More decaff for issue 678

[sainthkh]

• More preparation for #678

NEVER SQUASH THIS PR.

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[jennifer-shehane]

Some minor things to look at. Should be good to merge after that.

[sainthkh]

I was again careless about the translated code quality. Thank you for thorough review.

1. The two arrow functions are originally arrow functions in CoffeeScript code.
2. I decided to return cmds and setSubjectAndSkip function. In original CoffeeScript code, it was a copy of that array. It doesn't matter because setSubjectAndSkip is only used in then() function without using its return value.

[jennifer-shehane]

I did not squash this commit!