// eslint-disable-next-line
WebFontConfig = {
  typekit: {
    id: ''
  },
  google: {
    families: []
  },
  timeout: 2000,
  active: function() { clearFout(); },
  inactive: function() { clearFout(); }
};

function clearFout() {
  sessionStorage.fonts = true;
}

// Uncomment the lines below and remove line 'clearFout()' once webfonts have been included.

(function(d) {
  // var wf = d.createElement('script'), s = d.scripts[0];
  // wf.src = 'https://ajax.googleapis.com/ajax/libs/webfont/1.6.16/webfont.js';
  // s.parentNode.insertBefore(wf, s);
  clearFout()
  if(sessionStorage.fonts) {
    d.getElementsByTagName('html')[0].classList.add('wf-active');
  }
})(document);

// eslint-disable-next-line
WebFontConfig = {
  google: {
    families: ['Droid Sans', 'Droid Serif']
  },
  timeout: 2000,
  active: function() { clearFout(); },
  inactive: function() { clearFout(); }
};

function clearFout() {
  sessionStorage.fonts = true;
}

(function(d) {
  var wf = d.createElement('script'), s = d.scripts[0];
  wf.src = 'https://ajax.googleapis.com/ajax/libs/webfont/1.6.16/webfont.js';
  s.parentNode.insertBefore(wf, s);
  if(sessionStorage.fonts) {
    d.getElementsByTagName('html')[0].classList.add('wf-active');
  }
})(document);

Swap out comments in webfont loader for real example