[heap] No more old-to-new slot deletion during GC pause

Right trimming of arrays was deleting old-to-new slots during a GC pause.
Disable slots removal for right trimming of arrays and ensure no more slots
are deleted during a GC pause.

Bug: v8:9454
Change-Id: I6268d63b82713d765247dca4aaadadfe275b7dcd
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1691915Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62604}

src/heap/heap.cc

@@ -3120,7 +3120,7 @@ void Heap::CreateFillerForArray(T object, int elements_to_trim,
   // We do not create a filler for objects in a large object space.
   if (!IsLargeObject(object)) {
     HeapObject filler =
-        CreateFillerObjectAt(new_end, bytes_to_trim, ClearRecordedSlots::kYes);
+        CreateFillerObjectAt(new_end, bytes_to_trim, ClearRecordedSlots::kNo);
     DCHECK(!filler.is_null());
     // Clear the mark bits of the black area that belongs now to the filler.
     // This is an optimization. The sweeper will release black fillers anyway.

src/heap/store-buffer.cc

@@ -104,16 +104,7 @@ void StoreBuffer::InsertDuringRuntime(StoreBuffer* store_buffer, Address slot) {
 
 void StoreBuffer::DeleteDuringGarbageCollection(StoreBuffer* store_buffer,
                                                 Address start, Address end) {
-  // In GC the store buffer has to be empty at any time.
-  DCHECK(store_buffer->Empty());
-  DCHECK(store_buffer->mode() != StoreBuffer::NOT_IN_GC);
-  Page* page = Page::FromAddress(start);
-  if (end) {
-    RememberedSet<OLD_TO_NEW>::RemoveRange(page, start, end,
-                                           SlotSet::PREFREE_EMPTY_BUCKETS);
-  } else {
-    RememberedSet<OLD_TO_NEW>::Remove(page, start);
-  }
+  UNREACHABLE();
 }
 
 void StoreBuffer::InsertDuringGarbageCollection(StoreBuffer* store_buffer,