Speed up clearing of old to new slots in dead objects.

src/heap/remembered-set.cc

Index: src/heap/remembered-set.cc
diff --git a/src/heap/remembered-set.cc b/src/heap/remembered-set.cc
index 3ceca5551d7eb883d273f65457861e618727891c..403c99b05712ec53d2920b40e5ee6ff9e3a2f84c 100644
--- a/src/heap/remembered-set.cc
+++ b/src/heap/remembered-set.cc
@@ -22,9 +22,9 @@ void RememberedSet<direction>::ClearInvalidSlots(Heap* heap) {
     chunk = it.next();
     SlotSet* slots = GetSlotSet(chunk);
     if (slots != nullptr) {
-      slots->Iterate([heap](Address addr) {
+      slots->Iterate([heap, chunk](Address addr) {
         Object** slot = reinterpret_cast<Object**>(addr);
-        return IsValidSlot(heap, slot) ? KEEP_SLOT : REMOVE_SLOT;
+        return IsValidSlot(heap, chunk, slot) ? KEEP_SLOT : REMOVE_SLOT;
       });
     }
   }
@@ -54,7 +54,8 @@ void RememberedSet<direction>::VerifyValidSlots(Heap* heap) {
 }
 
 template <PointerDirection direction>
-bool RememberedSet<direction>::IsValidSlot(Heap* heap, Object** slot) {
+bool RememberedSet<direction>::IsValidSlot(Heap* heap, MemoryChunk* chunk,
+                                           Object** slot) {
   STATIC_ASSERT(direction == OLD_TO_NEW);
   Object* object = *slot;
   if (!heap->InNewSpace(object)) {
@@ -64,8 +65,8 @@ bool RememberedSet<direction>::IsValidSlot(Heap* heap, Object** slot) {
   // If the target object is not black, the source slot must be part
   // of a non-black (dead) object.
   return Marking::IsBlack(Marking::MarkBitFrom(heap_object)) &&
-         heap->mark_compact_collector()->IsSlotInLiveObject(
-             reinterpret_cast<Address>(slot));
+         heap->mark_compact_collector()->IsSlotInBlackObject(
+             chunk, reinterpret_cast<Address>(slot));
 }
 
 template void RememberedSet<OLD_TO_NEW>::ClearInvalidSlots(Heap* heap);