diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Frame-onStep-08.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Frame-onStep-08.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,29 @@
+// frame.onStep can coexist with breakpoints.
+
+var g = newGlobal();
+var dbg = Debugger(g);
+var log = '';
+dbg.onEnterFrame = function (frame) {
+    var handler = {hit: function () { log += 'B'; }};
+    var lines = frame.script.getAllOffsets();
+    for (var line in lines) {
+        line = Number(line);
+        var offs = lines[line];
+        for (var i = 0; i < offs.length; i++)
+            frame.script.setBreakpoint(offs[i], handler);
+    }
+
+    frame.onStep = function () { log += 's'; };
+};
+
+g.eval("one = 1;\n" +
+       "two = 2;\n" +
+       "three = 3;\n" +
+       "four = 4;\n");
+assertEq(g.four, 4);
+
+// Breakpoints hit on all four lines.
+assertEq(log.replace(/[^B]/g, ''), 'BBBB');
+
+// onStep was called between each pair of breakpoints.
+assertEq(/BB/.exec(log), null);