diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Frame-onStep-07.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Frame-onStep-07.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,23 @@
+// The tracejit does not interfere with frame.onStep.
+//
+// The function f() writes 'L' to the log in a loop. If we enable stepping and
+// write an 's' each time frame.onStep is called, any two Ls should have at
+// least one 's' between them.
+
+var g = newGlobal();
+g.N = 11;
+g.log = '';
+g.eval("function f() {\n" +
+       "    for (var i = 0; i <= N; i++)\n" +
+       "        log += 'L';\n" +
+       "}\n");
+g.f();
+assertEq(/LL/.exec(g.log) !== null, true);
+
+var dbg = Debugger(g);
+dbg.onEnterFrame = function (frame) {
+    frame.onStep = function () { g.log += 's'; };
+};
+g.log = '';
+g.f();
+assertEq(/LL/.exec(g.log), null);