=== tests/cases/compiler/contextualSignatureInstatiationContravariance.ts ===
interface Animal { x }
>Animal : Animal
>x : any

interface Giraffe extends Animal { y }
>Giraffe : Giraffe
>Animal : Animal
>y : any

interface Elephant extends Animal { y2 }
>Elephant : Elephant
>Animal : Animal
>y2 : any

var f2: <T extends Animal>(x: T, y: T) => void;
>f2 : <T extends Animal>(x: T, y: T) => void
>T : T
>Animal : Animal
>x : T
>T : T
>y : T
>T : T

var g2: (g: Giraffe, e: Elephant) => void;
>g2 : (g: Giraffe, e: Elephant) => void
>g : Giraffe
>Giraffe : Giraffe
>e : Elephant
>Elephant : Elephant

g2 = f2; // valid because both Giraffe and Elephant satisfy the constraint. T is Animal
>g2 = f2 : <T extends Animal>(x: T, y: T) => void
>g2 : (g: Giraffe, e: Elephant) => void
>f2 : <T extends Animal>(x: T, y: T) => void

var h2: (g1: Giraffe, g2: Giraffe) => void;
>h2 : (g1: Giraffe, g2: Giraffe) => void
>g1 : Giraffe
>Giraffe : Giraffe
>g2 : Giraffe
>Giraffe : Giraffe

h2 = f2; // valid because Giraffe satisfies the constraint. It is safe in the traditional contravariant fashion.
>h2 = f2 : <T extends Animal>(x: T, y: T) => void
>h2 : (g1: Giraffe, g2: Giraffe) => void
>f2 : <T extends Animal>(x: T, y: T) => void