update elements and fix some bugs

lib/google_signin.dart

 // DO NOT EDIT: auto-generated with `pub run custom_element_apigen:update`
 
 /// Dart API for the polymer element `google_signin`.
 @HtmlImport('google_signin_nodart.html')
 library polymer_elements.lib.src.google_signin.google_signin;
 
 import 'dart:html';
 import 'dart:js' show JsArray, JsObject;
 import 'package:web_components/web_components.dart';
 import 'package:polymer_interop/polymer_interop.dart';
@@ skipping 29 matching lines @@
 ///
 /// The `scopes` attribute allows you to specify which scope permissions are required
 /// (e.g do you want to allow interaction with the Google Drive API). Many APIs also
 /// need to be enabled in the Google Developers Console before you can use them.
 ///
 /// The `requestVisibleActions` attribute is necessary if you want to write app
 /// activities (https://developers.google.com/+/web/app-activities/) on behalf of
 /// the user. Please note that this attribute is only valid in combination with the
 /// plus.login scope (https://www.googleapis.com/auth/plus.login).
 ///
+/// The `offline` attribute allows you to get an auth code which your server can
+/// redeem for an offline access token
+/// (https://developers.google.com/identity/sign-in/web/server-side-flow).
+/// You can also set `offline-always-prompt` instead of `offline` to ensure that your app
+/// will re-prompt the user for offline access and generate a working `refresh_token`
+/// even if they have already granted offline access to your app in the past.
+///
 /// Use label properties to customize prompts.
 ///
 /// The button can be styled in using the `height`, `width`, and `theme` attributes.
 /// These attributes help you follow the Google+ Sign-In button branding guidelines
 /// (https://developers.google.com/+/branding-guidelines).
 ///
 /// The `google-signin-success` event is triggered when a user successfully authenticates
-/// and `google-signed-out` is triggered when user signeds out.
+/// and `google-signed-out` is triggered when user signs out.
 /// You can also use `isAuthorized` attribute to observe user's authentication state.
 ///
 /// Additional events, such as `google-signout-attempted` are
 /// triggered when the user attempts to sign-out and successfully signs out.
 ///
+/// When requesting offline access, the `google-signin-offline-success` event is
+/// triggered when the user successfully consents with offline support.
+///
 /// The `google-signin-necessary` event is fired when scopes requested via
 /// google-signin-aware elements require additional user permissions.
 ///
 /// #### Testing
 ///
 /// By default, the demo accompanying this element is setup to work on localhost with
 /// port 8080. That said, you *should* update the `clientId` to your own one for
 /// any apps you're building. See the Google Developers Console
 /// (https://console.developers.google.com) for more info.
 @CustomElementProxy('google-signin')
@@ skipping 28 matching lines @@
   /// True if *any* element has google+ scopes
   bool get hasPlusScopes => jsElement[r'hasPlusScopes'];
   set hasPlusScopes(bool value) { jsElement[r'hasPlusScopes'] = value; }
 
   /// The height to use for the button.
   ///
   /// Available options: short, standard, tall.
   get height => jsElement[r'height'];
   set height(value) { jsElement[r'height'] = (value is Map || (value is Iterable && value is! JsArray)) ? new JsObject.jsify(value) : value;}
 
+  /// The Google Apps domain to which users must belong to sign in.
+  /// See the relevant [docs](https://developers.google.com/identity/sign-in/web/reference) for more information.
+  String get hostedDomain => jsElement[r'hostedDomain'];
+  set hostedDomain(String value) { jsElement[r'hostedDomain'] = value; }
+
   /// True if authorizations for *this* element have been granted
   bool get isAuthorized => jsElement[r'isAuthorized'];
   set isAuthorized(bool value) { jsElement[r'isAuthorized'] = value; }
 
   /// An optional label for the button for additional permissions.
   String get labelAdditional => jsElement[r'labelAdditional'];
   set labelAdditional(String value) { jsElement[r'labelAdditional'] = value; }
 
   /// An optional label for the sign-in button.
   String get labelSignin => jsElement[r'labelSignin'];
   set labelSignin(String value) { jsElement[r'labelSignin'] = value; }
 
   /// An optional label for the sign-out button.
   String get labelSignout => jsElement[r'labelSignout'];
   set labelSignout(String value) { jsElement[r'labelSignout'] = value; }
 
   /// True if additional authorization required globally
   bool get needAdditionalAuth => jsElement[r'needAdditionalAuth'];
   set needAdditionalAuth(bool value) { jsElement[r'needAdditionalAuth'] = value; }
 
+  /// Allows for offline `access_token` retrieval during the signin process.
+  bool get offline => jsElement[r'offline'];
+  set offline(bool value) { jsElement[r'offline'] = value; }
+
+  /// Forces a re-prompt, even if the user has already granted offline
+  /// access to your application in the past. You only need one of
+  /// `offline` and `offlineAlwaysPrompt`.
+  bool get offlineAlwaysPrompt => jsElement[r'offlineAlwaysPrompt'];
+  set offlineAlwaysPrompt(bool value) { jsElement[r'offlineAlwaysPrompt'] = value; }
+
   /// If true, the button will be styled with a shadow.
   bool get raised => jsElement[r'raised'];
   set raised(bool value) { jsElement[r'raised'] = value; }
 
   /// The app activity types you want to write on behalf of the user
   /// (e.g http://schemas.google.com/AddActivity)
   String get requestVisibleActions => jsElement[r'requestVisibleActions'];
   set requestVisibleActions(String value) { jsElement[r'requestVisibleActions'] = value; }
 
   /// The scopes to provide access to (e.g https://www.googleapis.com/auth/drive)
@@ skipping 19 matching lines @@
 
   /// Sign in user. Opens the authorization dialog for signing in.
   /// The dialog will be blocked by a popup blocker unless called inside click handler.
   signIn() =>
       jsElement.callMethod('signIn', []);
 
   /// Sign out the user
   signOut() =>
       jsElement.callMethod('signOut', []);
 }