This handles arithmetic addition operations during the early type-hint
lowering (i.e. during graph construction). The string addition case is
still handled by {JSTypedLowering} as it needs static type information.

R=bmeurer@chromium.org

Change-Id: I9df47dfc5bf7613c51f6d803ab43d5d3f6c21be8
Reviewed-on: https://chromium-review.googlesource.com/443185Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#43235}