... which was using incorrect cage base value for reading map field.

Drive-by: fix CodeDataContainer verifier - the value returned by
code().InstructionStart() might not always be equal to cached code
entry point value when shared pointer compression cage is enabled.

Bug: v8:11880, chromium:1291299
Change-Id: I1338717095a9a1ad2c056f0af0181eabaef88431
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3420308Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78815}