update elements and fix some bugs

lib/paper_tabs.dart

 // DO NOT EDIT: auto-generated with `pub run custom_element_apigen:update`
 
 /// Dart API for the polymer element `paper_tabs`.
 @HtmlImport('paper_tabs_nodart.html')
 library polymer_elements.lib.src.paper_tabs.paper_tabs;
 
 import 'dart:html';
 import 'dart:js' show JsArray, JsObject;
 import 'package:web_components/web_components.dart';
 import 'package:polymer_interop/polymer_interop.dart';
 import 'iron_resizable_behavior.dart';
 import 'iron_menubar_behavior.dart';
 import 'iron_menu_behavior.dart';
 import 'iron_multi_selectable.dart';
 import 'iron_selectable.dart';
 import 'iron_a11y_keys_behavior.dart';
 import 'iron_flex_layout.dart';
 import 'iron_flex_layout/classes/iron_flex_layout.dart';
 import 'iron_icon.dart';
 import 'paper_icon_button.dart';
 import 'color.dart';
 import 'paper_tabs_icons.dart';
 import 'paper_tab.dart';
 
+/// Material design: [Tabs](https://www.google.com/design/spec/components/tabs.html)
+///
 /// `paper-tabs` makes it easy to explore and switch between different views or functional aspects of
 /// an app, or to browse categorized data sets.
 ///
 /// Use `selected` property to get or set the selected tab.
 ///
 /// Example:
 ///
 ///     <paper-tabs selected="0">
 ///       <paper-tab>TAB 1</paper-tab>
 ///       <paper-tab>TAB 2</paper-tab>
@@ skipping 77 matching lines @@
   bool get scrollable => jsElement[r'scrollable'];
   set scrollable(bool value) { jsElement[r'scrollable'] = value; }
 
   String get selectable => jsElement[r'selectable'];
   set selectable(String value) { jsElement[r'selectable'] = value; }
 
   /// Gets or sets the selected element. The default is to use the index of the item.
   get selected => jsElement[r'selected'];
   set selected(value) { jsElement[r'selected'] = (value is Map || (value is Iterable && value is! JsArray)) ? new JsObject.jsify(value) : value;}
 }