function run_test() { var sb1 = Cu.Sandbox('http://example.com'); var sb2 = Cu.Sandbox('http://example.org'); var chromeObj = {foo: 2}; var sb1obj = Cu.evalInSandbox('new Object()', sb1); chromeObj.__proto__ = sb1obj; sb2.wrapMe = chromeObj; Assert.ok(true, "Didn't crash"); Assert.equal(sb2.wrapMe.__proto__, sb1obj, 'proto set correctly'); }