A fancy new stdlib addition for creating JSObjects from a collection of
key/value pairs, coming soon to a javascript runtime near you.

BUG=v8:8021
R=gsathya@chromium.org, adamk@chromium.org

Change-Id: I5eb1dea75bfef009281eef9864c8c0226af4f1fc
Reviewed-on: https://chromium-review.googlesource.com/c/1363293Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#58051}