ObservableSet.size is not observable

[iownbey]

const set = observable(new Set());

reaction(() => set.size, (size) => console.log("size changed"));

set.add(7);

This code isn't triggering a reaction due to a missing wrapper around the native Set.size call

[jereklas]

I assume this also exists on maps, should verify when we make a fix.

Also verify that the following causes a reaction:

const map = observable(new  Map());

reaction(() => map, () => console.log("map changed"));

map.set("a","a")