diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testNegZero1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testNegZero1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+function testNegZero1Helper(z) {
+    for (let j = 0; j < 5; ++j) { z = -z; }
+    return Math.atan2(0, -0) == Math.atan2(0, z);
+}
+
+var testNegZero1 = function() { return testNegZero1Helper(0); }
+testNegZero1.name = 'testNegZero1';
+testNegZero1Helper(1);
+assertEq(testNegZero1(), true);