[vm, gc] Require a safepoint for heap iteration.

runtime/vm/benchmark_test.cc

 // 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.
 
 #include "vm/benchmark_test.h"
 
 #include "bin/builtin.h"
 #include "bin/file.h"
 #include "bin/isolate_data.h"
 
@@ skipping 478 matching lines @@
       "\n";
 
   // Start an Isolate, load a script and create a full snapshot.
   uint8_t* vm_snapshot_data_buffer;
   uint8_t* isolate_snapshot_data_buffer;
   // Need to load the script into the dart: core library due to
   // the import of dart:_internal.
   TestCase::LoadCoreTestScript(kScriptChars, NULL);
   Api::CheckAndFinalizePendingClasses(thread);
 
+  TransitionNativeToVM transition(thread);
   // Write snapshot with object content.
   FullSnapshotWriter writer(Snapshot::kFull, &vm_snapshot_data_buffer,
                             &isolate_snapshot_data_buffer, &malloc_allocator,
                             NULL, NULL /* image_writer */);
   writer.WriteFullSnapshot();
   const Snapshot* snapshot =
       Snapshot::SetupFromBuffer(isolate_snapshot_data_buffer);
   ASSERT(snapshot->kind() == Snapshot::kFull);
   benchmark->set_score(snapshot->length());
 
@@ skipping 17 matching lines @@
       "\n";
 
   // Start an Isolate, load a script and create a full snapshot.
   uint8_t* vm_snapshot_data_buffer;
   uint8_t* isolate_snapshot_data_buffer;
   // Need to load the script into the dart: core library due to
   // the import of dart:_internal.
   TestCase::LoadCoreTestScript(kScriptChars, NULL);
   Api::CheckAndFinalizePendingClasses(thread);
 
+  TransitionNativeToVM transition(thread);
   // Write snapshot with object content.
   FullSnapshotWriter writer(Snapshot::kFull, &vm_snapshot_data_buffer,
                             &isolate_snapshot_data_buffer, &malloc_allocator,
                             NULL, NULL /* image_writer */);
   writer.WriteFullSnapshot();
   const Snapshot* snapshot =
       Snapshot::SetupFromBuffer(isolate_snapshot_data_buffer);
   ASSERT(snapshot->kind() == Snapshot::kFull);
   benchmark->set_score(snapshot->length());
 
@@ skipping 146 matching lines @@
   timer.Stop();
   int64_t elapsed_time = timer.TotalElapsedTime();
   benchmark->set_score(elapsed_time);
 }
 
 BENCHMARK_MEMORY(InitialRSS) {
   benchmark->set_score(OS::MaxRSS());
 }
 
 }  // namespace dart