The Tor Browser / file revision

 // reentering the debugger several times via onDebuggerStatement and apply/call on a single stack

 var g = newGlobal();

 var dbg = Debugger(g);

 function test(usingApply) {

     dbg.onDebuggerStatement = function (frame) {

         var n = frame.arguments[0];

         if (n > 1) {

             var result = usingApply ? frame.callee.apply(null, [n - 1])

                 : frame.callee.call(null, n - 1);

             result.return *= n;

             return result;

         }

     };

     g.eval("function fac(n) { debugger; return 1; }");

     assertEq(g.fac(5), 5 * 4 * 3 * 2 * 1);

 }

 test(true);

 test(false);