MD Settings: show part of a11y page on Mac/Windows/Linux

chrome/browser/resources/settings/a11y_page/a11y_page.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.
 
 /**
  * @fileoverview
  * 'settings-a11y-page' is the settings page containing accessibility
  * settings.
  *
  * Example:
  *
  *    <iron-animated-pages>
  *      <settings-a11y-page prefs="{{prefs}}"></settings-a11y-page>
  *      ... other pages ...
  *    </iron-animated-pages>
  */
 Polymer({
   is: 'settings-a11y-page',
 
   properties: {
     /**
      * Preferences state.
      */
     prefs: {
       type: Object,
       notify: true,
     },
 
+<if expr="chromeos">
     /**
      * Whether to show experimental accessibility features.
      * @private {boolean}
      */
     showExperimentalFeatures_: {
       type: Boolean,
       value: function() {
         return loadTimeData.getBoolean('showExperimentalA11yFeatures');
       },
     }
+</if>
   },
 
   /** @private */
   onMoreFeaturesTap_: function() {
     window.open(
         'https://chrome.google.com/webstore/category/collection/accessibility');
   },
 });