Revert "Isolates: allow sending of arbitrary objects in dart2js."

tests/isolate/object_leak_test.dart

Index: tests/isolate/object_leak_test.dart
diff --git a/tests/isolate/object_leak_test.dart b/tests/isolate/object_leak_test.dart
index d15f2b51ca8518a3dcf6be9109e7ad3e7f2c45df..4511b43fd99bfe74285ccb437f40588c55e85c14 100644
--- a/tests/isolate/object_leak_test.dart
+++ b/tests/isolate/object_leak_test.dart
@@ -16,23 +16,25 @@ class A {
 }
 
 fun(msg) {
-  var a = msg[0];
-  var replyTo = msg[1];
-  print("received: ${a.x}");
-  a.x = 1;
-  print("done updating: ${a.x}");
-  replyTo.send("done");
+  print("received: ${msg.x}");
+  msg.x = 1;
+  print("done updating: ${msg.x}");
 }
 
 main() {
   asyncStart();
   var a = new A();
-  ReceivePort rp = new ReceivePort();
-  Isolate.spawn(fun, [a, rp.sendPort]);
-  rp.first.then((msg) {
-    Expect.equals("done", msg);
-    // Changes in other isolate must not reach here.
-    Expect.equals(0, a.x);
+  // Sending an A object to another isolate should not work.
+  Isolate.spawn(fun, a).then((isolate) {
+    new Timer(const Duration(milliseconds: 300), () {
+      // Changes in other isolate must not reach here.
+      Expect.equals(0, a.x);
+      asyncEnd();
+    });
+  }, onError: (e) {
+    // Sending an A isn't required to work.
+    // It works in the VM, but not in dart2js.
+    print("Send of A failed:\n$e");
     asyncEnd();
   });
 }