If we already know it has CompressedPointer representation, let's use
that information to decompress more efficiently.

Cq-Include-Trybots: luci.v8.try:v8_linux64_pointer_compression_rel_ng
Cq-Include-Trybots: luci.v8.try:v8_linux64_arm64_pointer_compression_rel_ng
Bug: v8:7703
Change-Id: I3591bf67a7c0369c40ca6e7af16183530f8cd269
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1709049Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62887}