Remove AsyncError with Expando.

sdk/lib/io/io_sink.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.
 
 part of dart.io;
 
 /**
  * Helper class to wrap a [StreamConsumer<List<int>>] and provide
  * utility functions for writing to the StreamConsumer directly. The
  * [IOSink] buffers the input given by all [StringSink] methods and will delay
@@ skipping 15 matching lines @@
   Encoding encoding;
 
   /**
    * Writes the bytes uninterpreted to the consumer.
    */
   void add(List<int> data);
 
   /**
    * Writes an error to the consumer.
    */
-  void addError(AsyncError error);
+  void addError(error);
 
   /**
    * Adds all elements of the given [stream] to `this`.
    */
   Future addStream(Stream<List<int>> stream);
 
   /**
    * Close the target.
    */
   Future close();
@@ skipping 69 matching lines @@
   }
 
   void writeCharCode(int charCode) {
     write(new String.fromCharCode(charCode));
   }
 
   void add(List<int> data) {
     _controller.add(data);
   }
 
-  void addError(AsyncError error) {
+  void addError(error) {
     _controller.addError(error);
   }
 
   Future addStream(Stream<List<int>> stream) {
     if (_isBound) {
       throw new StateError("IOSink is already bound to a stream");
     }
     _isBound = true;
     // Wait for any sync operations to complete.
     Future targetAddStream() {
@@ skipping 76 matching lines @@
                 } else {
                   // No new stream. No need to close target, as it have already
                   // failed.
                   _completeDone(error: error);
                 }
               });
     }
     return _controllerInstance;
   }
 }