Fix destructuring assignment in arrow functions without block

[RubenVerborgh]

Q	A
Fixed Issues?	Fixes #8912
Patch: Bug Fix?	👍
Major: Breaking Change?	👎
Minor: New Feature?	👎
Tests Added + Pass?	👍
Documentation PR Link	n/a
Any Dependency Changes?	👎
License	MIT

• In Destructuring array assignment fails in arrow functions without block #8912, I reported that destructuring array assignment fails in arrow functions without a block.
• This pull requests adds fixtures for that case, as well as the neighboring case of arrow functions with block.
• It transforms such blockless functions into functions with a block and a return statement.

[babel-bot]

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/9280/

[RubenVerborgh]

@loganfsmyth Wrapping the body means making the return statement explicit, and detecting this case would be more complex in path.ensureBlock() than it is at the point of generation. I'm therefore proposing a more simple change that fixes the problem directly in the destructuring plugin, where we can easily insert a return statement.

[nicolo-ribaudo]

Thank you!