=== tests/cases/compiler/contextualTyping22.ts ===
var foo:(a:number)=>number = function(a){return a}; foo = function(b){return b};
>foo : (a: number) => number
>a : number
>function(a){return a} : (a: number) => number
>a : number
>a : number
>foo = function(b){return b} : (b: number) => number
>foo : (a: number) => number
>function(b){return b} : (b: number) => number
>b : number
>b : number