Load timer.js in fstests.html

tests/fstests.html

@@ -6,6 +6,7 @@
   <meta name="viewport" content="initial-scale=1.0">
   <script type="text/javascript" src="../libs/async_storage.js" defer></script>
   <script type="text/javascript" src="../libs/fs.js" defer></script>
+  <script type="text/javascript" src="../timer.js" defer></script>
   <script type="text/javascript">
   console.log = function() {
     var s = Array.prototype.join.call(arguments, ",") +"\n";