Removes whitespaces at the end of self-closing tags

Tidy automatically adds one (see line 1347 at
http://tidy.cvs.sourceforge.net/viewvc/tidy/tidy/src/pprint.c?revision=1.119&view=markup),
but api-site does not want them.

Change-Id: Ibcd1dcfd18f673af3fb7e45fb746ee0466487072