Revert "MD user manager (learn more page, user manager tutorial)"

chrome/browser/resources/md_user_manager/supervised_user_learn_more.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.
-
-/**
- * @fileoverview 'supervised-user-learn-more' is a page that contains
- * information about what a supervised user is, what happens when a supervised
- * user is created, and a link to the help center for more information.
- */
-Polymer({
-  is: 'supervised-user-learn-more',
-
-  /**
-   * Handler for the 'Done' button click event.
-   * @param {!Event} event
-   * @private
-   */
-  onDoneTap_: function(event) {
-    // Event is caught by user-manager-pages.
-    this.fire('change-page', {page: 'create-user-page'});
-  }
-});