Fix a couple of minor issues in IO libraries.

runtime/bin/string_stream.dart

 // Copyright (c) 2011, 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.
 
 // Interface for decoders decoding binary data into string data. The
 // decoder keeps track of line breaks during decoding.
 interface _StringDecoder {
   // Add more binary data to be decoded. The ownership of the buffer
   // is transfered to the decoder and the caller most not modify it any more.
   int write(List<int> buffer);
@@ skipping 257 matching lines @@
     _clientLineHandler = callback;
     _clientDataHandler = null;
     _checkInstallDataHandler();
     _checkScheduleCallback();
   }
 
   void set closeHandler(void callback()) {
     _clientCloseHandler = callback;
   }
 
+  void set errorHandler(void callback()) {
+    _input.errorHandler = callback;
+  }
+
   void _dataHandler() {
     _readData();
     if (!_decoder.isEmpty() && _clientDataHandler !== null) {
       _clientDataHandler();
     }
     if (_decoder.lineBreaks > 0 && _clientLineHandler !== null) {
       _clientLineHandler();
     }
     _checkScheduleCallback();
     _checkInstallDataHandler();
@@ skipping 95 matching lines @@
   bool _inputClosed = false;  // Is the underlying input stream closed?
   bool _closed = false;  // Is this stream closed.
   bool _eof = false;  // Has all data been read from the decoder?
   Timer _scheduledDataCallback;
   Timer _scheduledLineCallback;
   Timer _scheduledCloseCallback;
   Function _clientDataHandler;
   Function _clientLineHandler;
   Function _clientCloseHandler;
 }