[heap] Remove obsolete was_marked_incrementally field.

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 d78e9bddee44b0f2a1b396e49a4bd90f60bd20d7..ea0d5e66e7bd45acf20c000a2cf8e7c108725d7b 100644
--- a/src/heap/mark-compact.h
+++ b/src/heap/mark-compact.h
@@ -778,11 +778,11 @@ class MarkCompactCollector {
   CollectorState state_;
 #endif
 
-  bool reduce_memory_footprint_;
-
-  bool abort_incremental_marking_;
-
-  bool finalize_incremental_marking_;
+  // The following flags are controlled via {SetFlags} by the caller, it has to
+  // be called before {Prepare} to take effect.
+  bool reduce_memory_footprint_;       // Heap::kReduceMemoryFootprintMask
+  bool abort_incremental_marking_;     // Heap::kAbortIncrementalMarkingMask
+  bool finalize_incremental_marking_;  // Heap::kFinalizeIncrementalMarkingMask
 
   MarkingParity marking_parity_;
 
@@ -790,8 +790,6 @@ class MarkCompactCollector {
   // candidates.
   bool compacting_;
 
-  bool was_marked_incrementally_;
-
   // True if concurrent or parallel sweeping is currently in progress.
   bool sweeping_in_progress_;