Remove deprecated parts of dart:async.

pkg/barback/lib/src/asset_cascade.dart

Index: pkg/barback/lib/src/asset_cascade.dart
diff --git a/pkg/barback/lib/src/asset_cascade.dart b/pkg/barback/lib/src/asset_cascade.dart
index cc9056012be4b7c2dd79ef0ca941970f889ef24e..3ee101af0e9e712273fe99d142998fc413226b4f 100644
--- a/pkg/barback/lib/src/asset_cascade.dart
+++ b/pkg/barback/lib/src/asset_cascade.dart
@@ -123,7 +123,7 @@ class AssetCascade {
     onLog.listen((entry) {
       if (entry.level == LogLevel.ERROR) {
         _accumulatedErrors.add(
-            new TransformerException(entry.transform, entry.message));
+            new TransformerException(entry.transform, entry.message, null));

[nweiz, 2013/10/30 22:48:18]

Can you add a TODO to track the stack trace of error log entries?

[floitsch, 2013/10/31 00:38:14]

Done.

       }
     });
   }
@@ -187,8 +187,8 @@ class AssetCascade {
         _loadingSources.remove(id);
       }).then((asset) {
         var controller = _sourceControllerMap[id].setAvailable(asset);
-      }).catchError((error) {
-        reportError(new AssetLoadException(id, error));
+      }).catchError((error, stack) {
+        reportError(new AssetLoadException(id, error, stack));
 
         // TODO(nweiz): propagate error information through asset nodes.
         _sourceControllerMap.remove(id).setRemoved();