[plugin-proposal-optional-chaining] Loose mode produces unoptimized code for class methods

Bug Report

• I would like to work on a fix!

Current Behavior The loose mode of optional-chaining plugin compiles class methods in non-optimized way repeating the call to the method instead of remembering its result.

It does not happen for function call though.

Input Code

• REPL or Repo link if applicable: Runkit.

a.get(b)?.();

compiles to:

a.get(b) == null ? void 0 : a.get(b)();

Expected behavior/code The result of method call should be memoized as it happens in the strict mode.

var a$get;

(a$get = a.get(b)) == null ? void 0 : a$get();

Babel Configuration (babel.config.js, .babelrc, package.json#babel, cli command, .eslintrc)

• Filename: babel.config.js

{
    plugins: [[require('@babel/plugin-proposal-optional-chaining'), {loose: true}]]
}

Environment

• Babel version(s): 7.8.4
• Node/npm version: v13.5.0/6.13.4
• OS: Windows 10
• Monorepo: Lerna
• How you are using Babel: cli/programmatically

[oliverdunk]

I’d love to work on this one 😃

[jridgewell]

All good. Happy to review an unfinished PR, please open one when you can.