[MD Bookmarks] Add keyboard navigation and selection to bookmark list.

chrome/browser/resources/md_bookmarks/item.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 
 <link rel="import" href="chrome://resources/cr_elements/icons.html">
 <link rel="import" href="chrome://resources/html/icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-icon/iron-icon.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-icon-button/paper-icon-button-light.html">
 <link rel="import" href="chrome://bookmarks/actions.html">
 <link rel="import" href="chrome://bookmarks/shared_style.html">
 <link rel="import" href="chrome://bookmarks/store_client.html">
 
@@ skipping 43 matching lines @@
       #icon {
         background-repeat: no-repeat;
         height: 16px;
         margin: 2px;
         width: 16px;
       }
 
       button.more-vert-button {
         -webkit-margin-end: 12px;
       }
+
+      a {
+        outline: none;
+      }
     </style>
-    <a id="url" href="[[openItemUrl_]]">
+    <a id="url" href="[[openItemUrl_]]" tabindex="-1">

[tsergeant, 2017/05/23 07:25:17]

As discussed, maybe change this <a> back into a <div> in this CL (😢), and then
we can follow up to re-enable middle click later.

[calamity, 2017/05/25 07:36:29]

Acknowledged.

       <div id="icon-wrapper">
         <iron-icon id="folder-icon" icon="cr:folder" hidden$="[[!isFolder_]]">
         </iron-icon>
         <div id="icon" hidden$="[[isFolder_]]"></div>
       </div>
       <div id="website-title">
         [[item_.title]]
       </div>
       <button is="paper-icon-button-light" class="more-vert-button"
           on-click="onMenuButtonClick_" on-dblclick="onMenuButtonDblClick_"
           tabindex$="[[ironListTabIndex]]" on-focus="onItemBlur_">
         <div></div>
         <div></div>
         <div></div>
       </button>
     </a>
   </template>
   <script src="chrome://bookmarks/item.js"></script>
 <dom-module>