diff -r 000000000000 -r 6474c204b198 js/src/jit-test/tests/basic/bug642772-1.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/src/jit-test/tests/basic/bug642772-1.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,19 @@
+var n1 = Number.prototype.toFixed;
+var s1 = String.prototype.split;
+delete Number;
+delete String;
+
+var n2 = (5).toFixed;
+var s2 = ("foo").split;
+
+// Check enumeration doesn't resurrect deleted standard classes
+for (x in this) {}
+
+// Ensure the prototypes are shared.
+var n3 = (5).toFixed;
+var s3 = ("foo").split;
+
+assertEq(s1, s2);
+assertEq(s1, s3);
+assertEq(n1, n2);
+assertEq(n1, n3);