[Intl] Merge constructors by template

Bug: v8:5751
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: Ibceb4412713c0bec82b234e2eea6c86aa0d275f7
Reviewed-on: https://chromium-review.googlesource.com/c/1295932
Commit-Queue: Frank Tang <ftang@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57047}