diff -r 000000000000 -r 6474c204b198 js/src/tests/ecma_5/RegExp/15.10.7.5-01.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/tests/ecma_5/RegExp/15.10.7.5-01.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,71 @@
+/*
+ * Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/licenses/publicdomain/
+ */
+
+var BUGNUMBER = 465199;
+var summary = "RegExp lastIndex property set should not coerce type to number";
+
+print(BUGNUMBER + ": " + summary);
+
+/**************
+ * BEGIN TEST *
+ **************/
+
+var called = false;
+var o = { valueOf: function() { called = true; return 1; } };
+var r = /a/g;
+var desc, m;
+
+assertEq(r.lastIndex, 0);
+
+desc = Object.getOwnPropertyDescriptor(r, "lastIndex");
+assertEq(desc.enumerable, false);
+assertEq(desc.configurable, false);
+assertEq(desc.value, 0);
+assertEq(desc.writable, true);
+
+r.lastIndex = o;
+
+assertEq(r.lastIndex, o);
+
+desc = Object.getOwnPropertyDescriptor(r, "lastIndex");
+assertEq(desc.enumerable, false);
+assertEq(desc.configurable, false);
+assertEq(desc.value, o);
+assertEq(desc.writable, true);
+
+assertEq(called, false);
+assertEq(r.exec("aaaa").length, 1);
+assertEq(called, true);
+assertEq(r.lastIndex, 2);
+
+desc = Object.getOwnPropertyDescriptor(r, "lastIndex");
+assertEq(desc.enumerable, false);
+assertEq(desc.configurable, false);
+assertEq(desc.value, 2);
+assertEq(desc.writable, true);
+
+
+r.lastIndex = -0.2;
+assertEq(r.lastIndex, -0.2);
+
+m = r.exec("aaaa");
+assertEq(Array.isArray(m), true);
+assertEq(m.length, 1);
+assertEq(m[0], "a");
+assertEq(r.lastIndex, 1);
+
+m = r.exec("aaaa");
+assertEq(Array.isArray(m), true);
+assertEq(m.length, 1);
+assertEq(m[0], "a");
+assertEq(r.lastIndex, 2);
+
+
+/******************************************************************************/
+
+if (typeof reportCompare === "function")
+  reportCompare(true, true);
+
+print("All tests passed!");