function foo() { (function() { Object.preventExtensions(this); setJitCompilerOption("ion.warmup.trigger", 4); var g = newGlobal({newCompartment: true}); g.debuggeeGlobal = this; g.eval("(" + function () { dbg = new Debugger(debuggeeGlobal); dbg.onExceptionUnwind = function (frame, exc) { var s = '!'; for (var f = frame; f; f = f.older) debuggeeGlobal.log += s; }; } + ")();"); try { j('Number.prototype.toString.call([])'); } catch (exc) {} })(); } foo();