Assigning elements from a stylus hash adds a set of parentheses on each save

[nachocab]

<style lang="stylus" scoped>
$abc = {
  one: 1,
  two: 2
}
$abc[three] = $abc.one + 2 // 👎  becomes: $abc[three] = ($abc.one + 2)
$abc.four = $abc[two] + 2 // 👎 becomes: $abc.four = ($abc[two] + 2)
$abc[five] = 2 + 3 // 👍 nothing gets added
$abc.six = 6 // 👍 nothing gets added 
</style>

Each time you save, a new set of parentheses gets added. Eventually you might end up with something like $abc[three] = ((((((((((((($abc.one + 2)))))))))))))

[nachocab]

Also, the same happens when adding multiple box shadows (separated by commas):

box-shadow: inset 0 -9px 0 ((($color.blue))), inset 0 9px 0 ((($color.blue)))

[HerringtonDarkholme]

cc @ThisIsManta

I cannot reproduce @nachocab 's report, but I do find other glitch.

Before:

After:

[ThisIsManta]

Thanks for letting me know. I'll check this out after my vacation.

[ThisIsManta]

This should be fixed by #659