This makes the API more consistent and reduces the cognitive load of
switching between 'next' and 'Next'.

Bug: v8:9183
Change-Id: Ia81b874374626887d6af8c90f8ac185812f0573f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1635689Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Cr-Commit-Position: refs/heads/master@{#61946}