michael@0: a = {}
michael@0: a.getOwnPropertyDescriptor = Array;
michael@0: b = Proxy.create(a)
michael@0: for (x in this)
michael@0: try {
michael@0:   (function() {
michael@0:     "use strict";
michael@0:     b[2] = x // don't assert
michael@0:   })()
michael@0: } catch (e) {}