MD Settings: Replace paper-item with button under iron-dropdown, part1.

chrome/browser/resources/settings/search_engines_page/search_engine_entry.css

 /* Copyright (c) 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. */
 
 .favicon-image {
   -webkit-margin-end: 8px;
   background-repeat: no-repeat;
   background-size: contain;
   display: inline-block;
   height: 20px;
   vertical-align: middle;
   width: 20px;
 }
 
 .name {
   margin: auto;
 }
 
 #container {
   border-top: 1px solid lightgray;
   display: flex;
   padding: 2px 0;
 }
 
 .dropdown-content {
   background: white;
   box-shadow: 0 2px 6px grey;
 }
 
-paper-item:hover {
-  background-color: var(--settings-hover-color);
-}
-
 paper-icon-button {
   -webkit-padding-end: 0;
   padding-bottom: var(--search-engines-list-item-vertical-space);
   padding-top: var(--search-engines-list-item-vertical-space);
 }