code: public BaseFunction getBuiltinCtor(Builtins type) {
          return ctors != null ? ctors.get(type) : null;
      }
docs: Get the cached built-in object constructor from this scope with the
  given <code>type</code>. Returns null if {@link #cacheBuiltins()} has not
  been called on this object.
  @param type the built-in type
  @return the built-in constructor