Roll third_party/polymer.

third_party/polymer/v1_0/components-chromium/iron-selector/iron-multi-selectable-extracted.js

 /** @polymerBehavior Polymer.IronMultiSelectableBehavior */
   Polymer.IronMultiSelectableBehaviorImpl = {
     properties: {
 
       /**
        * If true, multiple selections are allowed.
        */
       multi: {
         type: Boolean,
         value: false,
@@ skipping 14 matching lines @@
        */
       selectedItems: {
         type: Array,
         readOnly: true,
         notify: true
       },
 
     },
 
     observers: [
-      '_updateSelected(selectedValues)'
+      '_updateSelected(selectedValues.splices)'
     ],
 
     /**
      * Selects the given value. If the `multi` property is true, then the selected state of the
      * `value` will be toggled; otherwise the `value` will be selected.
      *
      * @method select
      * @param {string|number} value the value to select.
      */
     select: function(value) {
@@ skipping 77 matching lines @@
         return this._valueToItem(value);
       }, this);
     }
   };
 
   /** @polymerBehavior */
   Polymer.IronMultiSelectableBehavior = [
     Polymer.IronSelectableBehavior,
     Polymer.IronMultiSelectableBehaviorImpl
   ];