[MD settings] update polymer

third_party/polymer/v1_0/components-chromium/iron-a11y-keys-behavior/iron-a11y-keys-behavior-extracted.js

 (function() {
     'use strict';
 
     /**
      * Chrome uses an older version of DOM Level 3 Keyboard Events
      *
      * Most keys are labeled as text, but some are Unicode codepoints.
      * Values taken from: http://www.w3.org/TR/2007/WD-DOM-Level-3-Events-20071221/keyset.html#KeySet-Set
      */
     var KEY_IDENTIFIER = {
@@ skipping 218 matching lines @@
      * node.
      * The `keys-pressed` event will fire when one of the key combinations set with the
      * `keys` property is pressed.
      *
      * @demo demo/index.html
      * @polymerBehavior
      */
     Polymer.IronA11yKeysBehavior = {
       properties: {
         /**
-         * The HTMLElement that will be firing relevant KeyboardEvents.
+         * The EventTarget that will be firing relevant KeyboardEvents. Set it to
+         * `null` to disable the listeners.
+         * @type {?EventTarget}
          */
         keyEventTarget: {
           type: Object,
           value: function() {
             return this;
           }
         },
 
         /**
          * If true, this property will cause the implementing element to
@@ skipping 125 matching lines @@
 
       _resetKeyEventListeners: function() {
         this._unlistenKeyEventListeners();
 
         if (this.isAttached) {
           this._listenKeyEventListeners();
         }
       },
 
       _listenKeyEventListeners: function() {
+        if (!this.keyEventTarget) {
+          return;
+        }
         Object.keys(this._keyBindings).forEach(function(eventName) {
           var keyBindings = this._keyBindings[eventName];
           var boundKeyHandler = this._onKeyBindingEvent.bind(this, keyBindings);
 
           this._boundKeyHandlers.push([this.keyEventTarget, eventName, boundKeyHandler]);
 
           this.keyEventTarget.addEventListener(eventName, boundKeyHandler);
         }, this);
       },
 
@@ skipping 44 matching lines @@
           detail: detail,
           cancelable: true
         });
         this[handlerName].call(this, event);
         if (event.defaultPrevented) {
           keyboardEvent.preventDefault();
         }
       }
     };
   })();