It doesn’t have a `@flow` annotation. We should start Flow-ifying it to avoid bugs like https://github.com/facebook/react/pull/11173.

@iamdustan Wanna take it?
child = null;
      }
    }
    validateRenderResult(child, Component);
    var childContext;
    if (typeof inst.getChildContext === 'function') {
      var childContextTypes = Component.childContextTypes;
      invariant(
        typeof childContextTypes === 'object',
        '%s.getChildContext(): childContextTypes must be defined in order to ' +
          'use getChildContext().',
        getComponentName(Component) || 'Unknown',
      );
      childContext = inst.getChildContext();
      for (let contextKey in childContext) {
        invariant(
          contextKey in childContextTypes,
          '%s.getChildContext(): key "%s" is not defined in childContextTypes.',
          getComponentName(Component) || 'Unknown',
          contextKey,
        );
      }
    }
    if (childContext) {
      context = Object.assign({}, context, childContext);
    }
  }
  return {child, context};
}
class ReactDOMServerRenderer {