title: XMLHttpRequest returns wrongly encoded characters
body: <p>I use XMLHttpRequest to read the PDF document
  <a href="http://www.virtualmechanics.com/support/tutorials-spinner/Simple2.pdf" rel="noreferrer">http://www.virtualmechanics.com/support/tutorials-spinner/Simple2.pdf</a> </p>
  
  <pre><code>%PDF-1.3
  %âãÏÓ
  [...]
  </code></pre>
  
  <p>and print its content out to console:</p>
  
  <pre><code>var xhr = new XMLHttpRequest();
  xhr.onreadystatechange = function() {
      if (xhr.readyState === 4 &amp;&amp; xhr.status === 200) {
        console.log(xhr.responseText);
        console.log('âãÏÓ');
      }
  };
  xhr.open('GET', 'http://www.virtualmechanics.com/support/tutorials-spinner/Simple2.pdf', true);
  xhr.send();
  </code></pre>
  
  <p>However, the console says</p>
  
  <pre><code>%PDF-1.3
  %����
  [...]
  âãÏÓ
  </code></pre>
  
  <p>(The last line is from the reference <code>console.log</code> above to verify that the console can actually display those characters.)
  Apparently, the characters are wrongly encoded at some point. What's going wrong and how to fix this?</p>