The Tor Browser / file revision

 // Basic getOffsetLine test, using Error.lineNumber as the gold standard.

 var g = newGlobal();

 var dbg = Debugger(g);

 var hits;

 dbg.onDebuggerStatement = function (frame) {

     var knownLine = frame.eval("line").return;

     assertEq(frame.script.getOffsetLine(frame.offset), knownLine);

     hits++;

 };

 hits = 0;

 g.eval("var line = new Error().lineNumber; debugger;");

 assertEq(hits, 1);

 hits = 0;

 g.eval("var s = 2 + 2;\n" +

        "s += 2;\n" +

        "line = new Error().lineNumber; debugger;\n" +

        "s += 2;\n" +

        "s += 2;\n" +

        "line = new Error().lineNumber; debugger;\n" +

        "s += 2;\n" +

        "assertEq(s, 12);\n");

 assertEq(hits, 2);