WPT details: WebGPU/WGSL have a conformance test suite (https://github.com/gpuweb/cts) that is regularly pulled into Chromium and part of the testing of Dawn/Tint in Chromium. While the CTS can be embedded in WPT, the WebGPU team opted to keep it separate in Chromium testing to use a customized harness for robustness and performance. All the tests about this feature in WebGPU CTS can be found through the below link: https://github.com/gpuweb/cts/pull/4228
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.