Remove unwanted attributes for <sup> elements
Remove unwanted attributes for <sup> elements

In preparation for reference links to be wrapped in <sup>, not <span>
(I7c83d12d).

Change-Id: I6804f294c480e3548c1b3afa9ecfa240d814e0ed

wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps,wikimedia/mediawiki-services-mobileapps