Remove Map/MapWithDefault/Set polyfills after beta.12 is released

[fivetanley]

No description provided.

[igorT]

Ping

[sly7-7]

Seems like there is no more polyfill for map, since the map file is basically empty: https://github.com/emberjs/data/blob/master/packages/ember-data/lib/system/map.js

Also @wecc, you were overriding some behavior for Ember.OrderedSet (not preserving the right order ?)

So I'm a bit confused of what to do exactly for this issue

[sly7-7]

@wecc @fivetanley ping ?

[wecc]

I don't think we can remove our changes in Ember.OrderedSet as they are not upstreamed.

[sly7-7]

Ok, so that means this issue could be closed ?

[wecc]

We might still want to remove the other ones?

[sly7-7]

Ok, so I guess it's basically removing this file and replace its use by import from Ember the Map and MapWithDefault ?