Do not break iframes in the iframe output of TMH

Change-Id: I0ff8af367f58a379bf08f5c842fa195e56899351
Follow-up: ecd5c8423f7fb3
Bug: 66143
(cherry picked from commit 5e85580f97d352cb060c3c320959e84b38882f63)
Merge "Do not break iframes in the iframe output of TMH" into wmf/1.24wmf10