Reland "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 ad83dfb8c7e02843df2b4851d5e14e5131e1bd2d..dfd799da36ebc1416ceca04781f4e0ed70734219 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -3575,11 +3575,12 @@ 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;