- Provide GetRealStackAddressForSlot that deals with ASAN fake stacks
  properly, also accounting for the fact that ASAN gets its real stack
  address in a nested call.
- Fix cppgc on-stack getter.
- Reuse platform routines in global handles.

Bug: chromium:1139914, chromium:1056170
Change-Id: If11a40d543b33edcea220bb70f170ac018e15053
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2509594
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70899}