diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/gc-08.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/gc-08.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,22 @@
+// Debuggers with enabled onExceptionUnwind hooks should not be GC'd even if
+// they are otherwise unreachable.
+
+load(libdir + "asserts.js");
+
+var g = newGlobal();
+var actual = 0;
+var expected = 0;
+
+function f() {
+    for (var i = 0; i < 20; i++) {
+        var dbg = new Debugger(g);
+        dbg.num = i;
+        dbg.onExceptionUnwind = function (stack, exc) { actual += this.num; };
+        expected += i;
+    }
+}
+
+f();
+gc();
+assertThrowsValue(function () { g.eval("throw 'fit';"); }, "fit");
+assertEq(actual, expected);