MD Downloads: simplify font preloading further

chrome/browser/resources/md_downloads/downloads.js

 // Copyright 2015 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.
 
 window.addEventListener('load', function() {
   downloads.Manager.onLoad();
-
-  if (!cr.isChromeOS) {
-    // TODO(dbeam): this is copied out of roboto.css. I excluded roboto.css from
-    // vulcanize.py and tried to re-use the "src:" rule from the file via
-    // querySelector(href$=roboto.css).sheet.rules[2].style.src, but alas .rules
-    // can't be accessed because the origins don't match (chrome://resources vs
-    // chrome://downloads). So it's duplicated.
-    new FontFace('Roboto', "local('Roboto Bold'), local('Roboto-Bold'), " +
-        "url(chrome://resources/roboto/roboto-bold.woff2) format('woff2')",
-        {weight: 'bold'}).load();
-  }
+  document.fonts.load('bold 12px Roboto');
 });