Bug 649842 - Generate real unique values, instead of relying on Math.random() to generate unique values, which will lead into intermittent oranges; r=zpao

browser/components/sessionstore/test/browser/head.js

@@ -99,6 +99,7 @@ function waitForSaveState(aSaveStateCallback) {
   }, topic, false);
 };
 
+var gUniqueCounter = 0;
 function r() {
-  return Date.now() + Math.random();
+  return Date.now() + "-" + (++gUniqueCounter);
 }