tting `customStyle` and then calling `updateStyles`.
      */
      updateStyles: function(properties) {
        // force properties update.
        this._properties = null;
        if (properties) {
          Polymer.Base.mixin(this.customStyle, properties);
        }
        // invalidate the cache
        this._styleCache.clear();
        // update any custom-styles we are tracking
        for (var i=0, s; i < this._styles.length; i++) {
          s = this._styles[i];
          s = s.__importElement || s