WebUI: Stop keypresses on the close icon from firing the Enter handler.

ui/webui/resources/cr_elements/cr_dialog/cr_dialog.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.
 
 /**
  * @fileoverview 'cr-dialog' is a component for showing a modal dialog. If the
  * dialog is closed via close(), a 'close' event is fired. If the dialog is
  * canceled via cancel(), a 'cancel' event is fired followed by a 'close' event.
  * Additionally clients can inspect the dialog's |returnValue| property inside
  * the 'close' event listener to determine whether it was canceled or just
@@ skipping 124 matching lines @@
   },
 
   /**
    * @param {string=} opt_returnValue
    * @override
    */
   close: function(opt_returnValue) {
     HTMLDialogElement.prototype.close.call(this, 'success');
   },
 
+  /**
+   * @private
+   * @param {Event} e
+   */
+  onCloseKeypress_: function(e) {
+    // Because the dialog may have a default Enter key handler, prevent
+    // keypress events from bubbling up from this element.
+    e.stopPropagation();
+  },
+
   /** @return {!PaperIconButtonElement} */
   getCloseButton: function() {
     return this.$.close;
   },
 
   /**
    * @param {!Event} e
    * @private
    */
   onKeypress_: function(e) {
     if (e.key != 'Enter')
       return;
 
     // Accept Enter keys from either the dialog, or a child paper-input element.
     if (e.target != this && e.target.tagName != 'PAPER-INPUT')
       return;
 
     var actionButton =
         this.querySelector('.action-button:not([disabled]):not([hidden])');
     if (actionButton) {
       actionButton.click();
       e.preventDefault();
     }
   },
 });