Drive-by-fix: Remove command line API fn.toString() override, which was
still in place from the early days when much of the inspector was
implemented in JavaScript.

Fixed: chromium:1207867
Bug: chromium:1206620
Change-Id: I8429f109da5f021f729f184fd824160a24e60897
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2887508
Auto-Submit: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74516}