1. Added new flag verify_gc_contains and moved all the asserts that do a

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 "include/dart_native_api.h"
 #include "platform/assert.h"
 #include "platform/text_buffer.h"
@@ skipping 1712 matching lines @@
     }
   }
 }
 
 
 void Isolate::Shutdown() {
   ASSERT(this == Isolate::Current());
   StopBackgroundCompiler();
 
 #if defined(DEBUG)
-  if (heap_ != NULL) {
+  if (heap_ != NULL && FLAG_verify_on_transition) {
     // The VM isolate keeps all objects marked.
     heap_->Verify(this == Dart::vm_isolate() ? kRequireMarked : kForbidMarked);
   }
 #endif  // DEBUG
 
   Thread* thread = Thread::Current();
 
   // Don't allow anymore dart code to execution on this isolate.
   thread->ClearStackLimit();
 
@@ skipping 1230 matching lines @@
 void IsolateSpawnState::DecrementSpawnCount() {
   ASSERT(spawn_count_monitor_ != NULL);
   ASSERT(spawn_count_ != NULL);
   MonitorLocker ml(spawn_count_monitor_);
   ASSERT(*spawn_count_ > 0);
   *spawn_count_ = *spawn_count_ - 1;
   ml.Notify();
 }
 
 }  // namespace dart