Based on https://github.com/prettier/prettier/pull/2676
* Thread `path` and `options` through helpers so we don't need to add `needsParens` onto the AST node anymore (mutation)
* Pull test call detection logic out into helper method so it can be re-used for arrow function parens
* Add arrow function parens option implementation (avoid/always)
* Don't break arrow function parens around (done) in test call
This commit updates `npm run format:all` to not only format .js files in
src/ and bin/, but also tests_config/ and scripts/, as well as all
jsfmt.spec.js files.
It also includes the result of running `npm run format:all`, except
changes to src/ and bin/.
I've tried a lot of places where to fix this and this is the only one that gives correct results. This is likely not exhaustive but works for that use case. It's been reported twice in issues and I've seen it happen a few other times so we probably want to get it fixed.
Fixes#922Fixes#797