This aids debugging as it gives the root set a name.

Bug: chromium:1164553, chromium:1186901
Change-Id: I2c2aed369823b059629b35bb170b4966b47156d0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2933661
Auto-Submit: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74960}