Wrong type captured in 0.6

I think I found another minor type bug. Running on e3e912a, the `F2` type below is captured as a `SimpleVector` which is incorrect,

```julia
struct Foo{A,B} end
bar(::F1,::F2) where {B1,B2,F1<:Foo{B1,<:Any},F2<:Foo{B2}} = F1,F2,B1,B2
bar(Foo{1,2}(),Foo{1,2}())
> (Foo{1,2}, SimpleVector, 1, 1)
```

Getting rid of the `<:Any`, or capturing that parameter explicitly, seems to fix it.  