There are cases where using VariableList is the way to go, e.g BuildFastLoop.

Change-Id: I0dad242b69145b94725ce206938455127aabeb29
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1806684Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63885}