text: /**
   * Copyright 2016 Google Inc. All rights reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  
  export function getTopOffset( element ) {
      let offset = 0;
  
      do {
          if ( !isNaN( element.offsetTop ) ) {
              offset += element.offsetTop;
          }
      } while( element - element.offsetParent );
  
      return offset;
  }
  
  
  export function addMobileHover() {
      let target;
  
      function onTouchStart( event ) {
          event.target.classList.add( "mobile-active" );
          target = event.target;
      }
  
      function onTouchEnd() {
          target && target.classList.remove( "mobile-active" );
      }
  
      document.body.addEventListener( "touchstart", onTouchStart );
      document.addEventListener( "touchend", onTouchEnd );
  
      return {
          remove() {
              document.body.removeEventListener( "touchstart", onTouchStart );
              document.removeEventListener( "touchend", onTouchEnd );
          }
      };
  }
  