Before this change, the tagged pointer that was loaded was not decompressed.
This makes LoadTaggedPointerFromInstance match the x64 implementation.

Bug: v8:9568
Change-Id: I8fd6d3e8dd13514ae3ef423d1c417f72e1396e4a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1730993
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63038}