Add chain support to barback.

pkg/barback/lib/src/build_result.dart

Index: pkg/barback/lib/src/build_result.dart
diff --git a/pkg/barback/lib/src/build_result.dart b/pkg/barback/lib/src/build_result.dart
index 52b341e5af4615f51ce552f19ba635f781ffdf91..faeb2566a5fd746e29bbf630ed03810a7f72cf5e 100644
--- a/pkg/barback/lib/src/build_result.dart
+++ b/pkg/barback/lib/src/build_result.dart
@@ -4,10 +4,6 @@
 
 library barback.build_result;
 
-import 'dart:async';
-
-import 'package:stack_trace/stack_trace.dart';
-
 import 'errors.dart';
 import 'utils.dart';
 
@@ -49,14 +45,14 @@ class BuildResult {
     return "errors:\n" + errors.map((error) {
       var stackTrace = null;
       if (error is TransformerException || error is AssetLoadException) {
-        stackTrace = new Trace.from(error.stackTrace);
+        stackTrace = error.stackTrace.terse;
       }
 
       var msg = new StringBuffer();
       msg.write(prefixLines(error.toString()));
       if (stackTrace != null) {
         msg.write("\n\n");
-        msg.write("Stack trace:\n");
+        msg.write("Stack chain:\n");
         msg.write(prefixLines(stackTrace.toString()));
       }
       return msg.toString();