[JS] casting a .NET Dictionary to ICollection JS should not use .push

[goswinr]

Casting a .NET Dictionary to an ICollection emits .push for .Add, but a JS Map has no .push member.

open System.Collections.Generic

let dic = Dictionary<int,string>()  

let coll = dic :> ICollection<KeyValuePair<_,_>>    

let kv = KeyValuePair(1,"a")

coll.Add(kv) // emits .push on a JS Map, but Map has no .push member

REPL

fable 4.21