MD Settings: split browser tests per-file

chrome/test/data/webui/settings/dropdown_menu_tests.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 Suite of tests for settings-dropdown-menu. */
 cr.define('settings_dropdown_menu', function() {
   function registerTests() {
     suite('SettingsDropdownMenu', function() {
-      // Import settings_dropdown_menu.html before running suite.
-      suiteSetup(function() {
-        return Promise.all([
-          PolymerTest.importHtml('chrome://md-settings/i18n_setup.html'),
-          PolymerTest.importHtml(
-              'chrome://md-settings/controls/settings_dropdown_menu.html'),
-        ]);
-      });
-
       /** @type {SettingsDropdownMenu} */
       var dropdown;
 
       /**
        * The IronSelectable (paper-listbox) used internally by the dropdown
        * menu.
        * @type {Polymer.IronSelectableBehavior}
        */
       var selectable;
 
@@ skipping 73 matching lines @@
         // Pref should not have changed.
         assertEquals('f', dropdown.pref.value);
       });
     });
   }
 
   return {
     registerTests: registerTests,
   };
 });