Same as https://github.com/facebook/react/issues/10103, but for the server renderer. You can look at implementation in https://github.com/facebook/react/pull/11168 and do something very similar in `ReactPartialRenderer.js`.
static childContextTypes = {
        flag: PropTypes.bool,
      };
      state = {
        flag: true,
      };
      getChildContext() {
        return {
          flag: this.state.flag,
        };
      }
      render() {
        return <div>{this.props.children}</div>;
      }
    }
    class Child extends React.Component {