Synchronize store buffer processing and concurrent sweeping.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 89267e5c6fc23b2aacd33aa81c7335a1acfb1a81..757f16562491eeb4cc8011a671b7ed48107f6b10 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1807,6 +1807,7 @@ class HeapObject: public Object {
 
   // Set the map using release store
   inline void synchronized_set_map(Map* value);
+  inline void synchronized_set_map_no_write_barrier(Map* value);
   inline void synchronized_set_map_word(MapWord map_word);
 
   // During garbage collection, the map word of a heap object does not
@@ -4807,6 +4808,9 @@ class FreeSpace: public HeapObject {
   inline int size();
   inline void set_size(int value);
 
+  inline int nobarrier_size();
+  inline void nobarrier_set_size(int value);
+
   inline int Size() { return size(); }
 
   // Casting.