Initializing formals can't be optional parameters

runtime/bin/process.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.
 
 interface Process factory _Process {
   /*
    * Creates a new process object preparing to run the executable
    * found at [path] with the specified [arguments].
    */
   Process(String path, List<String> arguments);
@@ skipping 32 matching lines @@
   bool kill();
 
   /*
    * Terminates the streams and closes the exit handler of a process.
    */
   void close();
 }
 
 
 class ProcessException implements Exception {
-  const ProcessException([String this.message, int this.errorCode = 0]);
+  const ProcessException([String message, int errorCode = 0])
+      : this.message = message, this.errorCode = errorCode;
   String toString() => "ProcessException: $message";
 
   /*
    * Contains the system message for the process exception if any.
    */
   final String message;
 
   /*
    * Contains the OS error code for the process exception if any.
    */
   final int errorCode;
 }