With our [deprecation of IE11 support](https://github.com/dequelabs/axe-core/releases/tag/v4.5.0) we no longer need to run axe-core through babel. For v5 we should stop babeling axe-core, meaning v5 will no longer run in IE11. This also gains us [some performance improvements](https://github.com/dequelabs/axe-core/issues/4008#issuecomment-2839481477).