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diff --git a/js/src/tests/non262/Symbol/for-in-order.js b/js/src/tests/non262/Symbol/for-in-order.js
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+++ b/js/src/tests/non262/Symbol/for-in-order.js
@@ -0,0 +1,33 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/ */
+
+// ES6 does not specify enumeration order, but implementations mostly retain
+// property insertion order -- and must, for web compatibility. This test checks
+// that symbol-keyed properties do not interfere with that order.
+
+var obj = {};
+obj[Symbol("moon")] = 0;
+obj.x = 1;
+obj[Symbol.for("y")] = 2
+obj.y = 3;
+obj[Symbol.iterator] = function* () { yield 4; };
+obj.z = 5;
+Object.prototype[Symbol.for("comet")] = 6;
+
+var keys = [];
+for (var k in obj)
+    keys.push(k);
+assertDeepEq(keys, ["x", "y", "z"]);
+assertDeepEq(Object.keys(obj), ["x", "y", "z"]);
+
+// Test with more properties.
+for (var i = 0; i < 1000; i++)
+    obj[Symbol(i)] = i;
+obj.w = 1000;
+keys = []
+for (var k in obj)
+    keys.push(k);
+assertDeepEq(keys, ["x", "y", "z", "w"]);
+
+if (typeof reportCompare === "function")
+    reportCompare(0, 0);