Fix test failure in list_selection_model_test.html and port to automated browser test.

chrome/test/data/webui/webui_resource_test.js

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 /**
  * Tests that an observation matches the expected value.
  * @param {Object} expected The expected value.
  * @param {Object} observed The actual value.
  * @param {string=} opt_message Optional message to include with a test
  *     failure.
@@ skipping 55 matching lines @@
     f();
   } catch(err) {
     triggeredError = true;
   }
   if (!triggeredError)
     throw new Error('Assertion Failed: throw expected.');
 }
 
 /**
  * Verifies that the contents of the expected and observed arrays match.
- * @param {Array} expected The expected result.
- * @param {Array} observed The actual result.
+ * @param {!Array} expected The expected result.
+ * @param {!Array} observed The actual result.
  */
 function assertArrayEquals(expected, observed) {
   var v1 = Array.prototype.slice.call(expected);
   var v2 = Array.prototype.slice.call(observed);
   var equal = v1.length == v2.length;
   if (equal) {
     for (var i = 0; i < v1.length; i++) {
       if (v1[i] !== v2[i]) {
         equal = false;
         break;
@@ skipping 43 matching lines @@
  * @param {boolean} success Indicates if the test completed successfully.
  */
 function endTests(success) {
   domAutomationController.setAutomationId(1);
   domAutomationController.send(success ? 'SUCCESS' : 'FAILURE');
 }
 
 window.onerror = function() {
   endTests(false);
 };