012/07/03 19:13:46]

weird, why is this needed? what if it was 'var' or we omit any annotation here?

[nweiz, 2012/07/03 21:39:26]

With "var" or "final", the stack trace isn't captured. "catch (ex" doesn't
compile at all. Only "Exception" works. I have no idea why this is the case.

[Siggi Cherem (dart-lang), 2012/07/03 22:10:06]

weird... if you haven't already, file a bug on the VM about this issue. 

         completer.completeException(ex, stackTrace);
         return;
       }
@@ -191,19 +191,19 @@ 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) {
       var future = null;
       try {
         future = transformation(v);
-      } catch (final ex, final stackTrace) {
+      } catch (Exception ex, final stackTrace) {
         completer.completeException(ex, stackTrace);
         return;
       }
       future.handleException((e) {
-        completer.completeException(e);
+        completer.completeException(e, this.stackTrace);
         return true;
       });
       future.then((b) => completer.complete(b));