[MD settings] scroll to section find host

chrome/browser/resources/settings/settings_page/main_page_behavior.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.
 
 // Fast out, slow in.
 var EASING_FUNCTION = 'cubic-bezier(0.4, 0, 0.2, 1)';
 var EXPAND_DURATION = 350;
 
 /**
  * Provides animations to expand and collapse individual sections in a page.
@@ skipping 328 matching lines @@
   scrollToSection_: function() {
     // TODO(dschuyler): Determine whether this setTimeout can be removed.
     // See also: https://github.com/Polymer/polymer/issues/3629
     setTimeout(function pollForScrollHeight() {
       // If the current section changes while we are waiting for the page to be
       // ready, scroll to the newest requested section.
       var element = this.getSection_(this.currentRoute.section);
       if (!element)
         return;
 
-      if (element.parentNode.host.scrollHeight == 0) {
+      var host = findAncestor(element, function(n) { return n.host; }).host;

[michaelpg, 2016/06/06 20:13:03]

This is more complicated than necessary (this.scrollHeight would have sufficed).
If this is due to changes "coming down the pipeline" it would've been cool to
have a comment or TODO or something, or even a comment in the CL at the very
least. Also curious why Polymer.Base.domHost doesn't suffice.

+      if (host.scrollHeight == 0) {
         setTimeout(pollForScrollHeight.bind(this), 100);
         return;
       }
 
       element.scrollIntoView();
     }.bind(this));
   },
 
   /** @private */
   currentRouteChanged_: function(newRoute, oldRoute) {
@@ skipping 36 matching lines @@
         this.$$('[section=' + section + ']'));
   },
 };
 
 
 /** @polymerBehavior */
 var RoutableBehavior = [
   MainPageBehavior,
   RoutableBehaviorImpl
 ];