This removes the heap sandbox's dependency on being able to reconstruct
an Isolate from the pointer cage base address.

Bug: v8:11460
Change-Id: I501ace5b83a2cefdf717de0d7387fd816edfb3f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2783673
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73887}