class Foo {
-   [Deno.customInspect]() {
+   denoCustomInspect() {
      return "foo";
    }
  }

This should be a progressively enhanced thing like WorkerOptions::deno. It should no-op in browsers, not require verbose feature detection to be compatible.

I think the alias should be made and Deno.customInspect should be deprecated for 1.8.0, and the latter should be removed for 2.0.