title: onpopstate event not fired on window.history.forward()
body: <p>Im experimenting with the History API and ran into a problem which im not not able to resolve. After pushing a new state to the api im not able to get the popstateEvent fired on window.history.forward() (simulating the click on the forward button of the browser). With window.history.back() everything works as expected. Im wondering why this behaviour is happening. Is this intended?</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>window.onpopstate = function(event) {
      console.log(event);
  };
  
  window.history.pushState({'state': 'test'}, '', '/testurl');
  
  window.history.go(1);
  window.history.back();</code></pre>
  </div>
  </div>
  </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>window.onpopstate = function(event) {
      console.log(event);
  };
  
  window.history.pushState({'state': 'test'}, '', '/testurl');
  
  window.history.go(1);
  window.history.forward();</code></pre>
  </div>
  </div>
  </p>
  
  <p>resources:</p>
  
  <ol>
  <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/Window/history" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/Window/history</a></li>
  <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onpopstate" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/WindowEventHandlers/onpopstate</a></li>
  <li><a href="https://developer.mozilla.org/en-US/docs/Web/API/History_API" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/History_API</a></li>
  </ol>
  
  <p>Tried Browsers:
  Latest FireFox Quantum Beta
  Latest Google Chrome Stable</p>