Change the default for the len argument to writeFrom on OutputStream

tests/standalone/src/EchoServerStreamTest.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.
 //
 // Echo server test program to test socket streams.
 //
 // VMOptions=
 // VMOptions=--short_socket_read
 // VMOptions=--short_socket_write
 // VMOptions=--short_socket_read --short_socket_write
@@ skipping 73 matching lines @@
             }
           }
         }
 
         if (_messages % 2 == 0) data = new List<int>(MSGSIZE);
         inputStream.dataHandler = dataReceived;
       }
 
       _socket.closeHandler = closeHandler;
       _socket.errorHandler = errorHandler;
-      stream.write(_buffer);
+
+      // Test both write and writeFrom in different forms.
+      switch (_messages % 2) {
+        case 0:
+          stream.write(_buffer);
+          break;
+        case 1:
+          stream.write(_buffer, false);
+          break;
+        case 2:
+          stream.writeFrom(_buffer);
+          break;
+        case 3:
+          stream.writeFrom(_buffer, len: _buffer.length ~/ 2);
+          stream.writeFrom(_buffer, _buffer.length ~/ 2);
+          break;
+      }
       stream.close();
       dataSent();
     }
 
     _socket = new Socket(EchoServer.HOST, _port);
     if (_socket !== null) {
       _socket.connectHandler = connectHandler;
     } else {
       Expect.fail("socket creation failed");
     }
@@ skipping 77 matching lines @@
       }
     });
   }
 
   ServerSocket _server;
 }
 
 main() {
   EchoServerStreamTest.testMain();
 }