Instead of instantiating each function multiple times, just call out to
a common function, passing the variadic number of arguments in an
initializer list.

R=tebbi@chromium.org

Bug: v8:7754
Change-Id: Idb2d77cef7cf8e590de6aa3cea02c0e0773da45f
Reviewed-on: https://chromium-review.googlesource.com/1101689
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53785}