diff -r 000000000000 -r 6474c204b198 js/xpconnect/tests/unit/test_textDecoder.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/js/xpconnect/tests/unit/test_textDecoder.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+function run_test() {
+  var Cu = Components.utils;
+  sb = new Cu.Sandbox('http://www.example.com',
+                      { wantGlobalProperties: ["TextDecoder", "TextEncoder"] });
+  sb.do_check_eq = do_check_eq;
+  Cu.evalInSandbox('do_check_eq(new TextDecoder().encoding, "utf-8");' +
+                   'do_check_eq(new TextEncoder().encoding, "utf-8");',
+                   sb);
+  Cu.importGlobalProperties(["TextDecoder", "TextEncoder"]);
+  do_check_eq(new TextDecoder().encoding, "utf-8");
+  do_check_eq(new TextEncoder().encoding, "utf-8");
+}