I initially left them out because I thought they are harder to
implement than the other float binops, but it turns out it is actually
just the same.

R=ahaas@chromium.org

Bug: v8:6600
Change-Id: I68b98daf4dfaf4e00d57fc68257fe43977c4ae6a
Reviewed-on: https://chromium-review.googlesource.com/948543Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51745}