
<link rel="import" href="boot.html">
<link rel="import" href="async.html">
<link rel="import" href="debounce.html">

<script>
(function() {

  'use strict';

  // detect native touch action support
  let HAS_NATIVE_TA = typeof document.head.style.touchAction === 'string';
  let GESTURE_KEY = '__polymerGestures';
  let HANDLED_OBJ = '__polymerGesturesHandled';
  let TOUCH_ACTION = '__polymerGesturesTouchAction';
  // radius for tap and track
  let TAP_DISTANCE = 25;
  let TRACK_DISTANCE = 5;
  // number of 