Fix sdk/lib/io errors found by the analyzer.

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 20 matching lines @@
   /**
    * Writes the bytes uninterpreted to the consumer. While the call is
    * synchronous, the data may be buffered until the underlying resource is
    * ready. The data should not be modified after a call to [add].
    */
   void add(List<int> data);
 
   /**
    * Writes an error to the consumer.
    */
-  void addError(error);
+  void addError(error, [StackTrace stackTrace]);
 
   /**
    * Adds all elements of the given [stream] to `this`.
    */
   Future addStream(Stream<List<int>> stream);
 
   /**
    * Close the target.
    */
   Future close();
@@ skipping 17 matching lines @@
 
   _StreamSinkImpl(StreamConsumer<T> this._target) {
     _doneFuture = _doneCompleter.future;
   }
 
   void add(T data) {
     if (_isClosed) return;
     _controller.add(data);
   }
 
-  void addError(error) {
-    _controller.addError(error);
+  void addError(error, [StackTrace stackTrace]) {
+    _controller.addError(error, stackTrace);
   }
 
   Future addStream(Stream<T> stream) {
     if (_isBound) {
       throw new StateError("StreamSink is already bound to a stream");
     }
     _isBound = true;
     if (_hasError) return done;
     // Wait for any sync operations to complete.
     Future targetAddStream() {
@@ skipping 134 matching lines @@
 
   void writeln([Object obj = ""]) {
     write(obj);
     write("\n");
   }
 
   void writeCharCode(int charCode) {
     write(new String.fromCharCode(charCode));
   }
 }