diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/Map-Set-moving-gc.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/Map-Set-moving-gc.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,16 @@
+var m = new Map;
+var s = new Set;
+
+var A = [];
+for (var i = 0; i < 1024; ++i) {
+    var key = {i:i};
+    m.set(key, i);
+    s.add(key);
+    A.push(key);
+}
+gc();
+for (var i in A) {
+    var key = A[i];
+    assertEq(m.has(key), true);
+    assertEq(s.has(key), true);
+}