Fix superclass method access

[t4ccer]

Description

The following snippet should compile

To Reproduce

class Eq a where
  eq :: a -> a -> Boolean

class Eq a <= Ord a where
  compare :: a -> a -> Int

instance Eq Int where
  eq _ _ = true

instance Ord Int where
  compare _ _ = 42

testEqViaOrd :: forall a. Ord a => a -> a -> Boolean
testEqViaOrd a b = eq a b

Expected behavior

It compiles

Additional context

tests: An internal error occurred during compilation: Error while desugaring record accessor. No type provided for expression: 
$dictOrd6."Eq0"

Purus version

c8fac0a