timers: internal unref timers should use Timer.now

Author: tjfontaine

lib/timers.js

@@ -377,7 +377,7 @@ var unrefList, unrefTimer;
 
 
 function unrefTimeout() {
-  var now = Date.now();
+  var now = Timer.now();
 
   debug('unrefTimer fired');
 
@@ -436,7 +436,7 @@ exports._unrefActive = function(item) {
     unrefTimer.ontimeout = unrefTimeout;
   }
 
-  var now = Date.now();
+  var now = Timer.now();
   item._idleStart = now;
 
   if (L.isEmpty(unrefList)) {