diff -r 000000000000 -r 6474c204b198 js/src/tests/js1_8_5/extensions/proxy-enumerateOwn-duplicates.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/js1_8_5/extensions/proxy-enumerateOwn-duplicates.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,40 @@
+// Any copyright is dedicated to the Public Domain.
+// http://creativecommons.org/licenses/publicdomain/
+
+//-----------------------------------------------------------------------------
+var BUGNUMBER = 580200;
+var summary =
+  'Assertion failure enumerating own properties of proxy returning ' +
+  'duplicated own property name';
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var x = Proxy.create({ keys: function() { return ["0","0"]; } }, [1,2]);
+var ax = Object.keys(x);
+assertEq(ax.length, 1, "array: " + ax);
+assertEq(ax[0], "0");
+
+var p = Proxy.create({ keys: function() { return ["1","1"]; } }, null);
+var ap = Object.keys(p);
+assertEq(ap.length, 1, "array: " + ap);
+assertEq(ap[0], "1");
+
+var x = Proxy.create({ getOwnPropertyNames: function() { return ["0","0"]; } }, [1,2]);
+var ax = Object.getOwnPropertyNames(x);
+assertEq(ax.length, 1, "array: " + ax);
+assertEq(ax[0], "0");
+
+var p = Proxy.create({ getOwnPropertyNames: function() { return ["1","1"]; } }, null);
+var ap = Object.getOwnPropertyNames(p);
+assertEq(ap.length, 1, "array: " + ap);
+assertEq(ap[0], "1");
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("All tests passed!");