Remove code duplication by having one method for generating the code
for binary operations, templatized by the actual instruction(s) to emit
for the operation.

R=titzer@chromium.org

Bug: v8:6600
Change-Id: I6303475682416727e6a6c9c4ec33ca1cde112092
Reviewed-on: https://chromium-review.googlesource.com/924862Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51385}