After after double field unboxing deletion, there was no need for this
method.

Bug: v8:11422
Change-Id: I540ffc80ad21c4cfec62fd8c80a343b8b8eed4bc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2691047
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#72708}