Reclaim the CreatedFromSnapshot bit and use it to indicate VM Heap object

tests/isolate/message3_test.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.
 
 // Dart test program for testing serialization of messages.
 // VMOptions=--enable_type_checks --enable_asserts
 
 library MessageTest;
 import 'dart:async';
 import 'dart:collection';
@@ skipping 376 matching lines @@
   ping.send(g2);
   ping.send(g3);
 
   checks.add((x) {  // g1.
     Expect.isTrue(x is G);
     Expect.isFalse(identical(g1, x));
     F f = x.field;
     Expect.equals("field", f.field);
     Expect.isFalse(identical(nonConstF, f));
   });
-  checks.add((x) {  // g1.
+  checks.add((x) {  // g2.
     Expect.isTrue(x is G);
     Expect.isFalse(identical(g1, x));
     F f = x.field;
     Expect.equals("field", f.field);
     Expect.identical(constF, f);  /// constInstance: continued
   });
   checks.add((x) {  // g3.
     Expect.isTrue(x is G);
-    Expect.identical(g1, x);  /// constInstance: continued
+    Expect.identical(g3, x);  /// constInstance: continued
     F f = x.field;
     Expect.equals("field", f.field);
     Expect.identical(constF, f);  /// constInstance: continued
   });
 
   // Make sure objects in a map are serialized and deserialized in the correct
   // order.
   Map m = new Map();
   Value val1 = new Value(1);
   Value val2 = new Value(2);
@@ skipping 36 matching lines @@
     .spawn(echoMain, [initialReplyPort.sendPort, testPort.sendPort])
     .then((_) => initialReplyPort.first)
     .then((SendPort ping) {
       runTests(ping, checks);
       Expect.isTrue(checks.length > 0);
       completer.future
         .then((_) => ping.send("halt"))
         .then((_) => asyncEnd());
     });
 }