The Tor Browser / file revision

 // evalWithBindings to call a method of a debuggee object

 var g = newGlobal();

 var dbg = new Debugger;

 var global = dbg.addDebuggee(g);

 var hits = 0;

 dbg.onDebuggerStatement = function (frame) {

     var obj = frame.arguments[0];

     var expected = frame.arguments[1];

     assertEq(frame.evalWithBindings("obj.toString()", {obj: obj}).return, expected);

     hits++;

 };

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

 g.eval("f(new Number(-0), '0');");

 g.eval("f(new String('ok'), 'ok');");

 g.eval("f({toString: function () { return f; }}, f);");

 assertEq(hits, 3);