Making them private was a way to hide the constructor, we can
explicitly delete them, which give a better compilation error message as
well.

Also see: https://stackoverflow.com/q/55205874

Bug: v8:10488
Change-Id: I624efdb03edb4d1d07f95e756f2c87baba4b3ffe
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2223236Reviewed-by: Clemens Backes <clemensb@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68121}