update elements and fix some bugs

lib/src/paper-item/paper-icon-item.html

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@@ skipping 15 matching lines @@
     </paper-icon-item>
     <paper-icon-item>
       <div class="avatar" item-icon></div>
       Avatar
     </paper-icon-item>
 
 ### Styling
 
 The following custom properties and mixins are available for styling:
 
-Custom property | Description | Default
-----------------|-------------|----------
-`--paper-item-icon-width` | Width of the icon area     | `56px`
-`--paper-icon-item`       | Mixin applied to the item  | `{}`
+Custom property               | Description                                    | Default
+------------------------------|------------------------------------------------|----------
+`--paper-item-icon-width`     | Width of the icon area                         | `56px`
+`--paper-icon-item`           | Mixin applied to the item                      | `{}`
+`--paper-item-selected-weight`| The font weight of a selected item             | `bold`
+`--paper-item-selected`       | Mixin applied to selected paper-items                | `{}`
+`--paper-item-disabled-color` | The color for disabled paper-items             | `--disabled-text-color`
+`--paper-item-disabled`       | Mixin applied to disabled paper-items        | `{}`
+`--paper-item-focused`        | Mixin applied to focused paper-items         | `{}`
+`--paper-item-focused-before` | Mixin applied to :before focused paper-items | `{}`
 
 -->
 
 <dom-module id="paper-icon-item">
   <template>
     <style include="paper-item-shared-styles"></style>
     <style>
       :host {
         @apply(--layout-horizontal);
         @apply(--layout-center);
@@ skipping 23 matching lines @@
         'tabindex': '0'
       },
 
       behaviors: [
         Polymer.IronControlState,
         Polymer.IronButtonState
       ]
     });
   </script>
 </dom-module>