MD Settings: Fix CrSettingsPeoplePageSyncPageTest.SyncPage test when Vulcanized.

chrome/test/data/webui/settings/people_page_sync_page_test.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.
 
 cr.define('settings_people_page_sync_page', function() {
   /**
    * @constructor
    * @implements {settings.SyncBrowserProxy}
    * @extends {settings.TestBrowserProxy}
    */
@@ skipping 256 matching lines @@
         assertFalse(encryptWithPassphrase.disabled);
         assertFalse(encryptWithPassphrase.checked);
 
         var link = encryptWithPassphrase.querySelector('a[href]');
         assertTrue(!!link);
 
         // Suppress opening a new tab, since then the test will continue running
         // on a background tab (which has throttled timers) and will timeout.
         link.target = '';
         link.href = '#';
+        // Prevent the link from triggering a page navigation when tapped.
+        // Breaks the test in Vulcanized mode.
+        link.addEventListener('tap', function(e) { e.preventDefault(); });
 
         MockInteractions.tap(link);
 
         assertFalse(encryptWithPassphrase.checked);
       });
 
       test('SaveButtonDisabledWhenPassphraseOrConfirmationEmpty', function() {
         MockInteractions.tap(encryptWithPassphrase);
         Polymer.dom.flush();
 
@@ skipping 175 matching lines @@
       });
     });
   }
 
   return {
     registerTests: function() {
       registerAdvancedSyncSettingsTests();
     },
   };
 });