Avoid changing select element via synthesized keydown from ChromeVox test

chrome/browser/resources/chromeos/chromevox/cvox2/background/background_test.extjs

 // Copyright 2014 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.
 
 // Include test fixture.
 GEN_INCLUDE(['../../testing/chromevox_next_e2e_test_base.js',
              '../../testing/assert_additions.js']);
 
 GEN_INCLUDE(['../../testing/mock_feedback.js']);
 
@@ skipping 201 matching lines @@
         .expectSpeech('t');
     mockFeedback.call(doCmd('nextWord'))
         .expectSpeech('echo', 'Link');
     mockFeedback.replay();
   });
 });
 
 TEST_F('BackgroundTest', 'SelectSingleBasic', function() {
   var mockFeedback = this.createMockFeedback();
   this.runWithLoadedTree(this.formsDoc, function() {
-    var sendDownToSelect =
-        this.sendKeyToElement.bind(this, undefined, 'ArrowDown', '#fruitSelect');
+    var incrementSelectedIndex =
+        this.incrementSelectedIndex.bind(this, undefined, '#fruitSelect');
     mockFeedback.expectSpeech('apple', 'has pop up', 'Collapsed')
         .expectBraille('apple btn +popup +')
-        .call(sendDownToSelect)
+        .call(incrementSelectedIndex)
         .expectSpeech('grape', /2 of 3/)
         .expectBraille('grape mnuitm 2/3')
-        .call(sendDownToSelect)
+        .call(incrementSelectedIndex)
         .expectSpeech('banana', /3 of 3/)
         .expectBraille('banana mnuitm 3/3');
     mockFeedback.replay();
   });
 });
 
 TEST_F('BackgroundTest', 'ContinuousRead', function() {
   var mockFeedback = this.createMockFeedback();
   this.runWithLoadedTree(this.linksAndHeadingsDoc, function() {
     mockFeedback.expectSpeech('start')
@@ skipping 683 matching lines @@
   */}, function(root) {
     mockFeedback.call(doCmd('nextHeading'))
         .expectNextSpeechUtteranceIsNot('NE')
         .expectSpeech('NW')
         .call(doCmd('previousHeading'))
         .expectNextSpeechUtteranceIsNot('NE')
         .expectSpeech('NW')
         .replay();
   });
 });