[heap] Assert that there's no recodred slot corresponding to unboxed double field.

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index b42720f178b797279c77615fdac02523aa9453eb..ba94930faae6820e4e3431b3ed7e8468b68491b8 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -5891,6 +5891,18 @@ void Heap::ClearRecordedSlot(HeapObject* object, Object** slot) {
   }
 }
 
+bool Heap::HasRecordedSlot(HeapObject* object, Object** slot) {
+  if (InNewSpace(object)) {
+    return false;
+  }
+  Address slot_addr = reinterpret_cast<Address>(slot);
+  Page* page = Page::FromAddress(slot_addr);
+  DCHECK_EQ(page->owner()->identity(), OLD_SPACE);
+  store_buffer()->MoveAllEntriesToRememberedSet();
+  return RememberedSet<OLD_TO_NEW>::Contains(page, slot_addr) ||
+         RememberedSet<OLD_TO_OLD>::Contains(page, slot_addr);
+}
+
 void Heap::ClearRecordedSlotRange(Address start, Address end) {
   Page* page = Page::FromAddress(start);
   if (!page->InNewSpace()) {