Fix visible position calculation in accessible setSelection

chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors_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']);
 
 /**
  * Test fixture for cvox2.cursors.
  * @constructor
@@ skipping 379 matching lines @@
     assertEquals(1, cursor.selectionIndex_);
   });
 });
 
 TEST_F('CursorsTest', 'InlineElementOffset', function() {
   this.runWithLoadedTree(function() {/*!
     <p>This<br> is a<a href="#g">test</a>of selection</p>
   */}, function(root) {
     root.addEventListener('textSelectionChanged', this.newCallback(function(evt) {
       // This is a little unexpected though not really incorrect; Ctrl+C works.
       assertEquals(testNode, root.anchorObject);

[David Tseng, 2016/08/18 22:18:39]

FYI; this is still wrong.

       assertEquals(ofSelectionNode, root.focusObject);
       assertEquals(4, root.anchorOffset);

[David Tseng, 2016/08/18 22:18:39]

As is this. The selection is on the ofSelection node.

       assertEquals(1, root.focusOffset);
     }));
 
     // This is the link's static text.
     var testNode = root.lastChild.lastChild.previousSibling.firstChild;
     assertEquals(RoleType.staticText, testNode.role);
     assertEquals('test', testNode.name);
 
     var ofSelectionNode = root.lastChild.lastChild;
     var cur = new cursors.Cursor(ofSelectionNode, 0);
     assertEquals('of selection', cur.selectionNode_.name);
     assertEquals(RoleType.staticText, cur.selectionNode_.role);
-    assertEquals(13, cur.selectionIndex_);
+    assertEquals(0, cur.selectionIndex_);
 
     var curIntoO = new cursors.Cursor(ofSelectionNode, 1);
     assertEquals('of selection', curIntoO.selectionNode_.name);
     assertEquals(RoleType.staticText, curIntoO.selectionNode_.role);
-    assertEquals(14, curIntoO.selectionIndex_);
+    assertEquals(1, curIntoO.selectionIndex_);
 
     var oRange = new cursors.Range(cur, curIntoO);
     oRange.select();
   });
 });