Fix some ChromeVox Closure compiler errors.

chrome/browser/resources/chromeos/chromevox/common/traverse_table.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.
 
 /**
  * TODO(stoarca): This class has become obsolete except for the shadow table.
  * Chop most of it away.
  * @fileoverview A DOM traversal interface for navigating data in tables.
  */
 
@@ skipping 42 matching lines @@
 
 /**
  * Whether or not this cell is spanned by a colspan
  * @type {?boolean}
  */
 ShadowTableNode.prototype.colSpan;
 
 
 /**
  * The row index of the corresponding active table cell
- * @type {?number}
+ * @type {number}
  */
-ShadowTableNode.prototype.i;
+ShadowTableNode.prototype.i = -1;
 
 
 /**
  * The column index of the corresponding active table cell
- * @type {?number}
+ * @type {number}
  */
-ShadowTableNode.prototype.j;
+ShadowTableNode.prototype.j = -1;
 
 
 /**
  * The corresponding <TD> or <TH> node in the active table.
  * @type {?Node}
  */
 ShadowTableNode.prototype.activeCell;
 
 
 /**
@@ skipping 171 matching lines @@
         if (this.getCell() == null) {
           this.attachCursorToNearestCell_();
         }
       }, this), false);
 };
 
 
 /**
  * Finds the cell cursor containing the specified node within the table.
  * Returns null if there is no close cell.
- * @param {!Node} node The node for which to find the cursor.
+ * @param {Node} node The node for which to find the cursor.
  * @return {Array<number>} The table index for the node.
  */
 cvox.TraverseTable.prototype.findNearestCursor = function(node) {
+  if (!node) {
+    return null;
+  }
   // TODO (stoarca): The current structure for representing the
   // shadow table is not optimal for this query, but it's not urgent
   // since this only gets executed at most once per user action.
 
   // In case node is in a table but above any individual cell, we go down as
   // deep as we can, being careful to avoid going into nested tables.
   var n = node;
 
   while (n.firstElementChild &&
          !(n.firstElementChild.tagName == 'TABLE' ||
@@ skipping 1022 matching lines @@
 };
 
 
 /**
  * Resets the table cursors.
  *
  */
 cvox.TraverseTable.prototype.resetCursor = function() {
   this.currentCellCursor = null;
 };