Speed up the LookupIterator

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 3b5ee6e81b30516d5a29812269f8bb76a4ef3e45..0598afa94c5990d480aa5423101c1629f461293d 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -3574,11 +3574,12 @@ AllocationResult Heap::CopyJSObject(JSObject* source, AllocationSite* site) {
   // Make the clone.
   Map* map = source->map();
 
-  // We can only clone regexps, normal objects or arrays. Copying anything else
-  // will break invariants.
+  // We can only clone regexps, normal objects, api objects or arrays. Copying
+  // anything else will break invariants.
   CHECK(map->instance_type() == JS_REGEXP_TYPE ||
         map->instance_type() == JS_OBJECT_TYPE ||
-        map->instance_type() == JS_ARRAY_TYPE);
+        map->instance_type() == JS_ARRAY_TYPE ||
+        map->instance_type() == JS_SPECIAL_API_OBJECT_TYPE);
 
   int object_size = map->instance_size();
   HeapObject* clone = nullptr;