increase test timeout to 10 seconds from 5 seconds

tests/index.html

@@ -12,7 +12,7 @@
   <script src="../node_modules/mocha/mocha.js"></script>
 
   <script>
-    mocha.setup('bdd').timeout(5000).slow(250);
+    mocha.setup('bdd').timeout(10000).slow(250);
 
     window.onload = function() {
       mocha.checkLeaks();