[heap] VerifyPointersVisitor should check that non-HeapObjects are Smis

src/heap/heap-inl.h

Index: src/heap/heap-inl.h
diff --git a/src/heap/heap-inl.h b/src/heap/heap-inl.h
index 4d060f8e431a7ec8164645f0a6cfd47a2fe56f25..11b587886e013f331d354254e484fdca2d28895a 100644
--- a/src/heap/heap-inl.h
+++ b/src/heap/heap-inl.h
@@ -850,6 +850,8 @@ void VerifyPointersVisitor::VisitPointers(Object** start, Object** end) {
       HeapObject* object = HeapObject::cast(*current);
       CHECK(object->GetIsolate()->heap()->Contains(object));
       CHECK(object->map()->IsMap());
+    } else {
+      CHECK((*current)->IsSmi());
     }
   }
 }