For a range surrounding a node, set selection index to 0.

chrome/browser/resources/chromeos/chromevox/cvox2/background/cursors.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.
 
 /**
  * @fileoverview Classes related to cursors that point to and select parts of
  * the automation tree.
  */
 
 goog.provide('cursors.Cursor');
@@ skipping 119 matching lines @@
     return this.index_;
   },
 
   /**
    * An index appropriate for making selections.
    * @return {number}
    * @private
    */
   get selectionIndex_() {
     if (this.index_ == cursors.NODE_INDEX)
-      return cursors.NODE_INDEX;
+      return 0;
 
     var adjustedIndex = this.index_;
 
     if (this.node.role == RoleType.inlineTextBox) {
       var sibling = this.node.previousSibling;
       while (sibling) {
         adjustedIndex += sibling.name.length;
         sibling = sibling.previousSibling;
       }
     }
@@ skipping 442 matching lines @@
   /**
    * Returns whether this range has valid start and end cursors.
    * @return {boolean}
    */
   isValid: function() {
     return this.start.isValid() && this.end.isValid();
   }
 };
 
 });  // goog.scope