implemented element with polyfill

Author: haydenmcp

deep-intersection-observer.html

@@ -1,5 +1,5 @@
 <link rel="import" href="../polymer/polymer.html">
-<script src="path/to/intersection-observer.js"></script>
+<script src="../intersection-observer/polyfill/intersection-observer.js"></script>
 
 <dom-module id="deep-intersection-observer">
   <script>