ChromeVox should not speak live regions that aren't in the document.

chrome/browser/resources/chromeos/chromevox/common/dom_util_test.js

 // 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_unittest_base.js']);
 
 /**
  * Test fixture.
  * @constructor
@@ skipping 123 matching lines @@
   node = $('nested_display_block');
   assertEquals(false, cvox.DomUtil.isVisible(node));
 
   // Options tests (for performance).
   node = $('nested_display_block');
   assertEquals(true,
       cvox.DomUtil.isVisible(node, {checkAncestors: false}));
   node = $('nested_visibility_hide');
   assertEquals(false,
       cvox.DomUtil.isVisible(node, {checkDescendants: false}));
+
+  // Test that an element not part of the DOM is treated as invisible.
+  var div = document.createElement('div');
+  assertEquals(false, cvox.DomUtil.isVisible(div));
+  document.body.appendChild(div);
+  assertEquals(true, cvox.DomUtil.isVisible(div));
 });
 
 /** Test determining if a node is a leaf node or not. @export */
 TEST_F('CvoxDomUtilUnitTest', 'IsLeafNode', function() {
   this.loadDomUtilTestDoc_();
 
   var node = $('normal_node');
   assertEquals(false, cvox.DomUtil.isLeafNode(node));
   node = $('display_none');
   assertEquals(true, cvox.DomUtil.isLeafNode(node));
@@ skipping 1409 matching lines @@
   cvox.Memoize.scope(function() {
     container.style.visibility = 'hidden';
     assertFalse(cvox.DomUtil.isVisible(target));
 
     container.style.visibility = 'visible';
     // This should be true! It will return the wrong answer because
     // we're deliberately leaving memoization on while modifying the DOM.
     assertFalse(cvox.DomUtil.isVisible(target));
   });
 });