MD Settings: Convert all usages of .bind(this) to use ES6 arrow function.

chrome/browser/resources/settings/search_engines_page/search_engines_page.js

Index: chrome/browser/resources/settings/search_engines_page/search_engines_page.js
diff --git a/chrome/browser/resources/settings/search_engines_page/search_engines_page.js b/chrome/browser/resources/settings/search_engines_page/search_engines_page.js
index 57cf8a0a8ec52e9ac8b17d8f18c623022d3d5f07..656f272ec60e15abfbb05cbf1c991392b5676174 100644
--- a/chrome/browser/resources/settings/search_engines_page/search_engines_page.js
+++ b/chrome/browser/resources/settings/search_engines_page/search_engines_page.js
@@ -105,16 +105,16 @@ Polymer({
   onAddSearchEngineTap_: function(e) {
     e.preventDefault();
     this.showAddSearchEngineDialog_ = true;
-    this.async(function() {
+    this.async(() => {
       var dialog = this.$$('settings-search-engine-dialog');
       // Register listener to detect when the dialog is closed. Flip the boolean
       // once closed to force a restamp next time it is shown such that the
       // previous dialog's contents are cleared.
-      dialog.addEventListener('close', function() {
+      dialog.addEventListener('close', () => {
         this.showAddSearchEngineDialog_ = false;
         cr.ui.focusWithoutInk(assert(this.$.addSearchEngine));
-      }.bind(this));
-    }.bind(this));
+      });
+    });
   },
 
   /** @private */