[WebUI] use one-way Polymer binding on dom-if, dom-repeat, and iron-list

chrome/test/data/webui/cr_elements/cr_scrollable_behavior_tests.js

 // Copyright 2017 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.
 
 suite('cr-scrollable-behavior', function() {
   /** @type {CrScrollableListElement} */ var testElement;
   /** @type {HTMLDivElement} */ var container;
   /** @type {IronListElement} */ var ironList;
 
   suiteSetup(function() {
     document.body.innerHTML = `
       <dom-module is="test-element">
         <template>
           <style>
             #container {
               height: 30px;
               overflow-y: auto;
             }
           </style>
           <div id="container" scrollable>
-            <iron-list scroll-target="container" items=[[items]]>
+            <iron-list scroll-target="container" items="[[items]]">

[dpapad, 2017/05/19 19:35:19]

Was this caught by a PRESUBMIT? I recall that we added such a check a while ago,
but maybe only recently is being applied to test files?

[dschuyler, 2017/05/19 19:37:10]

It wasn't. I was grepping for issues (just lookin' for trouble) and found it.
The presubmit may need a touch-up or config change(?)

               <template>
                 <div>[[item]]</div>
               </template>
             </iron-list>
           </div>
         </template>
       </dom-module>
     `;
 
     Polymer({
@@ skipping 54 matching lines @@
     testElement.saveScroll(ironList);
     testElement.items = ['apple', 'bannana', 'cactus', 'cucumber', 'doughnut'];
     testElement.restoreScroll(ironList);
     Polymer.dom.flush();
     Polymer.Base.async(function() {
       assertEquals(scrollTop, container.scrollTop);
       done();
     });
   });
 });