title: Ant design react TypeScript added from input required doesn't work
body: <p>I tried to add  <code>react Typescript</code> project to <a href="https://stackblitz.com/edit/react-hkzvcx" rel="nofollow noreferrer">Antdeisgn forms</a> input required it doesn't work.</p>
  
  <p><strong>error here</strong> 
  when i added this      <code>const { getFieldDecorator } = this.props.form;</code></p>
  
  <p>i faced following error</p>
  
  <blockquote>
  <pre><code>  TS2339: Property 'form' does not exist on type 'Readonly&lt;Props&gt; &amp; Readonly&lt;{ children?: ReactNode; }&gt;'.
  </code></pre>
  </blockquote>
  
  <p>anyone know how to fix that correctly
  <strong><a href="https://stackblitz.com/edit/react-ts-qmqrky" rel="nofollow noreferrer">stack blitz here</a></strong></p>
  
  <p><strong>My code here</strong></p>
  
  <pre><code>    import React from 'react';
      import ReactDOM from 'react-dom';
      import 'antd/dist/antd.css';
      import { Form, Input, Button, Checkbox } from 'antd';
  
      const formItemLayout = {
        labelCol: { span: 4 },
        wrapperCol: { span: 8 },
      };
      const formTailLayout = {
        labelCol: { span: 4 },
        wrapperCol: { span: 8, offset: 4 },
      };
    export  class DynamicRule extends React.Component&lt;any&gt; {
  
  
        check = () =&gt; {
          this.props.form.validateFields(err =&gt; {
            if (!err) {
              console.info('success');
            }
          });
        };
  
  
  
        render() {
          const { getFieldDecorator } = this.props.form;
          return (
            &lt;div&gt;
              &lt;Form.Item  label="Name"&gt;
                {getFieldDecorator('username', {
                  rules: [
                    {
                      required: true,
                      message: 'Please input your name',
                    },
                  ],
                })(&lt;Input placeholder="Please input your name" /&gt;)}
              &lt;/Form.Item&gt;
  
  
              &lt;Form.Item &gt;
                &lt;Button type="primary" onClick={this.check}&gt;
                  Check
                &lt;/Button&gt;
              &lt;/Form.Item&gt;
            &lt;/div&gt;
          );
        }
      }
  </code></pre>