Making them private was a way to hide the functions, 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: I3d3227c3a87ee4de983b0d4a52f46203729b99f2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2233983Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68308}