Split GlobalObject tagging into collecting pairs of tags, followed by
writing those tags into an unordered_map after entering a safepoint
scope. This ensures that we follow moved global objects if they move
in the GCs between the tagging and the safepoint.

Bug: v8:11050
Change-Id: I333d50d000ec49e6c4218e71f0cc84a49b460ecf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2494932
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70749}