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

runtime/vm/dart_api_impl.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 "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "lib/stacktrace.h"
 #include "platform/assert.h"
@@ skipping 1482 matching lines @@
   CHECK_NULL(isolate_snapshot_data_size);
   // Finalize all classes if needed.
   Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   I->StopBackgroundCompiler();
 
 #if defined(DEBUG)
   I->heap()->CollectAllGarbage();
-  CheckFunctionTypesVisitor check_canonical(T);
-  I->heap()->IterateObjects(&check_canonical);
+  {
+    HeapIterationScope iteration(T);
+    CheckFunctionTypesVisitor check_canonical(T);
+    iteration.IterateObjects(&check_canonical);
+  }
 #endif  // #if defined(DEBUG)
 
   Symbols::Compact(I);
 
   FullSnapshotWriter writer(Snapshot::kFull, vm_snapshot_data_buffer,
                             isolate_snapshot_data_buffer, ApiReallocate,
                             NULL /* vm_image_writer */,
                             NULL /* isolate_image_writer */);
   writer.WriteFullSnapshot();
   if (vm_snapshot_data_buffer != NULL) {
@@ skipping 13 matching lines @@
   CHECK_NULL(script_snapshot_size);
   // Finalize all classes if needed.
   Dart_Handle state = Api::CheckAndFinalizePendingClasses(T);
   if (::Dart_IsError(state)) {
     return state;
   }
   Library& lib = Library::Handle(Z, I->object_store()->root_library());
 
 #if defined(DEBUG)
   I->heap()->CollectAllGarbage();
-  CheckFunctionTypesVisitor check_canonical(T);
-  I->heap()->IterateObjects(&check_canonical);
+  {
+    HeapIterationScope iteration(T);
+    CheckFunctionTypesVisitor check_canonical(T);
+    iteration.IterateObjects(&check_canonical);
+  }
 #endif  // #if defined(DEBUG)
 
   ScriptSnapshotWriter writer(script_snapshot_buffer, ApiReallocate);
   writer.WriteScriptSnapshot(lib);
   *script_snapshot_size = writer.BytesWritten();
   return Api::Success();
 }
 
 DART_EXPORT void Dart_InterruptIsolate(Dart_Isolate isolate) {
   if (isolate == NULL) {
@@ skipping 5220 matching lines @@
 #endif
 }
 
 DART_EXPORT void Dart_DumpNativeStackTrace(void* context) {
 #ifndef PRODUCT
   Profiler::DumpStackTrace(context);
 #endif
 }
 
 }  // namespace dart