The Tor Browser / file revision

 // The same object gets the same Debugger.Object wrapper at different times, if the difference would be observable.

 var N = 12;

 var g = newGlobal();

 var dbg = Debugger(g);

 var wrappers = [];

 dbg.onDebuggerStatement = function (frame) { wrappers.push(frame.arguments[0]); };

 g.eval("var originals = []; function f(x) { originals.push(x); debugger; }");

 for (var i = 0; i < N; i++)

     g.eval("f({});");

 assertEq(wrappers.length, N);

 for (var i = 0; i < N; i++)

     for (var j = i + 1; j < N; j++)

         assertEq(wrappers[i] === wrappers[j], false);

 gc();

 dbg.onDebuggerStatement = function (frame) { assertEq(frame.arguments[0], wrappers.pop()); };

 g.eval("function h(x) { debugger; }");

 for (var i = 0; i < N; i++)

     g.eval("h(originals.pop());");

 assertEq(wrappers.length, 0);