[third_party] add polymer 1.2.3

polymer_1.2.3/bower_components/paper-menu/README.md

+
+<!---
+
+This README is automatically generated from the comments in these files:
+paper-menu.html  paper-submenu.html
+
+Edit those files, and our readme bot will duplicate them over here!
+Edit this file, and the bot will squash your changes :)
+
+-->
+
+[![Build Status](https://travis-ci.org/PolymerElements/paper-menu.svg?branch=master)](https://travis-ci.org/PolymerElements/paper-menu)
+
+_[Demo and API Docs](https://elements.polymer-project.org/elements/paper-menu)_
+
+
+##&lt;paper-menu&gt;
+
+
+Material design: [Menus](https://www.google.com/design/spec/components/menus.html)
+
+`<paper-menu>` implements an accessible menu control with Material Design styling. The focused item
+is highlighted, and the selected item has bolded text.
+
+    <paper-menu>
+      <paper-item>Item 1</paper-item>
+      <paper-item>Item 2</paper-item>
+    </paper-menu>
+
+An initial selection can be specified with the `selected` attribute.
+
+    <paper-menu selected="0">
+      <paper-item>Item 1</paper-item>
+      <paper-item>Item 2</paper-item>
+    </paper-menu>
+
+Make a multi-select menu with the `multi` attribute. Items in a multi-select menu can be deselected,
+and multiple items can be selected.
+
+    <paper-menu multi>
+      <paper-item>Item 1</paper-item>
+      <paper-item>Item 2</paper-item>
+    </paper-menu>
+
+### Styling
+
+The following custom properties and mixins are available for styling:
+
+Custom property | Description | Default
+----------------|-------------|----------
+`--paper-menu-background-color`   | Menu background color                                            | `--primary-background-color`
+`--paper-menu-color`              | Menu foreground color                                            | `--primary-text-color`
+`--paper-menu-disabled-color`     | Foreground color for a disabled item                             | `--disabled-text-color`
+`--paper-menu`                    | Mixin applied to the menu                                        | `{}`
+`--paper-menu-selected-item`      | Mixin applied to the selected item                               | `{}`
+`--paper-menu-focused-item`       | Mixin applied to the focused item                                | `{}`
+`--paper-menu-focused-item-after` | Mixin applied to the ::after pseudo-element for the focused item | `{}`
+
+### Accessibility
+
+`<paper-menu>` has `role="menu"` by default. A multi-select menu will also have
+`aria-multiselectable` set. It implements key bindings to navigate through the menu with the up and
+down arrow keys, esc to exit the menu, and enter to activate a menu item. Typing the first letter
+of a menu item will also focus it.
+
+
+
+##&lt;paper-submenu&gt;
+
+
+`<paper-submenu>` is a nested menu inside of a parent `<paper-menu>`. It
+consists of a trigger that expands or collapses another `<paper-menu>`:
+
+    <paper-menu>
+      <paper-submenu>
+        <paper-item class="menu-trigger">Topics</paper-item>
+        <paper-menu class="menu-content">
+          <paper-item>Topic 1</paper-item>
+          <paper-item>Topic 2</paper-item>
+          <paper-item>Topic 3</paper-item>
+        </paper-menu>
+      </paper-submenu>
+      <paper-submenu>
+        <paper-item class="menu-trigger">Faves</paper-item>
+        <paper-menu class="menu-content">
+          <paper-item>Fave 1</paper-item>
+          <paper-item>Fave 2</paper-item>
+        </paper-menu>
+      </paper-submenu>
+      <paper-submenu disabled>
+        <paper-item class="menu-trigger">Unavailable</paper-item>
+        <paper-menu class="menu-content">
+          <paper-item>Disabled 1</paper-item>
+          <paper-item>Disabled 2</paper-item>
+        </paper-menu>
+      </paper-submenu>
+    </paper-menu>
+
+Just like in `<paper-menu>`, the focused item is highlighted, and the selected
+item has bolded text. Please see the `<paper-menu>` docs for which attributes
+(such as `multi` and `selected`), and styling options are available for the
+`menu-content` menu.
+
+