Socket.available should never return a negative value.

runtime/bin/socket_impl.dart

 // Copyright (c) 2012, 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.
 
 
 class _SocketBase {
   // Bit flags used when communicating between the eventhandler and
   // dart code. The EVENT flags are used to indicate events of
   // interest when sending a message from dart code to the
   // eventhandler. When receiving a message from the eventhandler the
@@ skipping 329 matching lines @@
     });
     return socket;
   }
 
   _Socket._internal();
   _Socket._internalReadOnly() : _pipe = true { super._closedWrite = true; }
   _Socket._internalWriteOnly() : _pipe = true { super._closedRead = true; }
 
   int available() {
     if (_id >= 0) {
-      return _available();
+      var result = _available();
+      if (result is OSError) {
+        _reportError(result, "Available failed");
+        return 0;
+      } else {
+        return result;
+      }
     }
     throw new
         SocketIOException("Error: available failed - invalid socket handle");
   }
 
-  int _available() native "Socket_Available";
+  _available() native "Socket_Available";
 
   int readList(List<int> buffer, int offset, int bytes) {
     if (_id >= 0) {
       if (bytes == 0) {
         return 0;
       }
       if (offset < 0) {
         throw new IndexOutOfRangeException(offset);
       }
       if (bytes < 0) {
@@ skipping 211 matching lines @@
   bool _seenFirstOutEvent = false;
   bool _pipe = false;
   Function _clientConnectHandler;
   Function _clientWriteHandler;
   SocketInputStream _inputStream;
   SocketOutputStream _outputStream;
   String _remoteHost;
   int _remotePort;
   static SendPort _socketService;
 }