ios document title refreash in vue-router

ios document title refreash in vue-router

``` js
/**
   * fix ios title刷新不了的bug
   * @iframeLoad
   * @author hiluluke
   */
  const iframeLoad = function (src) {
    let iframe = document.createElement('iframe')
    iframe.style.display = 'none'
    iframe.src = src
    document.body.appendChild(iframe)
    iframe.addEventListener('load', function () {
      setTimeout(function () {
        iframe.remove()
      }, 0)
    })
  }
  // document title change
  router.afterEach((transition) => {
    document.title = transition.to.title || 'CNode.js'
    if (navigator.userAgent.match(/\(i[^;]+;( U;)? CPU.+Mac OS X/)) {
      let src = '/static/fixrouter.html?' + Math.random()
      iframeLoad(src)
    }
  })
  ```