The 'core-features-and-limits' feature signifies a WebGPU adapter and device support the core features and limits of the spec. Explainer: https://gist.github.com/greggman/0dea9995e33393c546a4c2bd2a12e50e
At this stage the spec requires that all WebGPU implementations report this feature. In the future, if a developer requests WebGPU compatibility mode (not yet shipping), this feature lets a developer distinguish between an adapter/device that only supports compatibility mode and one that supports core WebGPU.