Due to the limits of ia32's calling convention, being able to
avoid construction of "Digits" objects (thanks to inlining)
helps a lot for microbenchmarks.

Fixed: chromium:1192133
Change-Id: I5676640d96a99dc6422f3946c608bcc93ef222ba
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2947410
Commit-Queue: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Auto-Submit: Jakob Kummerow <jkummerow@chromium.org>
Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#75028}