diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/debug/gc-04.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/debug/gc-04.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,25 @@
+// Storing a Debugger.Object as a key in a WeakMap protects it from GC as long as
+// the referent is alive.
+
+var g = newGlobal();
+var N = g.N = 10;
+var dbg = Debugger(g);
+var cache = new WeakMap;
+
+var i = 0;
+dbg.onDebuggerStatement = function (frame) {
+    cache.set(frame.arguments[0], i++);
+};
+g.eval("function f(x) { debugger; }");
+g.eval("var arr = [], j; for (j = 0; j < N; j++) arr[j] = {};");
+g.eval("for (j = 0; j < N; j++) f(arr[j]);");
+assertEq(i, N);
+
+gc(); gc();
+
+i = 0;
+dbg.onDebuggerStatement = function (frame) {
+    assertEq(cache.get(frame.arguments[0]), i++)
+};
+g.eval("for (j = 0; j < N; j++) f(arr[j]);");
+assertEq(i, N);