The Tor Browser / file revision

 // When multiple frames have onPop handlers, they are called in the correct order.

 var g = newGlobal();

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

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

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

 g.eval("function i() { h(); }");

 var dbg = new Debugger(g);

 var log;

 function logger(frame, mark) { 

     return function (completion) {

         assertEq(this, frame);

         assertEq('return' in completion, true);

         log += mark;

     };

 }

 dbg.onEnterFrame = function handleEnter(f) {

     log += "(" + f.callee.name;

     // Note that this establishes a distinct function object as each

     // frame's onPop handler. Thus, a pass proves that each frame is

     // remembering its handler separately.

     f.onPop = logger(f, f.callee.name + ")");  

 };

 dbg.onDebuggerStatement = function handleDebugger(f) {

     log += 'd';

 };

 log = '';

 g.i();

 assertEq(log, "(i(h(g(fdf)g)h)i)");