Remove unnecessary field reduction again.

test/DataView.test.js

@@ -159,8 +159,7 @@ describe('DataView', function () {
     var view = new DataView(data, {
       filter: function (item) {
         return item.group === 2;
-      },
-      fields:["id","title"]
+      }
     });
 
     var dataUpdates = [];