Unexpected stack overflow with mutually recursive local definitions in object

As Effekt being a language with tail calls, I would expect the following to reduce infinitely in JS instead of having its stack overflow.

Found while working on #801, probably related.

``` scala
interface Foo {
def a(): Int
def b(): Int
}

def main() = {
def o = new Foo {
def a() = o.b()
def b() = o.a()
}
println(o.a())
}
```