[heap] Cleanup: Remove WAS_SWEPT flag.

src/heap/mark-compact.h

Index: src/heap/mark-compact.h
diff --git a/src/heap/mark-compact.h b/src/heap/mark-compact.h
index 304bd1e4c4cea80747d1da7c76a49ea6efbbb1f6..e8407dfd0eb58b3ae68619c45b49c3985a409378 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -749,8 +749,6 @@ class MarkCompactCollector {
   // swept in parallel.
   void ParallelSweepSpacesComplete();
 
-  void ParallelSweepSpaceComplete(PagedSpace* space);
-
   // Updates store buffer and slot buffer for a pointer in a migrating object.
   void RecordMigratedSlot(Object* value, Address slot,
                           SlotsBuffer** evacuation_slots_buffer);