[heap] Remove ObjectMarking::ClearMarkBit.

src/heap/mark-compact.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_HEAP_MARK_COMPACT_H_
 #define V8_HEAP_MARK_COMPACT_H_
 
 #include <deque>
 
 #include "src/base/bits.h"
@@ skipping 55 matching lines @@
   V8_INLINE static bool IsGrey(HeapObject* obj) {
     return Marking::IsGrey(MarkBitFrom<mode>(obj));
   }
 
   template <MarkingMode mode = MarkingMode::FULL>
   V8_INLINE static bool IsBlackOrGrey(HeapObject* obj) {
     return Marking::IsBlackOrGrey(MarkBitFrom<mode>(obj));
   }
 
   template <MarkingMode mode = MarkingMode::FULL>
-  V8_INLINE static void ClearMarkBit(HeapObject* obj) {
-    Marking::MarkWhite(MarkBitFrom<mode>(obj));
-  }
-
-  template <MarkingMode mode = MarkingMode::FULL>
   V8_INLINE static void BlackToGrey(HeapObject* obj) {
     DCHECK(IsBlack<mode>(obj));
     MarkBit markbit = MarkBitFrom<mode>(obj);
     Marking::BlackToGrey(markbit);
     MemoryChunk::IncrementLiveBytes<mode>(obj, -obj->Size());
   }
 
   template <MarkingMode mode = MarkingMode::FULL>
   V8_INLINE static void WhiteToGrey(HeapObject* obj) {
     DCHECK(IsWhite<mode>(obj));
@@ skipping 744 matching lines @@
 
  private:
   MarkCompactCollector* collector_;
 };
 
 V8_EXPORT_PRIVATE const char* AllocationSpaceName(AllocationSpace space);
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_MARK_COMPACT_H_