title: How to force Firefox addon charset/encoding?
body: <p>I'm having a trouble with a mobile addon: it shows me the new elements added by scripting with a different charset of the page. E.g. I can read "cuadrúpedo" but the same word in my plugin show "cuadrÂ¡pedo".</p>
  
  <p>I tryed writing the next line to the beginning of my addon, but it didn't work:</p>
  
  <pre><code>document.getElementsByTagName("html")[0].setAttribute("lang", "es");
  </code></pre>
  
  <p>Then, I wrote a "converter function" which replaces the special characters with unicode, like the next line, but it didn't work.</p>
  
  <pre><code>str.replace( /&amp;#250;/g, "/xfa&amp;#1470;" );
  </code></pre>
  
  <p>What can I do? </p>