This affects VisitChangeUint32ToUint64 and VisitTruncateInt64ToInt32.

The geometric mean of changes across octane, ares6-1.0.1, jetstream2,
and web-tooling-0.5.3, was an improvement of 1.2% when running on a
Cortex-A53.

Change-Id: Ib551641fb78ce4060100129e12f23cd02b0b3b27
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1669690Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Sigurd Schneider <sigurds@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62327}