As an optimization, I think we can avoid always making another call to `wym.selected()`, right? If we don't hit the case on [line 255](https://github.com/wymeditor/wymeditor/pull/482/files#diff-53df80c1a5e5f0628d3d43bd255d1348R255), then we can just pass `container`. If we do hit that case, then we should do a `container = wym.selected()` right after the `wym.switchTo` call, which allows us to always use `container` as the argument to `correctInvalidListNesting`.