> Is execArgv.some guaranteed to be defined?

IDK if the compiler is supposed to run on old IE (if it is: does someone test that?), but, in case it is, there seems to be [a helper for that](https://github.com/jashkenas/coffee-script/blob/26200f46406f524309baaeef37aba310f6b03f5b/src/helpers.coffee#L69) available.