Raise max device pixel ratio to 3

Author: ntrrgc

Diff for: cocos2d/core/platform/CCEGLView.js

@@ -936,7 +936,7 @@ cc.ContainerStrategy = cc.Class.extend(/** @lends cc.ContainerStrategy# */{
         // Setup pixel ratio for retina display
         var devicePixelRatio = view._devicePixelRatio = 1;
         if (view.isRetinaEnabled())
-            devicePixelRatio = view._devicePixelRatio = Math.min(2, window.devicePixelRatio || 1);
+            devicePixelRatio = view._devicePixelRatio = Math.min(3, window.devicePixelRatio || 1);
         // Setup canvas
         locCanvas.width = w * devicePixelRatio;
         locCanvas.height = h * devicePixelRatio;