The Tor Browser / file revision

 // Test setting return value;

 function bail() { bailout(); }

 function bail2() { bailout(); return 2; }

 // Test 1: Test setting/getting return value in ionmonkey

 function test() {

     return evalcx("1;");

 }

 assertEq(test(), 1)

 // Test 3: Test ion -> baseline

 function test2() {

     return evaluate("1; bail2();");

 }

 assertEq(test2(), 2)

 // Test 3: Test ion -> baseline

 function test3() {

     return evaluate("1; bail2(); 3");

 }

 assertEq(test3(), 3)

 // Test4: Test baseline -> ion entering (very fragile, since iterations need to be precise, before it gets tested)

 function test4() {

     return evaluate("1; for(var i=0; i<1097; i++) { 3; };");

 }

 assertEq(test4(), 3)