Fix: missing functor instances for IDictionary and IReadOnlyDictionary

Author: gusty

src/FSharpPlus/Control/Functor.fs

@@ -92,6 +92,8 @@ type Map =
     static member Map ((x: Map<'Key,'T>        , f: 'T->'U), _mthd: Map) = Map.map (const' f) x : Map<'Key,'U>
     static member Map ((x: Dictionary<_,_>     , f: 'T->'U), _mthd: Map) = Dictionary.map f x : Dictionary<'Key,'U>
     #if !FABLE_COMPILER
+    static member Map ((x: IDictionary<_,_>        , f: 'T->'U), _mthd: Map) = Dict.map f x : IDictionary<'Key,'U>
+    static member Map ((x: IReadOnlyDictionary<_,_>, f: 'T->'U), _mthd: Map) = IReadOnlyDictionary.mapValues f x : IReadOnlyDictionary<'Key,'U>
     static member Map ((x: Expr<'T>            , f: 'T->'U), _mthd: Map) = Expr.Cast<'U> (Expr.Application (Expr.Value (f), x))
     #endif
 
@@ -129,7 +131,7 @@ type Map with
     static member        Map ((x: NonEmptySeq<_>          , f: 'T->'U), _mthd: Default2) = NonEmptySeq.map f x      : NonEmptySeq<'U>
     static member        Map ((x: IEnumerator<_>          , f: 'T->'U), _mthd: Default2) = Enumerator.map f x       : IEnumerator<'U>
     static member        Map ((x: IDictionary<_,_>        , f: 'T->'U), _mthd: Default2) = Dict.map f x             : IDictionary<'Key,'U>
-    static member        Map ((x: IReadOnlyDictionary<_,_>, f: 'T->'U), _mthd: Default2) = IReadOnlyDictionary.map f x : IReadOnlyDictionary<'Key,_>
+    static member        Map ((x: IReadOnlyDictionary<_,_>, f: 'T->'U), _mthd: Default2) : IReadOnlyDictionary<'Key,_> = IReadOnlyDictionary.mapValues f x
     static member        Map ((x: IObservable<'T>         , f: 'T->'U), _mthd: Default2) = Observable.map f x       : IObservable<'U>
     #if !FABLE_COMPILER
     static member        Map ((x: Nullable<_>             , f: 'T->'U), _mthd: Default2) = Nullable.map f x         : Nullable<'U>