The Tor Browser / file revision

 // evalWithBindings ignores non-enumerable and non-own properties.

 var g = newGlobal();

 var dbg = new Debugger(g);

 var hits = 0;

 dbg.onDebuggerStatement = function (frame) {

     assertEq(frame.evalWithBindings("toString + constructor + length", []).return, 112233);

     var obj = Object.create({constructor: "FAIL"}, {length: {value: "fail"}});

     assertEq(frame.evalWithBindings("toString + constructor + length", obj).return, 112233);

     hits++;

 };

 g.eval("function f() { var toString = 111111, constructor = 1111, length = 11; debugger; }");

 g.f();

 assertEq(hits, 1);