<!doctype html>
<html>
  <head>
    <title>Foreign content in mi</title>
  </head>

  <body>

    <math><mi>x<span></span></mi></math>

    <math><mi>sin<span></span></mi></math>

    <math><mi>x</mi></math>

    <math><mi>sin</mi></math>

  </body>
</html>