Inconsistent empty splat assignment

``` livescript
[..., a, b] = [1]
[...x, y, z] = [1]
a is void and b is 1 and
x.length is 0 and y is 1 and z is void
```

Since line 2 is widely accepted as the correct behavior (i.e. splat cannot "unconsume") I don't see why line 1 shouldn't.
