This is a deprecated ajax dispatcher call. It should be possible to rework this to make use of templates.
The content it produces is a header above the two diffs, containing:
<div id="mw-fr-diff-headeritems"><form id="mw-fr-diff-dataform"><input type="hidden" value="858469997" name="oldid"><input type="hidden" value="858470036" name="newid"></form> <table class="fr-diff-ratings"><tbody><tr><td style="text-align: center; width: 50%;"><span class="flaggedrevs-color-1">[accepted revision]</span></td><td style="text-align: center; width: 50%;"><span class="flaggedrevs-color-1">[accepted revision]</span></td></tr></tbody></table> </div>
I think all the information should be present based on the action=review call, or can otherwise be retrieved from the log via action=query.
