removed unneeded "else" statements

[yaroslavya]

As mode function ( https://github.com/stacktracejs/stacktrace.js/blob/master/stacktrace.js#L68 ) return right away, else keywords are not needed.

[victor-homyakov]

That's the matter of taste. mode had this else if style for years (almost from the initial commit), and it was well understandable and easily changeable. @eriwen what do you think?

[eriwen]

I would agree with @yaroslavya if JS were a language that supported postfix conditions like CoffeeScript (e.g. return "foo" if bar but in this case I want it be clear to the reader that each option is mutually exclusive from one another.

If either of you feel strongly that this style is more correct, we can merge it but I don't see any advantage to doing so.

[victor-homyakov]

If this change makes code more readable at least for two people, then I'm OK. Just one note. @yaroslavya please remove trailing space from empty lines before merge.

[yaroslavya]

@victor-homyakov ok, seems no more trailing spaces.