diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/testToUpperToLower.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/testToUpperToLower.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,9 @@
+function testToUpperToLower() {
+    var s = "Hello", s1, s2;
+    for (i = 0; i < 100; ++i) {
+        s1 = s.toLowerCase();
+        s2 = s.toUpperCase();
+    }
+    return s1 + s2;
+}
+assertEq(testToUpperToLower(), "helloHELLO");