[heap] Don't clear black areas when deserializing, they will be marked black later anyway.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 8178a1ab4854217aa3986576f3d4b47c4c8eb2bb..05d0910f6b249660686a0fa05765b493fd3304c9 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -1146,7 +1146,7 @@ bool Heap::ReserveSpace(Reservation* reservations, List<Address>* maps) {
             // deserializing.
             Address free_space_address = free_space->address();
             CreateFillerObjectAt(free_space_address, Map::kSize,
-                                 ClearRecordedSlots::kNo);
+                                 ClearRecordedSlots::kNo, ClearBlackArea::kNo);
             maps->Add(free_space_address);
           } else {
             perform_gc = true;
@@ -1176,7 +1176,7 @@ bool Heap::ReserveSpace(Reservation* reservations, List<Address>* maps) {
             // deserializing.
             Address free_space_address = free_space->address();
             CreateFillerObjectAt(free_space_address, size,
-                                 ClearRecordedSlots::kNo);
+                                 ClearRecordedSlots::kNo, ClearBlackArea::kNo);
             DCHECK(space < SerializerDeserializer::kNumberOfPreallocatedSpaces);
             chunk.start = free_space_address;
             chunk.end = free_space_address + size;
@@ -3065,8 +3065,8 @@ AllocationResult Heap::AllocateBytecodeArray(int length,
   return result;
 }
 
-void Heap::CreateFillerObjectAt(Address addr, int size,
-                                ClearRecordedSlots mode) {
+void Heap::CreateFillerObjectAt(Address addr, int size, ClearRecordedSlots mode,
+                                ClearBlackArea black_area_mode) {
   if (size == 0) return;
   HeapObject* filler = HeapObject::FromAddress(addr);
   if (size == kPointerSize) {
@@ -3087,7 +3087,8 @@ void Heap::CreateFillerObjectAt(Address addr, int size,
 
   // If the location where the filler is created is within a black area we have
   // to clear the mark bits of the filler space.
-  if (incremental_marking()->black_allocation() &&
+  if (black_area_mode == ClearBlackArea::kYes &&
+      incremental_marking()->black_allocation() &&
       Marking::IsBlackOrGrey(ObjectMarking::MarkBitFrom(addr))) {
     Page* page = Page::FromAddress(addr);
     page->markbits()->ClearRange(page->AddressToMarkbitIndex(addr),