[MD Bookmarks] Convert bookmark list to iron-list.

chrome/browser/resources/md_bookmarks/list.js

 // Copyright 2016 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.
 
 Polymer({
   is: 'bookmarks-list',
 
   behaviors: [
     bookmarks.StoreClient,
   ],
@@ skipping 11 matching lines @@
 
     /** @private */
     searchTerm_: String,
   },
 
   listeners: {
     'click': 'deselectItems_',
   },
 
   attached: function() {
+    var list = /** @type {IronListElement} */ (this.$.bookmarksCard);
+    list.scrollTarget = this;
+
     this.watch('displayedList_', function(state) {
       return bookmarks.util.getDisplayedList(state);
     });
     this.watch('searchTerm_', function(state) {
       return state.search.term;
     });
     this.updateFromStore();
   },
 
   getDropTarget: function() {
     return this.$.message;
   },
 
   /** @private */
   emptyListMessage_: function() {
     var emptyListMessage = this.searchTerm_ ? 'noSearchResults' : 'emptyList';
     return loadTimeData.getString(emptyListMessage);
   },
 
   /** @private */
   isEmptyList_: function() {
     return this.displayedList_.length == 0;
   },
 
   /** @private */
   deselectItems_: function() {
     this.dispatch(bookmarks.actions.deselectItems());
   },
 });