[cleanup] Delete dead SlotsBuffer functions

Removes dead functions related to long removed SlotsBuffer class.

Bug: v8:10506
Change-Id: I79d6e77d2305e19048b62e2bc584fe986affd111
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2202908
Commit-Queue: Dan Elphick <delphick@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Auto-Submit: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67833}

src/heap/mark-compact.h

@@ -514,9 +514,6 @@ class MarkCompactCollector final : public MarkCompactCollectorBase {
                                    HeapObjectSlot slot, HeapObject target);
   void RecordLiveSlotsOnPage(Page* page);
 
-  void UpdateSlots(SlotsBuffer* buffer);
-  void UpdateSlotsRecordedIn(SlotsBuffer* buffer);
-
   bool is_compacting() const { return compacting_; }
 
   // Ensures that sweeping is finished.
@@ -566,7 +563,6 @@ class MarkCompactCollector final : public MarkCompactCollectorBase {
 
   void VerifyMarking();
 #ifdef VERIFY_HEAP
-  void VerifyValidStoreAndSlotsBufferEntries();
   void VerifyMarkbitsAreClean();
   void VerifyMarkbitsAreDirty(ReadOnlySpace* space);
   void VerifyMarkbitsAreClean(PagedSpace* space);

src/heap/spaces.h

@@ -53,7 +53,6 @@ class LocalArrayBufferTracker;
 class Page;
 class PagedSpace;
 class SemiSpace;
-class SlotsBuffer;
 
 // -----------------------------------------------------------------------------
 // Heap structures: