newsupernova/app/code/Smartwave/Porto/Block/Form/Login.php

<?php
namespace Smartwave\Porto\Block\Form; 

use Magento\Customer\Block\Form\Login as BaseLogin;

class Login extends BaseLogin
{
    /**
     * @return $this
     */
    protected function _prepareLayout()
    {
        return $this;
    }
}