diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/key-equality-NaN.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/key-equality-NaN.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,15 @@
+// NaN is equal to itself for the purpose of key lookups.
+
+var m = new Map;
+m.set(NaN, "ok");
+assertEq(m.has(NaN), true);
+assertEq(m.get(NaN), "ok");
+assertEq(m.delete(NaN), true);
+assertEq(m.has(NaN), false);
+assertEq(m.get(NaN), undefined);
+
+var s = new Set;
+s.add(NaN);
+assertEq(s.has(NaN), true);
+assertEq(s.delete(NaN), true);
+assertEq(s.has(NaN), false);