Fix return types for filter funcs without callback (#42185)
Fix return types for filter funcs without callback (#42185)

* Fix return types for filter funcs without callback

according to the docs, you can omit the callback. In this case the function will return a promise containing the filtered array.

http://caolan.github.io/async/v3/docs.html#filter

* [async] callback is obligated when no promise is returned

dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,dsebastien/DefinitelyTyped,georgemarshall/DefinitelyTyped,mcliment/DefinitelyTyped,markogresak/DefinitelyTyped,georgemarshall/DefinitelyTyped,georgemarshall/DefinitelyTyped