The sweeper thread should not write the page flags. Added a sweeping complete phase, where the main…

src/mark-compact.h

Index: src/mark-compact.h
diff --git a/src/mark-compact.h b/src/mark-compact.h
index 0773d0266683eb712f101a8f1bb026f3ca8d838a..f0d4aca30c038cec73034721c98f1c40f3c38806 100644
--- a/src/mark-compact.h
+++ b/src/mark-compact.h
@@ -940,6 +940,12 @@ class MarkCompactCollector {
 
   void SweepSpace(PagedSpace* space, SweeperType sweeper);
 
+  // Finalizes the parallel sweeping phase. Marks all the pages that were
+  // swept in parallel.
+  void ParallelSweepSpacesComplete();
+
+  void ParallelSweepSpaceComplete(PagedSpace* space);
+
 #ifdef DEBUG
   friend class MarkObjectVisitor;
   static void VisitObject(HeapObject* obj);