Behind a new --experimental-wasm-nn-locals flag.
The checking policy implemented here is that locals count as
initialized until the end of the current control structure,
as described here:
https://github.com/WebAssembly/function-references/issues/44#issuecomment-801977331

Bug: v8:7748
Change-Id: I954fdf1b4e02ed4b45ef61b8379b7c0bbe802400
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3010283Reviewed-by: Manos Koukoutos <manoskouk@chromium.org>
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75613}