Create an initial port.

lib/isolate/frog/isolateimpl.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.
 
 /**
  * Concepts used here:
  *
  * "manager" - A manager contains one or more isolates, schedules their
  * execution, and performs other plumbing on their behalf.  The isolate
  * present at the creation of the manager is designated as its "root isolate".
@@ skipping 20 matching lines @@
 // Running any Dart code outside the context of an isolate gives it
 // the change to break the isolate abstraction.
 _Manager get _globalState() native "return \$globalState;";
 set _globalState(_Manager val) native "\$globalState = val;";
 
 void _fillStatics(context) native @"""
   $globals = context.isolateStatics;
   $static_init();
 """;
 
-ReceivePort _port;
+ReceivePort _lazy_port;
+ReceivePort get _port() {
+  if (_lazy_port === null) {
+    _lazy_port = new ReceivePort();
+  }
+  return _lazy_port;
+}
 
 SendPort _spawnFunction(void topLevelFunction()) {
   final name = _IsolateNatives._getJSFunctionName(topLevelFunction);
   if (name == null) {
     throw new UnsupportedOperationException(
         "only top-level functions can be spawned.");
   }
   return _IsolateNatives._spawn2(name, null, false);
 }
 
@@ skipping 540 matching lines @@
     if (uri != null) throw new UnsupportedOperationException(
             "Currently spawnUri is not supported without web workers.");
     _globalState.topEventLoop.enqueue(new _IsolateContext(), function() {
       final func = _getJSFunctionFromName(functionName);
       _startIsolate2(func, replyPort);
     }, 'nonworker start');
   }
 
   static void _startIsolate2(Function topLevel, SendPort replyTo) {
     _fillStatics(_globalState.currentContext);
-    _port = new ReceivePort();
+    __port = new ReceivePort();
     replyTo.send(_SPAWNED_SIGNAL, port.toSendPort());
     topLevel();
   }
 
   /**
    * Spawns an isolate in a worker. [factoryName] is the Javascript constructor
    * name for the isolate entry point class.
    */
   static void _spawnWorker2(functionName, uri, replyPort) {
     if (functionName == null) functionName = 'main';
@@ skipping 14 matching lines @@
       'command': 'start2',
       'id': workerId,
       // Note: we serialize replyPort twice because the child worker needs to
       // first deserialize the worker id, before it can correctly deserialize
       // the port (port deserialization is sensitive to what is the current
       // workerId).
       'replyTo': _serializeMessage(replyPort),
       'functionName': functionName }));
   }
 }