title: Set value in html input not work
body: <p>i wanted to fill the first form on <a href="https://edit.yahoo.com/registration?" rel="nofollow">yahoo registration</a> automatically.
  for example when i click and choose inspect element on this page and change firstname input from </p>
  
  <pre><code>&lt;input type="text" title="First Name" name="firstname" id="firstname" value="" size="32" maxlength="32" class="fieldValInit" autocomplete="off" aria-required="true" tabindex="1"&gt;
  </code></pre>
  
  <p>to </p>
  
  <pre><code>&lt;input type="text" title="First Name" name="firstname" id="firstname" value="salam" size="32" maxlength="32" class="" autocomplete="off" aria-required="true" tabindex="1"&gt;
  </code></pre>
  
  <p>I do not see any changes on the page. Why?</p>