[Fx22+] Implicit use of window methods throws "Illegal operation on WrappedNative prototype object"

[ghost]

window.getComputedStyle(document.body); // works
getComputedStyle(document.body); // throws exception

window.btoa("Test"); // works
btoa("Test"); // throws exception

Strangely enough, window.alert("Test") and alert("Test") both work.

Tested with:
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:22.0) Gecko/20130402 Firefox/22.0
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:23.0) Gecko/20130402 Firefox/23.0
Scriptish 0.1.8

Greasemonkey 1.8 is not affected.

[ghost]

Looks like sandbox.__proto__ = safeWin; doesn't do anything anymore. Uncommenting the following line seems to fix it but I don't know enough about XPCOM or the inner workings of Scriptish to judge what the implications might be.

https://github.com/scriptish/scriptish/blob/master/extension/modules/utils/Scriptish_injectScripts.js#L53

[ghost]

@erikvold @supahgreg @nmaier
Anyone?