ObjectGraph: Establish a HeapIterationScope *before* making the heap writable, least the sweeper in…

runtime/vm/isolate.h

 // 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.
 
 #ifndef RUNTIME_VM_ISOLATE_H_
 #define RUNTIME_VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 842 matching lines @@
 
 #define REUSABLE_FRIEND_DECLARATION(name)                                      \
   friend class Reusable##name##HandleScope;
   REUSABLE_HANDLE_LIST(REUSABLE_FRIEND_DECLARATION)
 #undef REUSABLE_FRIEND_DECLARATION
 
   friend class Become;    // VisitObjectPointers
   friend class GCMarker;  // VisitObjectPointers
   friend class SafepointHandler;
   friend class Scavenger;  // VisitObjectPointers
+  friend class ObjectGraph;  // VisitObjectPointers
   friend class ServiceIsolate;
   friend class Thread;
   friend class Timeline;
   friend class NoReloadScope;  // reload_block
 
 
   DISALLOW_COPY_AND_ASSIGN(Isolate);
 };
 
 
@@ skipping 119 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_ISOLATE_H_