Add a "message" field to wrapped barback exceptions.

pkg/barback/lib/src/serialize.dart

 // Copyright (c) 2013, 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.
 
 library barback.serialize;
 
 import 'dart:async';
 import 'dart:isolate';
 
 import 'package:stack_trace/stack_trace.dart';
@@ skipping 86 matching lines @@
         message = error['message'],
         stackTrace = error['stack'] == null ? null :
             new Chain.parse(error['stack']);
 
   /// Serializes [error] to an object that can safely be passed across isolate
   /// boundaries.
   static Map serialize(error, [StackTrace stack]) {
     if (stack == null && error is Error) stack = error.stackTrace;
     return {
       'type': error.runtimeType.toString(),
-      'message': _getErrorMessage(error),
+      'message': getErrorMessage(error),
       'stack': stack == null ? null : new Chain.forTrace(stack).toString()
     };
   }
 
   String toString() => "$message\n$stackTrace";
 }
-
-/// A regular expression to match the exception prefix that some exceptions'
-/// [Object.toString] values contain.
-final _exceptionPrefix = new RegExp(r'^([A-Z][a-zA-Z]*)?(Exception|Error): ');
-
-/// Get a string description of an exception.
-///
-/// Many exceptions include the exception class name at the beginning of their
-/// [toString], so we remove that if it exists.
-String _getErrorMessage(error) =>
-  error.toString().replaceFirst(_exceptionPrefix, '');