The Tor Browser / file revision

 // Trying to set an onPop handler on a dead frame throws an exception.

 var g = newGlobal();

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

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

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

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

 var dbg = new Debugger(g);

 var log;

 var frames = [];

 dbg.onEnterFrame = function handleEnter(f) {

     log += "(";

     assertEq(f.live, true);

     frames.push(f);

 };

 log = '';

 g.i();

 assertEq(log, "((((");

 assertEq(frames.length, 4);

 for (i = 0; i < frames.length; i++) {

     assertEq(frames[i].live, false);

     var set = false;

     try {

         frames[i].onPop = function unappreciated() { };

         set = true; // don't assert in a 'try' block

     } catch (x) {

         assertEq(x instanceof Error, true);

     }

     assertEq(set, false);

 }