Roll Polymer from 1.5.0 -> 1.6.0 to pick up native CSS custom props

third_party/polymer/v1_0/components-chromium/paper-behaviors/paper-checked-element-behavior-extracted.js

 /**
    * Use `Polymer.PaperCheckedElementBehavior` to implement a custom element
    * that has a `checked` property similar to `Polymer.IronCheckedElementBehavior`
    * and is compatible with having a ripple effect.
    * @polymerBehavior Polymer.PaperCheckedElementBehavior
    */
   Polymer.PaperCheckedElementBehaviorImpl = {
-
     /**
      * Synchronizes the element's checked state with its ripple effect.
      */
     _checkedChanged: function() {
       Polymer.IronCheckedElementBehaviorImpl._checkedChanged.call(this);
       if (this.hasRipple()) {
         if (this.checked) {
           this._ripple.setAttribute('checked', '');
         } else {
           this._ripple.removeAttribute('checked');
         }
       }
     },
 
     /**
      * Synchronizes the element's `active` and `checked` state.
      */
     _buttonStateChanged: function() {
       Polymer.PaperRippleBehavior._buttonStateChanged.call(this);
       if (this.disabled) {
         return;
       }
       if (this.isAttached) {
         this.checked = this.active;
       }
     }
-
   };
 
   /** @polymerBehavior Polymer.PaperCheckedElementBehavior */
   Polymer.PaperCheckedElementBehavior = [
     Polymer.PaperInkyFocusBehavior,
     Polymer.IronCheckedElementBehavior,
     Polymer.PaperCheckedElementBehaviorImpl
   ];