Don't intrusively mark in the heap snapshot generator

src/profiler/heap-snapshot-generator.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 #define V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_
 
 #include "include/v8-profiler.h"
 #include "src/base/platform/time.h"
 #include "src/objects.h"
@@ skipping 333 matching lines @@
                       HeapEntry::Type type,
                       const char* name,
                       size_t size);
 
   static String* GetConstructorName(JSObject* object);
 
  private:
   typedef bool (V8HeapExplorer::*ExtractReferencesMethod)(int entry,
                                                           HeapObject* object);
 
+  void MarkVisitedField(HeapObject* obj, int offset);
+
   HeapEntry* AddEntry(HeapObject* object);
   HeapEntry* AddEntry(HeapObject* object,
                       HeapEntry::Type type,
                       const char* name);
 
   const char* GetSystemEntryName(HeapObject* object);
 
   template<V8HeapExplorer::ExtractReferencesMethod extractor>
   bool IterateAndExtractSinglePass();
 
@@ skipping 94 matching lines @@
   StringsStorage* names_;
   HeapObjectsMap* heap_object_map_;
   SnapshottingProgressReportingInterface* progress_;
   SnapshotFiller* filler_;
   HeapObjectsSet objects_tags_;
   HeapObjectsSet strong_gc_subroot_names_;
   HeapObjectsSet user_roots_;
   HeapObjectsSet weak_containers_;
   v8::HeapProfiler::ObjectNameResolver* global_object_name_resolver_;
 
+  std::vector<bool> marks_;
+
   friend class IndexedReferencesExtractor;
   friend class RootsReferencesExtractor;
 
   DISALLOW_COPY_AND_ASSIGN(V8HeapExplorer);
 };
 
 
 class NativeGroupRetainedObjectInfo;
 
 
@@ skipping 135 matching lines @@
   friend class HeapSnapshotJSONSerializerIterator;
 
   DISALLOW_COPY_AND_ASSIGN(HeapSnapshotJSONSerializer);
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_PROFILER_HEAP_SNAPSHOT_GENERATOR_H_