Use src element and correct relative path for directory return value

Author: jcollins-g

lib/resources/script.js

@@ -240,9 +240,9 @@ function initSearch(name) {
   }
 
   var jsonReq = new XMLHttpRequest();
-  var scriptUrl = URI(document.getElementById("dartdoc_script_js"));
+  var scriptUrl = URI(document.getElementById("dartdoc_script_js").src);
 
-  jsonReq.open('GET', URI(scriptUrl.directory() + '/../..').absoluteTo(scriptUrl) + '/index.json', true);
+  jsonReq.open('GET', URI(scriptUrl.directory() + '/..').absoluteTo(scriptUrl) + '/index.json', true);
   jsonReq.addEventListener('load', function() {
     searchIndex = JSON.parse(jsonReq.responseText);
     initTypeahead();