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: I9268f42b9367cc1af4d58e71e2033c254ed4cbf7
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2210777Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67988}