Try blocks (whether catch or finally) will unconditionally create
handler tables and start a new basic block for the exception handler.
This can accidentally resurrect a dead block when the entire try block
is dead (and hence can never enter the exception handler in the first
place).

Add a deadness check to BuildTryCatch/Finally to fix this.

Bug: chromium:1273677
Change-Id: Icda9deb1459e47de5cb83e7b636299e24c3ebe77
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3306555
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Reviewed-by: Marja Hölttä <marja@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78179}