Packages with errors may still contain files that can be formatted.
Try to format the source of the files in packages that have errors.
This change will still not format files with parse errors.
Updates golang/go#31291
Change-Id: Ia5168d7908948d201eac7f2ee28534022a2d4eb0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/187757
Run-TryBot: Suzy Mueller <suzmue@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
