Expect objects in the VM-heap to be marked on shutdown verification.

runtime/vm/isolate.cc

 // Copyright (c) 2013, 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.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
 #include "vm/code_observers.h"
@@ skipping 1056 matching lines @@
   ASSERT(this == Isolate::Current());
   ASSERT(top_resource() == NULL);
 #if defined(DEBUG)
   if (heap_ != NULL) {
     // Wait for concurrent GC tasks to finish before final verification.
     PageSpace* old_space = heap_->old_space();
     MonitorLocker ml(old_space->tasks_lock());
     while (old_space->tasks() > 0) {
       ml.Wait();
     }
-    heap_->Verify(kForbidMarked);
+    // The VM isolate keeps all objects marked.
+    heap_->Verify(this == Dart::vm_isolate() ? kRequireMarked : kForbidMarked);
   }
 #endif  // DEBUG
 
   // Remove this isolate from the list *before* we start tearing it down, to
   // avoid exposing it in a state of decay.
   RemoveIsolateFromList(this);
 
   // Create an area where we do have a zone and a handle scope so that we can
   // call VM functions while tearing this isolate down.
   {
@@ skipping 542 matching lines @@
                            serialized_message_, serialized_message_len_);
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(I);
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart