Missing handling of default arguments in socket stream readInto

runtime/bin/socket_stream_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 _SocketInputStream implements SocketInputStream {
   _SocketInputStream(Socket socket) : _socket = socket {
     if (_socket._id == -1) _closed = true;
     _socket.onClosed = _onClosed;
   }
 
@@ skipping 17 matching lines @@
       return null;
     } else if (bytesRead < bytesToRead) {
       ByteArray newBuffer = new ByteArray(bytesRead);
       newBuffer.setRange(0, bytesRead, buffer);
       return newBuffer;
     } else {
       return buffer;
     }
   }
 
-  int readInto(List<int> buffer, int offset, int len) {
-    if (offset === null) offset = 0;
+  int readInto(List<int> buffer, [int offset = 0, int len]) {
+    if (_closed) return null;
     if (len === null) len = buffer.length;
     if (offset < 0) throw new StreamException("Illegal offset $offset");
     if (len < 0) throw new StreamException("Illegal length $len");
     return _socket.readList(buffer, offset, len);
   }
 
   int available() => _socket.available();
 
   void pipe(OutputStream output, [bool close = true]) {
     _pipe(this, output, close: close);
@@ skipping 134 matching lines @@
     if (_streamErrorHandler != null) _streamErrorHandler();
   }
 
   Socket _socket;
   _BufferList _pendingWrites;
   var _onNoPendingWrites;
   var _streamErrorHandler;
   bool _closing = false;
   bool _closed = false;
 }