Fixed command-line debugger to use new IO API.

tools/ddbg.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.
 
 // Simple interactive debugger shell that connects to the Dart VM's debugger
 // connection port.
 
 import "dart:io";
 import "dart:json" as json;
 import "dart:utf";
@@ skipping 51 matching lines @@
 }
 
 
 Future sendCmd(Map<String, dynamic> cmd) {
   var completer = new Completer();
   int id = cmd["id"];
   outstandingCommands[id] = completer;
   if (verbose) {
     print("sending: '${json.stringify(cmd)}'");
   }
-  vmSock.addString(json.stringify(cmd));
+  vmSock.write(json.stringify(cmd));
   return completer.future;
 }
 
 
 void processCommand(String cmdLine) {
   seqNum++;
   var args = cmdLine.split(' ');
   if (args.length == 0) {
     return;
   }
@@ skipping 475 matching lines @@
       process.stdin.close();
       process.exitCode.then((int exitCode) {
         print('${arguments.join(" ")} exited with $exitCode');
       });
       debuggerMain();
     });
   } else {
     debuggerMain();
   }
 }