code: static ObjectType getInstanceOfCtor(@Nullable JSType t) {
      if (t == null) {
        return null;
      }
      FunctionType ctor = JSType.toMaybeFunctionType(t.dereference());
      if (ctor != null && ctor.isConstructor()) {
        return ctor.getInstanceType();
      }
      return null;
    }
docs: Utility function that attempts to get an instance type from a potential constructor type