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

chrome/browser/resources/pdf/elements/viewer-bookmark/viewer-bookmark.html

 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-ripple/paper-ripple.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-styles/color.html">
 
 <dom-module id="viewer-bookmark" attributes="bookmark">
   <template>
     <style>
       #item {
         @apply(--layout-center);
         @apply(--layout-horizontal);
         cursor: pointer;
         height: 30px;
         position: relative;
       }
 
       #item:hover {
         background-color: rgb(237, 237, 237);
       }
 
       paper-ripple {
         /* Allowing the ripple to capture pointer events prevents a focus
          * rectangle for showing up for clicks, while still allowing it with
-         * tab-navigation. This undoes a paper-ripple bugfix aimed at
+         * tab-navigation. This undoes a paper-ripple bug fix aimed at
          * non-Chrome browsers. TODO(tsergeant): Improve focus in
          * viewer-bookmark so this can be removed (https://crbug.com/5448190).
          */
         pointer-events: auto;
       }
 
       #title {
         overflow: hidden;
         text-overflow: ellipsis;
         white-space: nowrap;
@@ skipping 20 matching lines @@
     </style>
     <div id="item" on-click="onClick">
       <paper-ripple></paper-ripple>
       <paper-icon-button id="expand" icon="cr:chevron-right"
           on-click="toggleChildren">
       </paper-icon-button>
       <span id="title" tabindex="0">{{bookmark.title}}</span>
     </div>
     <!-- dom-if will stamp the complex bookmark tree lazily as individual nodes
       are opened. -->
-    <template is="dom-if" if="{{childrenShown}}" id="sub-bookmarks">
-      <template is="dom-repeat" items="{{bookmark.children}}">
+    <template is="dom-if" if="[[childrenShown]]" id="sub-bookmarks">
+      <template is="dom-repeat" items="[[bookmark.children]]">
         <viewer-bookmark bookmark="{{item}}" depth="{{childDepth}}">
         </viewer-bookmark>
       </template>
     </template>
   </template>
   <script src="viewer-bookmark.js"></script>
 </dom-module>