The Tor Browser / file revision

 // Debugger.Object.prototype.displayName

 var g = newGlobal();

 var dbg = Debugger(g);

 var name;

 dbg.onDebuggerStatement = function (frame) { name = frame.callee.displayName; };

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

 assertEq(name, "f");

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

 assertEq(name, undefined);

 g.eval("Function('debugger;')();");

 assertEq(name, "anonymous");

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

 assertEq(name, "f");

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

 assertEq(name, "a.f");