Reduce ecma_{ref, deref}_object calls while using ecma_builtin_get (#2616)

The following stucture was highly frequented in the code base:

 - Get a builtin object // This operation increases the reference count of the object
 - Use it for create a new object
 - Deref the builtin object

After a builtin has been instantiated there is always at least one reference to "keep it alive",
so increase/decrease the reference count for getting the value only is unnecessary.

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/ecma/operations/ecma-map-object.c

@@ -48,8 +48,6 @@ ecma_op_map_create (const ecma_value_t *arguments_list_p, /**< arguments list */
                                                 sizeof (ecma_map_object_t),
                                                 ECMA_OBJECT_TYPE_CLASS);
 
-  ecma_deref_object (prototype_obj_p);
-
   ecma_map_object_t *map_object_p = (ecma_map_object_t *) object_p;
   map_object_p->header.u.class_prop.class_id = LIT_MAGIC_STRING_MAP_UL;
   map_object_p->header.u.class_prop.extra_info = 0;