Any warnings driven off of `warnAboutDeprecatedLifecycles` should use `shared/lowPriorityWarning` rather than `fbjs/lib/warning` to avoid thrashing automated tests.
if (this._instance) {
      if (typeof this._instance.componentWillUnmount === 'function') {
        this._instance.componentWillUnmount();
      }
    }
    this._context = null;
    this._element = null;
    this._newState = null;
    this._rendered = null;
    this._instance = null;
  }
  _mountClassComponent(element, context) {