diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/collections/key-equality-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/collections/key-equality-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,28 @@
+// Different representations of the same number or string are treated as the same Map key.
+
+var m = new Map;
+var test = function test(a, b) {
+    m.set(a, 'secret');
+    assertEq(m.get(b), 'secret');
+    m.set(b, 'password');
+    assertEq(m.get(a), 'password');
+
+    assertEq(a, b);
+};
+
+// Float and integer representations of the same number are the same key.
+test(9, Math.sqrt(81));
+
+// Ordinary strings and ropes are the same key.
+var a = Array(1001).join('x');
+var b = Array(501).join('x') + Array(501).join('x');
+test(a, b);
+
+// Two structurally different ropes with the same characters are the same key.
+a = "";
+b = "";
+for (var i = 0; i < 10; i++) {
+    a = Array(501).join('x') + a;
+    b = b + Array(501).join('x');
+}
+test(a, b);