Babel should transform delete obj?.#x.a

[JLHwung]

Bug Report

• I would like to work on a fix!

Current behavior
A clear and concise description of the behavior.

• REPL

Input Code

delete obj?.#x.a

Expected behavior
A clear and concise description of what you expected to happen (or code).
It should be transformed something like

obj == null ? true : (delete _privateGet(obj, Foo, x).a)

Note that true should be returned instead of undefined when obj is nullish.

Environment
REPL

Additional Context
Follow-up to https://github.com/babel/babel/pull/11248/files#r430537770

[babel-bot]

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