Similar to https://chromium-review.googlesource.com/c/v8/v8/+/1697246 but
for the Pointer case.

The three CLs combined bring good improvements to the code generation,
both in code size and then in runtime.

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: I0903df55f3e19d3ee4dddb3c069ddc27b3265cd3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1698395Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62678}