Check that processed i18n nodes are defined before marking them.

ui/webui/resources/js/i18n_template_no_process.js

 // Copyright (c) 2012 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.
 
 /** @typedef {Document|DocumentFragment|Element} */
 var ProcessingRoot;
 
 /**
  * @fileoverview This is a simple template engine inspired by JsTemplates
  * optimized for i18n.
@@ skipping 165 matching lines @@
     var isElement = root instanceof Element;
     if (isElement && root.matches(selector))
       processElement(/** @type {!Element} */(root), data, visited);
 
     var elements = root.querySelectorAll(selector);
     for (var i = 0; i < elements.length; ++i) {
       processElement(elements[i], data, visited);
     }
 
     if (mark) {
       var processed = isElement ? [root] : root.children;

[Dan Beam, 2015/07/22 00:20:40]

fwiw: this would probably work on iOS as well

  var processed = isElement ? [root] : root.childNodes;
  for (var i = 0; i < process.length; ++i) {
    if (processed.nodeType == Node.ELEMENT_NODE)
      processed[i].setAttribute('i18n-processed', '');
  }

or just

    if (processed instanceof Element)

-      for (var i = 0; i < processed.length; ++i) {
-        processed[i].setAttribute('i18n-processed', '');
+      if (processed) {

[Dan Beam, 2015/07/21 21:26:21]

I'm confused. if ([]) always triggers.  root.children should always be there. 
when is this actually happening?

+        for (var i = 0; i < processed.length; ++i) {
+          processed[i].setAttribute('i18n-processed', '');
+        }
       }
     }
   }
 
   /**
    * Run through various [i18n-*] attributes and populate.
    * @param {!Element} element
    * @param {!LoadTimeData} data
    * @param {!Array<ProcessingRoot>} visited
    */
   function processElement(element, data, visited) {
     for (var i = 0; i < attributeNames.length; i++) {
       var name = attributeNames[i];
       var attribute = element.getAttribute(name);
       if (attribute != null)
         handlers[name](element, attribute, data, visited);
     }
   }
 
   return {
     process: process
   };
 }());