[heap] Reland move slot filtering logic into sweeper.

src/heap/remembered-set.h

 // Copyright 2016 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_REMEMBERED_SET_H
 #define V8_REMEMBERED_SET_H
 
 #include "src/assembler.h"
 #include "src/heap/heap.h"
 #include "src/heap/slot-set.h"
@@ skipping 184 matching lines @@
     while ((chunk = it.next()) != nullptr) {
       chunk->ReleaseOldToOldSlots();
       chunk->ReleaseTypedOldToOldSlots();
     }
   }
 
   // Eliminates all stale slots from the remembered set, i.e.
   // slots that are not part of live objects anymore. This method must be
   // called after marking, when the whole transitive closure is known and
   // must be called before sweeping when mark bits are still intact.
-  static void ClearInvalidSlots(Heap* heap);
-
-  static void ClearInvalidSlots(Heap* heap, MemoryChunk* chunk);
   static void ClearInvalidTypedSlots(Heap* heap, MemoryChunk* chunk);
 
-  static void VerifyValidSlots(Heap* heap);
-
  private:
   static SlotSet* GetSlotSet(MemoryChunk* chunk) {
     if (direction == OLD_TO_OLD) {
       return chunk->old_to_old_slots();
     } else {
       return chunk->old_to_new_slots();
     }
   }
 
   static TypedSlotSet* GetTypedSlotSet(MemoryChunk* chunk) {
@@ skipping 160 matching lines @@
     return DEBUG_TARGET_SLOT;
   }
   UNREACHABLE();
   return CLEARED_SLOT;
 }
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_REMEMBERED_SET_H