Steps to reproduce:

1. Open http://docs.webplatform.org/wiki/guides/html5_form_features
2. Click to add or view comment of the section under "New form controls" (e.g. "<input type="range">")
3. Check out the heading of the comment popup

Take, '<input type="range">' section for example, the comment header shows a slider, which is the result of parsing '<input type="range">'.