Improve typing of predicate param to function WrapperArray<>.filter(predicate)

[ascott18]

What problem does this feature solve?

WrapperArray.filter is currently typed as filter (predicate: Function): WrapperArray<Vue>. The type of predicate should be more specific.

What does the proposed API look like?

filter (predicate: (value: Wrapper<V>, index: number, array: Wrapper<V>[]) => value is Wrapper<V>): WrapperArray<Vue>

This is the same signature as Array.filter since WrapperArray.filter passes the predicate down to Array.filter.