MD Settings: Change search engine add button to a paper-button

chrome/test/data/webui/settings/search_engines_page_test.js

Index: chrome/test/data/webui/settings/search_engines_page_test.js
diff --git a/chrome/test/data/webui/settings/search_engines_page_test.js b/chrome/test/data/webui/settings/search_engines_page_test.js
index 07456114a22c0a2967a6d2c46369a260053bfde0..6f26ef0fba090ec45bcac6fdf4a557defac3a3bf 100644
--- a/chrome/test/data/webui/settings/search_engines_page_test.js
+++ b/chrome/test/data/webui/settings/search_engines_page_test.js
@@ -328,7 +328,7 @@ cr.define('settings_search_engines_page', function() {
       // button is tapped.
       test('AddSearchEngineDialog', function() {
         assertFalse(!!page.$$('settings-search-engine-dialog'));
-        var addSearchEngineButton = page.$$('#addSearchEngine > a');
+        var addSearchEngineButton = page.$.addSearchEngine;
         assertTrue(!!addSearchEngineButton);
 
         MockInteractions.tap(addSearchEngineButton);