SendPort + ReceivePort changes:

lib/isolate/frog/isolateimpl.dart

Index: lib/isolate/frog/isolateimpl.dart
diff --git a/lib/isolate/frog/isolateimpl.dart b/lib/isolate/frog/isolateimpl.dart
index 2e096fc7776c8617eac806a0c62cb413ff4c5557..bc7267c10b5fb4dec57ac913beba79c5ef227889 100644
--- a/lib/isolate/frog/isolateimpl.dart
+++ b/lib/isolate/frog/isolateimpl.dart
@@ -293,8 +293,9 @@ class _IsolateNatives {
   /** JavaScript-specific implementation to spawn an isolate. */
   static Future<SendPort> spawn(Isolate isolate, bool isLight) {
     Completer<SendPort> completer = new Completer<SendPort>();
-    ReceivePort port = new ReceivePort.singleShot();
+    ReceivePort port = new ReceivePort();
     port.receive((msg, SendPort replyPort) {
+      port.close();

[eub, 2012/03/09 18:33:10]

I wonder how often people are going to write this idiom.  Maybe
SingleShotReceivePort is worth still having around?

[eub, 2012/03/09 18:33:10]

I saw about a dozen instances looking over this CL.

[Siggi Cherem (dart-lang), 2012/03/10 03:10:00]

Yeah - this is something that I saw commonly in tests and places where the
parent isolate wanted to 'wait' for the child isolate before the vm finishes
executing. The trick is to keep a port open, so that the vm knows that we are
not done. 

Using singleShot for this purpose made the idiom shorter to write, but a little
harder to see in my opinion.

       assert(msg == _SPAWNED_SIGNAL);
       completer.complete(replyPort);
     });
@@ -543,8 +544,9 @@ class _IsolateNatives {
 
   static _spawn2(String functionName, String uri, bool isLight) {
     Completer<SendPort> completer = new Completer<SendPort>();
-    ReceivePort port = new ReceivePort.singleShot();
+    ReceivePort port = new ReceivePort();
     port.receive((msg, SendPort replyPort) {
+      port.close();
       assert(msg == _SPAWNED_SIGNAL);
       completer.complete(replyPort);
     });