Recursive type with a legal Zero value fails to compile

Consider the following code:

```fsharp
type Foo<'t when 't : (static member Zero : 't)> =
| MkFoo of 't

type Bar =
| Nil
| MkBar of Foo // Error: The type 'Bar' does not support the operator 'get_Zero'

static member Zero
with get () = Nil

let zeroBar = LanguagePrimitives.GenericZero // this compiles fine, so Bar definitely has a legal Zero value
```

**Expected behavior**

Should compile with no problems.

**Actual behavior**

Compiler error: `The type 'Bar' does not support the operator 'get_Zero'`

**Known workarounds**

None