Use the base::bits::SignedAddOverflow32() function instead, which
performs an addition and checks for overflow.

Bug: v8:5267, v8:7109
Change-Id: I20a5316957a3f72131d318282e8b8e8bb500b4a7
Reviewed-on: https://chromium-review.googlesource.com/797451Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51028}