Fixes instanceof Object statements for objects from other windows and iFrames. (#2631)

* Replaces instanceof Object checks with typeof to prevent cross tab issues.

* Adds missing space.

lib/DataSet.js

@@ -211,7 +211,7 @@ DataSet.prototype.add = function (data, senderId) {
       addedIds.push(id);
     }
   }
-  else if (data instanceof Object) {
+  else if (data && typeof data === 'object') {
     // Single item
     id = me._addItem(data);
     addedIds.push(id);
@@ -261,14 +261,14 @@ DataSet.prototype.update = function (data, senderId) {
   if (Array.isArray(data)) {
     // Array
     for (var i = 0, len = data.length; i < len; i++) {
-      if (data[i] instanceof Object){
+      if (data[i] && typeof data[i] === 'object'){
         addOrUpdate(data[i]);
       } else {
         console.warn('Ignoring input item, which is not an object at index ' + i);
       }
     }
   }
-  else if (data instanceof Object) {
+  else if (data && typeof data === 'object') {
     // Single item
     addOrUpdate(data);
   }
@@ -707,7 +707,7 @@ DataSet.prototype._remove = function (id) {
   if (util.isNumber(id) || util.isString(id)) {
     ident = id;
   }
-  else if (id instanceof Object) {
+  else if (id && typeof id === 'object') {
     ident = id[this._fieldId]; // look for the identifier field using _fieldId
   }