Use the node aspect mechanism to find and cache tagged equivalents of
non-tagged nodes during merging.

Bug: v8:7700
Change-Id: If1e6210b34e23a3559bf6251dafa985e827f0d08
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3904234
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Jakob Linke <jgruber@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#83325}