Marks a <dfn> as defining a browser permission string, as used in the Permissions API. The permission name should be a quoted string.

<p>
  The Geolocation API is identified by the powerful feature name
  <dfn class="permission">"geolocation"</dfn>.
</p>

Or equivalently:

<dfn data-dfn-type="permission">"geolocation"</dfn>

• Permission names are quoted strings per the Permissions API spec (e.g., "geolocation", "camera")
• Using class="permission" is equivalent to data-dfn-type="permission"
• Permission definitions are exported and linkable via xref