diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/Frame-environment-04.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/Frame-environment-04.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+// frame.environment can be called from the onEnterFrame hook.
+
+var g = newGlobal();
+g.eval("function f(x) { return 2 * x; }");
+var dbg = Debugger(g);
+var hits = 0;
+dbg.onEnterFrame = function (frame) {
+    assertEq(frame.environment.names().join(","), "arguments,x");
+    hits++;
+};
+assertEq(g.f(22), 44);
+assertEq(hits, 1);