[Heap] Remove concept of MarkingParity.

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 5b7217ed74d2ef9439379db2b2278a5349536f84..b91ebe7e6475a06806fc31fa02c2149e0643a20c 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -484,8 +484,6 @@ class MarkCompactCollector {
 
   bool is_compacting() const { return compacting_; }
 
-  MarkingParity marking_parity() { return marking_parity_; }
-
   // Ensures that sweeping is finished.
   //
   // Note: Can only be called safely from main thread.
@@ -746,8 +744,6 @@ class MarkCompactCollector {
   CollectorState state_;
 #endif
 
-  MarkingParity marking_parity_;
-
   bool was_marked_incrementally_;
 
   bool evacuation_;