There's no need to depend on gtk-doc to install .html files. See the tracking bug for details.
This is already fixed in rawhide btw.
Would be good to backport to F13 and F12 anyway when there is a next update.
http://koji.fedoraproject.org/koji/taskinfo?taskID=2285547
http://admin.fedoraproject.org/updates/ibus-1.3.6-1.fc13