Test that Node is a function before using instanceof on it

Author: evanc

src/vendor/core/dom/isNode.js

@@ -23,7 +23,7 @@
  */
 function isNode(object) {
   return !!(object && (
-    typeof Node !== 'undefined' ? object instanceof Node :
+    typeof Node === 'function' ? object instanceof Node :
       typeof object === 'object' &&
       typeof object.nodeType === 'number' &&
       typeof object.nodeName === 'string'