Migrate <cr-dialog> from PaperDialogBehavior to native <dialog>.

chrome/browser/resources/settings/certificate_manager_page/ca_trust_edit_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 'settings-ca-trust-edit-dialog' allows the user to
  *  - specify the trust level of a certificate authority that is being
  *    imported.
  *  - edit the trust level of an already existing certificate authority.
  */
@@ skipping 24 matching lines @@
     this.explanationText_ = loadTimeData.getStringF(
         'certificateManagerCaTrustEditDialogExplanation',
         this.model.name);
 
     // A non existing |model.id| indicates that a new certificate is being
     // imported, otherwise an existing certificate is being edited.
     if (this.model.id) {
       this.browserProxy_.getCaCertificateTrust(this.model.id).then(
           /** @param {!CaTrustInfo} trustInfo */
           function(trustInfo) {
+            if (!this.isAttached) {
+              // This element might have been detached from the DOM during the
+              // async operation (happens in testing code). Do not attempt to
+              // open the dialog in such case.
+              return;
+            }
+
             this.trustInfo_ = trustInfo;
-            this.$.dialog.open();
+            this.$.dialog.showModal();
           }.bind(this));
     } else {
-      /** @type {!CrDialogElement} */ (this.$.dialog).open();
+      /** @type {!CrDialogElement} */ (this.$.dialog).showModal();
     }
   },
 
   /** @private */
   onCancelTap_: function() {
     /** @type {!CrDialogElement} */ (this.$.dialog).close();
   },
 
   /** @private */
   onOkTap_: function() {
@@ skipping 10 matching lines @@
       this.$.spinner.active = false;
       /** @type {!CrDialogElement} */ (this.$.dialog).close();
     }.bind(this),
     /** @param {!CertificatesError} error */
     function(error) {
       /** @type {!CrDialogElement} */ (this.$.dialog).close();
       this.fire('certificates-error', error);
     }.bind(this));
   },
 });