Replace all uses by the existing RoundUp function.

R=ulan@chromium.org

Bug: v8:7570
Change-Id: I7ff5e76ebea7b429ff4e4f3a8157ee831e7891ae
Reviewed-on: https://chromium-review.googlesource.com/1004898Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52525}