Fix Typo in exitCode documentation

sdk/lib/io/process.dart

 // Copyright (c) 2014, 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.
 
 part of dart.io;
 
 // TODO(ager): The only reason for this class is that we
 // cannot patch a top-level at this point.
 class _ProcessUtils {
   external static void _exit(int status);
@@ skipping 50 matching lines @@
  * See [exit] for more information on how to chose a value for the
  * exit code.
  */
 void set exitCode(int code) {
   if (code is !int) {
     throw new ArgumentError("Integer value for exit code expected");
   }
   _ProcessUtils._setExitCode(code);
 }
 
-/*
+/**
  * Get the global exit code for the Dart VM.
  *
  * The exit code is global for the Dart VM and the last assignment to
  * exitCode from any isolate determines the exit code of the Dart VM
  * on normal termination.
  *
  * See [exit] for more information on how to chose a value for the
  * exit code.
  */
 int get exitCode => _ProcessUtils._getExitCode();
@@ skipping 490 matching lines @@
   final int errorCode;
 
   const ProcessException(this.executable, this.arguments, [this.message = "",
                          this.errorCode = 0]);
   String toString() {
     var msg = (message == null) ? 'OS error code: $errorCode' : message;
     var args = arguments.join(' ');
     return "ProcessException: $msg\n  Command: $executable $args";
   }
 }