No layering rules for workbench/contrib?

I stumbled over this https://github.com/microsoft/vscode/commit/d685337db2e58c97c52387f080d698c5fa22753d and wondered how `semver-umd` can be imported without mentioning it `tslint.json` and I believe we actually don't have any layering rules configured for at least `src/vs/workbench/contrib/extensions/browser/extensionsWorkbenchService.ts`