IsCompiledScope retains code to protect against code flushing. The
current API is easily misused by forgetting to initialize
IsCompiledScope with a SFI's current state.

Change-Id: Ie8ab60acc4fb85c4b8b76c52040976e2e34f9d5e
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3674117Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80896}