fix dash array retina scaling when numbers are same value

When the values of a `numbers` object were different, scaling worked fine.  However when the values were the same, the declaration was getting dropped during compilation when scaled for retina (--2x)

ex.
```
dasharray: 2, 5;  <- worked
dasharray: 2, 2;  <- dropped
```

I'm not really clear why it was behaving this way, but the fix is to convert the `values` property of a `numbers` object back to a tuple after scaling, where previously it was a list after scaling.