The Tor Browser / file revision

 // Frame.script/offset and Script.getOffsetLine work in non-top frames.

 var g = newGlobal();

 var dbg = Debugger(g);

 var hits = 0;

 dbg.onDebuggerStatement = function (frame) {

     var a = [];

     for (; frame.type == "call"; frame = frame.older)

         a.push(frame.script.getOffsetLine(frame.offset) - g.line0);

     assertEq(a.join(","), "1,2,3,4");

     hits++;

 };

 g.eval("var line0 = Error().lineNumber;\n" +

        "function f0() { debugger; }\n" +

        "function f1() { f0(); }\n" +

        "function f2() { f1(); }\n" +

        "function f3() { f2(); }\n" +

        "f3();\n");

 assertEq(hits, 1);