Not-yet-visited keys deleted on a [[Get]] must not show up in the output

[ljharb]

Per https://bugzilla.mozilla.org/show_bug.cgi?id=1208464#c8:

a getter for one property can delete another property:

var o = {get a() {delete this.b; return 1}, b: 2, c: 3};
var keys = Object.keys(o);
var values = keys.map(key => o[key]);

This results in [1, undefined, 3], but should result in [1, 3].

This needs to be fixed in all three polyfills.

[ljharb]

Fixed in all three polyfills, and the two published ones have been bumped.