Missing IDictionary.key and IDictionary.values

[shtse8]

IDictionary saves my life while js object doesn't support non-string key.
it works well but it seems missing IDictionary.key and IDictionary.values.
I only can get the keys or values from enumerable.

dictionary.toEnumerable().select(x => x.key).toArray() // dictionary.keys
dictionary.toEnumerable().select(x => x.value).toArray() // dictionary.values

the drawback is I can't get the underlining array object and need to do O(n) on each get.

I hope it can add support of getting keys and values like C#.
https://docs.microsoft.com/en-us/dotnet/api/system.collections.idictionary.keys
https://docs.microsoft.com/en-us/dotnet/api/system.collections.idictionary.values